[ATM] Mirror support question

[Mark Lancaster <mslancas136@bellsouth.net>]

Hi,

I've searched the list archives for a solution regarding a particular 
form of lateral mirror support, but didn't really turn up a clear answer 
to my questions, although some posts came tantalizingly close.

I'm building a scope around a 16-inch Cassegrain mirror, which is 
2.8-inches thick and has a 6-inch wide central hole. My hope is to 
support the mirror laterally with 0.5-inch wall aluminum tubing, instead 
of the usual edge supports. My thoughts are these:

1. The lateral support tube would be firmly bolted or welded to the 
support for the flotation triangle beams (18-point support system).
2. The tube will have a retention ring just above the mirror surface to 
prevent the primary from falling forward.
3. I assume that there should be a small gap between the support tube 
wall and the wall of the primary's central hole.

I would appreciate any comments on the statements above, but in 
particular as to whether there should be some material such as felt 
between the mirror and tube, the mirror surface and retention ring, and 
what the allowable "slop" should be for both areas. I presently have 
some 0.5-inch wall aluminum tubing that only needs to be turned downed a 
few thousandths to allow a slip fit into the hole of the mirror.

Is my reasoning in the right direction, and have I overlooked anything 
fundamental?

Thanks very much!

Mark

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