[ATM] Re: Second Thoughts on Mirror Support

[jonah at eecs.berkeley.edu (Jeff Anderson-Lee)]

tkrajci@san.osd.mil wrote:

>>From: "Don D'Egidio" <djd521@comcast.net>
>>    
>>
>>I have a Discovery 17.5" TD dob that has the mirror secured with RTV. The
>>mirror is 2" thick and what Discovery did was to mount the mirror on one 
>>large
>>plate rather than 3 plates. 
>>    
>>
>No pivots?  Just RTV bonding of one mirror to one plate...at nine points?
>
>Got any photos or drawings of this?
>
>  
>
>>...They use 9 points to support the mirror,
>>simulating three separate triangles with three support points each....
>>    
>>
>How does one rigid plate (with 9 points) simulate three triangles (3 
>points each) that are free to move on pivots?  Again, I'm interested in 
>seeing photos or drawings.
>  
>
The plate doesn't simulate it -- the RTV does.  Make the plate thick 
enough that it doesn't bend significantly and the RTV can probably make 
up the difference: a compliant cell!

Jeff