On Fri, 22 Jan 2021 01:16:53 -0000 (UTC), John Doe
wrote:

Spehro Pefhany wrote:

John Doe wrote:
Spehro Pefhany wrote:

But, as of a few weeks ago, I have DROs on the lathe and mill, so
digital maybe makes more sense.

The lathe uses output from a micrometer?

I'm going to make a measurement with the micrometer, find the
difference from the desired measurement, and then move the tool some
number of tenths of a mm, say to take up half the difference and leave
enough for a finishing pass.

Is that what the data output on some micrometers is for?

No, AFAIUI, it's for SPC (statistical process control) where samples
are measured, recorded, and mean/standard deviations and trend lines
calculated to figure out when things have to be jiggered before the
parts start to go out of spec.

https://www.mscdirect.com/betterMRO/...ing-production

Of course if you have a lot of critical measurements and a big budget
you'll use a coordinate measuring machine (CMM) that automatically
probes the parts with a little sapphire ball.

https://ecatalog.mitutoyo.com/CRYSTA...CMM-C1840.aspx

Best regards,
Spehro Pefhany