Hole Measurement

There are various ways to measure hole diameters or bores, depending on how many measurement points will be used. Each of the methods listed below has advantages and disadvantages:

1. Two-point bore micrometer

2. Three-point bore micrometer

3. Bore gauges

One observation in production is that 3-point micrometers provide good repeatability. This performance is due to the self-centering nature of this instrument, making it easier to use and less likely to lead to incorrect measurements. However, a hole with ovality cannot be measured accurately with this type. A 2-point micrometer is more suitable so that measurements can be taken at various angular positions. Finally, bore gauges are usually used for smaller holes or in cases where measurement speed is more important than accuracy.