What is a pin gage primarily used for?

A pin gage is primarily used for measuring hole diameter. This tool is designed to provide a precise measurement of the size of holes, as it consists of a set of precise cylindrical pins of varying diameters. By inserting these pins into a hole, the user can determine whether the hole meets the required specifications based on whether the pin fits or does not fit.

The effectiveness of a pin gage lies in its accuracy and simplicity, making it an essential tool in quality control processes for confirming that holes are drilled, bored, or machined to the correct dimensions. In comparison, the other options involve different aspects of measurement that pin gages are not designed for—like thread length, surface finish, or overall part dimensions—making them less suitable for evaluating hole diameters specifically.