Air gaging and back pressure can be used to measure bores under 1 mm in size. For slightly larger holes (1 to 20mm), an entire family of gages can operate. These gages lack a centralizing plug and operate more like adjustable bore gages, except they can measure bores that are a lot smaller. The small probe gages require a setting master, a process that is easier given today’s digital indicators. The probes are available in through-hole and blind-hole configurations and for both normal wear and extreme wear applications. Small probe gages are often the only way to precisely measure bores in the 1 to 5 mm range.
- Adjustable bore gages can cover a broad range of parts, but with only a limited measuring range.
- Small probe gages require a setting master, but this process is easier with digital indicators.
- Small probe gages are sometimes the only option for precisely measuring bores in the 1 to 5 mm range.
“Increase the size, though, and there is a whole family of bore gages available for measuring holes that range from 1 mm to 20 mm; in other words, a whole family of bore gages for these small bores.”