[ATM] New? Idea for mirror support

[tkrajci at san.osd.mil (tkrajci@san.osd.mil)]

>From: "Doug Williams" <salguod@minbaritm.com>

>...But what if we glue only the very
>center of the mirror?  Just put one pad of RTV at the center to keep the
>mirror from sliding off the wiffle tree?  If there is any distortion, it 
is
>at the center of the mirror, which is in the shadow of the secondary 
anyway.

>But wait!  We can get rid of even that!  Glue a flange to the center of 
the
>mirror on the backside.  This flange holds a support post perpendicular to
>it.  

>Now when the scope is lowered toward the horizon, the rod
>restrains the mirror from sliding off of the wiffle tree.  The rod is
>performing the same function as the sling....

>Has anybody tried something like this?  

Yes, the pro’s sometimes do this with segmented mirrors.

See my post from a few days ago that listed some professional literature.  
This is a central post lateral support scheme.  Sometimes the pro’s will 
bond a thin disk to the rear of the mirror, and then bond a support post 
to the thin disk.  The thin disk is not very stiff in the axial (vertical) 
support direction, so it does not provide that direction of support...but 
it’s plenty stiff in the lateral (horizontal) direction.  

With this central support you have a lateral support, but not an axial 
support.

Now you need to ensure you minimize stiction of the whiffletree so that 
the whiffletree provides only axial support, and not lateral.

Please let me know how useful the professional literature was that I 
mentioned in my post a few days ago.

Thanks in advance.

Tom Krajci
Tashkent, Uzbekistan

PS.  Now that I think of it, see:
http://overton.tamu.edu/aset/krajci
especially
http://overton.tamu.edu/aset/krajci/cell-bearing.htm
and look at the designs from Tony Owens at the bottom of the page that use 
a flexible disk...stiff in one direction, flexible in another...but in 
this case to focus/move a mirror.  I hope this helps clear things up.