Design of a gauge should be such that minimum time is taken to position, engage and disengage a gauge. It should be light as possible and should not be the source of fatigue to the user. It should have dimensional stability during use. It does not affect with temperature and environmental conditions and also should be wear resistance either by case hardening or by using crome layers at contact surfaces.
Every gauge is a copy of the part which mates with the part for which the gauge is designed. For example, a bushing is made which is to mate with a shaft; in this case, the shaft is the opposed (mating part) part. The bushing is checked by a plug gauge, which in so far as the form of its surface and its size is concerned, is a copy of the opposed part (shaft).
If a gauge is designed as an exact copy of the opposed part in so far as the dimension to be checked is concerned, it is called a ‘Standard Gauge’. In design of a gauge, simplicity should be the main aim as simple gauges can take measurements continuously and accurately.