Re: [ATM] Grinding questions

["Bob May" <bobmay@nethere.com>]

It is now time to start doing some TOT grinding to open the radius up.
If you work at it a bit, you will be able to keep the ROC within 1/4" of the
desired ROC without any real problem.  I'll note that it isn't til you get
to a polished state that the real ROC will pop out.
As to the temp problem that you are seeing (thinking that you are seeing),
if you really are seeing such, consider that piece of glass very suspect for
stress as the ROC shouldn't be changing at all.  The larger grit size
produces pits of substantial size and you may be seeing the legs of the
spherometer falling into different holes as well as the nonsphericalicity of
the surface at that grit size if you are still using a long stroke with a
wide W.
Finally, measuring with a spherometer is indeed measutring the SAG of the
surface.
Bob May
bobmay@nethere.com
http://nav.to/bobmay
http://bobmay.astronomy.net

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