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Dob Tube restoration

Started by netmatt, 01/24/2008 03:00PM
Posted 01/24/2008 03:00PM Opening Post
I am going to start cleaning up my 12.5 Dob. It is an older one I bought, and it needs some work. I was going to paint the outside, and I was going to just use some Gloss black. I was also considering painting the inside with a Flat black. Any issues here, or recommendations?

Also, I read up on how to fix the sticking problems on the teflon, so will be doing that.

One post mentioned a Sliding Weight system, which sounds like a good idea that I can make, since different eyepieces seem to send the scope vertical. Anyone do this, and have a link or two with some pics or a how-to? The tube is a older Meade sonotube, so I am not sure the best way to attach..say a T-Bar or something. Any recommendations?

Any other things that are a good ideas I may be missing?

Thanks,
Matt

Attached Image:

netmatt's attachment for post 40589
Posted 01/24/2008 03:22PM | Edited 01/25/2008 02:09AM #1
Depending on how black the inside of the tube already is putting some black flocking material opposite the focuser should make the most difference in contrast. If there are a lot of stray lights where you observe then a light shield extending from the front of the scope would help too. As far as counterweights go, it would help if some of the weight on the back was attached to the bottom side of the tube (45 degrees around the tube so it doesn't hit the tube). That way the scope won't have a tendency to tip up when near vertical. For a sliding counter weight this kit from Rockler works great (change the cart quantity to 1 if you don't want 2 of them)
http://www.rockler.com/product.cfm?page=5209
I made a simple carrier from scrap wood which fits small sporting goods store weights. The kit has everything else except screws to attach it to the tube. In the case of my lightbridge it has a metal tube so I used heavy duty double sided tape to attach the rail to the tube. For a sonotube I think machine screws all the way through the tube with washers (painted black) on the inside would be the best bet.

Joplin

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Joplin Motisher-Chittenden's attachment for post 119833
Posted 01/24/2008 07:39PM #2
Remember one thing about gloss black, it is the most unforgiving of all paint colors as far as defects are concerned, it will show everything. Also, black is not the best color for a solid tube, the heating during the day will be a big problem. White is much better or another light color.
The inside in flat black is a good idea. The suggestion of having the paint mixed with extra black pigment is the best solution. The placing of a clocking paper or material opposite the focuser is also a good idea. The picture shows this on a truss Dob.

Attached Image:

fblue's attachment for post 119842

[SIZE="Large"][/SIZE][COLOR="Blue"][/COLOR] Floyd Blue grin
Amateur Imager
Posted 01/24/2008 07:39PM #3
Remember one thing about gloss black, it is the most unforgiving of all paint colors as far as defects are concerned, it will show everything. Also, black is not the best color for a solid tube, the heating during the day will be a big problem. White is much better or another light color.
The inside in flat black is a good idea. The suggestion of having the paint mixed with extra black pigment is the best solution. The placing of a flocking paper or material opposite the focuser is also a good idea. The picture shows this on a truss Dob.

Attached Image:

fblue's attachment for post 119843

[SIZE="Large"][/SIZE][COLOR="Blue"][/COLOR] Floyd Blue grin
Amateur Imager
Posted 01/26/2008 08:04PM #4
>>>Any other things that are a good ideas I may be missing?<<<



If you do not already have it, then active cooling.

This size scope can really really benefit from variable speed, vibration free, moving air. To cool the mirror, exchange the air in the tube, and clean the boundary layer thermal turbulances at the mirror surface.