Bore Gauges & Internal Micrometers
Bore gauges and internal micrometers measure internal diameters, checking bores and holes for size, taper and out-of-roundness. Everything on this page is Insize: dial-indicator bore gauges (2322 series, comparative measurement, needs setting against a ring gauge or micrometer first), mechanical three-point bore micrometers (3227 series, direct reading, sold as singles or sets), and digital three-point bore micrometers (3127 series, IP54/IP65 rated, direct digital readout). Between the three series, sizes run from 6mm up to 300mm.
Bore gauges need a setting ring or micrometer to calibrate before use, which makes them best suited to comparative work — checking a bore against a known good size. Internal micrometers give a direct reading on their own, so they're the better choice for a one-off measurement when you don't have a setting standard to hand.
Frequently Asked Questions
What is the difference between a bore gauge and an internal micrometer?
A bore gauge is typically used for comparative measurements and requires setting against a master such as a micrometer or ring gauge. An internal micrometer provides a direct reading of the internal diameter without the need for comparison.
What are bore gauges used for?
Bore gauges are used to measure the internal diameter of holes and bores, as well as to check for roundness, taper, and wear in components such as cylinders and machined parts.
Are Insize bore gauges accurate?
Yes, Insize bore gauges are known for their reliable accuracy and consistency, making them suitable for engineering, inspection, and general workshop use.
What sizes do internal micrometers cover?
Insize internal micrometers are supplied in sets covering 6mm up to 300mm across the 3127 and 3227 series, so you pick the set that matches the bore sizes you need to check.
Do I need setting rings for bore gauges?
Yes, bore gauges usually require setting rings or a micrometer to calibrate them before use to ensure accurate comparative measurements.
Can beginners use these tools?
Yes, both bore gauges and internal micrometers can be used by beginners, although some basic understanding of measurement techniques will help achieve the most accurate results.
