Calibration of Thread Pitch Micrometers

[56flh]

I have a good understanding of calibrating OD micrometers, but I'm a little unsure about pitch mics.

The preparation would be the same for OD mics and pitch mics, but the anvils of a pitch mic are removeable/interchangeable so do each pair of anvils have to be certified as a set? When using a pitch mic, it is set up based on zeroing the mic with the anvils closed.

 

[Hershal]

I would say that the set as a whole should be calibrated; and certainty each paring will have its own uncertainty contributions that must be considered.

 

[Steve Weber]

We have a 0-1", 1"-2", and a 2"-3" Pitch mic. Each mic included a standard used for setting the removable anvils. We send each of the standards out to an accredited lab for calibration. We use these approved standards to set the mic each time prior to use. We adjust the mic as close as possible to read whatever the standard indicates. To date, we have never had a quality problem or has it been an issue with the auditors.

 

[bwr1108]

Is lead error of the thimble screw tested for acceptance or is your procedure to only verify/set zero?