An outside caliper is a device which is used to measure the exterior diameter of an object, or to measure the thickness of an object. These tools can be tremendously useful in a wide range of settings, from archeology to zoology. They are available from scientific suppliers, some hardware stores, and other stores and companies which stock devices which can be used to take measurements. Specialty designs and designs with custom systems of measurement are available from some manufacturers by request.
The design of outside calipers consists of a pair of arms or jaws which curve inwards. People can extend the arms, and then tighten them around the object being measured. The inward curving points grip the object, and a reading can be taken from the calipers once it is clear that they are in position. By contrast, inside calipers designed to measure interior diameters have outward curving arms. Many different units of measurement are available with this measuring device.
One advantage to using a caliper for measurement is that the device is extremely precise. The points of the caliper allow the user to see precisely when the caliper is in position, and eliminate the need for eyeballing and guesswork, two common problems which arise when measuring three dimensional objects. These devices are also nondestructive, allowing people to take measurements without destroying or disturbing the object being measured, which can be important when working with rare or valuable objects. Outside calipers can measure anything from a delicate egg to a pipe used in plumbing.
The mechanism used to adjust and control the caliper depends on the design, with several options available. Spring and dial mechanisms are two common variations which are usually readily available. It is also possible to find locking devices which can be used to take and hold a measurement, which may be useful in various settings.
Like other measuring devices, outside calipers function best when they are cared for appropriately. It is important to make sure that the device is not bent or twisted, which can throw measurements off. It is also important to keep outside calipers clean and well oiled so that they will move smoothly, and to prevent the transfer of dirt or impurities between objects being measured. Outside calipers may sometimes come with a protective case which is designed to keep them in good condition, and it is a good idea to get in the habit of using the case when the device is not in use.