[ATM] Conic section manufacturing

[Chuck Taylor <chucktaylor@speakeasy.net>]

Everyone saw the spherical mirrors flexed into paraboloids. Has anyone 
here experimented with taking a spherical mirror, using a similar rig 
but flexing in the opposite direction (oblate) and then refiguring to a 
spheroid and releasing the tension to produce a paraboloid?

It seems it might give a smoother figure since figuring is producing a 
spheroidal surface. And, it opens up the possibility for easier testing 
once you know how much flex to dial in.

If it is not possible to flex all the way back to a sphere for fast 
mirrors, it might still mean you only have to test for a much smaller 
deviation from sphere than you do for a f/4 paraboloid --- flex part of 
it, polish to an elliptical surface and release tension to relax into a 
full paraboloid.

It would be similar to the method of attaching weights to figure an 
off-axis section of a paraboloid.

And, it might open up possibilities for producing a hyperboloid surface 
for those wanting to make an R-C.

Thoughts?

Chuck Taylor
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