A dial caliper is a versatile measuring device. It is designed to give accurate readings within .001 of an inch. The dial caliper is a modified vernier caliper. It can be used to measure inside and outside dimensions, as well as depth dimensions. Using a dial caliper is fairly simple.
Reading the Dimensions
Begin by ensuring that the the jaws of the caliper are completely closed and that the caliper reading is zero. A sliding scale on the caliper will mark of inches and hundredths of inches, and the dial will give the reading from .000 to .099.
Use your thumb to roll the thumb wheel, opening the jaws of the caliper. The line on the moving part of the caliper will slide along the scale, matching up to various hash marks on the scale. The scale is read like a ruler, except that it will be in decimal dimensions. If the line is past between the 1-inch and 2-inch marks, between the third and fourth hash mark within that division and the dial indicator is pointing at 55, the measurement is 1.355 inches.
Using the Jaws
For outside dimensions, place the open jaws over the points you want to measure. Rotate the thumb wheel, closing the jaws. Do not squeeze the jaws over the points, as this may throw off the dimension. Simply roll the thumb wheel until mild pressure will not let it continue.
At the top of the caliper are two jaws designed to measure inside dimensions. Operate the caliper the same way, but rolling the wheel in the opposite direction to allow those jaws to open to the points of measurement.
Depth Dimensions
You will note, while using the calipers, that a bar extends from the rear of the caliper as the jaws are opened. This bar can be used to find depth dimension. Place the base of the caliper on the edge of the item from which you want to take the depth dimension. The caliper will be positioned so that the jaws are upward. Roll the thumb wheel, extending the depth bar. The caliper reading is determined in the same way as with other measurements.
