Posted by BillS on December 06, 2005 at 20:04:12:
In Reply to: Re: accurate span measurment posted by John Thomas on December 06, 2005 at 17:45:59:
Yep - you could squeeze .0006 out of a pair of disk mics since the disc surfaces are not fully supported in the measurement.
I agree with you - an over pin would probably be more practical and accurate than a span measurement, anyway.
We used to use a Zygo laser gage and measure over pins to avoid differences due to micrometer pressure, especially with small pitches and tight tolerances. That Zygo could be calibrated to +/- 10 millionths as I recall.
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