Micrometer

The micrometer caliper or simply micrometer is, as the name suggests, a direct reading caliper arrangement.

A micrometer is show below. Accuracy of measurement of a micrometer is superior to the vernier caliper and is obtained by means of a finely threaded screw.

The required reading is a combination of the main scale of the micrometer and the thimble scale of the micrometer. Increased precision is obtained by increasing the thimble diameter to, say 60 mm, thus giving an enlarged scale, and in some cases a circular vernier scale is incorporated.

 Figure 3: A micrometer

The example below shows a Micrometer reading of 20.3mm. Under good science experimental conditions, a standard 25mm micrometer should be capable of reading to within 0.005mm.

Figure 4: Reading a Micrometer