How are miceometers and vernier calipers calibrated?

Question

And also what is a runout and what is it used for?

Answer 1

I liked "miceometers" better.

Answer 2

Ironically even though called Micrometers, they can be calibrated in thousandths of inches, empirical, as well as metric.  I'ts a Micro Meter.  Run-out is the affect of the dimension.

Run out is normally associated with round objects where the concern is interference with two mating components and the resulting Annulus interface.  Normally it's a measurement of the inner portion, ID  and would be significant with seal tolerance. as the outer portion, ID is normally static.

Speaking of Mice:

Hickory Dickory Doc,

Three mice ran up the clock,

The clock struck one,

But the other two escaped without serious injury~

Answer 3

They are calibrated using a set of standard blocks or a super-micrometer traceable to NIST. Even these are subject to calibration. You make comparative measurements within a specified tolerance depending on how many decimal points of measurement you intend to be measuring with these instruments. There is a mil-spec standard outlining the requirements. Most vendors for inspection equipment can calibrate these for you and supply you with a certificate of accuracy.