1.Open the jaws of the caliper and position them on both sides of the piece you are measuring.
2.Push the jaws firmly against the workpiece.
3.Lock the clamp screw so that the jaws don't move
4.On the vernier scale is a small number 0. Look at how many inch divisions it is past on the bar scale.
5.See how many smaller (numbered) divisions the small 0 has gone past. This represents how many tenths of an inch the workpiece is measuring in addition to the number of whole inches.
6.How many smaller divisions has the small 0 gone past the last numbered division, this number multiplied by 25 is how many hundredths of an inch
7.Determine which division line on the vernier scale best lines up with a division on the bar scale. This is how many thousandths of an inch.
8.By adding the inch measurement, the tenths of an inch, the hundredths, and the thousandths, you will have a measurement to a 3 decimal place accuracy