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pyotr filipivich pyotr filipivich is offline
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Default SPC - Stop Production Completely Micrometer time!

Spehro Pefhany on Fri, 22 Jan 2021
00:12:59 -0500 typed in rec.crafts.metalworking the following:
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)


Or as my instructor as Tech School said SPC - "Slows Production
Completely". That old "we expect 100% perfection at all times" when
reality is a bit more imprecise.

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.


When it works, it is wonderful. But ...
--
pyotr filipivich
"With Age comes Wisdom. Although far too often, Age travels alone."