Selecting a Caliper on Amazon.com
A caliper is an instrument for measuring the distance between two sides of an object and is available in different styles and variations. The constant among all styles is that a caliper includes two legs or jaws that mark the two points being measured.
The most basic form of caliper has a central screw or pivot to hold the legs at an exact distance. The measurement is then read by comparing the gap of the legs against a ruler. The legs of pivot-style calipers may be designed for measuring either inside dimensions or outside dimensions, or may combine a straight and a curved leg for scribing lines along a consistent distance.
Other caliper types provide greater accuracy by integrating the measurement display into the instrument. These are variations of the slide caliper, where one measuring jaw is fixed while the other jaw slides along a ruler or measuring face. Most slide-style calipers are able to measure both inside and outside dimensions, and specialty jaws or attachments may be available to measure depth, stepped or uneven surfaces, narrow grooves, centerlines of holes and other unique requirements.
Slide calipers come in three styles. A digital caliper measures distance electronically and display readings on a digital screen. It is easy to read, can take measurements in difficult circumstances, and is easy to set to zero at any point. It may offer data output to a computer or recorder. Although subject to damage from liquid, waterproof and coolant-proof models can be purchased. Solar-powered calipers are available to negate the need for batteries. A dial caliper measures through a system of gears and displays readings on a dial. It also can be zeroed at any point, and measurements can be easily read. A vernier caliper displays readings on a vernier scale. It is sturdier than other styles, but can be challenging to read.
Calipers have a vast range of applications, including machining, metalworking, woodworking, architecture, medicine, scientific research, and mechanical engineering. They are available with scales marked in inches or millimeters, and electronic models may offer both.