[ATM] Sun Test During Rough Grinding

[Bob May]

Accuracy results with a spherometer kind of depend upon the size
of them and the meter used.  Running the formula bakwards for
several ROCs will show how easy it will be to get any particular
ROC from the spherometer. I've found that at 80 grit, the ROC can
be off by a fair bit on a 4" dia. spheromeer with a 0.001" meter.
On the other hand, at that grit, a 2" error in ROC for something
around 80" ROC isn't a big deal as that can be easily fixed at
the 220 grit level.  When it gets down to getting an accurate
ROC, I usually end up doing the flashlight test on the Foucault
tester.  This allows me to see what the ROC is in a stale
enviroment.
Bob May

rmay at nethere.com
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