A caliper or a pair of calipers is a measurement tool that is used to measure the distance between two opposite sides of an object. Calipers usage is very wide: from medicine, science, mechanical engineering, woodworking metalworking to forestry.
People are using calipers some two thousand and six hundred years ago in ancient Greece. The oldest calipers are the one that was found near the Italian island Giglio in the ship from sixth century BC. Those calipers were wooden. Greeks and also Romans were using calipers. Another caliper is found in China dating from 9 AD during the Chinese Xin Dynasty. Joseph R. Brown invented the modern caliper. That caliper was invented in 1851, and it could read to thousandths of an inch. It was also a very cheap tool which means that ordinary machinist could afford it.
There are a few types of a calipers. Most popular are:
An inside caliper is a measurement tool used for measuring internal size of an object. It can be adjusted manually with the screw.
Unlike inside calipers, there are outside calipers, and they are used to measure the external size of an object. This tool can give a high level of accuracy. It works similarly like inside caliper with and without the screws. This kind of calipers is usually made from high carbon steel.
Another type of calipers is a divider caliper or a compass which is a popular name for it. A divider caliper is used for marking out locations.
Oddleg caliper is a type of caliper that is used to draw a line a set distance from the edge of a workpiece.
Vernier scale is a measuring instrument which can measure with a huge precision. Vernier scale is used in navigation, by scientists, machinists, and surveys. The other name for a vernier scale is a nonius which was commonly used in the English language by the eighteenth century.
One of the primary usages of vernier scale is a measurement of external diameters, internal diameters and a depth of an object. When measuring with the vernier scale, user first must read the fixed scale and then must read the finer scale for the most accurate result of measuring. It can show the results of a measuring with the accuracy up to two decimals.
One of the main reasons why vernier scales work so good is because of the ability of most people to detect which of the lines is aligned and which is not. This ability can even improve with the practice. The name of his ability is vernier acuity and because of it, the vernier scale has advantage comparing to other measuring devices.
A dial caliper is a type of caliper which has a simple dial instead of a vernier mechanism. That dial is used for reading the final fraction of a millimeter or inch. The dial rotates once per every inch or millimeter.
Digital caliper is also a type of caliper but with the digital display which gives the information about the precise result of a measuring by showing the numbers on it.
One of the calipers that use a screw for measurement rather than a slide is called a micrometer.