A micrometer is a tool incorporating a calibrated screw used widely for precise measurement of small distances in mechanical engineering and machining as well as most mechanical trades, along with other metrological instruments such as dial, vernier, and digital calipers. Many are precise down to thousands of a MM or an inch.
There are many specialized micrometers, but three basic types:
- Outside micrometer (aka micrometer caliper), typically used to measure wires, spheres, shafts and blocks.
- Inside micrometer, used to measure the diameter of holes.
- Depth micrometer, measures depths of slots and steps.