Anyone in the fastener or screw machine business producing screw threads is familiar with ‘pitch’ micrometers. These relatively simple devices are often used to set up production equipment and monitor their output, but there are many misconceptions about them which can call their usefulness into question. 

A reader emailed me after reading some of my rants on thread ring gages dealing with the problems that come up in their use and calibration. But he added another dimension to the problem since he is in the calibration business: How do the Europeans deal with their solid thread ring gages?

My last column gave the background to an extensive study of results on the calibration of some thread plug gages.

Working thread plug gages are the fixed limit functional gages used to inspect product threads on a pass/fail basis.

Most threaded products such as fasteners are verified using fixed limit gages when their ability to assemble with mating parts is of primary concern.