Hole Standards and Inspection

Hole inspection ensures that a hole will meet its proper job specifications, including fit, diameter, roundness, and condition. Gaging instruments, like pin and plug gages, determine fit. Variable instruments determine size and must make three points of contact to find out-of-round conditions. Variable instruments may be mechanical, electronic, optical, or pneumatic. More complex handheld devices include telescoping gages, split-ball gages, calipers, inside micrometers, and bore gages. Job specifications, environmental concerns, and economic issues all determine which hole inspection device to use. Choosing the wrong tool could result in an out-of-tolerance hole passing inspection. After taking this class, users should be able to explain how to measure common hole features with plug gages, pin gages, and calipers and verify they are within tolerance.