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Equipment Discussions >> Reflectors

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Tim L
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Reged: 12/17/08

Loc: Missouri
Mega-mod thread for Zhumell dobs
      #3590484 - 01/28/10 10:49 PM

When I decided to replace my 60mm refractor with a larger dob, I turned to the internet to compare scopes. That was how I discovered the Zhumell line. And further searching on Google turned up this thread called "New Zhumell owners upgrade mega list thread." That was my introduction to Cloudy Nights.

Once I got a Z10, I returned to that thread over and over for help and new ideas for improvements to make. Since that thread is now in the archives, and the Zhumell line has gone through some changes since then (different alt and az bearings), I thought it would be a good idea to collect suggestions and links people have that will help new Z owners get the most out of their scopes.

So, here are the mods I'll start us off with:

    Improvements for secondary mirror adjustment
  • Change the screws! Why? Using a screwdriver is a hassle, and has the potential of being dropped down the tube. Many people use Bob's Knobs, which have large plastic heads on them. I used allen-wrench screws, which have a barrel on the end that can be tightened with the fingers. These can be found cheap at the local hardware store.

  • Insert a washer (or two!). Jason D brought this great idea up in this post in the "squirrely secondary mirror adjustments" thread (the thread is a great read by itself). The basic idea is to cut out a washer out of a plastic milk jug to make rotating your secondary easier and allow adjustment of just one screw without having to also tweak the other two. I believe Jason now advocates stacking two of these washers together for greater improvement.

    Improve your laser
    Getting a laser with your scope--how cool is that! But, here's how to make it better...
  • Collimate your laser. Someone please locate a good thread for this with pictures! The adjustments aren't too hard, once you understand what you're trying to do. Use a jig, or two sets of nails in "V" formation in a block, or anything else that lets you rotate the laser freely while pointing at a paper taped to the wall. Use the three tiny allen screws at the back of the laser to adjust the beam until it rotates without inscribing a circle.

  • Add an aperture stop to your laser. Described in good detail in this thread. You can get your laser down to a dot instead of a "bar" (making it easier to collimate, and collimate with). You'll get diffraction rings that will cast a shadow of your primary donut back onto the target face of the laser for more accurate collimation (using a barlow is even better).

    Optical improvements
  • Flocking! There are lots of threads and articles on CN on how to do it. I went with a black velvet from Joanne Fabrics since it was highly rated in this test. You can choose to flock a little or a lot, but I went with the whole tube--turns it into a nice black hole for light to get sucked into!

  • Blacken all the mirror edges and shiny parts. Use a sharpie to darken all reflective edges and surfaces. Be VERY CAREFUL around the mirrors!

  • Check the primary mirror clips. They might be too tight. Back them off until there's a slight gap (enough to slide a business card in) to avoid "pinching" the optics.

  • Check your center spot. It might be accurate, then again, it might not. Mine was off a couple millimeters. Catseye tools has a template you can use to put a new spot in place, or you can make your own template.

  • Change your primary springs? Many people do. You can find stiffer ones at a local hardware store. I replaced mine, but then went back to the originals so I could get the mirror closer to the bottom of the tube.

  • Add a dew/light shield. I made mine out of a long strip of felt 3.5' long by 9" wide. I glued three 9x11" pieces of craft foam to one side, leaving about 1/4" between the pieces. I added velcro tabs to the ends, and now I have a cover I can wrap around the end of the tube. The foam gives it rigidity, it rests against the secondary holder screws, and it can be folded up for storage.

  • Dew/lightshields for your finderscope. For this, I cut a piece of craft foam in half, and added velcro to make a simple wrap for the end of my finderscope. Not pretty, but functional. I also made a small "sleeve" of black felt that sits around the eyepiece end of the finder. In dewy conditions, I can raise the sleeve to give some protection to the eyepiece. Easier than putting the cap on and off.

    Other additions
  • Add a Rigel Quikfinder or Telrad. Telrad seems to have the market share around here, but I went with a Rigel, because it fits perfectly between the focuser and the finderscope! Either one of these tools will be a benefit to your star-hopping.

  • Rotate your focuser. Why? In its stock position, the focus knobs are never horizontal unless you're looking at the horizon. Got this idea from Don Pensack: There are two tiny grub screws on the side of the focuser base--one toward the mirror, one toward the tube opening. Loosen them, and rotate the focuser 45° so that the focus knobs are level when the scope points at 45°. This mod's more of a personal preference, but I think it makes the scope more comfortable to use.

  • Improve your airflow. Adding a baffle to the back of the tube will direct more air up the pipe. Check out this sample posted by Hudson Yak.

  • Keep all things in balance... The adjustable hubs are a great "coarse adjustment" for balance, but a counterweight also helps. Numerous threads on this topic, but I recommend a heavy magnet like this bad boy. I wrapped mine in felt to protect the tube, added a little duct tape for friction, and put it on the belly just below the hubs, on the side opposite the focuser. When changing to different weight EPs, I just push the weight up or down the tube a bit. This saves the rubber in your alt brakes for light duty work only, and makes the motion smoother without the "bounce back" if the brakes are too tight.

  • Get a shower cap--to seal the bottom of the tube against spiders, etc., when stored. Very cheap, can be found anywhere.

  • Align your finderscope crosshairs. Somehow, for me it's just easier if the up-down and side-to-side motion of the scope corresponds to the crosshairs in the finderscope. You can change the orientation of the hairs by rotating the finder in the holder, or if you're adventurous, you can unscrew the EP and CAREFULLY rotate the ring the crosshairs are in.


So, what mods have you made? Feel free to add to this list, or include some links to help illustrate mods already mentioned. I hope this will be a help to others like the original thread helped me!


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FLYcrash
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Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
      #3590583 - 01/28/10 11:47 PM

Thanks for updating and newly posting this info! I was recently looking for the archived upgrade thread and had trouble finding it.

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rinalmj
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Reged: 11/23/09

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Re: Mega-mod thread for Zhumell dobs new [Re: FLYcrash]
      #3591253 - 01/29/10 11:16 AM

Tim, can you post a picture of your scope with all the mods?

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Tim L
Carpal Tunnel
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Reged: 12/17/08

Loc: Missouri
Re: Mega-mod thread for Zhumell dobs new [Re: rinalmj]
      #3591671 - 01/29/10 02:23 PM Attachment (589 downloads)

Okay, this is my first attempt to attach a photo with a post...

This is the dew/lightshield folded up. It can also just be wrapped around the "waist" of the scope for storage.


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Tim L
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Reged: 12/17/08

Loc: Missouri
Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
      #3591676 - 01/29/10 02:24 PM Attachment (481 downloads)

Here's the lightshield in place, showing how the wrap attaches with velcro. Felt on the inside, foam on the outside for stiffness.

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Tim L
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Reged: 12/17/08

Loc: Missouri
Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
      #3591682 - 01/29/10 02:26 PM Attachment (495 downloads)

Photo of the rotated focuser and Rigel placement

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Tim L
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Reged: 12/17/08

Loc: Missouri
Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
      #3591688 - 01/29/10 02:29 PM Attachment (364 downloads)

Close-up of the sleeve for the finder eyepiece. This is made from enough felt to wrap around 2x, held together with a band of electrical tape. Nice thing is, I never have to take it off. It slides down far enough to replace the cap when I'm done viewing.

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Tim L
Carpal Tunnel
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Reged: 12/17/08

Loc: Missouri
Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
      #3591691 - 01/29/10 02:30 PM Attachment (341 downloads)

Dew/light shield for the finder--can it get any simpler than this?

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Tim L
Carpal Tunnel
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Reged: 12/17/08

Loc: Missouri
Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
      #3591696 - 01/29/10 02:31 PM Attachment (294 downloads)

Finderscope dewshield in place

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Tim L
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Reged: 12/17/08

Loc: Missouri
Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
      #3591737 - 01/29/10 02:48 PM Attachment (451 downloads)

Here's a shot of the unbarlowed laser after the aperture stop has been installed. Notice the diffraction shows the silhouette of the primary mirror donut. My primary collimation is slightly off here.

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Tim L
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Reged: 12/17/08

Loc: Missouri
Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
      #3591741 - 01/29/10 02:50 PM Attachment (431 downloads)

Here's the laser barlowed. I threw the collimation way out so you could see the curve of the center spot. It's very large and "mushy." (Sorry about the focus issue here).

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Tim L
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Loc: Missouri
Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
      #3591752 - 01/29/10 02:52 PM Attachment (359 downloads)

When collimating this way, the primary donut is so large, it's hardly a good gauge of accuracy. However, there are some concentric diffraction rings that show up within the center of the donut that make an excellent "target," as shown here:

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Tim L
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Loc: Missouri
Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
      #3591754 - 01/29/10 02:53 PM Attachment (376 downloads)

Here's one showing where I placed the counterweight magnet for optimum balance:

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Tim L
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Reged: 12/17/08

Loc: Missouri
Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
      #3591759 - 01/29/10 02:54 PM

One more very simple mod I should mention with the laser--put a piece of scotch tape around the barrel to help it fit a little more snugly in the focuser.

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Jason D
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Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
      #3591833 - 01/29/10 03:30 PM

Quote:

Here's one showing where I placed the counterweight magnet for optimum balance:




Refer to my post. I described how I built my magnet-based counter-weight in such a way to yield maximum grasp.
Jason



Edited by Jason D (01/29/10 04:10 PM)


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Jason D
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Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
      #3591861 - 01/29/10 03:44 PM Attachment (284 downloads)

Quote:

However, there are some concentric diffraction rings that show up within the center of the donut that make an excellent "target," as shown here:



I prefer this method over the aperture stop method. See attachment. The method with the barlow is less sensitive to tilts because the barlow lens and the laser window will move in opposite directions cancelling each other -- unlike the aperture stop method.
The negative lens of the barlowed laser method magnifies the returned center spot shadow – that is why it appears larger. Of course, such a problem will not exist with Glatter’s TuBlug.
Jason

EDIT: I updated the attachment:
1- Top figure represents a barlowed laser setup regardless whether the laser has an aperture stop or not.
2- Bottom figure represents a laser with an aperture stop where the center spot shadow is aligned without the aide of a barlow.

Edited by Jason D (01/30/10 01:38 AM)


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Jason D
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Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
      #3591897 - 01/29/10 03:59 PM

Quote:

Use a jig, or two sets of nails in "V" formation in a block, or anything else that lets you rotate the laser freely while pointing at a paper taped to the wall. Use the three tiny allen screws at the back of the laser to adjust the beam until it rotates without inscribing a circle.




I came up with a jigless laser collimator collimation setup few years ago. An easy alternative method.
Jason



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Jason D
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Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
      #3591905 - 01/29/10 04:01 PM

Quote:

Improve your airflow. Adding a baffle to the back of the tube will direct more air up the pipe. Check out this sample posted by Hudson Yak.



Many are happy with this method -- not me. It did not work for me as expected. I ended up removing it sometime ago.
Jason


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Tim L
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Reged: 12/17/08

Loc: Missouri
Re: Mega-mod thread for Zhumell dobs new [Re: Jason D]
      #3591914 - 01/29/10 04:06 PM

Quote:

Quote:

Here's one showing where I placed the counterweight magnet for optimum balance:




Refer to my post. I described how I built my magnet-based counter-weight is such a way to yield maximum grasp.
Jason




Thanks for adding that link, Jason! Later in that same thread that you included some excellent diagrams helping to show visually how weights affect the center of gravity of a scope. Someone wrestling with this for the first time should definitely check it out!


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Jason D
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Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
      #3591915 - 01/29/10 04:06 PM

Quote:

Insert a washer (or two!). Jason D brought this great idea up in this post in the "squirrely secondary mirror adjustments" thread (the thread is a great read by itself). The basic idea is to cut out a washer out of a plastic milk jug to make rotating your secondary easier and allow adjustment of just one screw without having to also tweak the other two. I believe Jason now advocates stacking two of these washers together for greater improvement.



Nice recommendation
My XT10 has two stacked Milk jug washers which I believe is working better for me
Jason


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Jason D
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Re: Mega-mod thread for Zhumell dobs new [Re: Jason D]
      #3591919 - 01/29/10 04:07 PM

By the way great thread, Tim
Jason


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Tim L
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Re: Mega-mod thread for Zhumell dobs new [Re: Jason D]
      #3591952 - 01/29/10 04:18 PM

Quote:

Quote:

However, there are some concentric diffraction rings that show up within the center of the donut that make an excellent "target," as shown here:



I prefer this method over the aperture stop method. See attachment. The method with the barlow is less sensitive to tilts because the barlow lens and the laser window will move in opposite directions cancelling each other -- unlike the aperture stop method.
The negative lens of the barlowed laser method magnifies the returned center spot shadow – that is why it appears larger. Of course, such a problem will not exist with Glatter’s TuBlug.
Jason




Hi Jason,

Hey, help clarify this for me (and other newbies who might also need it). When you said "I prefer this method" I assume you're referring to the barlowed method, right? Will use of a barlow without the aperture stop also produce the inner "target rings" for collimation?

Right now I'm using both. The aperture stop gives me a nice dot for tweaking the secondary alignment, then I pop in the barlow for the primary mirror alignment.

Thanks for your input!


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Jason D
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Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
      #3591981 - 01/29/10 04:32 PM

I meant the method of using the combination of a barlow and a laser collimator is more accurate regradless of whether an aperture stop is used or not. If the aperture stop introduces more rings with the barlow, then I can see how the additional rings would be useful as references.
Jason


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Tim L
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Re: Mega-mod thread for Zhumell dobs new [Re: Jason D]
      #3593808 - 01/30/10 04:22 PM

I'd like to get some more links or other info in this thread. Anyone have a good link for collimating the laser? A good "how-to" flocking link (with photos) would be a good addition as well.

Thanks!


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Tim L
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Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
      #3593864 - 01/30/10 04:46 PM

Here's one I found for how to flock your scope. It's got great pictures, shows clearly how to strip the tube and how to apply the flocking material. If you have been thinking about flocking your dob, this is a great place to start.

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devourment77
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Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
      #3594484 - 01/30/10 09:57 PM

I just did the milk jug double washer "mod" tonight. I was thinking of using one of those foam washers that usually come in a spindle of CD-Rs but ended up just cutting them out of the milk jug instead.

Now I can actually see what screws do what (each one sticks to a single axis). Before the washers, I was turning them at random because they never gave consistent results.


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JayinUTModerator
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Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
      #3594768 - 01/31/10 01:25 AM

Tim,

Here are a couple of links of collimating a laser collimator. The Astromart article is from 2004 and the review from here is 2003 so they are older (wow, I can't believe 2003 and 2004 are 6 and 7 years ago!).

Astromart Collimating a Laser Collimator

Cloudy Nights Collimating a Laser Collimator

I made a base today like what Hugh has in his article, we'll see how it goes.


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Tim L
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Re: Mega-mod thread for Zhumell dobs new [Re: devourment77]
      #3595735 - 01/31/10 03:13 PM

Quote:

I just did the milk jug double washer "mod" tonight. I was thinking of using one of those foam washers that usually come in a spindle of CD-Rs but ended up just cutting them out of the milk jug instead.

Now I can actually see what screws do what (each one sticks to a single axis). Before the washers, I was turning them at random because they never gave consistent results.



Hi Brandon,

I agree totally with you. This is a great and very simple mod to make to the secondary holder. Before I put in the washer, my screws kept wanting to return to the dents they had made in the soft metal washer that comes with the scope. Installing the washer made it easier for me to figure out the movement that each screw controls, also.

I still only have one washer in mine. The second is ready to go, just waiting for when I pull my secondary again to do some other housekeeping on it!

Clear skies,


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Tim L
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Reged: 12/17/08

Loc: Missouri
Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
      #3608569 - 02/06/10 01:24 PM

Here's another simple mod I just did...

My primary was a little loose side-to-side in the cell, so I added some shims to fix it in place a little more securely.

I used two small rectangles of cereal-box cardboard, and placed them between the primary and the cork support that is ABOVE the mirror when the scope is tilted.

In other words, gravity wants to pull the mirror to one side of the cell when the scope looks at the horizon; I shimmed the other side.

Hopefully this will help keep the primary from knocking about when I carry the tube out.

And as a reminder: Don't tighten the mirror clips to try to hold the mirror in place! They will affect your views negatively. There should be a tiny gap between the mirror clips and the surface of the mirror.



Anybody else have good suggestions for inexpensive improvement mods?


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Tim L
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Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
      #3633289 - 02/18/10 07:31 PM Attachment (133 downloads)

If you're just starting out, and haven't yet bought a collimation combination sight-tube/cheshire eyepiece, you might want to add a homemade collimation cap to let you make a quick visual check in addition to your Zhumell laser.

You can make one easily from an old film canister. Cut off the bottom and drill a hole in the center of the lid. When placed in the focuser, the primary is collimated when the hole in the canister lid appears right in the center of the donut sticker. This is not a precise method of collimation, and other tools will help you fine-tune your results.


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Tim L
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Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
      #3633302 - 02/18/10 07:40 PM Attachment (138 downloads)

Collimating a laser for the first time can be a time-consuming process. I burned through a set of batteries just trying to get it all figured out! In addition to the links provided above, here are some tips for collimating your laser...

Place the laser in a sturdy jig (some great ideas have already been suggested above. I use a small table-top picture frame holder braced with heavy books!). Start with the on/off screw at the top, aim at a post-it on the wall, and mark where the dot hits with a "1." Rotate in 1/4 turn increments, and mark numbers "2," "3," and "4." Finally, rotate back to position "1." Does it still hit your previous mark? If not, something isn't stable enough with your jig. Brace it and try again.

Now, look at your pattern on the paper. If the laser is out of collimation, it will have made a circle similar to the one below. (Your numbers may be in different positions, that's fine).

The trick to collimating is: move dot #1 to the center of the circle.


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Tim L
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Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
      #3633318 - 02/18/10 07:54 PM Attachment (122 downloads)

So, how do we bring the dots to the center? Near the back of the laser barrel you will find three small allen-head screws recessed in the body. These take a 1.5mm wrench.

Inside the barrel, the laser module is fixed at the aperture end, and is raised and lowered by the screws at the back end. So, think teeter-totter here: If you TIGHTEN a screw, you push it DOWN, which will make the opposite end (the laser dot) move UP. If you need the dot to move DOWN, you LOOSEN the screw opposite. That's all there is to it.

So, for the pattern in the above post, dot #1 (my reference point) needs to come DOWN. I would therefore LOOSEN the screw on the top of the barrel (see photo below), and then slightly tighten both of the screws on the bottom of the barrell.

Make small adjustments, put it back in the jig, retest, and keep trying until the dot rotates in one place.

Remember: Don't over-tighten or you could strip a screw! If you need to tighten a screw, loosen the ones opposite first.

Tip: It's always easiest if you only have to work in one plane for your final adjustment (as in my example above) Once your #1 dot lines up with one of the 3 axes of the adjustment screws, it gets much simpler.

These lasers work well, but they need often need a little tweaking at the start to get optimum performance out of them.

This is a good project to tackle early on, as it will improve the collimation of your scope, and give you a good useable tool!

Best of luck!

Post what you learn or your mods here to help out other newbies!


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Sarkikos
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Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
      #3634208 - 02/19/10 09:08 AM

Tim,

Nice list of mods! Some of these I've already done, others I'm going to do.

Where you place the weight is right on. It just makes good sense. I use a sports pack (also called a "fanny pack") to hold lead shot. You can't get anything heavier in as small a volume as lead, unless you want to go radioactive! That would not be prudent. I pour the lead shot into a small fabric pencil case, the kind you can get from dollar stores. Then I put the fabric case into the sports pack and strap the pack onto the correct position on the OTA.

Another idea is to set up your scope with its heaviest eyepiece, and put enough weight in the sports pack (or whatever you use) to counter that eyepiece. Then when you replace your heaviest eyepiece with a lighter one, you can compensate for the lose of weight and prevent imbalance by placing a small magnetic weight on the OTA near the focuser. I use a flat, felt-covered magnet. I also attach a small strip of Velcro (the side with "ribs") just below the focuser to help grip the felt on the magnet, otherwise the magnet might slide down the OTA during dewy conditions. I think this is a good solution to the problem of a scope losing its balance when eyepieces are changed.

Keep in mind, though, that my 8" Zhumell and my 10" Dob do not have the newer type of altitude bearings that have a tension feature. My 8" just has the springs, and my 10" has no tension device at all!

Mike


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TMK
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Re: Mega-mod thread for Zhumell dobs new [Re: Sarkikos]
      #3634288 - 02/19/10 10:04 AM

Hmmmmmmmm.

That's got me wondering if I have enough flocking material left over to make a makeshift light shield. Looks like some tinkering is in order this evening.

I would think if the backing was left on and I used a sharpie to blacken out, why would it not work? Tim, how do you feel about the benifit of a light Shield? on a scope thats already flocked?

Tim, thanks for posting

Edited by nobody special (02/19/10 10:07 AM)


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Sarkikos
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Re: Mega-mod thread for Zhumell dobs new [Re: TMK]
      #3634302 - 02/19/10 10:10 AM

Tom,

Quote:

Tha's got me wondering if I have enough flocking material left over to make a makeshift light shield. Looks like some tinkering is in order this evening.

I would think if the backing was left on and I used a sharpie to blacken out, why would it not work?




Flocking by itself might not be stiff enough to hold its shape, especially under dew. Go to a crafts store and get some black foam sheeting for the outer layer of the shield, line with flocking, and use Velcro strips to close/open it. The only problem may be finding a foam sheet big enough for a dew shield for your scope. It's better to make it from one continuous piece of foam sheeting if you can find it.

Mike


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Tim L
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Re: Mega-mod thread for Zhumell dobs new [Re: TMK]
      #3634452 - 02/19/10 11:18 AM

Quote:

Tim, how do you feel about the benifit of a light Shield? on a scope thats already flocked?




Tom,

I would do it. Get something stiff to hold its shape, and just glue the flocking material to it. I just used felt for mine, instead of the velvet I used for flocking.

You've posted before about stray light issues in your backyard--a light shield will help. I noticed this one night when I was getting a bit of a light glow in the EP from one of the neighbor's security lights. I added the light-shield, and got the contrast back. I also use it whenever the moon's bright.

I like using the three pieces of foam on mine because I can fold it up without creasing the foam.

Put your creative mind to the problem and I'm sure you'll come up with a good way to make one!


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Tim L
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Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
      #3634485 - 02/19/10 11:32 AM

Quote:

I think this is a good solution to the problem of a scope losing its balance when eyepieces are changed.




Hi Mike,

On mine, when I change EP's, I just reach down and shove the magnet up or down a little. A small strip of duct tape gives it enough friction to keep it from sliding.

Working without any tension device like you do certainly makes balancing more critical! Glad you found a way that works.

Clear skies!


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Tim L
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Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
      #3634489 - 02/19/10 11:34 AM

Regarding milk-jug washers...

I ought to add that I did finally put a second one in (they go right between the secondary adjustment screws and the metal washer on top of the secondary mirror). I like the extra smoothness and ease of adjustment.

Thanks again Jason D for this excellent idea!


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Sarkikos
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Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
      #3634687 - 02/19/10 01:16 PM

Tim,

Quote:

On mine, when I change EP's, I just reach down and shove the magnet up or down a little. A small strip of duct tape gives it enough friction to keep it from sliding.

Working without any tension device like you do certainly makes balancing more critical! Glad you found a way that works.




I like to keep the main counterweight where it is and not touch it in the field, because it's in an awkward position under the OTA and sometimes inside the Dob mount. Also, I find that the farther I place this weight toward the bottom end of the OTA, the better, because I will be able to minimize the actual weight used. I keep a small bag of magnetic counterweights hanging near me on the Dob mount, so that when I change eyepieces, I can just reach over and place a weight directly below the focuser as I remove the heavy eyepiece, which keeps the scope in balance when I install a lighter EP. But YMMV. Whatever works is good.


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Tim L
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Re: Mega-mod thread for Zhumell dobs new [Re: Sarkikos]
      #3803573 - 05/13/10 03:20 PM

Time to add another cheap improvement to these scopes...

The stock 2"-1.25" adapter is threaded on the bottom for 2" filters (yay!). That means you can use one filter there while you swap your 1.25" EPs for the best view.

However, the adapter is not long enough (boo!). This means that the barrel of many EPs (including the 9mm plossl that comes with the scope) will bump into a filter that is placed on the bottom of the adapter, possibly scratching the filter.

Solution: Lengthen the adapter. I purchased a Hyperion 14mm fine-tuning ring ($13 at Agena), screwed it to the bottom of the 2"-1.25" adapter, and left it there.

Now, I have no worries about something hitting any filter placed on the end of the adapter! I can even put my 1.25" barlow in the adapter and it has enough clearance.

Added benefit: With a 2" polarizing filter on the bottom of the adapter, and a 1.25" polarizing filter on the EP, I can dial in just the right amount of filtration by simply rotating the EP in the focuser. Pretty nifty.


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Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
      #3893984 - 06/29/10 09:49 PM

In the interest of helping a beginner who has never used a finderscope before:

I'm not sure if the info is in the Zhumell instruction manual (which many report is missing, anyway), but focusing the finderscope is very easy to do.

There is a ribbed locking ring just below the objective lens (where the company name and info is printed). Loosen this ring, and then rotate the objective portion of the finderscope until the image is in focus in the eyepiece. Re-tighten the locking ring. That's all there is to it, though it's a bit different than your binoculars.

If you wear glasses, decide whether you will use the finder with or without your glasses most frequently, and set the focus accordingly.

Not really a "mod," but I hope helpful nonetheless.
Clear skies!


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Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
      #3894002 - 06/29/10 09:56 PM

Here's another for new Z owners:

Several have posted having problems bringing their 30mm eyepiece that comes with the scope into proper focus. The common complaint is that there is not enough "out-focus" travel. This is most often heard about the Z8 model.

There's a simple fix for this. On the front of the focuser are two thumbscrews. The upper screw controls tension for the crayford focuser. But the lower screw is a focus lock, useful for astrophotography, but not much needed on a dob used for visual.

The problem is, that lower screw keeps the focuser drawtube from extending all the way. The solution is to loosen the screw several turns (or remove it if you wish), which will let your focuser extend an additional 1/4" and bring your 2" eyepiece to focus.

Clear skies!


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Re: Mega-mod thread for Zhumell dobs new [Re: Jason D]
      #4119332 - 10/16/10 01:03 AM

O.K. Heres an Idea that I doubt anyones considered yet? Its especially for you Zhumell users that have incorperated the added use of a Hand truck or dolly to haul your scope in and out of the garage/house for observing.
As everyone knows the Zhumell tube has a knurled lock seam down the length of the tube.
I have expressed before that if the tube is bounced around or accidently jared, this seam could slip and put your tube out of square! Along with other problems one would all of a sudden wonder what happened to my collimation?
A simple thing can be done to help insure from this problem.
After you've disassembled your scope for flocking, and before you flock. With the tube laying on its side, the seam at the bottom, Take some Locktite on the inside of the tube and apply a reasonable amount on this seam. Before you stand the tube up, be sure the Locktite has hardined. Another good idea would be to place the tube on some plastic just in case some Locktite leaks thru. I also checked for this every 10-15 minutes. If some does come thru WD40 on a rag will remove the Locktite if its not totally dryed.
Clear and dark skies, D.Sireci


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Re: Mega-mod thread for Zhumell dobs new [Re: d.sireci51]
      #4119339 - 10/16/10 01:09 AM

A strip of fiberglass tape and some epoxy resin would work even better.

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Re: Mega-mod thread for Zhumell dobs new [Re: sailor70623]
      #4119375 - 10/16/10 01:40 AM

Good idea Sailor, You need something that will leak into the knurling to lock it into place.

Clear and dark skies, D.sireci


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Donnie
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Re: Mega-mod thread for Zhumell dobs new [Re: d.sireci51]
      #4149159 - 10/28/10 09:09 PM

Great thread Tim, and great additions by everyone else as well.

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Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
      #4150907 - 10/29/10 04:45 PM

Quote:

One more very simple mod I should mention with the laser--put a piece of scotch tape around the barrel to help it fit a little more snugly in the focuser.




If you can get your hands on some, aluminum tape works well for this. I keep a roll in my field case because it comes in handy for all kinds of quick shimming applications. Be careful when using aluminum tape because it can cut like a razor blade if mishandled.


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GeneT
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Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
      #4151488 - 10/29/10 10:12 PM

Excellent, excellent thread!

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NewAstronomer
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Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
      #4152543 - 10/30/10 01:37 PM

Unless it was posted and I missed it, the next big mod you want for these scopes (at least for my pre-Zhumell GSO 10" f/5 Dob) was a scopestuff kit Ebony Star laminate bearing with virgin teflon (PTFE) pads.

http://www.scopestuff.com/ss_ldxx.htm

Many recommend a car wax paste applied and buffed out on the laminate strip to help with stiction. I haven't done this yet and keep Jupiter in the FOV at around 300x easy enough.


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Mary B
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Re: Mega-mod thread for Zhumell dobs new [Re: NewAstronomer]
      #4152600 - 10/30/10 02:10 PM

The current Zhumells use a roller bearing sandwiched between 2 steel plates.

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Enig
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Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
      #4159836 - 11/02/10 11:01 PM

Quote:

Improve your laser
  • Collimate your laser.
  • Add an aperture stop to your laser.




  • Got this done tonight. I had previously collimated the laser, but I really wanted to squeeze that beam into a tighter dot, so I did the mod exactly as shown in the thread you linked, then re-collimated to a tighter tolerance. All of this had *exactly* the results described... and then my batteries were depleted, so I will be forced into going to Wal Mart, tomorrow I suppose. I think I'll get a goodly supply (maybe three sets) to insure that it will be a decent while before it happens again, and maybe when I get down to one set left I can wait till my wife is going and get her to get them while *she's* there!

    Anyway, thanks *very* much for these helpful instructions, everyone involved! I think my next upgrade from this thread will be the Rigel QuikFinder... I too like the idea of it being able to fit between the focuser and finder, and I also like the built in pulse, and the higher profile which should require less neck / head contortion, no?


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    Sarkikos
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    Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
          #4159847 - 11/02/10 11:06 PM

    Tim,

    Yep, you've put the counterweight in the right place. That way you'll balance the scope horizontally and vertically. Putting the weight along the top of the OTA is not the best solution. I use a sports pack (fanny pack) containing lead weights. I strap the sports pack around the OTA.

    Mike


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    Tim L
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    Re: Mega-mod thread for Zhumell dobs new [Re: Enig]
          #4159904 - 11/02/10 11:40 PM

    Quote:

    I think my next upgrade from this thread will be the Rigel QuikFinder... I too like the idea of it being able to fit between the focuser and finder, and I also like the built in pulse, and the higher profile which should require less neck / head contortion, no?




    Hey Enig,

    I think it's only a fraction of an inch taller than a Telrad in actuality, so there are still some contortions needed if viewing near zenith. But, I do like the small footprint that lets it tuck in close to the finder / focuser.

    During the blazing summer heat, my double-sided tape loosened in the garage, and the Rigel fell off once. No damage done, but I'm taking it off after each use now.

    Glad the laser mod worked for you. I burned up a set of batteries when I first collimated it as well, but now a set lasts a good long time, and collimation of the laser, if needed, is much quicker.

    Clear skies!


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    Enig
    sage


    Reged: 06/24/09

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    Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
          #4159909 - 11/02/10 11:44 PM

    Quote:

    I'm taking it off after each use now.






    Does that not put the fear of the dreaded tab breakage issue into you?


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    Tim L
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    Re: Mega-mod thread for Zhumell dobs new [Re: Enig]
          #4159927 - 11/02/10 11:55 PM

    Not since I've seen Rigel offer to fix broken tabs for free!

    I do try to be very careful when removing it, however. I suppose the smart thing to do would be to just replace the tape.


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    VikingRaider
    sage


    Reged: 01/29/08

    Loc: Mukwonago, Wisconsin
    Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
          #4161294 - 11/03/10 05:04 PM

    I'll throw in my hat here...I've used a lot of these tips on my new Z8 (well, new as in July...) especially the ones about focusing with the Crayford (those little thumbscrews on the bottom had me stymied for a few days) and the finderscope focusing trick.

    I've since added a Telrad in between the focuser and the RA finder, but a little futher back down the tube. I find there's no real problem sighting on the Telrad, because the tube is so long to begin with it doesn't feel awkward. I took some black nylon "zip-ties" I had picked up at Home Depot for another project and put 5 together, head to tail to make on big one. They're the standard 12" or so variety.

    This I threaded betwen the base and the Telrad itself. One at the front and one at the rear and tighten. The Telrad doesn't move AT ALL and there's no harm to the paint's finish on the OTA. I decided to do it this way because in the middle of the summer my garage can get pretty hot when it's 110 outside. In fact, it was hot enough to melt the glue on the four little felt pads that are around the edge of the OTA cover. A dab of superglue on each fixed that.

    Also, speaking of the cover, I drilled a small hole and bought a wooden ball from an arts and crafts store, of a size comfortable to my hand. It was flat on one side and had a pre-drilled hole. This I painted about 3 times with dollar store paint, let dry and attached to the cover with a screw and some wood glue in the ball. Now my cover has a convenient and very secure grip to pull the cover off without groping for the edge in the dark.

    Also, I like the way the Orion scopes had a little knob on the front of the OTA by the opening to allow for easier positioning of the OTA during your viewing session. I felt real nervous about drilling a hole in the OTA so I used some more of the zip-ties (I guess they're technically called cable ties) and cut a piece of 1" black PVC in half. Next, I bought a clearance cabint knob from the Depot for .59 (already black!) and drilled a hole in the slice of pipe. Attach the "handle" to the OTA with cable ties and I now have a very secure handle for moving the OTA around while viewing without getting fingerprints all over the tube (or sticking my fingers around the lip of the opening).

    Next up, flocking!


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    Enig
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    Re: Mega-mod thread for Zhumell dobs new [Re: VikingRaider]
          #4161601 - 11/03/10 07:36 PM

    Quote:

    four little felt pads that are around the edge of the OTA cover.




    ??? There are felt pads on yours? Curious... mine is just a plastic disc with little "bumps" around the edge that just sorta friction fits... evidently they've made some sort of change. A pic would be great, also of where you have mounted your Telrad and your wooden OTA lid handle!

    Laser Batteries

    Went to Wal Mart to get replacements... they are $5 and some change for 3 of them... *but*, if yours is like mine, up in one of the checkout lane impulse items they have little laser pointer keychains for about $2.40 that have a set of three inside them, *plus* an extra set of three in the package... I bought three lights for $7 and change which provided 6 sets of batteries (total of 18).


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    VikingRaider
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    Reged: 01/29/08

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    Re: Mega-mod thread for Zhumell dobs new [Re: Enig]
          #4165846 - 11/05/10 04:09 PM Attachment (116 downloads)

    Quote:

    ??? There are felt pads on yours? Curious... mine is just a plastic disc with little "bumps" around the edge that just sorta friction fits... evidently they've made some sort of change. A pic would be great, also of where you have mounted your Telrad and your wooden OTA lid handle!





    Sure thing. I'll have to do it as attachments one at a time though. Okay:

    "felt.jpg" this is a picture of the little square patch of felt that was glued at 4 spots around the inside rim of the "lid".



    Edited by VikingRaider (11/05/10 04:10 PM)


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    VikingRaider
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    Reged: 01/29/08

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    Re: Mega-mod thread for Zhumell dobs new [Re: VikingRaider]
          #4165852 - 11/05/10 04:11 PM Attachment (133 downloads)

    This is a picture of the underside of the lid, showing a few of the pads I reglued, and the screw and some washers holding the handle on the other side.

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    VikingRaider
    sage


    Reged: 01/29/08

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    Re: Mega-mod thread for Zhumell dobs new [Re: VikingRaider]
          #4165856 - 11/05/10 04:12 PM Attachment (143 downloads)

    This is a shot of the ball I painted and attached to the outside of the lid. Makes putting that lid on REAL easy now. The washers have the added benefit of giving the lid just a bit of weight---just enough to keep it in place when I'm observing and a slight breeze blows up (which is pretty often where I live...no trees or anything to block that ever present Texas wind).

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    VikingRaider
    sage


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    Re: Mega-mod thread for Zhumell dobs new [Re: VikingRaider]
          #4165860 - 11/05/10 04:13 PM Attachment (188 downloads)

    Sorry about all the posts guys but I can't seem to get more than one picture per post....please forgive

    This is the little clearance cabinet knob I got at Home Depot, attached to a cut piece of 1" black PVC pipe (again from the Depot). All held together with cable ties. Nice and secure, all pre-painted black and no marring to the paint on the OTA.


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    VikingRaider
    sage


    Reged: 01/29/08

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    Re: Mega-mod thread for Zhumell dobs new [Re: VikingRaider]
          #4165862 - 11/05/10 04:14 PM Attachment (143 downloads)

    The Telrad base, strapped on with cable ties...that way I don't have to worry about the glue on the adhesive strips giving way when stored in the garage in the summer.

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    VikingRaider
    sage


    Reged: 01/29/08

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    Re: Mega-mod thread for Zhumell dobs new [Re: VikingRaider]
          #4165867 - 11/05/10 04:16 PM Attachment (124 downloads)

    And the Telrad installed... Still plenty of room on this thing for me to take a peek up the barrel. I find I end up with my head somewhere over the altitude brakes or a little further up. I'm 6'3" and it doesn't seem to bother me all that much because I built a base on casters to wheel this baby in and out of the garage...next post has a picture.

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    VikingRaider
    sage


    Reged: 01/29/08

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    Re: Mega-mod thread for Zhumell dobs new [Re: VikingRaider]
          #4165878 - 11/05/10 04:21 PM Attachment (217 downloads)

    Here's my homemade base built of scrap 2x4s and other bits of wood I had laying around. Cost me $3 in paint (contractor 99 cents a can paint at Depot), $18 in casters (two 3-inch casters $3 ea., and two 3-inch swivel casters $6 ea.) and $2 for a pair of hinges. Has a little table on a hinge that lowers when it's stored in the garage out of the way. My wife thinks it looks like a black hot water heater in the corner of the garage (I store OTA vertical). Crude but it serves it's purpose. I'm fixin to upgrade the hard plastic casters with some rubber or pneumatic wheels from Harbor Freight by Christmas. The casters tend to give a rougher ride than I thought on smooth concrete and like to get stuck in the grooves of my driveway. No big deal, but a minor annoyance that's easy to fix so why not?

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    Tim L
    Carpal Tunnel
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    Reged: 12/17/08

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    Re: Mega-mod thread for Zhumell dobs new [Re: VikingRaider]
          #4166113 - 11/05/10 06:19 PM

    Steve,

    Thanks for including the pics. Those are great ideas!

    Like Enig said above, mine doesn't have those felt pads in the lid, either.

    I like your ideas for attaching knobs.


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    Enig
    sage


    Reged: 06/24/09

    Loc: NW GA, U.S.A.
    Re: Mega-mod thread for Zhumell dobs new [Re: VikingRaider]
          #4167068 - 11/06/10 06:26 AM

    Quote:

    I'm fixin to




    Yep... he's one of *us*... (blows Dixie horn)!

    Man, those are some *awesome* mods you've done! That's definitely a different OTA tube lid... I wonder what caused them to go to the trouble of changing *that*?

    That sure is a neat base roller thang you've made there... so you observe standing? Does that alter the length of your viewing sessions? That definitely makes the Telrad position seem more ok than it might from my seated observations... it looks like I'd have to twist and contort back a bit much for that.


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    VikingRaider
    sage


    Reged: 01/29/08

    Loc: Mukwonago, Wisconsin
    Re: Mega-mod thread for Zhumell dobs new [Re: Enig]
          #4167940 - 11/06/10 04:47 PM

    Yeah, I stand...I find it easier to grab my sketchbook, pencil, lights, EPs, etc., than sitting. Plus, thanks to 7 years in retail, sitting just isn't as comfortable as standing. Not to mention it's way easier to swat the bugs (or stamp my feet in the winter).

    Quote:

    Yep...he's one of *us*...(blows Dixie horn)!



    Would you believe I was born in Delaware?

    I've been reading the other mod threads and I have another I'll do maybe tomorrow or Monday. I'm going to fashion a pad on the front of the rocker box to cushion the OTA should the alt locks give out and the tube come down. I have some pipe insulation I'm going to line the rocker box with. Simple and should do the trick (now that I've added all the extra weight to the front of the OTA).

    Soon I'm going to add counterweights because she's a bit topheavy.


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    Adam Mendelson
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    Re: Mega-mod thread for Zhumell dobs new [Re: VikingRaider]
          #4171355 - 11/08/10 10:13 AM

    VikingRaider,
    I really like the push to knob addition. I have been thinking about this since I picked up my Z12 a few weeks ago. Looks like this is the route for me!


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    VikingRaider
    sage


    Reged: 01/29/08

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    Re: Mega-mod thread for Zhumell dobs new [Re: Adam Mendelson]
          #4178291 - 11/11/10 07:50 AM

    It was actually very easy----the only thing I had to do was use a hack saw to trim the length of the little bolt that came with the cabinet knob. It was obviously designed to go through wood, not 1/8" of PVC.

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    graffias79
    sage


    Reged: 10/01/10

    Loc: Edgerton, WI
    Re: Mega-mod thread for Zhumell dobs new [Re: VikingRaider]
          #4184888 - 11/14/10 12:01 PM

    Regarding the fans that come attached to the back of the Z dobs, is it possible to use an alternative battery pack with them? Has anyone done this? Perhaps one of the rechargeable camping batteries with the cigarette lighter style plugs? I don't fancy buying loads of D batteries. To me it's just not economically feasible or ecologically responsible. Besides, I will want to use the camping battery to power other devices as well.

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    Sarkikos
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    Re: Mega-mod thread for Zhumell dobs new [Re: graffias79]
          #4185066 - 11/14/10 01:09 PM

    graffias79,

    Try the battery pack first and see how long the D batteries will last for you. I have a 10" Newt Dob with which I use a Orion battery pack that contains eight D batteries. I bought it over two years ago. I probably use the scope and battery pack at least a half-dozen time a month. I think I've only had to replace a D battery once or twice in all that time. If the Zhumell battery pack is similar to the Orion - and it probably is - you won't have to replace the batteries very often. Just buy an extra pack of D batteries for when you need to replace any, which might not be for well over a year.

    Also, it's a good idea to check the batteries in the pack before you take the scope out. It only takes a couple minutes.

    Mike


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    Tim L
    Carpal Tunnel
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    Reged: 12/17/08

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    Re: Mega-mod thread for Zhumell dobs new [Re: graffias79]
          #4185332 - 11/14/10 03:23 PM

    Quote:

    Regarding the fans that come attached to the back of the Z dobs, is it possible to use an alternative battery pack with them? Has anyone done this? Perhaps one of the rechargeable camping batteries with the cigarette lighter style plugs? I don't fancy buying loads of D batteries. To me it's just not economically feasible or ecologically responsible. Besides, I will want to use the camping battery to power other devices as well.




    Graffias,

    Mine came with a battery pack for AA batteries (8 of them = 12v) to run the fan. I think as long as you're getting the same voltage you could probably use other power sources for the fan. A 9v battery might be a little low on airflow.

    I've been thinking of putting some kind of regulator on mine to control how much power the fan gets, so I can turn it down once it's close to ambient, but still have a little air flowing down the tube.


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    capstain
    journeyman


    Reged: 11/25/10

    Loc: Boulder City, NV
    Re: Mega-mod thread for Zhumell dobs new [Re: Jason D]
          #4226071 - 12/03/10 04:26 PM

    Just bought my first DOB and chose the Z10 because of price and accessories included. I also own a Meade AR6 refractor so this is my first experience with Collimation and am slowly learning the ropes.

    One question I have is regarding the collimation of the collimator. Do I put it on a stable stand and then rotate it in a circle in one place with the beam on a wall, adjusting the screws until it doesn't create a circle during the entire 360 degree rotation?

    Does anyone in this thread have pictures of this procedure? Sorry for my obvious confusion. I'm really excited about the viewing through a bigger scope and want to make sure I have everything set up correctly.

    Also, has anyone had an issue with getting an object in the center of the crosshairs on the finder scope? No matter how much I turn the adjustment screws the best I can do is get the object about a half inch below and then compensate with the OTA. Thank you.


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    jimbo216
    super member


    Reged: 08/25/10

    Loc: SC
    Re: Mega-mod thread for Zhumell dobs new [Re: capstain]
          #4226310 - 12/03/10 06:13 PM

    Does anyone know the polarity (tip) of the battery pack for the fan is for the Z10 ?

    Edited by jimbo216 (12/05/10 05:53 PM)


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    Tim L
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    Reged: 12/17/08

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    Re: Mega-mod thread for Zhumell dobs new [Re: capstain]
          #4228299 - 12/04/10 03:57 PM

    Quote:

    One question I have is regarding the collimation of the collimator. Do I put it on a stable stand and then rotate it in a circle in one place with the beam on a wall, adjusting the screws until it doesn't create a circle during the entire 360 degree rotation?

    Does anyone in this thread have pictures of this procedure?




    Capstain,

    You've got it right--point the laser at the wall and rotate it in a secure holder.

    Scroll up in this thread to posts #3633302 and 3633318. There's a little more "how to" in those posts.

    Jason D also posted a diagram early in this thread showing how you can use your OTA as a jig.

    Best to you!


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    scottder
    member


    Reged: 03/23/10

    Loc: Warwick RI USA
    Re: Mega-mod thread for Zhumell dobs new [Re: Jason D]
          #4230328 - 12/05/10 04:25 PM

    Has anyone replaced the screws that hold the finder in place, one of the plastic ones got 'stripped' so I can't really adjust it now.

    Scott


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    Mary B
    Vendor - Echo Astronomy and Electronics
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    Reged: 05/21/10

    Loc: Minnesota
    Re: Mega-mod thread for Zhumell dobs new [Re: scottder]
          #4230621 - 12/05/10 06:29 PM

    Mine arrived with a broken one and Zhummel was quick to drop one in the mail. It is a standard size screw, I tried a 6-32(I think, one of the small screw sizes) and it fit.

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    scottder
    member


    Reged: 03/23/10

    Loc: Warwick RI USA
    Re: Mega-mod thread for Zhumell dobs new [Re: Mary B]
          #4230734 - 12/05/10 07:21 PM

    Mary, excellent thanks!

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    GrafikDihzahyn
    member


    Reged: 07/16/10

    Loc: Oklahoma
    Re: Mega-mod thread for Zhumell dobs new [Re: scottder]
          #4290373 - 01/03/11 11:54 PM

    I just got my first scope, a Z10 and I am loving it. I used a cheshire/site tube to collimate it, and once I bought a barlow, I used that with my laser. I did have to remove the center spot on my primary and replace with a new one, as the original from the factory was about half a centimeter off. Jupiter looks AMAZING through this thing. Was able to find Uranus while I was out this evening. Couldn't see any of it's moons, but we have a lot of light pollution here.

    QUESTION - I've read about the fans for cooling down the primary. The Z10 comes with one, but I've read that it should be blowing air TOWARDS the fan. Mine is blowing air AWAY. Should I remove and reinstall, or is it supposed to be blowing away?


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    Tim L
    Carpal Tunnel
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    Reged: 12/17/08

    Loc: Missouri
    Re: Mega-mod thread for Zhumell dobs new [Re: GrafikDihzahyn]
          #4291001 - 01/04/11 11:14 AM

    Quote:

    QUESTION - I've read about the fans for cooling down the primary. The Z10 comes with one, but I've read that it should be blowing air TOWARDS the fan. Mine is blowing air AWAY. Should I remove and reinstall, or is it supposed to be blowing away?




    Hi Grafik,

    I think the fan should be blowing toward the mirror, not away. Are you sure yours isn't? Even when pointed in the right direction, the air hitting the mirror will "bounce back" and make a lot of airflow off the back of the scope.

    Try holding a piece of string right in front of the fan to see if it's really blowing away from the mirror or not. If it is, reversing it probably isn't too hard.

    Clear skies,


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    GrafikDihzahyn
    member


    Reged: 07/16/10

    Loc: Oklahoma
    Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
          #4291192 - 01/04/11 12:48 PM

    Yeah, it's definitely blowing the opposite direction. No big deal in removing and switching it around, as I am planning on creating a baffle for it anyways.

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    Rob E
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    Re: Mega-mod thread for Zhumell dobs new [Re: jimbo216]
          #4291464 - 01/04/11 02:45 PM

    Quote:

    Does anyone know the polarity (tip) of the battery pack for the fan is for the Z10 ?




    Center +
    Sleeve -


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    Rob E
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    Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
          #4291477 - 01/04/11 02:50 PM

    Quote:

    Quote:

    Regarding the fans that come attached to the back of the Z dobs, is it possible to use an alternative battery pack with them? Has anyone done this? Perhaps one of the rechargeable camping batteries with the cigarette lighter style plugs? I don't fancy buying loads of D batteries. To me it's just not economically feasible or ecologically responsible. Besides, I will want to use the camping battery to power other devices as well.




    Graffias,

    Mine came with a battery pack for AA batteries (8 of them = 12v) to run the fan. I think as long as you're getting the same voltage you could probably use other power sources for the fan. A 9v battery might be a little low on airflow.

    I've been thinking of putting some kind of regulator on mine to control how much power the fan gets, so I can turn it down once it's close to ambient, but still have a little air flowing down the tube.




    Running the fans at 9v may cut back on airflow but it also minimizes vibrations.

    Items like Fans Size adapters and Speed controllers for the computer industry come in very handy.


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    maakhand
    professor emeritus
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    Reged: 09/15/09

    Loc: florida, usa
    Re: Mega-mod thread for Zhumell dobs new [Re: GrafikDihzahyn]
          #4292191 - 01/04/11 08:09 PM

    Quote:

    I did have to remove the center spot on my primary and replace with a new one, as the original from the factory was about half a centimeter off.



    is it really that much.


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    Tim L
    Carpal Tunnel
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    Reged: 12/17/08

    Loc: Missouri
    Re: Mega-mod thread for Zhumell dobs new [Re: Rob E]
          #4292503 - 01/04/11 10:13 PM

    Quote:

    Items like Fans Size adapters and Speed controllers for the computer industry come in very handy.




    Thanks, Rob

    Only $4 for a fan speed controller--that price looks right!


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    GrafikDihzahyn
    member


    Reged: 07/16/10

    Loc: Oklahoma
    Re: Mega-mod thread for Zhumell dobs new [Re: maakhand]
          #4292621 - 01/04/11 11:09 PM

    It was pretty bad. I'm using a regular notebook reinforcement ring to replace the original. The edge of the new ring is on the center of the old one.

    Measure twice, stick once.

    Not too surprising though, as the fan was actually mounted backwards as well. The sticker was facing out, grill facing in. Other than those simple fixes, this Zhumell ROCKS.


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    txmnjim
    sage


    Reged: 03/31/09

    Loc: Rochester, MN
    Re: Mega-mod thread for Zhumell dobs new [Re: GrafikDihzahyn]
          #4293144 - 01/05/11 08:24 AM

    Well, I'm just gonna have to wait until the mirror needs
    cleaning b4 I check this issue out ;-) (With someone else's
    post about how flimsy the tube is I'm afraid the whole thing
    will fall apart if I try and take the mirror cell out!)


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    maakhand
    professor emeritus
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    Reged: 09/15/09

    Loc: florida, usa
    Re: Mega-mod thread for Zhumell dobs new [Re: GrafikDihzahyn]
          #4294695 - 01/05/11 08:01 PM

    Quote:

    It was pretty bad. I'm using a regular notebook reinforcement ring to replace the original. The edge of the new ring is on the center of the old one.

    Measure twice, stick once.

    Not too surprising though, as the fan was actually mounted backwards as well. The sticker was facing out, grill facing in. Other than those simple fixes, this Zhumell ROCKS.



    thanks for the update. my fan is backwards too. it sucks the air out. looks like i have to pull the primary too to re-spot it. 'cause after using the telecat xl to collimate i am not impressed. i know i should have used the template before attempting collimation but i just wanted see how accurate it is out of the factory before pulling anything.
    did you happen to measure how big was the primary? 10" or 9.75"
    does anyone know the size of the secondary in Z10 and whether the FL is 1250mm?
    thanks.


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    txmnjim
    sage


    Reged: 03/31/09

    Loc: Rochester, MN
    Re: Mega-mod thread for Zhumell dobs new [Re: maakhand]
          #4302044 - 01/09/11 08:54 AM

    go to zhumell.com
    fl is 1250 but not sure about the secondary...


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    Sarkikos
    Postmaster
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    Reged: 12/18/07

    Loc: Suburban Maryland, USA
    Re: Mega-mod thread for Zhumell dobs new [Re: maakhand]
          #4302131 - 01/09/11 10:03 AM

    maakhand,

    Quote:

    did you happen to measure how big was the primary? 10" or 9.75"
    does anyone know the size of the secondary in Z10 and whether the FL is 1250mm?
    thanks.




    Just take out the primary and the secondary and measure them. I've done that with all my Newts. I have a Z8. Can the Z10 be any more fragile than the Z8?

    A white light headband is helpful when working on scope optics so you can have a better view of what you're doing. I take apart all my scopes on the top of my bed. That is the widest, softest surface in the house. Just don't let the covers scratch the mirrors. This isn't rocket science, it's just amateur astronomy!

    Mike


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    graffias79
    sage


    Reged: 10/01/10

    Loc: Edgerton, WI
    Re: Mega-mod thread for Zhumell dobs new [Re: Sarkikos]
          #4302333 - 01/09/11 11:39 AM

    Regarding flocking the tube; Suppose I were to buy some felt from Joann Fabrics. What would I use to adhere it to the tube? Would something like 3M Super 77 in a spray can work? I don't want to risk any of it falling off and landing on the mirror!

    Thanks


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    maakhand
    professor emeritus
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    Reged: 09/15/09

    Loc: florida, usa
    Re: Mega-mod thread for Zhumell dobs new [Re: graffias79]
          #4302394 - 01/09/11 12:23 PM

    thanks mike

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    Sarkikos
    Postmaster
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    Re: Mega-mod thread for Zhumell dobs new [Re: maakhand]
          #4302530 - 01/09/11 01:35 PM



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    Tim L
    Carpal Tunnel
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    Reged: 12/17/08

    Loc: Missouri
    Re: Mega-mod thread for Zhumell dobs new [Re: graffias79]
          #4302928 - 01/09/11 04:41 PM

    Quote:

    Regarding flocking the tube; Suppose I were to buy some felt from Joann Fabrics. What would I use to adhere it to the tube? Would something like 3M Super 77 in a spray can work? I don't want to risk any of it falling off and landing on the mirror!

    Thanks




    Graffias,

    That's exactly the way I did it--I got some wonderful dark velvet (not felt) from JoAnne and that 3M spray glue. I rolled the velvet around a long cardboard tube (like a poster tube), temporarily taped the end of the velvet near the scope tube seam, and started spraying and unrolling a little at a time until it was done all the way around. I lastly untaped the initial edge and sprayed the glue in there, too.

    Now, here's the problem: It all looked great as one piece, but with the thermal expansion of the tube in different temps, it wasn't long at all before I had the flocking puckering off and drooping in places.

    What solved the problem was cutting a slit down the middle of each bubble in the fabric, and lining it with some scotch double-sided tape (the thin kind, not the stuff with foam in the middle). So far, that's working very well.

    So my take is that velvet is a very good material to use, but be sure to give it some way to expand and contract with the tube or you'll have to fix it later.

    There's a link above in this thread to a good article on how to flock a tube from CN.

    Clear skies!


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    txmnjim
    sage


    Reged: 03/31/09

    Loc: Rochester, MN
    Re: Mega-mod thread for Zhumell dobs new [Re: maakhand]
          #4309800 - 01/12/11 04:05 PM

    Quote:

    Quote:

    It was pretty bad. I'm using a regular notebook reinforcement ring to replace the original. The edge of the new ring is on the center of the old one.

    Measure twice, stick once.

    Not too surprising though, as the fan was actually mounted backwards as well. The sticker was facing out, grill facing in. Other than those simple fixes, this Zhumell ROCKS.



    thanks for the update. my fan is backwards too. it sucks the air out. looks like i have to pull the primary too to re-spot it. 'cause after using the telecat xl to collimate i am not impressed. i know i should have used the template before attempting collimation but i just wanted see how accurate it is out of the factory before pulling anything.
    did you happen to measure how big was the primary? 10" or 9.75"
    does anyone know the size of the secondary in Z10 and whether the FL is 1250mm?
    thanks.



    btw, you might try reversing the polarity on those fan
    batteries to see if it blows the opposite direction?
    jim


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    maakhand
    professor emeritus
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    Re: Mega-mod thread for Zhumell dobs new [Re: txmnjim]
          #4310015 - 01/12/11 05:47 PM

    thanks jim
    i pulled the primary to re-spot it. it measured a hair less than 9.75". center spot was around 3mm off.also found out that the fan was mounted right but its so close to the mirror that air bounces back and gives the illusion that its sucking air.


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    skizoid
    member


    Reged: 01/12/11

    Loc: 43.223N / -85.551W
    Re: Mega-mod thread for Zhumell dobs new [Re: maakhand]
          #4310357 - 01/12/11 08:14 PM

    Quote:

    the fan was mounted right but its so close to the mirror that air bounces back and gives the illusion that its sucking air.




    Yup ... I was gonna post something to that effect a few days back, but had trouble getting my shiny new account approved. Third time was the try, with a bit of a hand for the admin.

    A bit of a hand for the admin, ok? <clap clap clap>

    Oh. BTW - HI!

    I'm already kinda regretting ever having seen this thread. Brand new shiny Z8, right out of the box, and I've got it torn to pieces. Two feet of snow outside - figured what better time to get to it? Here's my hitlist so far:

    - Loctite OTA seam. Done.

    - Add handles to OTA above pivot bearings. Done.

    - Add spinner handle on the tube up by the secondary to aid in aligning the scope. Done.

    - Replace spotter with Telrad. I'm planning to pop the original spotter off and just drill the Telrad base to accept the same mounting screws. I also replaced the white foam tape with some good 3M body moulding tape after seeing a few comments about the Telrad falling off when it gets hot and the tape fails. In process.

    - Flocking. In process. (Ask me about this - I need to get my post count up! <G>

    - Resealed and repainted the base after seeing comments about the particle board swelling and going south when exposed to moisture. Gotta figure that's a given, so what da hey, eh. Done.

    Added a rubber bumper to the inside back of the rocker box. Already managed to stumble knock the tube into the stand once just screwing around with the mods. The bumper looks suspiciously like one of the new legs - why reinvent the wheel?

    - Added a setting circle to the base. That was tricky. Yet another "ask me!". Done.

    - Found me a nice digital level for elevation. I've seen a few posts about adding a counterbalance weight at the bottom of the OTA, and figure kill two birds at the same time. The level is quite heavy and should be more than enough to make a killer counterweight. I've got a piece of "C" shaped rail that will accept a sliding carrier. Mount the level to the slider, move as needed, and twiddle a knurled knob to set it in place.

    So ... did I miss anything?


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    MessiToM
    scholastic sledgehammer
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    Reged: 12/21/09

    Loc: Huntingdon PA
    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4310413 - 01/12/11 08:40 PM

    Kendrick secondary dew heater




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    skizoid
    member


    Reged: 01/12/11

    Loc: 43.223N / -85.551W
    Re: Mega-mod thread for Zhumell dobs new [Re: MessiToM]
          #4310848 - 01/13/11 12:08 AM

    Oh my ... the cost of this inexpensive scope keeps going up ... I'm assUming you also need to upgrade the power pack to run one of these puppies for any length of time. Kendrick's prices on those are ... er ... astronomical! Lucky me, I've got a nice one sitting around that's plug in recharge and even puts out 120v if I need it. I may just slap that on there anyway even just to run the fan. Be nice to have some jams too.

    (Drat - now I gotta build some speakers into the rocker box.)

    Seems like it'd be a good investment tho - especially up here in cold country. Checked out the website and I see they have wraparound heaters for the two inch stalk mount like I've got on the 8".





    Haven't tried prying the mirror off to see how solid the mount is. Kendrick sez you may have heat transfer problems if it's foam mounted. Anybody sure one way or the other? Might be worth waiting a bit anyway. I see they offer "smart" heaters with dew sensors, but not so far in the barrel mount type. At least not that I could find on their web.

    Long as we're talking heaters, any thoughts on a primary heater? Can't imagine why you'd need the fan as well if you went that route - should be plenty of venturi effect to clear the barrel with both heaters running. Then again, sticking with the fan does save $80 - more on a big rig like yours.


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    MessiToM
    scholastic sledgehammer
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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4311398 - 01/13/11 10:00 AM

    Neat wrap around. I don't use the little battery pack anymore. I have a telrad heater eye piece heater and the secondary heater. 8 have a "power tank"I got my kendrick from a vendor at a star part for $40...There was NO foam or badding behind my secondary. It was also very hard to get the secondary out of its holder. Zhumell silicones and 3m tapes it in. I drilled small hole throgh the back of the holder so I could push the mirror out and not crack the secondary holder

    Holes in the secondary I drilled


    Edited by MessiToM (01/13/11 12:07 PM)


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    skizoid
    member


    Reged: 01/12/11

    Loc: 43.223N / -85.551W
    Re: Mega-mod thread for Zhumell dobs new [Re: MessiToM]
          #4311961 - 01/13/11 02:34 PM

    Beauty ... the wraparound should work then, and be a whole bunch easier than what you had to do for the behind the mirror setup. If I do decide to rip the thing apart and do it like yours, I expect I'll wait a while and work with it as is. At least then I'll know what I'm missing when it all goes horribly wrong.

    (I'm Polish. That sort of stuff happens to me all the time ...)

    If I were to attempt removing the mirror, I think I'd try a heat gun first. Looks like there's a bit of a gap around the edges of the barrel, so once the adhesive fails (somewhere around 300F if I remember right), the mirror should drop right out ... theoretically of course. I'm sure the mirror would survive, but depending on how they silver their glass, that could be a problem at those temps. Try it out on some sacrificial glass first. Reattachment is another thumb twiddler - I'd be tempted to try using a bit of that rope caulk 3M makes for seating windshields. Just happen to have a roll of that in the workshop. You can spread that real thin, and you're talking 100% coverage with superior bonding. A good wipe with isopropyl alcohol first of course. As in, no mirrors falling off and denting the primary.

    (Did I mention I was Polish?) <G>

    I was also interested in the "DewGuard" tech that Kendrick offers on some of their heaters. Supposed to take the guesswork right out of it and fire the heater only when needed. That'd certainly reduce power drain. Sent an email last night - already got a response. How's THAT for tech support?

    Unfortunately, they're not currently planning to offer that option on the wraparound heaters. They did say I could run one in series with one of their DigiFire controllers - starting at around $170. NOT including a power supply. Yeowch. That IS a four channel unit, so if you're right serious about dew, I supposed it'd be a good investment. I might have to wait till I hit the MegaBall numbers tho. I figure I'd have more into heaters than I've got into the entire setup at this point.

    * I'm gonna email them back and volunteer to test a protype DewGuard barrel heater for them. Hey, why not? Also plan to ask specifically about the 3M tape and potential heat conduction issues. That's pretty thin stuff, but we're also talking really low current thru the heater.


    <EDIT>
    Holy carp! Already got a response on the heat conduction issue - in a word ... not a problem.

    OK - that's three words. My bad.

    </EDIT>



    Edited by skizoid (01/13/11 03:06 PM)


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    skizoid
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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4312031 - 01/13/11 02:57 PM

    Here's my setting circle. Worked out right nice, even if I do say so myself ...



    Still looking around for a nice bubble level for the base. I've got a digital level for elevation - I suppose I could use that, but a bubble would be much easier for setting the rocker box on all axes simultaneously.


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    skizoid
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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4312084 - 01/13/11 03:17 PM

    Speaking of digital levels ... found this on Amazon. $30 and free shipping - kinda hard to beat.

    Pretty slick little unit. No backlight, but that's a good thing, right? Easy to read under red light, and that's the important thing. If I have a complaint, it's that there's no automatic power down. Not a biggie. It uses a standard CR2032 battery that you can get most anywhere.

    Thing is also surprisingly heavy for it's size. I figure to mount it on a slide on the OTA and get bonus value as a counterweight.

    Cloudy Nights TOS does not allow reproducing images from other web sites. Image removed by moderator.

    Ah. Missed that part. Must have been between the blah de blahs and the wa wa wawawa wa's ... my bad. <G>

    Worth a pic tho. Here's my certified personal photo, complete with the 9mm 1¼" supplied with the Z8 as a reference for size. Like I said, compact lil devil, it is. Two inch square, 1¼" deep.



    Just got done fabbing and painting the slide for the OTA. I'll post up a pic of that when I git er done.

    Edited by skizoid (01/14/11 07:36 PM)


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    MessiToM
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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4312745 - 01/13/11 08:06 PM

    As for heating the secondary holder I wouldn't really recomend it if your is plastic like mine. It mas easily distort

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    Re: Mega-mod thread for Zhumell dobs new [Re: MessiToM]
          #4313161 - 01/13/11 10:55 PM

    Give me a minute here - I'm still shaken up by the sudden change in the zodiac. Switching from Virgo to Leo is gonna have some major implications in my lifestyle!!

    Good catch - I've melted plastic with my heat gun before. I saw the metal mirror clip and base plate on the mount barrel and just assUmed the body was metal. Proof positive I haven't a clue what I'm doing here ... <G>

    Looks like PLAN A is going with the wraparound heater.

    Or Plan B? I'll eventually park the scope out in a shed so it stays more or less ambient temp. If I leave the fan on all the time running on a 12v wall wart, would dew even be an issue?


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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4314858 - 01/14/11 07:05 PM

    BTW - I mentioned earlier mounting the Telrad sight in place of the original. Good idea? Bad? Do those of you with both find the original still serves a purpose?

    If I do decide to go with both, preferred mounting location? Reason I ask now is the tube is still torn down and now would be a good time to add mounting holes if needed.


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    Sarkikos
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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4314995 - 01/14/11 08:26 PM

    Skizoid,

    I think the best finder setup is an illuminated optical finder with a RACI diagonal and a Telrad. I use the Telrad to get me in the general area of the object, use geometrical orientation, or to sight on the nearest obvious star. Then I use the optical finder and a star atlas to center the object more precisely before I view it in the telescope. I prefer the Sky & Telescope Pocket Sky Atlas. Who needs goto or DSCs?

    Mike


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    skizoid
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    Re: Mega-mod thread for Zhumell dobs new [Re: Sarkikos]
          #4315050 - 01/14/11 09:03 PM

    Thanx for the quick response. I had a feeling that would be the way to go - Telrad for rough centering, fine tune with the spotter, then go to the big un. The lighted RACI finder sounds like the way to go, but for now, I'll leave the original finder as is (give the old bank account a chance to recover) and install the Telrad a bit back and centered on the tube. A bit of duck tape to try out the location and make sure there's no blockage, then mount it up. I replaced the white foam tape that's prone to failure with some good 3M molding tape, so that should work well and save having to drill any (more) holes.

    Next step is flocking. I'm going with ProtoStar's new FlockBoard. No adhesive, so if I do need to get in there again, it's easy enough to remove and make any necessary changes. Stuff's just held in place with spring tension. Also good if I were to decide to add some other doodad down the road.

    The Sky & Telescope Pocket Sky Atlas sounds like it'd make a nice addition to my library. I did pick up on Nightwatch and Michigan Starwatch at the recommendation of a friend. Between those, I should be able to muddle thru.

    * PS ... I sent an email to ProtoStar when I was researching materials - they tell me they now have complete tube liners for all the GSO scopes. They're still working on the manuals and haven't listed them on the website, but will supply just the tube if anyone's interested. The 8" version is $84 shipped.

    Edited by skizoid (01/14/11 09:20 PM)


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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4316894 - 01/15/11 07:31 PM

    Me again ... 8 posts and I'm already a "journeyman". Wow ... talk about your easy forums.

    _______

    Finished up the altitude gauge/weight slider today. As promised ... pics!

    Here's a closeup of the slider with the Wixey mounted up. The magnetic base of the gauge holds tight to the mount, and just loosen the thumb screws to slide it up and down the OTA. The rail has to be sturdy and lock tight for a good read on the gauge, so that's 3M taped AND bolted to the OTA. It ain't never goin' nowhere. I lined the bottom of the slider with the fuzzy velcro, and with any kind of luck, that should keep the paint nice. I did nick the rail in a couple places during assembly (probably wouldn't have been an issue if I let the paint set for a day or so longer), but a quick dab with a Sharpy and you can't see it. Gotta love black.



    Here's the rail itself. Runs all the way from the base of the OTA to the pivots, so there's a LOT of adjustment range.



    I also added reinforcement rails to all the addons inside the tube. No worries about stressing holes and such. None of the screws stick out any more than the OEM stuff, so I don't expect any interference. Next step is flogging ... er flopping ... uh ... flocking the tube, so the shiny parts aren't an issue. You can also see the knob I mounted at the top of the OTA to help move it about when viewing.



    Last (for now anyway) but not least, a corner shot of the slider rail and the handles I added above the pivots to help when dropping the OTA into the rocker box.



    All in all, quite happy with way it's all working out so far ... Now that it's done and I've been playing around with it some, I'm thinking I may make another slider for the rail for the battery pack. With the rail as close to the center pivots as it is, I should be able to still balance the OTA easily.


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    KB2MAN
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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4317064 - 01/15/11 09:07 PM

    skizoid,
    Looking good. Nice work.
    Your giving me mod fever. I will soon be installing handles and a battery pack holder. Flocking in the future.
    Thanks for sharing...

    John in Oregon


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    RobDob
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    Re: Mega-mod thread for Zhumell dobs new [Re: KB2MAN]
          #4317091 - 01/15/11 09:22 PM

    Good stuff!

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    Re: Mega-mod thread for Zhumell dobs new [Re: KB2MAN]
          #4317395 - 01/16/11 12:50 AM

    Thanx for the flowers, all.

    This here is just me getting the silly out of my system. Amazing what you can find laying about when you're digging thru the parts bins ...



    Seemed somehow appropriate - the people's telescope, and all that ... <G>


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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4317402 - 01/16/11 01:02 AM

    I did stumble across a nice little bubble level for the base last trip to the hardware store.



    Had to complement the girl on the desk for their fantastic collection of telescope parts. Got one of THOSE looks ...


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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4317434 - 01/16/11 01:44 AM

    Just realized I never posted up any detail on the setting circle. 16" diameter to the outer ring is just about right to fit the base. I printed it on plain old 8½ x 11" photo paper, then stuck it together with invisible tape, then reinforced the back with clear packing tape. Should be interesting to see how it holds up. One of the problems with cutting and pasting up multiple pages is getting that perfect alignment on the seams. I solved that by - what else - a bit more cutting and pasting at the cardinal points. If you look real close, you'll notice the smaller section that overlaps the seam to clean it up. Eventually, I suppose I could get it professionally printed, but for now, it's decent enough.



    Here's how the circle goes together ...



    The circle goes on first, followed by the plexiglas protector, and then the first bearing surface. I cut the plexi from a 18"x24" poster frame I got at the big box store for $8. Nice and thin. Cut that at 18" to overlap the circle for protection. Word of warning - that stuff is VERY brittle and had a tendency to chip and crack a bit when I was cutting the circle. Not a biggie - I'm the only one that will ever see it. (OOps ... until now anyway). Same thing with cutting the paper - more or less round is good enough. The bearing seemed dry to me, so I swiped each roller with some blue lithium before adding the top bearing plate.

    Now for the hole. Doesn't do much good if you can't see it.

    Lay it out ...



    I went with 1¼" for the hole diameter. Ran it thru with a hole saw, then rounded the corners with a router. Cut a slot with a dremel and hot glued a piece of 22 guage telephone wire in for a reticule.



    Last step was adding a dress up ring on the top of the circle. Got that out of the lamp parts aisle. Just pops right in. All that, and this is what you see ...



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    MessiToM
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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4317677 - 01/16/11 08:53 AM

    I did something very similar to that and ended up never using it. Was a fun project tho

    BIG THANKS TO THE ORIGINAL POSTER I didn't. Know you could rotate your focuser


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    skizoid
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    Re: Mega-mod thread for Zhumell dobs new [Re: MessiToM]
          #4318018 - 01/16/11 12:00 PM

    So what you're saying here is, I'm not really inventing the wheel here, just re-inventing it? I can live with that. If I haven't already done so, a big thanx and tip o'the hat for this forum and the thread that suggested the mods. And yes, it was a fun project. Got to play with POWER TOOLS!!


    Power tools ... they make life easy
    Power tools ... they make life fun!


    (Let me guess - I'm the only Planet P fan out here)

    OK then ... something original. Hmmmmm. Well ... I DID straighten out the "Z". Talk about your lousy quality control!



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    Rob E
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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4318304 - 01/16/11 02:32 PM

    Here's the work I did on mine. I went with half degree markings for a little more control

    Half Degree Base Mod--Finally Finished


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    skizoid
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    Re: Mega-mod thread for Zhumell dobs new [Re: Rob E]
          #4318426 - 01/16/11 03:32 PM

    NICE!

    Real easy to replace the circle I'm using, but I'm having to do some serious resizing in photoshop to make yours fit my Z8. Mine ends up half the size of the original, so the degree markers are correspondingly closer. Here's an actual size section to show what I end up with. This is a jpeg - I saved the resized image as bmp to reduce any chance of artifacts, and that's a step or two clearer than this ...



    (Hardly finished my mod and now I gotta mod it) <G>

    Killer resolution, so I'm definitely going to get one professionally printed. My home laser is black and white, and my trusty old ink jet will never handle that resolution gracefully.

    I do have a small lens that fits the hole on mine. Seemed a bit overkill for the scale I was using, but I can see where it could be a big advantage going with the half degree marks. I <may> also have to reduce the size of the reticule to take advantage of the finer resolution - easy as stripping the same size wire I'm currently using and painting it red. I'll have to see what the actual circle looks like when done.

    Thanx for the link!


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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4318461 - 01/16/11 03:53 PM

    PM me your email and I'll send you a version with a bit less jpeg compression.. (about 6MB in size)

    Edited by Rob E (01/16/11 03:57 PM)


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    Re: Mega-mod thread for Zhumell dobs new [Re: Rob E]
          #4318475 - 01/16/11 03:58 PM

    There are a lot fewer JPEG artifacts.. (BTW, a simple unsharp mask takes care of a lot of it with the file you have.)

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    Rob E
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    Re: Mega-mod thread for Zhumell dobs new [Re: Rob E]
          #4318485 - 01/16/11 04:03 PM Attachment (109 downloads)

    Also, it's at 150 DPI so 2400X2400 should give you exactly what you are looking for. Here's a bit resized after the unsharp mask.

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    skizoid
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    Re: Mega-mod thread for Zhumell dobs new [Re: Rob E]
          #4318632 - 01/16/11 05:21 PM

    Done and done. Email sent. Thank you kindly sir.

    The JPG you posted is actually quite clear, but the higher quality pic would be greatly appreciated. I saved that to BMP (lossless) so there's no degradation. JPEGs typically hold up fairly well thru second generation anyway. After that, it's progressively worse. Just the nature of the beast. If you look close at the section I posted, you can see some ghosting on the lines - none of that in the BMP version I was planning to work with, even after resizing. At half the original print size, that weighs in at about six megs ...


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    Rob E
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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4318764 - 01/16/11 06:30 PM

    I tried to PM you back but you have that feature turned off. Sent you two different versions. One has every 5 degrees labelled.

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    sawacs
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    Re: Mega-mod thread for Zhumell dobs new [Re: Rob E]
          #4319701 - 01/17/11 02:56 AM

    Here is a link to some of the mods I have done to my Z10. The flocking and primary mirror cell mods make a world of difference..

    Z10 Mods

    Cheers, Shawn

    Edited by sawacs (01/17/11 03:01 AM)


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    MessiToM
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    Re: Mega-mod thread for Zhumell dobs new [Re: sawacs]
          #4320174 - 01/17/11 10:56 AM

    Nice baffle^ that's next on my list. I also think flocking was the best mod I've done so far

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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4320688 - 01/17/11 03:02 PM

    Quote:

    Done and done. Email sent. Thank you kindly sir.

    The JPG you posted is actually quite clear, but the higher quality pic would be greatly appreciated. I saved that to BMP (lossless) so there's no degradation. JPEGs typically hold up fairly well thru second generation anyway. After that, it's progressively worse. Just the nature of the beast. If you look close at the section I posted, you can see some ghosting on the lines - none of that in the BMP version I was planning to work with, even after resizing. At half the original print size, that weighs in at about six megs ...




    Did you receive the files I sent?


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    skizoid
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    Re: Mega-mod thread for Zhumell dobs new [Re: Rob E]
          #4321221 - 01/17/11 06:49 PM

    Yup - the 16" anyway. 3.2meg. My 3G decided to take a dump and I had to download them on dialup. That kept disconnecting, and the download would start all over again. 50 megs of trash later, I gave up and dumped the other one off the server. Thanks, but let's NOT do that again, ok. <G>

    I finished flocking the OTA today. Went with the Protostar FlockBoard. Real easy to use - just cut it to the circumference length of the tube, roll it up tight, slip it in, and it snaps into place. My only complaint was the overlap wouldn't lay flat, mostly because it'd been packed tight for shipping. I ended up pulling it out (one big advantage of the flockboard) and weighing it down with some books for a while to flatten it a bit. Don't imagine it'd be as much of a problem if it was warmer here. I expect a few minutes on low heat in the oven would make it easier to match to the curve too. Then again, a couple hours outside on a sunny day should even things out too.

    One thing I did do was pad out the tube a bit with closed cell foam tape. That way the flocking didn't hang up on any of the hardware and ended up nice and round. I also added a ring of foam to the back of the flocking at both ends of the tube to provide an air seal - extra insulation and temp control. Stuff comes in 2 foot widths, any length, and two sections did the job on my Z8. You've all seen flocked tubes, so I won't bore you with that, but here's the OTA after the tape and prior to the Flockboard.



    And here's a link to the flockboard website for more info on installation for anyone who's interested. Nice video and all.

    Protostar Flockboard

    More cosmetic than anything else. Had a raw edge on the flocking material at the top of the OTA, so I lapped that with Gorilla Tape. That works, but I've got some nice door edge molding somewhere around here that will dress it up nice.



    Obviously, all the other stuff complicated the flocking considerably. I can see where the Flockboard would be real slick for a standard installation flush to the inside of the tube. Just hole the stuff wherever you have any protruding hardware, and flat black the bolt heads and such.


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    skizoid
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    Re: Mega-mod thread for Zhumell dobs new [Re: sawacs]
          #4321274 - 01/17/11 07:20 PM

    Thanks for the link, Shawn. Got some good stuff there. I do plan to add a cap over the backside of the primary like yours. Only difference - I plan to build out around the fan so I can snap a cover over it to completely close off the bottom in storage.

    I see you're also not a big fan of the standard Telrad mount. All the empty pockets underneath don't leave much in the way of taping surface ... altho I do see they make handy places to put ceramic magnets! <G> Plan B for me, yet again. I just got done filling the base with bondo. Put a couple layers of wax paper on the OTA, then pressed the wet plastic into place so it's a perfect match for the Z8 tube. I got some peel 'n stick magnet tape that I'll cover the entire base with for now. Eventually, when I find the perfect sweet spot for the Telrad, I'll tap a couple holes and mount it permanently with screws and 3m tape. I got it roughed out right now. Skin coat, paint so the tape sticks, and I'm good to go. Still haven't figured out the best place to mount it ...



    PS - I think I saw that big rig of yours in last years Fourth of July parade. Might have been a howitzer, now that I think on it. <G>


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    skizoid
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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4321687 - 01/17/11 10:26 PM

    OK ... rotate the focuser. Harumph.

    By "grub screws", I assume we're talking the #2 allen heads located in the flat faces of the focuser mount right next to the tube, at the top and the bottom. I loosened them up all the way and couldn't get the thing to budge. Removed one entirely, and I can see a slight indentation where it locks into the main focuser tube.



    Am I missing something here, or did they change the focuser on the Z8 or what? Bigger hammer??


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    MessiToM
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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4323048 - 01/18/11 02:57 PM

    That's what mine looks like ^ the is one on the oposite side you have to loosen as well

    Edited by MessiToM (01/18/11 02:59 PM)


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    skizoid
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    Re: Mega-mod thread for Zhumell dobs new [Re: MessiToM]
          #4323462 - 01/18/11 06:03 PM

    I removed both of em entirely and the *#&^%^# thing still wouldn't turn, pull, push, or otherwise move. Firmly even. Gentle persuasion didna work either.



    Ah, well ... guess I'll have to join the 99% who buy these things and leave well the hell alone ...

    There went my new year's resolution never to use gremlins again.


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    GrafikDihzahyn
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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4323754 - 01/18/11 08:11 PM

    Finished with some basic mods on my Z10.



    Added a couple handles, mainly for ease of use while viewing. One of the handles is located at the viewing end of the tube, to steer my view, and the other is near the bearings, to help with controlling the alt/az movement. These also give a nice grip when separating the scope from the base. I placed rubber washers in between the OTA and metal washers, and tightened them all down.




    I've also installed a fan baffle at the base of the OTA. Another baffle is above the mirror that directs the air across the surface of the mirror itself. Go to youtube and search 'Meade Smoke Test'. Seems to cool a little bit faster, but it definitely looks cool.



    I also attached a pouch to the side to house the battery pack and the extra cord.




    Edited by GrafikDihzahyn (01/18/11 10:37 PM)


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    Tim L
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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4324124 - 01/18/11 11:01 PM

    skizoid,

    You've got the right screws on the side of the focuser. They are the only thing holding the square base to the rest of the unit. Maybe they made a slight gouging on the focuser that's making it stick into place.

    Just be sure not to let the focuser fall out on the floor while you're messing with them!


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    skizoid
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    Reged: 01/12/11

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    Re: Mega-mod thread for Zhumell dobs new [Re: GrafikDihzahyn]
          #4324302 - 01/19/11 12:56 AM

    Couple more goodies for the mod list.

    I checked out the smoke test with the top baffle in place and that's a fairly dramatic difference. I can see where that would also cut down on any dew buildup on the mirror surface. I'd be half tempted to try reversing the fan and see what happens then. Then again, once the mirror is equalized, shouldn't much matter which way the air is flowing.

    She's gone from suck to blow!!

    One concern is that the top baffle would seem to want to concentrate any dust or airborne particles towards the center of the tube. Probably not enough to make a matter tho. When I do my backplate for the bottom of the tube, I plan to build a cage out from the fan so I can snap in a cover and seal the whole shebang for storage. That'd also be a good place for some filtering media so you're only sending clean air up the barrel ...

    Had a brainfart looking at that battery pouch too. Went rooting around and found a leatherette case that came with my TomTom GPS - perfect!


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    Doug Culbertson
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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4324789 - 01/19/11 10:17 AM

    Question for you guys modding the Z's; does that knob on the altitude bearing rotate as the telescope is moved in alt? Just wondering about a way to fit DSC encoders on the Zhumells.

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    GrafikDihzahyn
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    Re: Mega-mod thread for Zhumell dobs new [Re: Doug Culbertson]
          #4325894 - 01/19/11 06:44 PM

    Wanted to get home to check before I gave you any info. Yes, it moves along with the scope.

    (Good thing I waited until after I checked, as I thought it stayed stationary)


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    Doug Culbertson
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    Re: Mega-mod thread for Zhumell dobs new [Re: GrafikDihzahyn]
          #4325925 - 01/19/11 06:58 PM

    Thanks, much appreciated!

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    Rob E
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    Re: Mega-mod thread for Zhumell dobs new [Re: Doug Culbertson]
          #4325935 - 01/19/11 07:02 PM

    Quote:

    Question for you guys modding the Z's; does that knob on the altitude bearing rotate as the telescope is moved in alt? Just wondering about a way to fit DSC encoders on the Zhumells.




    Argo Navis makes a version for the Z16 AT16 etc that have the same ALT system

    http://www.wildcard-innovations.com.au/kits/pn-gs-16-spec_describe.html

    Edited by Rob E (01/19/11 07:04 PM)


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    Doug Culbertson
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    Re: Mega-mod thread for Zhumell dobs new [Re: Rob E]
          #4325956 - 01/19/11 07:13 PM

    Thanks Rob, That is also handy information. Now that I get a close look, that trunnion appears to be slightly conical, which might make it a tad more difficult for a non-machinist such as myself to modify. Still, I continue to be tempted by the ridiculously low price of that Z-12.

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    skizoid
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    Re: Mega-mod thread for Zhumell dobs new [Re: Doug Culbertson]
          #4327726 - 01/20/11 03:32 PM

    I'm starting to feel a bit guilty about all the pixels I'm using up on this thread, but oh, well ... I've learned to live with guilt before ...

    The Z8 is now usable - soon as I get it collimated anyway. Still reading up on that. Quite the arcane science. If I do find it requires dancing naked under the full moon, at least I'll have an excuse this time ... <G>

    Finished up on the secondary mods. Added two milk bottle washers and changed out the adjuster screws. I went with slightly longer screws (4mm x70 x35) to account for the "T" handles. Those are nylon, and I added an extra nut right up at the head to give max mounting surface for the glue. I just glopped that in to fill the hole, then wiped the excess. Worked out nice. A bit hard to see, but there's a post in the center of the "T" to lock it onto an allen head. I tapped that out on the drill press. Worth mentioning, the contact cement does take a while to set up (I gave it 24 hours) but is rock solid with time.



    And the completed secondary ...



    Note the absolute lack of reflection due to the flocking. I also added rubber washers behind the chrome spider nuts on the outside of the OTA. I already had a couple chips in the paint there - that should stop that. With the washers and flocking, I had to be real careful starting the threads on the thumbscrews, but once they caught, everything compressed nicely to get a few good turns in so it's good and solid. I did have to remove one of the spider arms to fit the assembly in the OTA, then reattach that after the other three were set in the holes. I was a bit worried about how the thing would look mounted, what with the flocking and foam and gorilla tape and all, but it turned out clean and solid. First draft had a nylon washer over the tape, but I couldn't quite catch the threads on the thumb screws and had to junk those.



    * I've got another larger "T" nut that I may use for the center spindle on the secondary. Have to think on that. I'd have to add a shoulder to the screw to set inside the recess. That screw would also need to be about an inch longer to clear the outer ring of adjusters, and not sure if it would clear the tube cover when done.


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    skizoid
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    Reged: 01/12/11

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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4327781 - 01/20/11 03:52 PM

    Feet.

    Those silly little feet they put on the rocker box are just south of useless. Did some digging and came up with these ...



    Four inches, and they turn out another 1¼". That should keep the base above the mud 'n the blood 'n the beer and provide for more than enough leveling for the average viewing location.

    Here's the source for the legs. They do NOT come with any mounting hardware. The barrel is metal, and the foot is nylon so grass and gravel shouldn't hurt it. $10 each, but hey, I'm worth it.

    Camar Adjustable Legs from Closet Masters

    PS - just came in the mail today, so I haven't mounted them yet. I do plan to tear the rocker box down to where I can bolt them thru the bottom board. Don't trust surface mount in particle board. I already managed to knock the eyepiece holder a couple times and work that loose. That was easy enough to fix - I'll have to recess the heads on the foot hardware so they don't interfere with the bearing. Those large square mounting plates should make for a sturdy platform when done.

    Also didn't much care for all the raw edges on the rocker box (a common complaint I understand), so I did some serious sealing before assembly. I used a pipe cleaner to get paint into all the holes, primed all the edges, put a couple coats of gravel guard automotive paint for texture, then added a layer of black silicone to all the mating surfaces. Wiped the excess, then once that set, a couple coats of gloss fabric paint. That stands up to dents and dings a lot better than your average bug bomb.


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    skizoid
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    Reged: 01/12/11

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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4327796 - 01/20/11 03:59 PM

    (Better sneak this one in before the pixel police cut me off)



    Still need to do the bottom plate and damper for the fan, add a carrier for the battery pack, update to the 5 degree setting circle, and maybe a flame job for the OTA ... but ... I'm gettin' there!


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    Fimpster
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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4328071 - 01/20/11 06:00 PM

    Keep going skizoid! This is quite the show you're putting on. I cant wait to see what this thing will look like when your done. Will you ever be done?

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    dwright
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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4328107 - 01/20/11 06:20 PM

    Quote:

    (Better sneak this one in before the pixel police cut me off)



    Still need to do the bottom plate and damper for the fan, add a carrier for the battery pack, update to the 5 degree setting circle, and maybe a flame job for the OTA ... but ... I'm gettin' there!



    Cool... a Dub Dob...


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    skizoid
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    Re: Mega-mod thread for Zhumell dobs new [Re: dwright]
          #4328429 - 01/20/11 08:16 PM

    The People's Telescope - Fahrvergnugen!!

    Now that I've "borrowed" the logo, I'm thinking of asking VW if I can borrow Helga for a while to do a video on collimation. Betcha that'd get some hits on YouToob ...

    So far this has been more fun than a bunch of monkeys shooting paintballs on a roller coaster ...

    I did pick up on a 2x Barlow (mounted on the previous pic). One free with every two VW ornaments ... <G>

    If anyone is interested, you can either buy the emblems from VW for $40 each, or ...

    Here's where I got mine - $2.99

    The Zhumell barlow has a longer barrel than the 2" adapter that comes with the Z8. The barlow lens is standard thread, so you can screw that off and replace it with a 2" filter AND run the focuser all the way in without banging the lens. Kewl ... be interesting to see what effects combining filters has. I understand two polarizers can be pretty spectacular.

    Image removed by moderator. We do not allow reproducing images from other web sites on CN. Please do not do it.

    Edited by Don W (01/20/11 08:18 PM)


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    sawacs
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    Reged: 03/15/06

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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4330613 - 01/21/11 07:58 PM

    Small tip..

    You can easily reduce your secondary mirror size by using another brand secondary holder but you have to be willing to drill your 4 vane hub out

    Using a drill press, I successfully "wollered" the hole out enough to accommodate the 2.14" Protostar secondary mirror and mount. In fact, the aftermarket collimation screws many of us use for our Orion and Zhumell scopes fit perfectly in the Protostar dimples on the secondary.

    Although I do have the 3 vane spider from Protostar, I tried this out just for kicks:)

    Cheers,

    Shawn


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    Sarkikos
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    Re: Mega-mod thread for Zhumell dobs new [Re: sawacs]
          #4330929 - 01/21/11 10:44 PM

    I have a Z8. The secondary is oversized, at least for planetary/lunar observing. The 50mm ma yields a 25% central obstruction. I recently replaced mine with the 36mm secondary and diagonal hub made for a 5" Newt I have, which will reduce the CO to 18%.

    I removed the Z8's diagonal and hub from its spider vanes. When the Z8's diagonal vanes are attached to the OTA, they are a little too short to reach the smaller diagonal's hub. I went to Lowe's Hardware and found small, black rubber gaskets and longer screws to take up the slack between the hub and the spider vanes. It would be better to have longer spider vanes or longer bolts to attach the vanes to the OTA, but finding either is easier said than done. The gaskets and rubber screws do work for now. At this point, I don't want to buy a new, complete secondary mount.

    Now for a break in this cold, windy, snowy and icy weather so I can test the Z8 to see how it performs on Jupiter or Saturn. I hate winter astronomy! But at least it gives me plenty of time to work on scope modifications.

    Mike


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    Jason D
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    Re: Mega-mod thread for Zhumell dobs new [Re: Sarkikos]
          #4330949 - 01/21/11 10:53 PM

    Quote:

    I have a Z8. The secondary is oversized, at least for planetary/lunar observing. The 50mm ma yields a 25% central obstruction. I recently replaced mine with the 36mm secondary and diagonal hub made for a 5" Newt I have, which will reduce the CO to 18%.



    Rack the focuser's drawtube 1/2 way then insert a collimation cap or a cheshire. Can you see all primary mirror clips simultaneously? If no, your secondary mirror is too small.
    Jason


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    sawacs
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    Re: Mega-mod thread for Zhumell dobs new [Re: Jason D]
          #4330960 - 01/21/11 10:57 PM

    Jason,

    Wouldn't the fact than you can or cannot see the mirror clips be solely determined by what type of observing you do?

    For instance, a purely planetary observer would not mind light falloff with a smaller secondary?

    Just curious:)


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    skizoid
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    Reged: 01/12/11

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    Re: Mega-mod thread for Zhumell dobs new [Re: sawacs]
          #4330973 - 01/21/11 11:02 PM

    I've think I've already proven my willingness to drill, cut, hack, and otherwise hopefully not mangle beyond hope most anything ... <G>

    That said ... smaller secondary. Hmmmmm. I gooooogled it (yeah - I feel dirty) and I found some interesting stuff about maybe reducing chromatics and increasing contrast for planetary viewing? More light - more might kinda thing. I also saw some cautions about not undersizing the secondary, as that can cause light reflected from the primary to miss the corner, in effect making for a "smaller" scope. Wondering how you narrowed your choices down to the Protostar? Also wondering if anyone knows if all the Zee Dubs use the same secondary?

    The three vanes is an interesting idea and would be easy enough to do. I can see where that could definitely allow more light into the tube under certain conditions. Hadn't thought of that - I <almost> was going to try flocking the vanes on mine with some leftovers, but increasing the thickness, in retrospect, would have been a bad thing.

    (Hey! I thought my mod list was supposed to be getting shorter!!)

    Long as we're on the subject of light, I'm also having second thoughts about a flock shield I stuck around the focuser inside the OTA.



    Thumbs up or thumbs down? The 2x Barlow (minus lens) is completely retracted into the tube in this pic. With the lens mounted, the shield is even with the end ...


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    sawacs
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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4331029 - 01/21/11 11:34 PM

    Quote:

    I've think I've already proven my willingness to drill, cut, hack, and otherwise hopefully not mangle beyond hope most anything ... <G>

    That said ... smaller secondary. Hmmmmm. I gooooogled it (yeah - I feel dirty) and I found some interesting stuff about maybe reducing chromatics and increasing contrast for planetary viewing? More light - more might kinda thing. I also saw some cautions about not undersizing the secondary, as that can cause light reflected from the primary to miss the corner, in effect making for a "smaller" scope. Wondering how you narrowed your choices down to the Protostar?

    The three vanes is an interesting idea and would be easy enough to do. I can see where that could definitely allow more light into the tube. Hadn't thought of that - I <almost> was going to try flocking the vanes on mine with some leftovers, but increasing the thickness, in retrospect, would have been a bad thing.

    (Hey! I thought my mod list was supposed to be getting shorter!!)

    Long as we're on the subject of light, I'm also having second thoughts about a flock shield I stuck around the focuser inside the OTA.



    Thumbs up or thumbs down? At the very least I'm thinking I should shorten it up a bit ...





    Zkizoid,

    Regarding the secondary, you can go too small and a 2.14" on an 10" F5 mirror is about the smallest "I" would try and go.

    My mirror came back, from OWL right at F5 which means I could actually go to a 1.83" mirror but would be restricted to using 18mm eyepieces and under to retain full field illumination if my kakalations are correct:) The original specs on the Z10 were F/4.92, if I am not mistaken.

    My kind of observing is mainly planetary, moon and double stars with the Z10 scope so the smaller secondary is not a concern.

    The three vane vs four is always a hot topic which I will not dare get into. However, I much more prefer six dimmer spikes over four brighter spikes but this is just personal preference:)

    I would not try and flock the spider vanes but rather put a nice coat of flat black paint on them. The focuser flocking is a great idea so long as it does not intrude into the light path!

    My current Z10 is basically a prototype. Zhumell sent me two Z10's for the price of one due to some quality control issues. Once this scope is configured exactly, I plan on taking the second Z10 and drilling only one set of holes

    Regarding the Protostar decision, they looked like a good alternative to the four vane system and I decided to give it a try. I am not completely happy due to some randomness in the collimation system due to the plastic shaft but I am still working that issue:) When everything is in collimation and ya don't bump the scope, it works!

    Respectfully,

    Shawn


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    Jason D
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    Re: Mega-mod thread for Zhumell dobs new [Re: sawacs]
          #4331040 - 01/21/11 11:39 PM

    Quote:

    Jason,

    Wouldn't the fact than you can or cannot see the mirror clips be solely determined by what type of observing you do?

    For instance, a purely planetary observer would not mind light falloff with a smaller secondary?

    Just curious:)




    Shawn,
    If you can't see all primary mirror clips simultaneously from the focal plane, it means:
    1- You are not utilizing the whole aperture of your primary mirror. For example, if you can only see 90% of the diameter of your 10” mirror, then you have effectively 9” mirror – a 20% aperture area loss.
    2- Light cones touching the center of your FOV are reflecting off areas close to your secondary mirror edge – not the most ideal area of your secondary mirror.
    3- Your CO% calculation will have to be based on your effective aperture – not real aperture. Back to our example, do not calculate CO% as 2.14”/10” = 21.4% but rather as 2.14”/9”=23.8%. But wait, assuming the stock mirror was 2.5”, the original CO% was 25% -- not much different.
    Jason


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    sawacs
    sage


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    Re: Mega-mod thread for Zhumell dobs new [Re: Jason D]
          #4331047 - 01/21/11 11:42 PM

    Jason,

    I get it!

    Howly cow moo moo!

    Finally, the light bulb came on and is shining brightly..

    Thanks for the explanation sir..

    Respectfully,

    Shawn


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    Re: Mega-mod thread for Zhumell dobs new [Re: sawacs]
          #4331078 - 01/22/11 12:03 AM

    Shawn, when I upgraded my secodary mirror to Protostar quartz, I ordered the 2.6" mirror. The stock mirror size was 2.48". I felt the 2.14" was too small and too risky.

    By the way, anyone can use a temporary front-end aperture mask placed at the OTA/UTA opening to increase their CO% (OK, aperture will be lowered) to see if they can discern a difference.

    Jason


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    sawacs
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    Re: Mega-mod thread for Zhumell dobs new [Re: Jason D]
          #4331109 - 01/22/11 12:22 AM

    Copy all Jason..

    I went with the 2.14" from Protostar and have never been happier!

    Now, you do have me thinking on this mirror clips thing..

    When I take the CatsEye Teletube and place it in the focuser in the correct position for a F5 scope, I do see the clips. However, if I back it off to where the actual eyepiece would be, I do not see the clips? Am I confused?

    Even though I do not see the "ears" of the primary at the eyepiece height, I should still be getting all of the primary light in the center of the eyepiece correct?

    I feel myself becoming more discombobulated and I thought I had it figured out


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    skizoid
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    Reged: 01/12/11

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    Re: Mega-mod thread for Zhumell dobs new [Re: sawacs]
          #4331111 - 01/22/11 12:23 AM

    The focuser flocking is a great idea so long as it does not intrude into the light path!

    Heckfire ... the entire telescope intrudes into the light path, don't it? Kinda the objective, ok - capturing some celestial object's soul and all. Seems like it'd be more of a concern on the bounceback. Anyway, the shield just pops in and out of the hole, so I can experiment with it to see if there's any noticable difference with or without.

    Found some interesting reading on the subject.

    Sizing Up the Newtonian Secondary

    Interestinger and interestinger ...

    If I'm reading it right, seems that consensus of experts (yah - like THAT could happen) is that anything over 20% ratio, secondary to primary, can degrade the image. The Z8 (roughly 2") comes in at 25%, which leads me to believe they use the same secondary as the Z10 as a cost savings measure OR that they just have a different opinion on the subject. Theoretically, 1.6" would be ideal? Kinda simplistic - looks I'm going to have to do some math here to get the ideal size. Mirror size, focal length, pi (mmmmmmm ... pi!) ...

    PS - who's come up with a super duper easy and least destructive as possible way to clean the primary on these things? I was thinking a swiffer duster (modded of course) on an extension handle would be pretty slick for quickie cleanups ...


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    Rob E
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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4331129 - 01/22/11 12:32 AM

    Quote:

    PS - who's come up with a super duper easy and least destructive as possible way to clean the primary on these things? I was thinking a swiffer duster (modded of course) on an extension handle would be pretty slick for quickie cleanups ...




    Don't do it or you'll regret it forever..


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    sawacs
    sage


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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4331133 - 01/22/11 12:38 AM

    My best view ever of a planet was through and old Meade 6" Starfinder which I paid 100 bucks for back in 1991. To this day, I have not been able to produce that type of contrast and detail in the planets period! However, all of my scopes have become bigger than the 6"er.

    I had a chance to look at Jupiter through and 18" Obsession a while back and let me tell ya..... The planet was big but the details were not. It was simply too bright and washed everything out..

    There is a reason why folks build 10" f/6 scopes or 8" f/7 scopes and that is for the clarity they offer on the planets.

    Okay, where did the above statements come from...

    Regarding primary mirror cleaning, clean only as a last resort. One little handy device I found from the camera department is something called a "rocket blower". It looks just like a rocket and works great for taking dust of your eyepieces and or mirror. If you absolutely have to clean, do a search on the forums and you will come up with a wealth of information.

    Cheers,

    Shawn


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    skizoid
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    Re: Mega-mod thread for Zhumell dobs new [Re: Rob E]
          #4331144 - 01/22/11 12:44 AM

    Shhhhhhhh ... was that the "voice of doom"?

    OK - so chrome polish and an orbital buffer are definitely out of the picture. Gotcha.

    I understand the LESS you clean one of these things, the better. My problem right now is construction dust. Canned air maybe? I was thinking, tap a hole in the OTA above the mirror surface, add an o-ring, heat the plastic straw from a can so it angles down towards the mirror, then just give it a blast when needed ...

    I did find this ...

    Cleaning your telescope's mirrors


    <EDIT>

    On the canned air bit, I was just reading the contents on one. There's some strange stuff in those cans! Maybe not. I do like the straw thru the OTA thing tho - betcha you could mod a camera lens duster to do the same thing. One of those eye 'n ear spritzer bulbs should do the job nicely too.

    * Anybody know how to get earwax off a primary? <G>


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    sawacs
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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4331161 - 01/22/11 12:57 AM

    Quote:

    Shhhhhhhh ... was that the "voice of doom"?

    OK - so chrome polish and an orbital buffer are definitely out of the picture. Gotcha.

    I understand the LESS you clean one of these things, the better. My problem right now is construction dust. Canned air maybe?

    I did find this ...

    Cleaning your telescope's mirrors




    What you found will probably work great, when the time comes

    I am about the pickiest, most perfectionist kind of person you would ever want to meet when it comes to my scopes. However, after battling dust "grannies" over the years, I have relaxed. Don't sweat the small stuff and simply observe.

    If your constructing stuff, place the mirror aside, construct, then place it back in. It takes a lots and lots of buildup before you will ever notice image degradation.

    Earlier today, I was placing my Z10 mirror cell back into the scope and noticed a "splotch" on the mirror which I thought was coating failure. I literally could not stand it so I placed a drop of "ROR" on a Q-tip and rolled it onto the blob. Lo and behold, it came off with no ill effects along with a lowered blood pressure on my end:)

    Btw, if your gonna polish with an orbital polisher, make sure you use 80 grit and nothing more: it will polish much faster!

    Cheers, Shawn


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    Jason D
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    Re: Mega-mod thread for Zhumell dobs new [Re: sawacs]
          #4331187 - 01/22/11 01:37 AM

    Quote:

    When I take the CatsEye Teletube and place it in the focuser in the correct position for a F5 scope, I do see the clips. However, if I back it off to where the actual eyepiece would be, I do not see the clips? Am I confused?



    Then I think you are OK. It is natural to rack out the draw-tube for eyepieces since the field stop (leveled with the focal plane) is below the drawtube shoulder. When you use Catseye Teletube you will lower the drawtube to level the its shoulder with the focal plane.
    Bottom line, I would trust the Teletube assuming you are using it correctly.
    Do not worry...
    Jason


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    Re: Mega-mod thread for Zhumell dobs new [Re: Jason D]
          #4331709 - 01/22/11 10:54 AM

    Jason,

    Quote:

    Rack the focuser's drawtube 1/2 way then insert a collimation cap or a cheshire. Can you see all primary mirror clips simultaneously? If no, your secondary mirror is too small.
    Jason




    Yes, I can still see the mirror clips, but just barely, which apparently agrees with what the WinNewt program is telling me. In WinNewt, if I set the secondary ma just 1mm less, it will show "Diagonal too small to admit 100% ray: YES." So I have about the minimal-size diagonal that will not set off the red flags in that program.

    On the other hand, I intend to use my Z8 here at home for the planets and Moon only, no deep sky. This Z8 originally had a 25.5% CO, obviously intended for general observing. I have a 10" Newt with a 23.2% CO which I use for trips to dark sites for DSO. I don't need the Z8 for deep sky.

    For planetary/lunar, is the 100% illumination really that important? Isn't it OK to be right on the edge of not having 100% illumination or even to have a diagonal ma which is narrow enough to allow the scope to fall a little below that? True, you might lose a little aperture, but you could have a much larger reduction in CO% that would more than offset the loss of aperture. For planetary work, an increase in contrast can allow more details to be seen that might not be visible in a larger aperture with less contrast. Contrast isn't everything, but for planets it is a big something.

    I read your explanation above about not seeing the entire aperture if the entire primary is not seen at the focuser. That makes sense to me, but I'm still not at ease. For one thing, for planetary observation you use higher magnification and shorter focal length eyepieces, or even a binoviewer, so you would probably tend to rack the focuser in more than for deep sky. That might have a bearing on judging 100% illumination by racking the focuser only half-way in when you eye-ball it.

    I think it's probably better to gather accurate measurements of the specific telescope, feed that data into WinNewt, and look at the results. Or you could also rack the focuser in farther and see how much of the primary you can see.

    Here's something else to think about: If the diagonal does not see the outer 1/4" or so of the primary, it does not see edge errors such as TDE. That would be a good thing.

    Mike

    Edited by Sarkikos (01/22/11 11:32 AM)


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    Re: Mega-mod thread for Zhumell dobs new [Re: VikingRaider]
          #4331718 - 01/22/11 10:59 AM

    Steve,

    Quote:

    Here's my homemade base built of scrap 2x4s and other bits of wood I had laying around. Cost me $3 in paint (contractor 99 cents a can paint at Depot), $18 in casters (two 3-inch casters $3 ea., and two 3-inch swivel casters $6 ea.) and $2 for a pair of hinges. Has a little table on a hinge that lowers when it's stored in the garage out of the way. My wife thinks it looks like a black hot water heater in the corner of the garage (I store OTA vertical). Crude but it serves it's purpose. I'm fixin to upgrade the hard plastic casters with some rubber or pneumatic wheels from Harbor Freight by Christmas. The casters tend to give a rougher ride than I thought on smooth concrete and like to get stuck in the grooves of my driveway. No big deal, but a minor annoyance that's easy to fix so why not?




    Do you observe with the Z8 on that table? Why would you want it that high? It's better to sit when you're observing.

    Mike


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    Re: Mega-mod thread for Zhumell dobs new [Re: sawacs]
          #4331727 - 01/22/11 11:03 AM

    Shawn,

    Quote:

    Small tip..

    You can easily reduce your secondary mirror size by using another brand secondary holder but you have to be willing to drill your 4 vane hub out

    Using a drill press, I successfully "wollered" the hole out enough to accommodate the 2.14" Protostar secondary mirror and mount. In fact, the aftermarket collimation screws many of us use for our Orion and Zhumell scopes fit perfectly in the Protostar dimples on the secondary.

    Although I do have the 3 vane spider from Protostar, I tried this out just for kicks:)




    You have to be careful that the cross-section of your old hub is not wider than the minor axis of your new secondary mirror or the effort is futile. You won't be decreasing the size of your Central Obstruction. A smaller secondary is irrelevent if the CO% does not decrease.

    Mike


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    Re: Mega-mod thread for Zhumell dobs new [Re: Sarkikos]
          #4332357 - 01/22/11 03:18 PM

    Quote:

    For planetary/lunar, is the 100% illumination really that important?



    It is not the 100% illumination as much as getting the full-resolution of your primary mirror. In addition, secondary mirror imperfection close to its edge might reduce contrast. That is, whatever minute contrast you gain with a smaller secondary mirror might be lost with the secondary mirror imperfection. Of course, a quality secondary mirror might not have this issue.

    Quote:

    so you would probably tend to rack the focuser in more than for deep sky. That might have a bearing on judging 100% illumination by racking the focuser only half-way in when you eye-ball it.



    100% illumination calculation has nothing to do with the drawtube racking but rather with the focal plane location. When you rack the focuser for difference eyepieces, all you are doing is positioning the field stop of various EPs at the focal plane of the primary mirror – same location for all.
    I suggested the ½ drawtube position as a reasonable estimate for the location of the focal plane.

    Quote:

    Here's something else to think about: If the diagonal does not see the outer 1/4" or so of the primary, it does not see edge errors such as TDE. That would be a good thing.



    That depends in your primary mirror. If it suffers from TDE, then I would rather place an aperture mark on the top of the primary mirror. Do not count is a smaller secondary to do that for you because of three reasons:
    1- Your secondary mirror will have to be positioned perfectly to reduce TDE effect
    2- TDE will scatter light which means your secondary mirror will still pick up some of the scattered light
    3- Off-center objects will still see the primary mirror edge
    Jason


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    Re: Mega-mod thread for Zhumell dobs new [Re: Jason D]
          #4332563 - 01/22/11 05:12 PM

    Jason,

    Quote:

    It is not the 100% illumination as much as getting the full-resolution of your primary mirror.




    As I said, for planetary observation, greater contrast can allow finer detail to be seen at the eyepiece. Getting the full-resolution in a theorectical sense will not matter if you cannot actually see the detail because of poor contrast.

    Quote:

    In addition, secondary mirror imperfection close to its edge might reduce contrast. That is, whatever minute contrast you gain with a smaller secondary mirror might be lost with the secondary mirror imperfection. Of course, a quality secondary mirror might not have this issue.




    Yes, I was aware of this. Ideally if a minimal-size secondary is used, it should be of high quality. What I'm doing now with my Z8 is an experiment to see if in my case with my equipment, there will be an improvement in planetary/lunar. If there isn't, I can always bring back the over-sized diagonal or buy a better narrow-diagonal.

    Quote:

    100% illumination calculation has nothing to do with the drawtube racking but rather with the focal plane location. When you rack the focuser for difference eyepieces, all you are doing is positioning the field stop of various EPs at the focal plane of the primary mirror – same location for all. I suggested the ½ drawtube position as a reasonable estimate for the location of the focal plane.




    Yes, agreed. The collimation cap or sight tube or just your eye looking into the focuser need to be at the focal plane location to get an accurate idea of how much of the primary will actually be seen. By the same token, in order that their field stops will be at the focal plane of the primary, shorter focal length eps and binoviewers will be farther down in the focuser than are longer focal length eyepieces. But they all need to be at that focal plane.

    Mike

    Edited by Sarkikos (01/22/11 09:20 PM)


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    Re: Mega-mod thread for Zhumell dobs new [Re: Jason D]
          #4332588 - 01/22/11 05:21 PM

    Quote:

    Quote:

    Here's something else to think about: If the diagonal does not see the outer 1/4" or so of the primary, it does not see edge errors such as TDE. That would be a good thing.




    That depends in your primary mirror. If it suffers from TDE, then I would rather place an aperture mark on the top of the primary mirror. Do not count is a smaller secondary to do that for you because of three reasons:
    1- Your secondary mirror will have to be positioned perfectly to reduce TDE effect
    2- TDE will scatter light which means your secondary mirror will still pick up some of the scattered light
    3- Off-center objects will still see the primary mirror edge
    Jason




    All good points to keep in mind. The first thing is to perform a star test to see if the primary does have TDE or other edge errors. From what you say, it would make more sense to hide those errors by a narrow aperture ring above the primary. If you have a fan blowing onto the back of primary, such a ring could also direct the air onto the surface of the primary to help break up a boundary layer.

    Mike


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    Re: Mega-mod thread for Zhumell dobs new [Re: Jason D]
          #4333402 - 01/23/11 12:47 AM

    Here are a few photos of the Protostar secondary mirror and holder coupled to the Zhumell hub...

    Okay, I give up on trying to get the images to stick so here is a link:)

    Zhumell Spider With Protostar Secondary

    Cheers, Shawn


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    Re: Mega-mod thread for Zhumell dobs new [Re: sawacs]
          #4333423 - 01/23/11 01:02 AM

    Shawn,

    I don't see the photos.

    Mike


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    Re: Mega-mod thread for Zhumell dobs new [Re: Sarkikos]
          #4333458 - 01/23/11 01:36 AM

    Quote:

    All good points to keep in mind. The first thing is to perform a star test to see if the primary does have TDE or other edge errors. From what you say, it would make more sense to hide those errors by a narrow aperture ring above the primary.




    That is correct. Instead of letting the light be scatter by the TDE then try to deal with it, place the mask above the primary to prevent light from getting there in the first place.

    Quote:

    If you have a fan blowing onto the back of primary, such a ring could also direct the air onto the surface of the primary to help break up a boundary layer.




    Yes, this is another known advantage for the mask.

    There is also a 3rd advantage which is to prevent accidental small rolling objects down the tube from hitting the mirror.

    Jason


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    Re: Mega-mod thread for Zhumell dobs new [Re: Jason D]
          #4333999 - 01/23/11 10:58 AM

    Jason,

    Yes, even if there are no edge errors on the primary, if a fan is blowing onto its back, an annular baffle directly above the mirror is a good mod to direct air over the surface to break up a boundary layer. If the primary has edge errors, the baffle should be constructed so that it extends over the edge of the primary about 1/4".

    I haven't made a combination air flow/TDE baffle for any of my mirrors. From what I can tell through star tests, neither my 8" or 10" have TDE or other edge errors, so when I get around to making baffles, I would set it up just to direct air over the mirror surface. I have an observing buddy who made a baffle from steel (or had it made for him) to mount over his mirror in its rocker box. He had the ring cover the edge of the mirror, assuming it had a TDE. He claims it has made a big difference in his views.

    All my Newts are solid tube, so a steel baffle would not be a good solution for me. I would instead make it from two rings of black foam core with another material - such as ABS plastic or stiff cardboard - sandwiched between to create a sharp edge. (A sharp edge would be more important, though, if the baffle is serving to cover a TDE.) The baffle would be snug tight to fit inside the OTA. I'd measure where I should place it, mark that around with a circle, and nudge the ring up into position. I would not bother drilling holes and screwing it onto the tube. I avoid that type of business whenever possible. I would find some other way to position it securely, if necessary.

    Mike


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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4334104 - 01/23/11 11:30 AM Attachment (65 downloads)

    skizoid,

    Quote:

    Long as we're on the subject of light, I'm also having second thoughts about a flock shield I stuck around the focuser inside the OTA.




    You stuck a tube of flocking around the focuser tube? If that's what you did, I don't think that's the best solution. It's better to directly attach the flocking paper to the outside of the focuser tube, so that it is retracted when the focuser retracts. Cut out sections of flocking and attach them so they will not be bound up with the focusing mechanism when you move the focuser tube in and out. Use black marking pen to go over the areas that you cannot cover with flocking.

    Here's how the focuser for 10" Newt looked after I covered it with Protostar and blackened some areas with black marking pen.

    Mike


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    skizoid
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    Reged: 01/12/11

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    Re: Mega-mod thread for Zhumell dobs new [Re: Sarkikos]
          #4335309 - 01/23/11 07:42 PM

    Gotcha - Didn't take long to notice the shield was partially blocking the mirror when I got around to adjusting the optics. The flock board isn't going to work in small patches I don't think - it's kinda stiff for that. Maybe use velcro - the fuzzy side? Got a bunch of that laying about. I'll come up with something. Either way, I'll cut the shield down just proud of the flocking and leave it in place. That's part of the sealing system for the airgap between the flocking and the tube itself.

    Gave the Dub Dob (I like that) it's first field test tonite. 8F ... perfect viewing weather! Clear sky anyway. Gives new meaning to the phrase "crisp air". Set it up about an hour before sunset, then went out to play. Jupiter was an easy target, so I used that to align the finders with the OTA. That Telrad is sweet for quick 'n dirty! I could see Uranus, but wasn't getting any decent detail, so I'm gonna have another go at fine tuning the mirrors. Wasn't too long after sunset, so I still had quite a bit of heat distortion to deal with. I'm happy enough that I could see anything at all first time out. Speaking of first time out ...



    Was going to spend some more time out eyeballing the nether regions, but I could feel MY nether regions going numb, so called it a day. Thinking I may thaw out enough by midnite to take a quick peek at the moon. That's when it's supposed to rise according to Stellarium. Or not - I don't imagine it'll be warming up by then. This arctic blast is only supposed to last another week, so I think I'll wait a bit before I get into some serious work. That'll also give me some time to work on a "Denver Chair" - my back ain't what it usta be.

    Speaking of significant shrinkage - my first surprise was the OTA cap. That's usually a tight fit. After some time outside, I could spin it around in the opening. Least it didn't fall thru ... <G>


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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4335493 - 01/23/11 09:05 PM

    I've heard Zhumell's documentation is ... less than stellar. Their PDF manual sez ...

    4. Loosen 3 locking screws on bottom of optical tube (the thin ones that stick farther out from the back of the mirror).

    5. Align the laser to the center of the reticle by adjusting the 3 primary mirror adjustment screws (the thick screws in the back of the mirror). Do not over-turn these screws (max of ¼ turn at a time).

    Not seeing any thick or thin screws, I assUme the white ones are the locks. Loosen those up so they're out of the way, then adjust the tilt with the black ones. Right? Seems to work that way anyway.


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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4335600 - 01/23/11 10:10 PM

    Skizoid,

    Quote:

    Gotcha - Didn't take long to notice the shield was partially blocking the mirror when I got around to adjusting the optics. The flock board isn't going to work in small patches I don't think - it's kinda stiff for that. Maybe use velcro - the fuzzy side? Got a bunch of that laying about.




    You bought the flock board and not the flocking in a flexible roll with an adhesive backing? For doing smaller parts like the focuser, the adhesive-backed flocking would be easier to work with. Maybe you could just get a small section or two.

    Mike


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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4335609 - 01/23/11 10:14 PM

    Skizoid,

    Quote:

    I could see Uranus, but wasn't getting any decent detail, so I'm gonna have another go at fine tuning the mirrors. Wasn't too long after sunset, so I still had quite a bit of heat distortion to deal with. I'm happy enough that I could see anything at all first time out. Speaking of first time out ...




    Chances are you won't see much detail on Uranus in a 10" scope. Jupiter and Saturn are better tests.

    Mike


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    Re: Mega-mod thread for Zhumell dobs new [Re: GrafikDihzahyn]
          #4339832 - 01/25/11 05:17 PM

    OK - finished the fan shield.

    Thing is, all the pics I've seen show the fan mounted INSIDE the shield with just the grill showing. No way I was going to fit mine in there - it's at least a quarter inch too tall. I ended up mounting it to the shiny new shield instead of the original location. May be a bonus - there's more space for the air to develop velocity, so I'd think better flow around the edges of the primary. This way too, I'll be able to add a box around the fan for a filter. Maybe. Still thinking on that.



    They change the fan, or am I just having a Polish moment? Not complaining if they did - a deeper fan would have more pitch to the blades and be able to move a lot more air at lower rpm. I did consider replacing the 80mm stock fan with a 120mm fan that's half the height. Leftover from another project, but I already had the shield cut, so there.

    Oh. Saw a few posts about the fan being mounted backwards. Rule of thumb, air blows towards the label on the hub.


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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4340161 - 01/25/11 07:57 PM

    Applied the KISS (Keep It Simple Stupid) principle to the diverter ring for the fan. Closed cell foam tape, 1/4" tall, 3/4" wide. Just set a gauge and stuck it on so that it clears the top of the primary by about 1/4" ...



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    skizoid
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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4341889 - 01/26/11 03:32 PM

    ... and with this, I do believe I'm about ready to hit the road.





    I did pick up on a cheepie golf bag caddy to haul the OTA about. Good size wheels, and it folds up small. Have to rework the base a bit, add a couple padded straps, maybe some baby moon hubcaps ...

    ... a modding we will go! Hi ho the derry oh ...


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    graffias79
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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4358570 - 02/02/11 04:19 PM Attachment (80 downloads)

    I don't like the idea of permanently applying or modifying my telescope. I like to keep things completely reversible, at least for a while after I've had them. Having said that, I had an idea. I have been working on PCs for years and have amassed quite a collection of dead hard drives. A few months ago I decided to remove all of the rare earth magnets from them and throw the rest of the parts away. I am glad I did because the magnets come in handy:

    For the Telrad, I sandwiched 2 hard drive magnets between some double sided tape and some craft store foam:


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    graffias79
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    Re: Mega-mod thread for Zhumell dobs new [Re: graffias79]
          #4358578 - 02/02/11 04:20 PM Attachment (135 downloads)

    Another view (Yeah 100 posts!)

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    graffias79
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    Re: Mega-mod thread for Zhumell dobs new [Re: graffias79]
          #4358592 - 02/02/11 04:23 PM Attachment (90 downloads)

    Now I can place it on the scope and removed it when I'm done. Between the very strong magnets and the friction from the foam, the Telrad stays put!

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    Re: Mega-mod thread for Zhumell dobs new [Re: graffias79]
          #4358597 - 02/02/11 04:24 PM

    I guess it would help to mount it the other way around though! Haha!

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    Re: Mega-mod thread for Zhumell dobs new [Re: graffias79]
          #4359037 - 02/02/11 07:27 PM

    Those magnets are plenty strong and useful for all sorts of stuff. Never toss them!

    I obviously don't have any problems hacking and slashing, but in the case of the Telrad, I wasn't all that sure I'll be happy with the location I chose. If you peek back, you'll see I mounted mine other side of the Zhumell sight. I do have to walk around the tube to use it, but no biggie - I can use the exercise. It's currently stuck to the OTA with 3M tape. If I decide I need to move it, just saw thru the center foam with some dental tape and roll the adhesive off with a finger. If I do find it's ok where it is, I <may> drill for screws, but ... after flattening out the inside surface of the telrad mount, there's all kinds of mounting surface, and the 3M tape is plenty strong and heat resistant enough to hold it in place permanently all by itself.




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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4359210 - 02/02/11 08:44 PM

    More than a year ago I mounted my Telrad on a homemade wooden base then attached magnet to the bottom of the base. The wooden base works as a rise and it allows me to place it on the top of the finder scope dovetail base for better location.
    Reference post




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    Re: Mega-mod thread for Zhumell dobs new [Re: Jason D]
          #4359599 - 02/02/11 11:29 PM

    Use some computer duster in a can sprayed upside down on the adhesive. It will come off easier.

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    Re: Mega-mod thread for Zhumell dobs new [Re: Jason D]
          #4359672 - 02/03/11 12:17 AM

    I was thinking on how it would work to put a riser on the Telrad, then mount it between the eyepiece and spotter, only farther down the tube. Seems there'd be a sweet spot where you could see both easily with just a sweep of the mark one eyeball. That'd certainly work a bunch better from a Denver chair or some other such comfy perch.

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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4360104 - 02/03/11 08:55 AM

    On my Z8 and my Celestron 10" Newt, I place the Telrad on the far side of the optical finder, so that the optical finder is between the focuser and the Telrad. When the Telrad is between the focuser and optical finder, I feel that the Telrad is in the way, especially when it's on a riser. I have a 70mm optical finder that I attach to the 10" Newt for star-hopping at dark sites. I just use the Telrad to get in the general neighborhood of an object, so it doesn't matter if I need to lean up a bit to look through the Telrad. I don't spend a lot of time viewing through the Telrad.

    I attach the Telrad by itself on my Z8. I mostly observe planets and the Moon at home through the Z8. The Telrad is good enough without an optical finder to sight planets or the Moon. Also, if I take the 10" Newt out at home, I just attach the Telrad without an optical finder. I only need to briefly position the Telrad on bright objects, I don't need to star hop to them, so I don't spend a lot of time sighting through the Telrad. In that case, it doesn't matter if I need to stand up and lean over the scope a bit.

    I don't feel the need to move the Telrad to different positions on a scope. I bought a couple extra Telrad bases and used super-tacky adhesive tape to secure them to my scopes in the optimum position for me.

    The only justification I could see to moving the Telrad to different positions on a scope is if I want to view from the opposite side of the OTA in order to prevent my body heat from disrupting the image when observing planets or the Moon. That might be justifiable in my 10", since the OTA is in rings and I can rotate the OTA. But it would not make sense in any scope that cannot be rotated. Other than that, I see no reason to be moving the Telrad around on a scope.

    Mike


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    Re: Mega-mod thread for Zhumell dobs new [Re: Sarkikos]
          #4361814 - 02/03/11 10:10 PM

    Good stuff - plenty food for thought.

    Sounds like your setup is similar to mine then.



    The couple times I've had the Z8 out, I haven't had any issues with walking around the back of the scope for quickie alignment with the Telrad. I CAN use it from the same side as the focuser, but it's just more comfortable. I did a dirty fit between the focuser and finder just for yuks, and like you found it to be a bit ... crowded. One other thing I want to try is mounting the Telrad on a riser directly behind the finder, just making sure there's enough room to get an eyeball in without poking it out. I figure that way, I can glance back to the Telrad, let it do it's thing, then just swivel into the eyepiece for fine tuning and hopping. Then again, I may just be able to get away with using the same mounting location, but further down the OTA. One way to find out.

    I'm sure a lot of it is personal preference. In my case, I've got some weird discs in my back and neck, so I have to consider those when coming up with a plan.

    Oh. Lookie what I scored on eBay.



    No excuses for bad imaging now. AssUming I can figure out how to use them ... I did order a copy of the Tectron book, which I understand is real handy to have. Just came in today, so I haven't had a chance to play with them yet - should be interesting to see how it compares to what I got with the laser.


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    graffias79
    sage


    Reged: 10/01/10

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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4362312 - 02/04/11 06:42 AM

    That's the beauty of magnets, I can mount it wherever I feel comfortable using it.

    Battery pack magnetic mod coming soon.


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    Sarkikos
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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4362398 - 02/04/11 08:27 AM

    skizoid,

    Yes, that looks a lot like my setup for the Z8. For both my Z8 and the 10", I can sit down on an adjustable stool and view comfortably through focuser or optical finder without having to stand up. I do need to lean up and over a bit, or even stand, to view through the Telrad, but as I explained, that's really no big deal. I don't have to stand up and walk around to the back of the scope as you describe, so I'm not really sure what you're talking about there.

    Positioning the Telrad or any other gizmo farther back on the OTA may not work out for you. I tried that when I experimented with mounting an ST80 on my 10" Newt. I placed it way back above the altitude bearings to make it easier to balance. But since the ST80 was so far down on the tube, it was difficult if not impossible to hunker down far enough to actually look through it, even though it had a RACI diagonal. Especially if you have back problems, it probably would not be a good idea to place the Telrad much farther down the OTA.

    By the way, I decided not to use the ST80 on my 10". It was just too cumbersome and heavy for that setup. I use a much lighter 70mm finder that I put together from parts of different scopes.

    Mike


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    rkayakr
    sage
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    Reged: 10/27/10

    Loc: Northeast Ohio
    Re: Mega-mod thread for Zhumell dobs new [Re: graffias79]
          #4363046 - 02/04/11 01:51 PM

    I moved the right angle finder over 1/4" on my Z10 to fit the Telrad between the focuser and the finder with no riser. It is convenient, but when I use the finder I often breath on the Telrad diagonal and fog it up. A dew shield is next, but it will have to be low and tight to not block access to the finder.

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    skizoid
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    Re: Mega-mod thread for Zhumell dobs new [Re: Sarkikos]
          #4363759 - 02/04/11 07:21 PM

    OK then - I do plan to leave it as is for now and see what happens. My biggest concern with going down the tube and higher was how much adjustment range the Telrad has. I see they do sell four inch risers, so I don't expect that would be an issue. Hadn't thought about the fogging issue - have to check that out. I've been wearing a balaclava when I'm out, Michigan being Michigan and all, and I can see where that might be the way to go till we're out of steamy breath season. Anyway, lots will depend on what the viewing angle is from the Denver chair when I get that built.

    (This here astro-onomy stuff shore do keep a body buzy!)

    UPS just left after dropping off my latest accessory.

    FORE !!



    I really like it! Folds up nice and small too. Thought I'd have to do some mods to fit the OTA properly, but it slides right in. The saddles would be a bit small for anything larger than an 8", but you could fix that by adding a couple rubber bumpers for the tube to sit on. Straps in and rides good too. The only contact points with the OTA are at the saddles, and I plan to felt those. I do need to mod up a new base for it - right now the fan sits right on it, and that's not good, especially for cross country.

    Mag wheels too! Fastest scope at the meet!

    $30 including S&H from Amazon. Not sure how they even make any money on something like that, but I ain't complaining.

    Intech folding OTA holder ... er ... golf cart


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    poodle
    sage
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    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4431064 - 03/06/11 09:30 PM

    OK I have read through the post several times and I would swear somewhere the screw sizes for the secondary adjustment were posted but I cannot find it. If anyone knows I would appreciate it if you would repost it. I am looking for secondary adj. screws on a Z12.
    Thanks again.


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    Jason D
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    Re: Mega-mod thread for Zhumell dobs new [Re: poodle]
          #4431201 - 03/06/11 10:28 PM


    Could it be this post?
    http://www.cloudynights.com/ubbthreads/showthreaded.php/Cat/0/Number/4230621/page/0/view/collapsed/sb/5/o/all/vc/1


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    poodle
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    Re: Mega-mod thread for Zhumell dobs new [Re: Jason D]
          #4431447 - 03/07/11 01:19 AM

    No that one is for a screw for the finder holder but thanks anyway. I think the ones I am talking about are metric.

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    Maverick199
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    Re: Mega-mod thread for Zhumell dobs new [Re: poodle]
          #4431627 - 03/07/11 06:15 AM

    Mag wheels too! Fastest scope at the meet!

    Good one that. I am debating on a Telrad or a Rigelquick finder on my Z8. The RACI needs fine tuning.


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    Sarkikos
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    Re: Mega-mod thread for Zhumell dobs new [Re: Maverick199]
          #4431792 - 03/07/11 08:39 AM

    I have a Telrad and a Quikfinder. The Quickfinder has a much smaller footprint on the OTA. I've mostly used that on my smaller scopes. It can also fit on big binos, but I discovered I don't really need a finder for binos. You can buy an add-on for the Quikfinder so it can use rechargeable AAA batteries. The Quikfinder also has a setting to adjust the blinking rate of the light. The Telrad does not blink, but you can buy an add-on for that. I hardly ever use the blinker on my Quikfinder, so I never bought one for the Telrad. I don't spend a lot of time with either of these finders. I just use them to get in the neighborhood of an object, then I use the optical finder to star hop closer.

    On the negative side, the Quikfinder does not have the outer 4 degree circle that the Telrad has. (That never mattered to me because, as I said, I just use these bulls-eye finders to get in the general neighborhood. I don't use them to star hop.) The Quikfinder is easier to break, because it has a more vertical profile than the Telrad. Also, the plastic tab which attaches the Quikfinder to the mount is easy to break. Mine is nearly broken off now, which makes it less securely mounted when attached to the OTA.

    On balance, I would advise the Telrad for a Z8 or larger scope.

    Mike


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    MikePDX
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    Re: Mega-mod thread for Zhumell dobs new [Re: Sarkikos]
          #4435297 - 03/08/11 04:06 PM

    Steve - The secondary adjustment screws are M4 x 35mm for my Z8 - I used socket caps screws and added a Press-Loc knob. The tough part is not in finding screws long enough it's in finding screws that are fully threaded. I finally did and had to purchase a dozen. For some reason I have 9 left over. PM if you are interested and I would be glad send you a set.

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    poodle
    sage
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    Re: Mega-mod thread for Zhumell dobs new [Re: MikePDX]
          #4441026 - 03/10/11 09:02 PM

    Thanks Mike for the info. What is a press-loc knob?

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    Scanning4Comets
    Markus
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    Reged: 12/26/04

    Re: Mega-mod thread for Zhumell dobs new [Re: poodle]
          #4441745 - 03/11/11 06:57 AM Attachment (149 downloads)

    Nice mods !!!

    I know Mike has wanted to see this pic I have added for a while. It is an apodizing screen to boost the contrast on the planets I put on my 12" reflector in 2005...and yes , it really does work !!!....I no longer have the 12" tho.


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    Sarkikos
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    Re: Mega-mod thread for Zhumell dobs new [Re: Scanning4Comets]
          #4441801 - 03/11/11 08:17 AM

    Markus,

    Thanks for posting that pic. Looks good. Where did you get the ratios to construct the screens? Did you give the apodizing mask to the buyer?

    I'm working on an apodizing mask for my Z8 now. This time I went to the trouble of going to Harold Suiter's website, downloading his spreadsheet, and using that to calculate the aperture percentages for the three screens. For my 10", I just copied the ratios from another observer who had virtually the same telescope, so I also got the same level of good results that he did.

    For the Z8 mask, I cut the two retaining rings out of black foam core. The rim is the diameter of the OTA, the inner edge is the diameter of the primary mirror minus the bevel. The mask will rest on the rim of the OTA, and will be snugly held in place by the dew/light shield. That way, I won't have to push the mask down inside the OTA.

    I cut ring templates out of white poster cardboard for the three screens. Then for each ring, I placed a square of charcoal aluminum screen on a piece of corrugated cardboard and set the template over the screen, keeping the edges in place with metal weights. I went around the template with an Xacto knife, carefully punching down on the screen until I hear each wire pop. Afterwards, I took regular household scissors and cut around and inside the wire ring to free it from the screen, trimming or repositioning loose ends as necessary.

    Next I took the two foam core rings and the three aluminum rings up to the attic to paint them with flat black spray paint. It was raining, so I should not paint outside, and I do not have a basement. I positioned the items in a big box and sprayed them there. I was careful to spray the wire rings with quick movements back and forth, never letting my arm stop while spraying, and keeping the spray can at least a foot above the screens. The paint did not clog the holes in the wire screens.

    Today I'll use Gorilla Glue or something similar to glue the screen rings between the foam core rings. I'll use a clear protractor to position the screen rings at 30 degrees from each other. Finally I'll brush matte sealant on the surfaces and outer edge of the foam core rings to protect them from dew.

    Mike


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    Scanning4Comets
    Markus
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    Re: Mega-mod thread for Zhumell dobs new [Re: Sarkikos]
          #4443045 - 03/11/11 07:40 PM Attachment (100 downloads)

    Mike,

    I still have the screen put away in case I ever get a 12" reflector again !!! I always say I won't but a 12" on deep sky shows quite a bit. I got the plans for it in a book at the library, or online.

    As you can see in the pic in my previous post above, there is a huge difference between the flocked part and the grey paint inside the tube. I ended up flocking the entire scope from top to bottom eventually. All three screens are different size and turned certain degrees from each other.

    Here are a few pics of the screen, the 12" mirror, and a quick shot of the moon through the 12" reflector I had.


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    Scanning4Comets
    Markus
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    Reged: 12/26/04

    Re: Mega-mod thread for Zhumell dobs new [Re: Scanning4Comets]
          #4443066 - 03/11/11 07:52 PM Attachment (103 downloads)

    12" mirror...I eventually loosened the clips so the mirror wasn't getting "pinched".

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    Scanning4Comets
    Markus
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    Reged: 12/26/04

    Re: Mega-mod thread for Zhumell dobs new [Re: Scanning4Comets]
          #4443069 - 03/11/11 07:53 PM Attachment (134 downloads)

    finally...the moon through the 12" scope!

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    Scanning4Comets
    Markus
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    Reged: 12/26/04

    Re: Mega-mod thread for Zhumell dobs new [Re: Scanning4Comets]
          #4443079 - 03/11/11 07:55 PM Attachment (129 downloads)

    ok...last pic, I promise.

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    Sarkikos
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    Re: Mega-mod thread for Zhumell dobs new [Re: Scanning4Comets]
          #4443234 - 03/11/11 09:27 PM

    Nice pics, especially along the terminator in the second one.

    By the way, I have seen pics of planets shot through telescopes which had apodizing masks. The "before" and "after" pics really show the contrast increase AND increase in detail using the mask. That is a true proof of concept. Apodizing masks do work!

    Mike


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    Jaxdialation
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    Re: Mega-mod thread for Zhumell dobs new [Re: Sarkikos]
          #4443475 - 03/11/11 11:35 PM

    Wow guys, this thread kicks butt.

    I'm the guy who did the original Zhumell Mega Mod thread a few years back.

    Tim got this thread waaayy further. Funny how that works.
    CN is packed with talent, and this thread proves it!

    I almost feel like I need to get another Z10 as kind of a statement lol

    Do you EVER see threads like this on Orion reflectors?
    Know why? They suck too bad to try to get them fixed up

    Proceed with your tweaksmanship guys!

    Tim --->> <----


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    Norm42
    super member
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    Loc: Webster, NY
    Re: Mega-mod thread for Zhumell dobs new [Re: Jaxdialation]
          #4444126 - 03/12/11 10:05 AM

    Not necessarily a mod to the scope, but a low cost way to carry the OTA.

    CN Link to Post


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    Tim L
    Carpal Tunnel
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    Reged: 12/17/08

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    Re: Mega-mod thread for Zhumell dobs new [Re: Jaxdialation]
          #4447175 - 03/13/11 04:47 PM

    John (Jaxdialation),

    Thank you for your kind words!

    My Z's had to be in storage so long, I know the "wow" factor will be there all over again when I can put it back into service.

    And now, I've got a lot more mods to try thanks to everyone else adding to this thread!


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    Twilight
    scholastic sledgehammer


    Reged: 06/03/10

    Loc: Englewood Tennessee
    Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
          #4669496 - 07/02/11 04:11 AM

    Quote:

    Here's another for new Z owners:

    Several have posted having problems bringing their 30mm eyepiece that comes with the scope into proper focus. The common complaint is that there is not enough "out-focus" travel. This is most often heard about the Z8 model.

    There's a simple fix for this. On the front of the focuser are two thumbscrews. The upper screw controls tension for the crayford focuser. But the lower screw is a focus lock, useful for astrophotography, but not much needed on a dob used for visual.

    The problem is, that lower screw keeps the focuser drawtube from extending all the way. The solution is to loosen the screw several turns (or remove it if you wish), which will let your focuser extend an additional 1/4" and bring your 2" eyepiece to focus.

    Clear skies!




    Just an update to Tims information. I just checked the back focus/out focus on my Z12" which I purchased in December of 2010 and was having a problem with obtaining enough out focus on several of my eyepieces. After removing the focuser locking screw I am able to obtain 0.27" more out focus. Also the draw tube does not come completely out of the focuser which I was concerned about after reading Tims post. So there is no danger of you expensive eyepieces hitting the ground. Thank you Tim for this recomendation.
    Phil


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    MrJones
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    Reged: 09/15/10

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    Re: Mega-mod thread for Zhumell dobs new [Re: Twilight]
          #4779922 - 08/31/11 11:48 AM

    This is a great thread, here's my feedback and contributions after 2 weeks with my Z12.

    1) Laser collimator collimation. It's easy to check and adjust. I used a book wedged in a pot rather than making a v-block to rotate the tube in. I found 20' to be plenty of distance - adjusting at 60' made no difference. I taped a piece of paper to the wall and marked 3 positions, with each of the adjustment screws pointing up. This made it easy to figure out which screw(s) to turn.

    2) Laser aperture stop. My beam was elliptical as per others' posts. Apparently you can actually go in and properly seat the lens to fix this but I just added an aperture stop as per the OP. The easiest way to do this IMO is cut a small piece of business card and tape it to the back of the diagonal insert. I used a pin then small nail for the hole in the center, it is slightly smaller than 1mm.

    3) Primary holder springs. I replaced mine with stiffer springs cut to the same length (1/2") from a hardware store. Google "#98 wire coil springs". I had to use a Dremel cutting wheel to cut them. I really do believe they help hold collimation better but I would rate this as a low priority mod - the original springs are ok. I also do not quite fully tighten the lock knobs with the new springs.

    4) Secondary collimation screws. Rather than buy Bob's Knobs I got replacement screws 5mm longer than the stock (I think original is 35mmx4mm and mine are 40mm) put nylon wingnuts on them (not metric but could be screwed on) then a nut to hold the wing nut. Works great.

    5) Counterweight. I got a 4' adjustable nylon strap from Walmart for about $4, wrapped it around the bottom and I hang a 2 lb velcro wrist weight from it with the weight opposite the focuser. This has worked pretty well. I do need to slide the strap some but the weight hanging rather than being tight against the tube seems to help with the zenith balance issue.

    Still to go:

    Milk jug washers for at least the secondary.
    Shower cap for bottom.
    Guide knob and either carrying handles or straps for OTA.


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    bob irvin
    sage


    Reged: 03/22/11

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    Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
          #4780291 - 08/31/11 02:38 PM

    Great Thread Tim, thanks.

    One thing I did was add two horizontal handles on each side of the base. This lets me lift up my Z10 OTA and base and move it around for short distances. You wouldn't want to carry it very far this way but for a few feet it's great. If you do this mod make sure you use through bolts to hold on the handles. I wouldn't trust wood screws to hold in the particle board.

    bob

    Edited by bob irvin (08/31/11 02:41 PM)


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    Tim L
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    Re: Mega-mod thread for Zhumell dobs new [Re: MrJones]
          #4781195 - 08/31/11 10:57 PM

    Quote:

    1) Laser collimator collimation. It's easy to check and adjust....I taped a piece of paper to the wall and marked 3 positions, with each of the adjustment screws pointing up. This made it easy to figure out which screw(s) to turn.




    MrJones,

    I like this idea a lot--seems easier than the four-position method I described earlier in the thread. I'll give it a shot next time I change batteries in the laser.

    Thanks!


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    MrJones
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    Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
          #4798869 - 09/09/11 07:58 PM Attachment (89 downloads)

    Thought I'd document my primary cell changes too.

    So glad I took my mirror out to send it for refiguring. I found a lot of problems and I recommend just taking it apart to fix things!

    - The screws holding the cell to the OTA were loose.
    - The mirror clips were loose.
    - The collimation screws had rough bottoms and directly press on metal supports of the cell (like the secondary) - grinding into the support.
    - The float support triangles were not aligned.
    - There were double sided tape pads on the float triangles and some of the top paper covers had come off so I had to cut the mirror free with a razor. (!)
    - The triangles were floppy. Turns out the nylon balls they pivot on had loose screws that would not stay tight.

    Attached is a photo of what I started with before removing triangle float supports.


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    MrJones
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    Re: Mega-mod thread for Zhumell dobs new [Re: MrJones]
          #4798886 - 09/09/11 08:07 PM Attachment (90 downloads)

    This is the new "top" of the cell. I left one nylon (might be HDPE) pivot ball exposed so you can see it. Even screwed all the way down they would not stay tight. After removing them (one piece with screw sticking out the bottom) I put a drop of glue on each and screwed them back in to hold them tight.

    The old float pads were stripped off with a razor and paint thinner and replaced with glued HDPE (milk jug) pads. I was very impressed with how easily the redone triangles slide across my granite kitchen counter - I think they'll be fine.

    CN'er sixela also suggested drilling holes in the triangles and inserting dowels through the triangles on either side of the supports so that the triangles can't rotate out of position (ie with a point facing the center). Still thinking about that one but note that the triangles do already have holes in them.


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    MrJones
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    Re: Mega-mod thread for Zhumell dobs new [Re: MrJones]
          #4798894 - 09/09/11 08:13 PM Attachment (88 downloads)

    Finally I put 2 layers of HDPE milk jug pads where the collimation screws contact the cell. You can see through the pads where the collimation screws have worn nice divots in the supports after just a few weeks of use. I also smoothed and flattened the ends of the collimation screws on a grinder.

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    Tim L
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    Re: Mega-mod thread for Zhumell dobs new [Re: MrJones]
          #4799152 - 09/09/11 11:10 PM

    Hey MrJones,

    Nice pics! The Z12 mirror cell is a lot different than the Z10. Thanks for adding your upgrades and improvements.

    I have a question about the last photo you posted. It looks to me like the spokes at 12, 4, and 8 o'clock have screw holes in them at the rim--is that where the collimation screws go? If so, then I would guess the ones with the milk jug plastic are for the locking screws, and I don't know if it's necessary to tighten those down hard. I usually just set mine to add a slight pressure while keeping an eye on the laser collimator.

    Clear skies!


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    MrJones
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    Re: Mega-mod thread for Zhumell dobs new [Re: Tim L]
          #4799169 - 09/09/11 11:24 PM

    You can see the scratch marks from installing replacement springs on those spokes around the holes for the lock screws. Still deciding if I want to do something about that. The collimation screws are threaded into the other piece. And strange that the Z10 cells are a lot different!

    Edit: Obviously backwards - sorry. The pads are for the locking screws which I do use.


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    ernie bogusch
    journeyman


    Reged: 03/01/11

    Re: Mega-mod thread for Zhumell dobs new [Re: skizoid]
          #4800935 - 09/10/11 11:44 PM

    Quote:


    Gave the Dub Dob (I like that) it's first field test tonite. 8F ... perfect viewing weather! Clear sky anyway. Gives new meaning to the phrase "crisp air". Set it up about an hour before sunset, then went out to play. Jupiter was an easy target, so I used that to align the finders with the OTA. That Telrad is sweet for quick 'n dirty! I could see Uranus, but wasn't getting any decent detail, so I'm gonna have another go at fine tuning the mirrors. Wasn't too long after sunset, so I still had quite a bit of heat distortion to deal with. I'm happy enough that I could see anything at all first time out. Speaking of first time out ...








    Skizoid,
    I realize this thread is old, but I just got my Z8 and I will be making some to the mods you suggested.

    Some questions.

    1) You placed the handles on both sides. Wouldn't one handle in the top center make carrying the OTA, and placing the OTA into the base much easier?

    2) I like the backup plate in the inside of the OTA. Is one handle strong enough to carry the OTA without stressing the steel tube? Is you backup plate steel or aluminum?

    3) Why didn't you mount the Telrad closer to the edge of the scope? The optical finder would not be in the way and it seems more convenient to use in that position.

    Thanks,
    Ernie


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    Tom Andrews
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    Loc: Albuquerque, NM
    Re: Mega-mod thread for Zhumell dobs new [Re: ernie bogusch]
          #4982221 - 12/23/11 11:43 PM Attachment (89 downloads)

    I just received a Z8 from a friend of mine 2 days ago. My priority mods were an azimuth degree circle and collimation bolt springs.

    I used the same degree circle mod that my Coulter 8" came with when I bought it used 16 years ago and that I also used on my Discovery (details/pictures in the Degree Circles thread in the Equipment Forum). It's fast, easy, reversible and so easy to use because you have 360 degrees of adjustable alignment. I can post more pictures of the details if anyone is interested.

    To me, the collimation springs upgrade is well worth it because it not only makes adjusting easier but holds collimation better. If the springs are heavy-duty enough, the locking bolts aren't necessary. I bought the springs at a local bolt shop and cut them down. Could have cut them shorter as I don't have many threads catching but as it turns out, I didn't need much adjustment. One tip that I've found very helpful is to tighten the collimation bolts completely to start then collimate by loosening. This keeps everything very tight and makes a big difference in holding things in place.

    I will be installing a handle for lifting/carrying and a knob for adjustments while observing. Other than that, I think it will work fine.

    Here are a few pictures:


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    Tom Andrews
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    Re: Mega-mod thread for Zhumell dobs new [Re: Tom Andrews]
          #4982222 - 12/23/11 11:44 PM Attachment (103 downloads)

    Close-up.

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    Tom Andrews
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    Re: Mega-mod thread for Zhumell dobs new [Re: Tom Andrews]
          #4982224 - 12/23/11 11:46 PM Attachment (83 downloads)

    Upgraded springs.

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    Tom Andrews
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    Re: Mega-mod thread for Zhumell dobs new [Re: Tom Andrews]
          #4982229 - 12/23/11 11:48 PM Attachment (86 downloads)

    Spring comparison: stock spring left, upgrade right.

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    kensvws
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    Reged: 09/17/10

    Loc: Whitby,ON, Canada
    Re: Mega-mod thread for Zhumell dobs new [Re: Tom Andrews]
          #4983094 - 12/24/11 02:27 PM

    Good job Tom. Those springs sure do look much more substantial and functional. Is the spring pictured on the right already cut down?

    Edited by kensvws (12/24/11 02:29 PM)


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    MessiToM
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    Loc: Huntingdon PA
    Re: Mega-mod thread for Zhumell dobs new [Re: kensvws]
          #4983172 - 12/24/11 03:11 PM

    Hmm I didn't know this thread existed. My best zhumell mod to my 12" would be adding a intelliscoe encoders and computerized object locater to. Second best would be flocking



    More pics http://m92.photobucket.com/albums/rougeneon97/IntellaZOB/

    My INTELLIZOB

    Edited by MessiToM (12/24/11 03:17 PM)


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    Tom Andrews
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    Re: Mega-mod thread for Zhumell dobs new [Re: kensvws]
          #4983712 - 12/24/11 10:36 PM

    Quote:

    Good job Tom. Those springs sure do look much more substantial and functional. Is the spring pictured on the right already cut down?




    Thanks!

    Yes, the spring is already cut to size. I figured I'd start long and cut more if needed. Since I always tighten the bolts to fully compress the springs then collimate by loosening and since on both my other dobs I've had to adjust very little, I figured I'd have enough threads to be safe. As with both other dobs, I've only had to turn 2 of the three collimation bolts, one ~ 1/2-3/4 thread and the other ~ 1/4-1/2 thread. The best part is getting rid of the locking bolts which always seem to throw your collimation off when you tighten them.


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    Mason Dixon
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    Reged: 06/29/07

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    Re: Mega-mod thread for Zhumell dobs new [Re: poodle]
          #5133459 - 03/21/12 11:15 AM

    Anybody made a solar filter for there zhumell yet?

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    Ian1957
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    Loc: Cocoa,Fl
    Re: Mega-mod thread for Zhumell dobs new [Re: Mason Dixon]
          #5264949 - 06/10/12 03:55 PM

    Hi
    Has anybody used one of these http://www.protostar.biz/tubeliner.htm
    I have a Z8 and it looks like a good solution for flocking the tube.
    Cheers
    Ian


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    stratocaster
    sage
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    Reged: 10/27/11

    Re: Mega-mod thread for Zhumell dobs new [Re: Ian1957]
          #5266974 - 06/11/12 07:40 PM

    Yep. I used the tube liner for my Z10.

    It took a little longer than I expected to cut the tube to size and cut out the focuser drawtube hole and holes for focuser attachment hardware and spider. The thin backing material was very sturdy in spite of how thin it is. It is also reasonably light.

    You'll need to remove the tube end cover and mirror cell to place the spacer foam in on both sides of the tube. Though I suppose if you had a long enough dowel or long/thin piece of wood you could work the foam all the way down the tube towards the mirror cell and just have to remove the tube end cover from the front of the tube.

    When I upgraded to a moonlight focuser I had to remove the liner because the focuser mounting holes didn't quite match up to those of the stock focuser. If you plan on upgrading to a moonlight you may want to consider doing that first as you will have the option of not creating any holes in the liner for the moonlight mounting hardware.

    I like how the liner helps with tube currents.

    I never did an A/B comparison on the reduction in glare/increase in contrast. It can't do anything but help, but the apparent difference is not obvious to me.


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    finyo
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    Reged: 05/24/12

    Re: Mega-mod thread for Zhumell dobs new [Re: MessiToM]
          #5267877 - 06/12/12 11:02 AM

    Hi MessiToM, I got a classic XT8 and I'm interested in adding an Intelliscope too, but can seem to find enough useful information on the net. Was the procedure difficult?

    Thanks,

    finyo


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    VikingRaider
    sage


    Reged: 01/29/08

    Loc: Mukwonago, Wisconsin
    Re: Mega-mod thread for Zhumell dobs new [Re: finyo]
          #5471397 - 10/15/12 11:57 AM

    Okay, I'm back to keep the thread alive

    I just posted this over in the DIY/ATM forum but realized that it should go here as it's a mod for my Z8. So here goes:

    I got tired of dealing with the RA finder so I made a wooden base for my Telrad and carved it to fit the dovetail mount for the RA finder. Then I angled the top of the wooden base with planes and chisels to match the plastic base of the Telrad. Screwed it down and voila! A perfect fit.

    If you'd like to the see details of the construction process, I have more pictures at my astronomy blog...

    Thanks for looking and lets keep these awesome mods coming! I've got a whole list of stuff to work on after reading this thread again after over a year away from the hobby.


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    VikingRaider
    sage


    Reged: 01/29/08

    Loc: Mukwonago, Wisconsin
    Re: Mega-mod thread for Zhumell dobs new [Re: VikingRaider]
          #5471400 - 10/15/12 11:59 AM Attachment (44 downloads)

    Might help if I included the picture...

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    Sarkikos
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    Re: Mega-mod thread for Zhumell dobs new [Re: VikingRaider]
          #5471406 - 10/15/12 12:04 PM

    The first mod I made to my Z8 was to replace the altitude detent springs on the altitude bearings. They were too difficult to hook up and unhook. Ridiculously strong. Has anyone else experienced this? I didn't want to have to take up weight lifting just to be able to deal with the altitude springs. What a freakin' PITA!

    I quickly threw them out and rigged up replacement springs from a hardware store. The new springs have plenty of force to keep the OTA from wandering but are very easy to hook up and unhook.

    Mike


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    Sarkikos
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    Re: Mega-mod thread for Zhumell dobs new [Re: VikingRaider]
          #5471411 - 10/15/12 12:07 PM

    Quote:

    I got tired of dealing with the RA finder so I made a wooden base for my Telrad and carved it to fit the dovetail mount for the RA finder. Then I angled the top of the wooden base with planes and chisels to match the plastic base of the Telrad. Screwed it down and voila! A perfect fit.




    I don't get this. Why didn't you just use the Telrad on the plastic Telrad base? Was the Telrad too low? You could have bought a ready-made Telrad riser to fit on the Telrad base for not much cash. That's what I did.

    Mike


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    Sarkikos
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    Re: Mega-mod thread for Zhumell dobs new [Re: Sarkikos]
          #5471439 - 10/15/12 12:20 PM

    What is the maximum distance anyone here has carried the Z8 Dob mount by it's built-in handle? Not the entire Z8 OTA + mount, but just the mount.

    The best site within a short distance from my house is about 500' away. I'd like to carry everything there in one trip. I want to carry the OTA by one hand, the mount by the other.

    I've already attached a SCUBA carrier to the OTA, which makes carrying the OTA by one hand a cinch. But I'm still reluctant to carry the heavy Dob mount by one hand. I'm concerned that the handle will separate from the mount. I've looped a Strap-a-Handle around the mount, but I'm afraid that will come undone in transit. In any case, I'd rather carry the mount by the built-in handle if that won't destroy the mount.

    Mike


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    csrlice12
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    Re: Mega-mod thread for Zhumell dobs new [Re: Sarkikos]
          #5471495 - 10/15/12 12:45 PM

    a drill, a couple of washers, longer screws, and that handle won't go anywhere...or you'll have a big chunk of particleboard attached to a handle....

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    Sarkikos
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    Re: Mega-mod thread for Zhumell dobs new [Re: csrlice12]
          #5471513 - 10/15/12 12:54 PM

    Yes, I'm sure the handle will remain in my hand ... but will it remain attached to the mount or just a chunk of particleboard, as you say?

    Mike


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    Sarkikos
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    Re: Mega-mod thread for Zhumell dobs new [Re: Sarkikos]
          #5471520 - 10/15/12 12:57 PM

    If I had the proper tools, a shop and the expertise, I'd cut big circles out of the sides of the mount to lessen the weight. But it seems most of the weight is in the turntable/lazy Susan/whatever-you-want-to-call-it. I don't think much can be done to reduce the weight of that.

    Mike


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    VikingRaider
    sage


    Reged: 01/29/08

    Loc: Mukwonago, Wisconsin
    Re: Mega-mod thread for Zhumell dobs new [Re: Sarkikos]
          #5471678 - 10/15/12 02:27 PM

    Quote:

    Quote:

    I got tired of dealing with the RA finder so I made a wooden base for my Telrad and carved it to fit the dovetail mount for the RA finder. Then I angled the top of the wooden base with planes and chisels to match the plastic base of the Telrad. Screwed it down and voila! A perfect fit.




    Why didn't you just use the Telrad on the plastic Telrad base? Was the Telrad too low?




    The standard issue base on the Telrad just wasn't high enough to be comfortable for me. When I leaned over it was just awkward enough that I decided to use the RA finder instead. And I didn't like using the Telrad AND the finder because it stood up so tall on that arm.

    Stepping into the waters of astrophotography lately caused me to think that the Telrad would make things a lot easier on me than the RA. But when I removed the RA finder, that metal dovetail mount just screamed "use me". So instead of removing the mount and covering it with the already too-low Telrad base I decided to practice some woodworking skills and carve a dovetail to fit the mount. Now it's the perfect height for me and I'm making use of the mount.

    More importantly, I guess I did it to see if I could


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    Sarkikos
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    Re: Mega-mod thread for Zhumell dobs new [Re: VikingRaider]
          #5471693 - 10/15/12 02:33 PM



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    csrlice12
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    Re: Mega-mod thread for Zhumell dobs new [Re: Tom Andrews]
          #5471750 - 10/15/12 03:11 PM

    It seems the degree circle, being mounted to the top board, would move along with the "needle". How did you stabilize the degree circle so it does not move?

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    Jaimo!
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    Reged: 10/11/07

    Loc: Exit 135 / 40° North
    Re: Mega-mod thread for Zhumell dobs new [Re: csrlice12]
          #5486003 - 10/23/12 08:35 PM

    Great thread!

    I have recently upgraded from a Z8 to a Z12, WOW! what a difference. The Z12 weighs a little more than the Z8, which I was able to schlep the tube and mount outside together as a single unit. With the Z12 I need to make 2 trips and I set the tube on the floor of the basement and carry out the mount. The tube sat upright on top of the columation adjustment screws and it made me cringe every time I did it. I am planning on upgrading the springs, secondary screws, milk jug washers, and flocking. While looking at the mirror cell this afternoon I noticed and extra set of 3x M8 holes in the mirror cell. I had just finished upgrading a friends old Coulter Odyssey 8. The gentlemen at Coulter did one thing right, they added rubber feet on the bottom to keep the columation screws out of harms way. Well one thing let to another... Now she can sit in the upright position on the floor without pressure on the columation adjustment screws.

    Sorry for the poor picture quality it was an impromptu upgrade, all I had was my phone.

    M8 hole in the mirror cell:


    Rubber feet from Home Depot:


    Milling some wooden feet:


    Feet in place with an M8 cap screw:



    Rubber feet attached:


    Feet in action, notice the clearance for the columation screws:


    Enjoy,
    Jaimo!

    Edited by Jaimo! (10/23/12 11:57 PM)


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    yonkrz
    scholastic sledgehammer


    Reged: 11/16/06

    Loc: SW Minnesota
    Re: Mega-mod thread for Zhumell dobs new [Re: Jaimo!]
          #5486133 - 10/23/12 10:01 PM

    Did the same to my last three z dobs,works great.Besides protecting the collimation screws its just a great way to set the ota when moving your setup around.

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    gene williams
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    Reged: 01/17/11

    Loc: Missouri
    Re: Mega-mod thread for Zhumell dobs new [Re: yonkrz]
          #5491958 - 10/27/12 05:22 PM

    Excellent idea! I will be doing that to my 10" soon...

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    Sarkikos
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    Re: Mega-mod thread for Zhumell dobs new [Re: gene williams]
          #5492326 - 10/27/12 10:00 PM

    I never set a Dob tube down vertically. I have a a long bench, like a park bench, in front of my house. First I bring out the OTA and rest that horizontally on the bench. Often I'll let it lie out there for an hour to acclimate. Then I'll take out the Dob base separately, position that where I'll be observing. Finally I'll bring the OTA over and set it in the Dob base.

    I never saw the necessity of setting the OTA up vertically on the ground, the floor or where ever. That never occurred to me as being necessary or convenient. When I store a Dob, I either have the OTA resting in the Dob base, or the OTA is lieing horizontally on a shelf at the back of my closet along the floor.

    Mike


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    Sarkikos
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    Re: Mega-mod thread for Zhumell dobs new [Re: Sarkikos]
          #5492334 - 10/27/12 10:04 PM

    There is no way I'd be able to schlep my Z8 outside on the Dob mount as a unit. That's just not happening. My telescopes are stored upstairs. I'd have to carry the Z8 - as a unit - down a flight of stairs in the house, then out onto my porch, and down another flight of the stairs to the ground. Like I said, that ain't happenin'!

    Taking out my Z8 or larger scopes requires at least two trips: one for the OTA, one for the base.


    Mike


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    Jaimo!
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    Re: Mega-mod thread for Zhumell dobs new [Re: Sarkikos]
          #5492451 - 10/27/12 11:36 PM

    Quote:

    There is no way I'd be able to schlep my Z8 outside on the Dob mount as a unit. That's just not happening. My telescopes are stored upstairs. I'd have to carry the Z8 - as a unit - down a flight of stairs in the house, then out onto my porch, and down another flight of the stairs to the ground. Like I said, that ain't happenin'!

    Taking out my Z8 or larger scopes requires at least two trips: one for the OTA, one for the base.


    Mike




    When I had the Z8, I had built my own base with substantial handles & a ball bearing lazy susan. It was a nice upgrade from the MDF base that it had originally came with. I was able to carry the scope and mount up a flight of stairs from my basement to my observing site, and the Z8 had become my grab-n-go scope.



    The Z12 is a little larger... It may take 2 trips.

    Oh, and lift with your legs.

    Jaimo!


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    Sarkikos
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    Re: Mega-mod thread for Zhumell dobs new [Re: Jaimo!]
          #5492475 - 10/27/12 11:56 PM

    I suspect you must be substantially taller and stronger than I. That would be a very awkward schlep for me.

    I still have to deal with the base that came with my Z8. It is rather heavy and wide. I don't have the expertise, tools or space to make my own base, so I have to modify or accept what comes with the scope.

    Mike


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    tag1260
    scholastic sledgehammer
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    Reged: 10/07/12

    Loc: Ohio, USA
    Re: Mega-mod thread for Zhumell dobs new [Re: Sarkikos]
          #5492920 - 10/28/12 10:50 AM

    A question on your base. Is it identical to the original? Did you modify the sides or bottom parts at all in shape or dimension?

    Thanks


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    Sarkikos
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    Re: Mega-mod thread for Zhumell dobs new [Re: tag1260]
          #5493035 - 10/28/12 12:10 PM

    tag1260,

    No, I have not modified my Z8 base in any substantial way. It is the original in form, weight and girth. I doubt that - for most folks -it would be an easy haul with OTA attached. Personally, I wouldn't move it more than a couple feet as one unit.

    I have made some minor modifications. I added a metal basket to the opposite side from the observer, and I attached a couple clamps so I could insert a pole for binoculars or an observing stand. But I recently removed all that business.

    Also, I lowered the eyepiece rack to get it out of the way of the springs from the altitude bearings. And I replaced those springs. IME, the altitude-bearing springs that came with the base were much too stiff and strong, too difficult to detach and reattach the OTA. A real PITA, IMO. My replacement springs are much easier to use.

    Mike


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    evil16v
    member


    Reged: 08/18/12

    Loc: N.E. Kansas
    Re: Mega-mod thread for Zhumell dobs new [Re: Sarkikos]
          #5493313 - 10/28/12 04:15 PM

    wow!... how did i miss this thread?

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    tag1260
    scholastic sledgehammer
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    Reged: 10/07/12

    Loc: Ohio, USA
    Re: Mega-mod thread for Zhumell dobs new [Re: evil16v]
          #5493436 - 10/28/12 05:45 PM

    Thanks. It didn't come out any lighter? I would have thought you have to make it from lead to equal the weight of that particle board these mounts are made of!!!

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    Sarkikos
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    Re: Mega-mod thread for Zhumell dobs new [Re: tag1260]
          #5493546 - 10/28/12 07:02 PM

    tag1260,

    Please be sure to direct your questions to Jaimo. He is the one that made a replacement Dob base for his Z8, not me. I wouldn't know how to start to do something like that. I lack the expertise, tools and working space to construct a Dob base. I'm strictly DIY, not ATM.

    I still have the original Z8 Dob base that mine came with. IME & IMO, the original Z8 Dob base is heavy, wide, awkward and very difficult to move with the OTA attached. I wouldn't do it.

    Mike


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    gene williams
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    Loc: Missouri
    Re: Mega-mod thread for Zhumell dobs new [Re: Jaimo!]
          #5493584 - 10/28/12 07:34 PM

    Well, I found that I don't have the pre-drilled holes so I guess I will be drilling three holes for the new feet. I really love being able to safely set the Zhumell dob down since it is so stable in that configuration. It's also easier on my back...

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    Sarkikos
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    Re: Mega-mod thread for Zhumell dobs new [Re: gene williams]
          #5493692 - 10/28/12 08:51 PM

    Place a long bench in front of your house. You can't beat that as a place to rest your OTA while you bring out the Dob base. The OTA is much more stable and secure lieing horizontally than standing upright. I really don't get you folks wanting to set that long tube upright. A nice gust of wind, or a rambunctious pet or child, and bye-bye OTA.

    Mike


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    Gastrol
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    Reged: 11/04/11

    Loc: los angeles
    Re: Mega-mod thread for Zhumell dobs new [Re: Sarkikos]
          #5493705 - 10/28/12 09:04 PM

    With rubber feet you can place your ota anywhere as you set up. I might not do this with slow F ratio solid tubes as they are tall and skinny with a relatively small footprint.

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    Jaimo!
    Pooh-Bah
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    Reged: 10/11/07

    Loc: Exit 135 / 40° North
    Re: Mega-mod thread for Zhumell dobs new [Re: tag1260]
          #5493744 - 10/28/12 09:33 PM

    Quote:

    A question on your base. Is it identical to the original? Did you modify the sides or bottom parts at all in shape or dimension?

    Thanks




    Same size as original, it seems the Zhumell's size for the Z8 works very well. I have made modifications to the new base I have built for my Z12... When I get the chance I'll snap a few photos and post. It may take a few days with the up coming Hurricane...

    Jaimo!


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