Re: [ATM] Conic section manufacturing

["Bill Kelley" <flex@commspeed.net>]

Chuck & list,

Subject: [ATM] Conic section manufacturing


> 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?

Works, but flexers consider field tweaking of the figure makes it 
desirable to put the flex system in the scope. Adler helped one worker 
make a secondary this way for a Cassegrain.
   
> 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.

Quite so. Tension ( read "compression" ) required is calculated in 
Adler's program Flex.exe.

> 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.

Not much to be gained it seems.(my opinion)

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

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

Quite so. Flex reproduces all the conics through the hyperboloid. The
R-C can be made with the sphere - in its flex cell - in the telescope..
 
> Thoughts?  
Chuck Taylor 

Make one Chuck and report back. - Bill Kelley


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