Micrometers – All about micrometers, what they’re used for, how they’re used, who makes them etc.
A micrometer is a term that refers to one-millionth of a meter; micrometers are units that are used in measuring the core of optical fiber or the line width on a microchip. In most cases however, when persons refers to a micrometer, they are not talking about the unit of measurement but rather the tool that is used to measure micrometers, which is a micrometer screw gauge.

A micrometer screw gauge is a device with a calibrated screw that is used for taking precise measurements of small distances in most mechanical professions; micrometer gauges typically come in one of three types: outside micrometers, inside micrometers, and depth micrometers. Outside micrometers are mostly used for measuring wires, shafts, or blocks, while inside micrometers are used primarily to measure the diameter of a hole, and depth micrometers measure the depth of slots and steps. There are specialized anvils and spindle tips that can work with each micrometer to take on specific measuring tasks if required.

A micrometer is made up of eight parts: the frame, which is the thick C-shaped part of the micrometer that holds the anvil and barrel in their place, the anvil which is the shiny part that the spindle moves towards, the sleeve which is the round part with the linear scale or markings on it, the lock nut which is the lever that can be tightened, the screw which is unseen inside the micrometer, the spindle which is the shiny, cylindrical part that moves toward the anvil, the thimble which is the part that a person’s thumb rests on, and the ratchet stop on the end of the handle that limits applied pressure.

Although those previously mentioned are the most common types of micrometers and they can be fitted with specialized tips, there are special micrometers that come with specific tips for specific tasks such as Universal micrometer sets such as the ones made by Mul-T-Anvil, Mitutoyo, and Uni-Mike, which come with interchangeable add-ons that allow it to function as any of the three main types of micrometers. Limit micrometers come with two anvils and two spindles; when using it the object being measured must pass through the first gap and stop at the second to be within the required specifications. These can be obtained from Mitutoyo and Sharpfine.

Blade micrometers come with narrow blades for measuring narrow spaces and are also made by Mitutoyo; Tube micrometers are used to measure the thickness of tubes as their name suggests, an can be obtained from Starrett or Mitutoyo. Pitch-diameter micrometers come with thread-shaped tips that are used for measuring the diameter of screw threads and can be found on the Gagemaker website; Micrometer stops are basically inside micrometers which are mounted on the table of a manual machine instead of simple stops and are used to precisely position the table. Micrometer stops are manufactured by Starrett or Mitutoyo.

Finally, three-anvil Bore micrometers are used to measure inside diameters and can be bought from Tesa Technology or Mitutoyo.