The noncontact nature of air gaging is gentler than mechanical contacts on some delicate, highly polished surfaces. Also, the absence of moving parts makes air tooling more durable. Liabilities, compared to mechanical systems, include the complexity and expense of providing clean, dry, compressed air, and the relative lack of mobility compared to a handheld mechanical gage. The high accuracy and speed of use of the indicating plug gage is largely due to its self-centralizing nature. With designed clearances of only a few thousandths of an inch between the plug body and the sides of the bore, the contacts are always ideally oriented on the bore's true diameter.
Operation is a piece of cake.
The user simply inserts the plug into the bore and reads the results on the display device. Because the gage remains centralized, bores can be explored axially to detect barrelshape, hourglass, or taper conditions, and radially to check for roundness. With 1 as the highest score per attribute and 4 as the lowest, you can quickly arrive at one or two choices. Rocking-type gages can be readily adjusted to gage IDs across broad ranges of sizes. Only three such gages are required to measure any ID from 0.500 through 8.000 in.