How to Read a Dial Caliper

A dial caliper makes measuring a lot easier. The popularity of this device is attributed to its ease of use and durability. It measures internal and external dimensions precisely just like a Vernier caliper, but at a much faster rate because readings are instantly read by a dial. It is also more durable than a digital caliper. In addition, a dial caliper can also be used to measure depth.

Step 1. Familiarize with the Dial Caliper’s Parts

The dial caliper has different parts for different functions. It has a dial indicator, a beam lock, a dial calibration lock, a depth rod, a main scale, and two sets of jaws. One set of jaws can be found on the upper portion of the caliper and is used for internal measurements. The other set of jaws can be found at the lower portion and is used for external measurements. The caliper also features a depth rod that is used for depth measurements in crevices or holes. There is also a dial indicator that can easily read measurements in either millimeters or inches. The dial indicator is the circular part of the device that has a needle inside to point at the correct measurement of an object being measured.

Step 2. Calibrate the Scale

Before using the dial caliper, calibrate it to zero first. This means that when the caliper is closed, the dial should read 0 (zero). Close the device by turning the thumb screw clockwise. If the needle does not point to zero when the caliper is closed, you need to adjust the needle until it reads zero. There is a screw on the bottom of the dial. Loosen this screw by turning it counterclockwise. Turn the dial and get the needle to point at zero before locking the dial back in place.

Step 3. Subject an Object to Measurement

To measure the diameter of an object, open the caliper and fit the lower jaws of the caliper around the object. Along the length of the caliper, there is a scale that uses the same principles as a ruler. If the measurement on the main scale reads 4 inches, the object measures at least 4 inches. The dial is used to get the precise measurement. It has a scale of 0 to 99 and each number equals .001 of an inch or depending on the unit of measurement used for the caliper. As an example, if the main scale reads 4 and the dial reads 20, the final reading will be 4.020 inches.

Step 4. Measure Distances and Depths

The upper jaws on the caliper can be used to measure external dimensions or distances between two objects or points. Have the jaws of the caliper rest on the objects to be measured and read the distance by following the same procedure as above. To measure depth, place the rear or base of the caliper on the edge of an object or a hole. The caliper jaws should be in an upward position. Extend the depth bar by rolling the thumb wheel until it reaches the end of the hole or crevice. The measurement can be read the same way as above.