Calipers and micrometers are used by engineers and those in the manufacturing industry to measure parts and dimensions with great accuracy. Although micrometers are the more accurate of the two, a good set of calipers can give you an accurate measurement within .0001 or an inch and can be used for a few different types of measurements, making it a bit more versatile than a micrometer, which is used for a single type of measurement in a narrow dimensional range.
Place what needs to be measured in between the large blades of the caliper. Slowly move the blade on the right toward the stationary blade. When the moving blade touches the side of the part, look on the slide for the measurement. The large number is inches and the smaller numbers on the slide are in .1 of an inch. The dial notes increments of .01 of an inch. If the blade top is just past the large 1 and the small 3 and reads 50 on the dial, the dimension is 1.350 inches.
Follow step 1 to use a micrometer. Instead of pushing a blade, you will use a thumb screw to slowly bring the measuring side toward what is being measured. Although most micrometers do not have dials, you can read the dimension on the thumbscrew in the same manner as the dimensions noted on the slide of a set of calipers. Micrometers come in 1-inch increments, so you must estimate the size of the part that you will measure, so you use the correct one within the part's size range. If the part to be measured is about 1.5 inches, you will need a 1- to 2-inch micrometer.
Place the small top blades of the calipers inside what is being measured to get accurate inner dimension readings. Place the stationary blade of the calipers, which will be on your left, against the left side of the inner dimension to be measured. Slowly bring the sliding blade out with the small thumb-wheel toward the other side to be measured until it just touches. Read the dimension as indicated in step 1.
Pull apart the large blades of the dial calipers, so the small, thin depth blade is fully extended. Place the small, thin depth blade in a hole to be measured. Slowly bring the bottom of the base of the slide to the top surface. This will give you a depth measurement of the hole. Read the dimension from the caliper as noted in step 1. You must make sure that the small, thin depth blade is touching the bottom of the hole for an accurate measurement.