Make sure the top diameter of a chamfered hole isn’t too big or too small. These gauges are often used as a quality control check after milling, drilling, and reaming. Press the three-blade probe into a chamfered hole and twist slightly to center. Once the blades touch the hole’s slopes, the dial will display the diameter. Zero set these gauges on a flat, ground surface when needed.

Choose a gauge with a measuring angle that’s greater than or equal to the angle of the chamfered hole you’re measuring.