[ATM] Crazy simple mirror cell idea

[Mike Carambat <mcaramb@rocketmail.com>]

Finally building my 14" scope with a primary of
moderate thickness (about 1.75"). Biggest scope I've
built so far is my 10". Now, I've found that these
larger mirrors need more complex mirror cells (9,12,18
points, etc)... to keep from warping due to gravity,
pressure, temperature, etc..

I'm just wondering why you can't just insert one into
a 14.5" diameter, 2" high x 1/8" thick cylinder, with
a wooden base, lined with foam rubber (I suppose,
kinda like that memory foam which adjusts to fit your
shape, giving equal pressure to all points). 

Cut three large air holes in the base for air
circulation, then put in your mirror. Fix the
arrangement into a regular mirror cell system. DONE.

Sure, it would fall out if turned upside down and
shaken, but if the right size and tightness, in
general it would be quite stable with the foam on the
sides providing friction to hold everything in place.

The cylindrical band would be sturdy enough to not
allow deformation when the scope is near horizontal,
so hopefully, the force of gravity wouldn't all be
focused on the very bottom, which could cause a pinch
point there. All in all, I'm assuming about an 1/8" of
foam around the mirror and it's base would suffice to
give enough play for potential expansion.

My only thought is that the friction from the foam on
the base may be uneven,  causing "hang points" which
wouldn't allow the mirror to move during expansion at
those points, thus causing pinch points. This is the
apparent drawback with using silicon glue to hold
mirrors down. It doesn't allow the mirror to move at
those points. My idea would allow movement and equal
friction everywhere (hopefully).

I dunno... anyone done this before?

-Mike

Mike Carambat
Design Wizardry - http://www.designwizardry.com

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