How to Use a Non-Digital Caliper

Calipers measure with preciseness to one-thousandth of a foot.

Calipers or micrometers are useful in measuring small diameters both inside and outside an object. Calipers record measurements in thousandths of a foot for technical information on blueprints, drawings, woodworking and measuring artifacts. There are two types of non-digital calipers: the Vernier manual calipers and dial-type calipers. Vernier manual calipers are the least expensive type and are available in a plastic version.

Instructions

Taking Measurements

1. Hold the calipers with the right hand so that the numbers on the tool face the user. Grip the thumbrest at the bottom of the tool while holding the calipers level with the right hand on the right side of the thumbrest.

2. Slide the thumbrest to the right to open the ends of the calipers for measurements. The jaws open wider as the thumbrest pulls farther to the tail of the instrument.

3. Place the large caliper jaws on the bottom of the tool over an item to measure its exterior width. Slide the thumbrest so that the jaws are touching the item without squeezing them. Slide the tool right to open the jaws farther and left to close them.

4. Place the small caliper jaws on the top of the tool inside of an object to measure the inner distance. Adjust the slide right or left to move the jaws so that they fit inside an object as a pipe and the jaws touch both sides of the pipe.

5. Insert the tailpiece into an item to measure its depth. Slide the jaws open and the depth gauge gets longer as it slides out of the tail of the instrument. Widen the jaws and extend the depth gauge until it touches the bottom inside of an item.

Reading Measurements

1. Hold the calipers level to read the measurements.

2. Observe the top and bottom numbers on the gauges to determine the measurement of an object. Read the top ruler first and then the bottom in the same manner as a slide ruler. For example, if the top number on the left edge of the scale is 3 and the bottom number on the left edge of the scale is 12, the measurement is .312 thousandths.

3. Adjust dial calipers in place on an item. Read the measurement on the bottom of the calipers first and then the dial. For example, if the number just to the left of the slide is 3 and the needle on the dial is pointing at 10, the measurement is .312 thousandths.

Tips & Warnings

• Holding calipers on an item needing exact measurements must be done so that the tail is horizontally level with the ground for accurate measuring. Even a slight shift from horizontal will change the measurements.

• Some workers who use calipers on a regular basis tape a small leveling strip on the top slide of the calipers to ensure accurate measurements. Small magnetic levels will adhere to metal calipers for accuracy.

References

• Woodjig.com: How To Use A Micrometer
• Archaelogica: How to Use Calipers