Quote:
Originally Posted by skies2clear
Wouldn't it matter how "thin" the mirror is in deciding whether to use a ring of silastic at the 60% zone or a proper 9 point flotation cell? It's easy to try the "ring" treatment and verify the performance on a star test. Making a proper 9 point cell will be a lot more work, but I confess, this is the way I'd be going to not take any chances, especially if you have a really nice optic. If it's so so, then maybe keep it simple.
Philip, how thick is your 13.1" mirror and what's it made of?
Cheers
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If I remember correctly they were full thickness plate glass. (I think 1" or 1.5" thick was about as thick as it came then). I don't think they were annealed in anyway either prior to grinding and figuring and polishing. They were the poormans big scopes of the day... I think they also had a 16" dob too.
Too bad the owner of Coulter Optical (the maker of the Odessy Line of dobs) had a massive heart attack and died. He was a very nice chap. Similarly with Kenneth Novak who did very fine mirror cells.
Velcro's fine for dobs , where the mirror is never likely to be rotated to an orientation where it might fall out. I'd be very hesitant about trusting velcro to hold a mirror in telescope on a equatorial which might wind up pointing downwards or even just very near or just past horizontal in park position .... that mirror might pull free and fall off the cell .... Ouch !!!!
