Knowledge about dial calipers
Some calipers are fitted with a dial to make measurement reading easier. To measure a component, use the thumb wheel to open the jaws, then close the jaws over the component. The dial uses a rack and pinion mechanism to transfer movement of the jaws to the dial needle. Like the vernier caliper, the base measurement is taken from the beam, and the dial reading is added to it. The base scale on an English dial caliper is marked in 0.100 inch increments, and the dial provides the thousandths (0.001) of an inch readings. Most metric calipers have base scale increments of 2 millimeters and dial increments of 0.01 millimeters.
The latest innovation in calipers provides a digital readout. An internal microprocessor calculates the position of the jaws and shows the reading in a display window.