Jump to content


Photo

Mega-mod thread for Zhumell dobs

  • Please log in to reply
501 replies to this topic

#251 Sarkikos

Sarkikos

    Hubble

  • *****
  • Posts: 16198
  • Joined: 18 Dec 2007
  • Loc: Per sylvam ad astra

Posted 28 October 2012 - 11:10 AM

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

#252 evil16v

evil16v

    Explorer 1

  • -----
  • Posts: 85
  • Joined: 18 Aug 2012
  • Loc: N.E. Kansas

Posted 28 October 2012 - 03:15 PM

wow!... how did i miss this thread?

#253 tag1260

tag1260

    Apollo

  • *****
  • Posts: 1040
  • Joined: 07 Oct 2012
  • Loc: Ohio, USA

Posted 28 October 2012 - 04:45 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!!!

#254 Sarkikos

Sarkikos

    Hubble

  • *****
  • Posts: 16198
  • Joined: 18 Dec 2007
  • Loc: Per sylvam ad astra

Posted 28 October 2012 - 06:02 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

#255 gene williams

gene williams

    Sputnik

  • *****
  • Posts: 43
  • Joined: 17 Jan 2011
  • Loc: Missouri

Posted 28 October 2012 - 06:34 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...

#256 Sarkikos

Sarkikos

    Hubble

  • *****
  • Posts: 16198
  • Joined: 18 Dec 2007
  • Loc: Per sylvam ad astra

Posted 28 October 2012 - 07:51 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

#257 Gastrol

Gastrol

    Apollo

  • -----
  • Posts: 1193
  • Joined: 04 Nov 2011
  • Loc: los angeles

Posted 28 October 2012 - 08:04 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.

#258 Jaimo!

Jaimo!

    Apollo

  • *****
  • Posts: 1338
  • Joined: 11 Oct 2007
  • Loc: Exit 135 / 40° North

Posted 28 October 2012 - 08:33 PM

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... :tonofbricks:

Jaimo!

#259 gene williams

gene williams

    Sputnik

  • *****
  • Posts: 43
  • Joined: 17 Jan 2011
  • Loc: Missouri

Posted 28 October 2012 - 09:44 PM

Yes I agree Gastrol. It's great to set in the upright position for a minute or so while setting up. I typically set it upright in the kitchen before I take the base out the back door, but I wouldn't want to try it with a slower scope. I don't have kids to worry about, and the thing is just ultra stable in that configuration.

It's not an issue when I transport it to the dark sky site since the OTA is laying sideways on the backseat of the car. However, I almost always take the 14" to the dark sky site rather than the 10".

In the end, it's all a matter of preference, and I really like the idea of the rubber feet. It will be my next project...

#260 Sarkikos

Sarkikos

    Hubble

  • *****
  • Posts: 16198
  • Joined: 18 Dec 2007
  • Loc: Per sylvam ad astra

Posted 28 October 2012 - 11:11 PM

I keep my Z8 secured on its Dob base in a corner of my bedroom upstairs. When I want to take it outside, first I unhook the OTA and rest it lengthwise on my bed. The OTA is always in one of three places: in its base, on the bed, or on the bench outside. I would never chance setting an OTA vertically on its own.

When I take my 10" to the dark site, it's in a large OTA bag. When I remove it from the bag, I immediately place it on the Dob mount. There's a lot of dew in our area, so I bring along a tarp that I can lay the OTA on at the end of the observing session, while I wipe the dew off with towels. Only then do I return the OTA to the bag in my vehicle. The idea never crossed my mind to rest any OTA vertically unless it's in the Dob mount. Not something I'd ever do. :shrug:

Mike

#261 Jaimo!

Jaimo!

    Apollo

  • *****
  • Posts: 1338
  • Joined: 11 Oct 2007
  • Loc: Exit 135 / 40° North

Posted 28 October 2012 - 11:26 PM

I keep my Z8 secured on its Dob base in a corner of my bedroom upstairs. When I want to take it outside, first I unhook the OTA and rest it lengthwise on my bed. The OTA is always in one of three places: in its base, on the bed, or on the bench outside. I would never chance setting an OTA vertically on its own.

When I take my 10" to the dark site, it's in a large OTA bag. When I remove it from the bag, I immediately place it on the Dob mount. There's a lot of dew in our area, so I bring along a tarp that I can lay the OTA on at the end of the observing session, while I wipe the dew off with towels. Only then do I return the OTA to the bag in my vehicle. The idea never crossed my mind to rest any OTA vertically unless it's in the Dob mount. Not something I'd ever do. :shrug:

Mike



Why would you not rest an OTA vertically?

Jaimo!

#262 BSJ

BSJ

    Apollo

  • *****
  • Posts: 1248
  • Joined: 22 Dec 2008
  • Loc: Grand Isle, VT

Posted 29 October 2012 - 06:24 AM

[/quote]
Why would you not rest an OTA vertically?
Jaimo! [/quote]

Cause nobody is going to yell TIMBER, to warn you when it starts to fall over!

#263 Sarkikos

Sarkikos

    Hubble

  • *****
  • Posts: 16198
  • Joined: 18 Dec 2007
  • Loc: Per sylvam ad astra

Posted 29 October 2012 - 08:31 AM

Exactly! Resting the OTA vertically is inherently the most unstable position ... unless it's in the Dob base.

My advice: buy a bench for your yard and lay the OTA on the bench. Benches usually have a curved seat that will prevent the OTA from rolling off onto the ground. What's going to prevent the OTA from falling when resting vertically? Three little pegs? :shrug:

At my dark site, I set up on grass. That is the best area to set up due to thermal properties. I would never rest an OTA vertically on grass. Not very stable.

Even inside my house, most areas are covered with plush carpet, not a very good surface for resting an OTA on-end.

YMMV

Mike

#264 Jaimo!

Jaimo!

    Apollo

  • *****
  • Posts: 1338
  • Joined: 11 Oct 2007
  • Loc: Exit 135 / 40° North

Posted 29 October 2012 - 12:51 PM

Exactly! Resting the OTA vertically is inherently the most unstable position ... unless it's in the Dob base.

My advice: buy a bench for your yard and lay the OTA on the bench. Benches usually have a curved seat that will prevent the OTA from rolling off onto the ground. What's going to prevent the OTA from falling when resting vertically? Three little pegs? :shrug:

At my dark site, I set up on grass. That is the best area to set up due to thermal properties. I would never rest an OTA vertically on grass. Not very stable.

Even inside my house, most areas are covered with plush carpet, not a very good surface for resting an OTA on-end.

YMMV

Mike


Sorry Mike,

I think we will have to agree to disagree. The 3 little pegs work fine for my purposes, especially as a majority of mass of the OTA is concentrated closer to the ground, there is little chance of it just falling over. I have once placed a Z8 OTA horizontally on the tailgate of my truck, similar to your bench, and I was scared it could roll and slip off... When taking the scope outside, I will remove it from the base and set it on the stable concrete floor of my basement. I then walk the base outside and return for the OTA. I find the easiest way to manage the OTA is in the vertical position, both in the carrying up the stairs and the subsequent placement into the mount, I would fear dropping the tube while moving the tube from vertical to horizontal a few time while transporting.

To each his own, find out what works for you and do it. I also set up in the grass as I feel not only for the thermal properties but for the shock absorbing properties as well, it's not as devastating when you drop an eyepiece onto the dew covered sod, rather than the driveway.

Jaimo!

#265 bob irvin

bob irvin

    Mariner 2

  • -----
  • Posts: 265
  • Joined: 22 Mar 2011
  • Loc: Greater Los Angeles, CA

Posted 29 October 2012 - 03:32 PM

Great idea, thanks for the post. I may well give this a try on my Z10.; after I fix the back door (for my wife)

;)

bob

#266 bob irvin

bob irvin

    Mariner 2

  • -----
  • Posts: 265
  • Joined: 22 Mar 2011
  • Loc: Greater Los Angeles, CA

Posted 29 October 2012 - 04:14 PM

Here's a transport/storage box I made for my Z10. I used the dimensions from the original packing box and the foam that was used in shipping. The wheels make it easy to move around and for storage I have a weather seal around the lid to keep dust out. Note the base can be strapped on top for easy moving of the whole scope around.

Great Thread, by the way. :bow:

bob

Attached Files



#267 tag1260

tag1260

    Apollo

  • *****
  • Posts: 1040
  • Joined: 07 Oct 2012
  • Loc: Ohio, USA

Posted 29 October 2012 - 04:18 PM

Hey Bob,

Guess who's gonna steal your idea for transport!!! ;)

#268 Sarkikos

Sarkikos

    Hubble

  • *****
  • Posts: 16198
  • Joined: 18 Dec 2007
  • Loc: Per sylvam ad astra

Posted 29 October 2012 - 04:29 PM

That would not work for me. No way to get something like that down the stairs and off the porch!

Here is what I use to carry my 10" f/4.8 OTA out of my house and into my vehicle to travel to the dark site:

47"x17"x18" Orion Padded Telescope Case

But I don't remember it costing that much when I bought mine five years ago. :thinking:

If I'm going to set up the 10" by my house I just carry out the OTA in my arms. No big deal.

:grin:
Mike

#269 gene williams

gene williams

    Sputnik

  • *****
  • Posts: 43
  • Joined: 17 Jan 2011
  • Loc: Missouri

Posted 29 October 2012 - 08:44 PM

yes, Mike I had a Z8 many years ago. At F6 I wouldn't set it up vertically either. I imagine it would tip over pretty easily. The Z10 and Z12 are F4.9 and very stable in the vertical position. I can literally tip it a good twenty degrees from vertical while it is upright, and when I let go it assumes its upright position. The mirror at the bottom represents most of the weight.

It's also very, very hard on a persons back once you get into the Z10 and Z12 size. The Z8 is really easy compared to these beasts. Anything a person can do to make the lifting easier just makes it that much more enjoyable to use the scope. Doing the bearhug on the Z10 and letting it gently lower to the floor is very satisfying, easy, and natural.

#270 fnowat

fnowat

    Explorer 1

  • *****
  • Posts: 60
  • Joined: 11 Jun 2012
  • Loc: N.E. Illinois (Chicago suburbs)

Posted 18 November 2012 - 04:55 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. :grin:
  • 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! :rainbow:


Thank you for the lead/link to cool mods for our "Z" telescopes! Here in the gap between the Midwest and the Northeast it is way-too often cold and cloudy. The Mrs and I did a simple thing, we gave our Dob 'pajamas' (aka-sweat pants) just to lessen the frost build-up. We leave the fan on under her to keep the mirror ambient.

Attached Files



#271 fnowat

fnowat

    Explorer 1

  • *****
  • Posts: 60
  • Joined: 11 Jun 2012
  • Loc: N.E. Illinois (Chicago suburbs)

Posted 18 November 2012 - 04:56 PM

Forgot- love it, love it, love it...

#272 Sarkikos

Sarkikos

    Hubble

  • *****
  • Posts: 16198
  • Joined: 18 Dec 2007
  • Loc: Per sylvam ad astra

Posted 18 November 2012 - 07:32 PM

fnowat,

Judging from your picture, I see one obvious upgrade for your Z Dob: a chair to sit in! You'll hurt your back bending over like that.

Don't stand when you can sit, don't sit when you can lie. - Old Civil Servant Saying

:grin:
Mike

#273 fnowat

fnowat

    Explorer 1

  • *****
  • Posts: 60
  • Joined: 11 Jun 2012
  • Loc: N.E. Illinois (Chicago suburbs)

Posted 20 November 2012 - 12:05 AM

LOL :)
Thanks Mike, that is on my Christmas list. And in the trunk of the care there ia a little 3-legged chair/stool which is only about 14" tall.

#274 Tim L

Tim L

    Vanguard

  • *****
  • Posts: 2044
  • Joined: 17 Dec 2008
  • Loc: Missouri

Posted 20 November 2012 - 04:06 PM

Thank you for the lead/link to cool mods for our "Z" telescopes! Here in the gap between the Midwest and the Northeast it is way-too often cold and cloudy. The Mrs and I did a simple thing, we gave our Dob 'pajamas' (aka-sweat pants) just to lessen the frost build-up. We leave the fan on under her to keep the mirror ambient.


I like the idea! Is it really just a pair of sweat pants big enough for the tube or did you use some other material?

#275 csrlice12

csrlice12

    Voyager 1

  • *****
  • Posts: 10454
  • Joined: 22 May 2012
  • Loc: Denver, CO

Posted 20 November 2012 - 04:39 PM

+1 on a laser to collimate your scope; but I recommend a Howie Glatter laser. That way you don't have to worry about collimating your collimater. Howie glatter lasers stay collimated unless you drop it while skydiving...Sometimes a quality product just can't be beat.






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics