Know Your Gage-Block Basics

Gage blocks have been used by metrologists for more than 85 years, yet they have not changed tangibly in design, application, or even accuracy in the past 70 years. Though gage blocks — defined as square, rectangular, or round shapes (manufactured of steel and other materials) that have flat and parallel opposing sides — are simple compared to most types of sophisticated gaging today, they are still the industry-standard length masters.

Gage blocks are used daily in a broad spectrum of applications, from measuring parts loosely on the factory floor to measuring to millionths in an environmentally controlled metrology laboratory.

Although gage blocks are quite familiar to metrologists, there are still misconceptions and considerable misuse in the field — and it is helpful to be reminded of the basics. This article will discuss the conditions necessary for optimum measurement, clarify the terms wringing and stacking, discuss how to wring gage blocks correctly, and provide an update about coming changes in gage-block specifications.

By Robert Edmunds III