RE: [ATM] machine generated zones

["Jerry Reddell" <jerry.p.reddell63@sbcglobal.net>]

Sounds like the center became thermally warmer than the rest of the mirror,
because of the lap overhang of about 2 inches. This warmer area expands
above the rest of the mirror and is ground  level with the rest...When the
mirror cools, the center contracts to be below the mirror surface, thus the
hole...

 Don't have any suggestions on curing unless it is running slower and for
less time....

Jerry Reddell

-----Original Message-----
From:  steve beccue


My first work with a polishing machine.  16" f/1.88 sphere.

There is a "hole" in about the inner 2 inches.  It looks much
like a crater on the moon.  There was no side-to-side motion on
the lap.  The lap was 12 inches diameter.  Other than the crater,
the finish was smooth, an excellent sphere, with no TDE.

Can anyone tell me the cause and cure?



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