From: "Tom Krajci" 
To: 
Reply-To: "Tom Krajci" 


>From: "Rick" 

>First off, i did not have time to leave the scope equalize, but it
>was out in barn so I doubt if it was that far off....

I recommend adding cooling fans to help speed this process.  It'll help in
those "I want to observe Jupiter NOW!" situations.  Holes in the
mirror cell are a good start...but active cooling will get you even faster
results.

>...The mirror is mounted on three layers of plywood laminated together,
>with 6 blobs of silicone placed according to plop,and three blobs
>in between the posts and the mirror, the mirror is 7/8" thick.

Does this mean you have glued the mirror to one piece of plywood with six
RTV blobs?  If yes, that's going to cause problems.  If you have glued the
mirror to the plywood with only three RTV blobs then there should not be a
problem with the mirror cell warping/stressing the mirror.

If you tell me what the thickness and material of your 10 inch mirror
is...we can run that on PLOP and see how many support points you need. My
10 inch, 1.3 inch thick, pyrex mirror is on a four point support...PLOP
says that was 'good enough'...and after five years of use...no signs of
mirror stress or warpage from the cell.

See:
http://overton.tamu.edu/aset/krajci
specifically the pages on mirror cells for ideas on support schemes. (The
oldest page on 12 point cells has a description of a four point support at
the top to start things off.)

Hope this helps,
Tom Krajci
Tashkent, Uzbekistan


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