Re: ATM Alternative grinding machine (Simplier?)

["Bill T." <twentiethwave@hotmail.com>]

I know of experiments that tried to "pre-parabolize" the mirror coming out 
of grinding.  John Dobson was advocating something like that in the early 
90's, as I recall he was recommending a short period of very long TOT 
strokes at the end of grinding.

Basically, it's just much easier to polish a spherical surface than a non 
spherical one.  We've all noticed how polishing pressures increase during 
figuring, as soon as the mirror is deformed away from spherical.  Also, you 
have to press the lap a lot more often when polishing non-spheroids.

Bill T.



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