Hmmm. 2 inches thick? Bizzarre. Typically you get about 1.25 to 1.5 inches thick.
> So now what are my options?
> 1. I could mask the mirror down to a 6" but I already have a 5"
> Celestron Comet Catcher. I don't need a big scope with a small
> aperture.
Easy solution, but only good as a temporary.
> 2. Can I correct the mirror without the original tool? I have never
> made a mirror but have read a lot about it. I'm handy with my
> hands and do a lot of wood and metal working. I have a home
> shop where I could do it. How do I make a tool to do this?
> Is it worth it?
Well, unless you wish to change the focal length, you don't need to have the original tool. You can cast a slab of plaster of paris/dental plaster/whatever on your mirror, and then cast your lap on that. No problem. Strip the old coating off (a solution of drano works pretty good) and polish away!
> 3. Maybe the mirror is not all that bad so I should just have it
> recoated and use it the way it. I used it as is last summer.
> I live in a suburb of St. Paul, Mn. and do my viewing from
> my back yard. The seeing is not very good. I have never seen more
> than the two brightest star of the little dipper with my naked eyes.
> So I think the magnitude limit is about 3.5. I am a rank beginner so
> there are a lot of objects that I can capture that are interesting
> to me. My goal is to log as many of the Messier (sp?) objects as I
> can from my back yard. I have about 10 so far.
The difference between a good mirror and a poor one _is_ noticeable. If you can stand futzing with it for awhile, I would advise to fix it.
> 4. Warp the mirror to the proper correction by pushing on the center
> of the back when it is mounted. I tried it on the bench with the
> tester and I got the mirror into 1/4 tolerance. I don't know what
> other distortion I caused. I saw and article in S&T about doing that
> to a spherical mirror by epoxying a bolt to the center of the mirror
> and supporting it all around the edge. Each time the scope was setup
> for use the mirror was adjusted using a Ronchi star test. The bolt
> pulled the mirror into a parabolic shape. I would need to do the
> opposite.
> That is push it into shape. I wonder if pushing it against only 3
> mirror clips would cause other distortion. Does anyone have an opinion?
> Perhaps I could devise some sort of ring that would rest against the
> front perimeter of the mirror.
Don't bother.
Mark VandeWettering