[ATM] Corrector cell design

[Chris Dalla Piazza]

I am getting ready to design the corrector cell for my Houghton Newtonian
and was wondering how to arrive at the final dimensions.  A assume that the
optics are held in place through compression; too little and the optics
rotate and shift, too much and you pinch the optics.  Also, how do you
protect yourself from temperature drops when the cell will shrink, pinching
the optics further?

My idea to is use a lens spacing material something like weather stripping
or double sided tape that has a spongy texture.  I am hoping that if I can
use adhesion to prevent the optics from shifting, I can reduce the amount of
pinching force needed to hold them in place.  I would like to have the first
corrector stationary since this will hold the secondary.  However, I want to
have the second lens adjustable with three centering screws around the
outside edge so that I center the second lens relative to the first lens.

I am assuming that a threaded ring like they use in eyepieces would be
prohibitively expensive to make.  So, how do I arrive at the inside
dimension for the cell and how much space around the edges of the lenses
should I leave?  Should the cell not be made to an exact inside dimension?
If I do this I can adjust the pinching force by tightening the screws that
hold the cell together, but then I have to worry about the screws coming
loose.  Do I just oversize the cell and then use shimming material as
needed?

Also, I would like to do this without committing to metal until I have
looked through the uncoated optics.  Do you think I could get away with wood
or another material?

Dimensions:
Corrector cell inside clear diameter: 6"
Corrector cell maximum outside diameter: 7.5" (a little less than the
telescope tube inside diameter)
Corrector lens outside diameter: 6.25"
Total corrector lens thicknesses: 1" (1/2" each)

Any ideas are welcome!