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kfiscus
Carpal Tunnel
*****

Reged: 07/09/12

Loc: Albert Lea, MN, USA
Re: Drilling holes in XT8 Dob new [Re: jimdp]
      #5621020 - 01/13/13 03:05 PM

PM sent.

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Allan...
sage


Reged: 10/24/12

Loc: Penticton B.C. Canada
Re: Drilling holes in XT8 Dob new [Re: kfiscus]
      #5621171 - 01/13/13 04:31 PM

Got er!

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Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Drilling holes in XT8 Dob new [Re: drewp]
      #5621458 - 01/13/13 07:04 PM

Quote:

i have never heard of heat from the hand having any effect on tube currents. turn on your fan and forget the knob.




A tube current caused by your body heat is not something you hear, it is something that you can see through the eyepiece.

To see the effect of your body heat, you need to start with a thermally stable scope. Point the scope at bright star using a moderate magnification (200x) and defocus the image, place your hand in front of the scope and you can see the heat rising. If the seeing is sufficiently stable you can see the effect of just touching the tube with your warm hand.

I have owned my trusted 10 inch F/5 Made in Taiwan GSO Dob for about 10 years. On an excellent night, it is capable of resolving double stars at the Dawes Limit.. 0.5 arc-seconds, about one fifth the separation of the double-double. Using gloves is one trick I learned that makes this possible.

Jon


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kenrenard
Carpal Tunnel


Reged: 12/13/12

Loc: Dunmore, PA
Re: Drilling holes in XT8 Dob new [Re: Jon Isaacs]
      #5621471 - 01/13/13 07:12 PM

Quote:

Quote:

i have never heard of heat from the hand having any effect on tube currents. turn on your fan and forget the knob.




A tube current caused by your body heat is not something you hear, it is something that you can see through the eyepiece.

To see the effect of your body heat, you need to start with a thermally stable scope. Point the scope at bright star using a moderate magnification (200x) and defocus the image, place your hand in front of the scope and you can see the heat rising. If the seeing is sufficiently stable you can see the effect of just touching the tube with your warm hand.

I have owned my trusted 10 inch F/5 Made in Taiwan GSO Dob for about 10 years. On an excellent night, it is capable of resolving double stars at the Dawes Limit.. 0.5 arc-seconds, about one fifth the separation of the double-double. Using gloves is one trick I learned that makes this possible.

Jon





That's interesting. Jon you are full of wisdom. I wouldn't even think of that. I thought I was clever using small magnets as counterweights and using a towel over my head to block out stray light.

It would be interesting to find some more tricks that experienced observers use. Sky and Telescope just this month had an observing article with using an eyepatch to dark adapt. I was thinking about it but my kids might think I am a pirate.

Ken


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skinnyonce
super member
*****

Reged: 03/23/11

Loc: ohio
Re: Drilling holes in XT8 Dob new [Re: Jon Isaacs]
      #5621488 - 01/13/13 07:26 PM

Quote:

Quote:

i have never heard of heat from the hand having any effect on tube currents. turn on your fan and forget the knob.




A tube current caused by your body heat is not something you hear, it is something that you can see through the eye front of the scope and you can see the heat rising. just touching the tube with your warm hand.
Jon




Just wear a glove then


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Mxplx2
sage


Reged: 09/12/12

Loc: NE PA USA
Re: Drilling holes in XT8 Dob new [Re: Allan...]
      #5621524 - 01/13/13 07:52 PM

There are glues like pliobond and silicone adhesive that hold well under normal use, but can be removed with a little effort, in case your not happy with the knob.

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JLovell
scholastic sledgehammer


Reged: 01/12/10

Loc: Georgia
Re: Drilling holes in XT8 Dob new [Re: Mxplx2]
      #5621802 - 01/13/13 10:12 PM

I love the knob on mine, and use it exactly as Jon described, one hand on the knob for alt, and one on the left side bearing of the base. I can push with one hand and pull with the other to give the scope a pure torque, and it makes the az movements smoother and much easier to control.

The knob also helped my instantly visualize how to move my scope to track objects. When I grab the knob when looking through the scope, I imaging I'm reaching into what I'm viewing, and grabbing the star or planet, and that I'm dragging it around. As soon as I realized that, I could track everything quite easily. Before that, I'd frequently go the wrong way.


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Bill Weir
Carpal Tunnel
*****

Reged: 06/01/04

Loc: Metchosin (Victoria), Canada
Re: Drilling holes in XT8 Dob new [Re: JLovell]
      #5621882 - 01/13/13 11:07 PM

Getting back to the drilling fear. Get a 1" thick block of wood and drill through it. Now you have something to hold against the tube while wrapping your fingers into the tube. It will guide the bit and prevent it from slipping. Straddle the tube to hold it steady and away you go. I've done this when I drilled a couple of holes when replacing the focuser on my 6" Orion.

Holding the block of wood on the inside of the tube gave some support when doing a light tap do set the point before begining the drilling.

Bill


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Achernar
Postmaster
*****

Reged: 02/25/06

Loc: Mobile, Alabama, USA
Re: Drilling holes in XT8 Dob new [Re: Allan...]
      #5622240 - 01/14/13 08:13 AM

I wouldn't use a center punch, but a piece of angle iron in the shape of a C with a hole drilled through it would work as a drill guide. So would a piece of wood with a vee cut out of one side, with the guide hole drilled at the vee. Start with a small drill bit to make a pilot hole, then follow up with the full sized drill bit. An alternative is to use a drill press, you would want to make a cradle to keep the tube from moving. If you go that route, you will want to have someone assist you in holding the tube. Otherwise, a cordless or corded hand held drill is how I would do it. It goes without saying that I would remove the optics before doing this. Just remove the spider and primary mirror cell with the mirrors in them, drill your hole, add the navigation handle, then replace and re-collimate the optics in the tube.

Taras


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kenrenard
Carpal Tunnel


Reged: 12/13/12

Loc: Dunmore, PA
Re: Drilling holes in XT8 Dob new [Re: Achernar]
      #5622332 - 01/14/13 09:36 AM

Clare,
I have the same XT8. After reading this. I am going to put a knob on my tube as well. Hope your drilling goes smooth.


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JLovell
scholastic sledgehammer


Reged: 01/12/10

Loc: Georgia
Re: Drilling holes in XT8 Dob new [Re: kenrenard]
      #5622415 - 01/14/13 10:20 AM

Another thought... Try removing one of the screws that hold the metal ring at the top of the tube. My scope has such a screw about 1/4 inch away from the knob mine came with. Take that screw to a hardware store to figure out the size and thread pitch. Get another screw the same size and pitch, and the type of knob with a hole all the way through so that the screw installs in that hole as opposed to from the inside. Get the new screw of appropriate length that it protrudes from the knob exactly the length of the original screw minus the head. Then simply screw the new screw with the knob back into the hole that is already there. No drilling required!

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SteveG
Post Laureate
*****

Reged: 09/27/06

Loc: Seattle, WA
Re: Drilling holes in XT8 Dob new [Re: JLovell]
      #5622726 - 01/14/13 01:50 PM

As others have said, it's an easy install. Use masking tape on the inside, start with a little hole and then drill the larger hole. Here's a nice little knob:
http://www.opticsmart.com/accessories/upgrades-and-tweaks.html


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NeilMac
Carpal Tunnel


Reged: 09/25/10

Loc: MedHat, AB, Canada
Re: Drilling holes in XT8 Dob new [Re: SteveG]
      #5622771 - 01/14/13 02:19 PM

As what SteveG says. When dealing with slippery surfaces, you tape them then use a sharp small (1mm) drill used for metals, slowly apply pressing lightly. Then the size you require for the screw mount.

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stargazer424
sage


Reged: 10/03/05

Loc: Central NJ
Re: Drilling holes in XT8 Dob new [Re: NeilMac]
      #5622884 - 01/14/13 03:28 PM

Just the title of this post makes me cringe. I can't imagine drilling holes in mine...good luck, however you do it.

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Allan...
sage


Reged: 10/24/12

Loc: Penticton B.C. Canada
Re: Drilling holes in XT8 Dob new [Re: SteveG]
      #5624909 - 01/15/13 06:09 PM

Just ordered one of those Soft grip guide knobs; thanks for the tip, Steve. I could've gone to the hardware store and picked out something that would work (and cost less) but this one looks good and I know it will do the job. Got lots of advice now on the drilling job, so not worried. thanks, Clare

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kenrenard
Carpal Tunnel


Reged: 12/13/12

Loc: Dunmore, PA
Re: Drilling holes in XT8 Dob [Re: Allan...]
      #5629400 - 01/18/13 06:42 AM Attachment (9 downloads)

Clare,
I installed the same knob last night. I attached some pictures and hopefully this helps anyone thinking of doing the same.

The first step was removing the band across the top of the tube. This is held in place with some phillips head screws. Next I removed the tube from the bas and set the tube open end down on a couch (My wife was not crazy about this idea!) I used electrical tape on both sides where I was going to drill and started with the smallest drill bit I have.

Edited by kenrenard (01/18/13 06:47 AM)


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kenrenard
Carpal Tunnel


Reged: 12/13/12

Loc: Dunmore, PA
Re: Drilling holes in XT8 Dob new [Re: kenrenard]
      #5629410 - 01/18/13 06:52 AM Attachment (9 downloads)

The next step I moved to a 7/32 bit which was perfect size for the knob screw. I used a damp paper towel to catch any drill droppings from the end. Then I used another wet paper towel followed by a dry one to wipe out the tube. Installing the knob was one screw so that was easy.

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kenrenard
Carpal Tunnel


Reged: 12/13/12

Loc: Dunmore, PA
Re: Drilling holes in XT8 Dob new [Re: kenrenard]
      #5629413 - 01/18/13 07:00 AM Attachment (12 downloads)

The finished product is shown below. I ended up placing the knob a bit off center which is where I wanted it for movements while at the eyepiece. I ordered the knob from opticsmart.com and it arrived in less than two days. I also installed a set of Bob's knobs which were extremely easy to install. I think the both items are easy upgrades for a beginner to install.

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NeilMac
Carpal Tunnel


Reged: 09/25/10

Loc: MedHat, AB, Canada
Re: Drilling holes in XT8 Dob new [Re: kenrenard]
      #5629667 - 01/18/13 10:45 AM

I like your secondary mirror adjustment screws
Good job on the knob


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kenrenard
Carpal Tunnel


Reged: 12/13/12

Loc: Dunmore, PA
Re: Drilling holes in XT8 Dob new [Re: NeilMac]
      #5629671 - 01/18/13 10:49 AM

Thanks I ordered the secondary screws from Bob's Knobs they are the 30mm length knobs. Bob e-mailed me the day I ordered and verified the right length. They arrived in 2 days with instructions they took only a few minutes to install.

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