A dial gauge is a type of measuring instrument which is used to accurately measure minute lengths and displacements.
And unlike other measuring instruments that directly measure numerical values, they are used for measuring the difference compared to a reference or correcting parallelism.
Dial gauges and indicators are one of the primary measuring tools used in precision engine building.
The dial gauges are typically used to measure deck clearances, crankshaft thrust and straightness, lifter travel and other measurements that involve the distance between two surfaces or small amounts of component travel.
Dial indicators or dial gauges are nifty instruments that measure points on a 3-dimensional surface by making quick work of accurately measuring angles or distance between two flat surfaces which would seldom be possible with the naked eye.
So, the Dial Gauge Least Count (or dial indicator least count) is 0.01 mm for general dials and 0.001 mm for special purpose indicators.
There are 3 types of dial gauges: Dial indicators in which the spindle is parallel to the dial face.
Dial indicator in which the spindle is perpendicular to the dial face.
Dial indicators in which the measuring contact member is a lever.
Range of travel of dial indicator is of the order of 10 mm.
On finished work, dial gauges are mostly used as comparators and a narrow range is needed to have high accuracy.
To calibrate a dial gauge.
Using your index finger, depress the IUT contact point slowly and evenly over the full range, slowly allow the contact point to return to its starting position.
Securely position the attachment arm onto the indicator checker.
Position the micrometer thimble and test indicator to obtain zero readings.