Editing Micrometer (device) (section)

{{Short description|Tool for the precise measurement of a component's length, width, and/or depth}}
{{hatnote group|
{{about|the measuring device|the unit of length|Micrometre|the angular scale|Angular micrometer}}
{{distinguish|Rangefinding micrometer}}
}}
[[File:Mahr Micromar 40A 0–25 mm Micrometer.jpg|upright=1.3|thumb|Modern micrometer with a reading of <!--DO NOT CHANGE THIS TO 1.640. MAKE SURE YOU ZOOM IN TO SEE THE READING. IF YOU STILL THINK 1.640 IS CORRECT, IT MEANS YOU MISUNDERSTAND HOW TO READ A MICROMETER!-->1.639&nbsp;±&nbsp;0.005&nbsp;mm. Assuming no zero error, this is also the measurement.  (One may need to enlarge the image to read it.)]]
[[File:Micrometers.jpg|upright=1.3|thumb|Outside, inside, and depth micrometers. The outside micrometer has a [[unit conversion]] chart between [[Fraction (mathematics)|fractional]] and [[decimal]] [[inch]] measurements etched onto the frame.]]

A '''micrometer''', sometimes known as a '''micrometer screw gauge''' ('''MSG'''), is a device incorporating a calibrated [[screw]] for [[Accuracy and precision|accurate]] measurement of the [[size]] of components.<ref>Encyclopedia Americana (1988) "Micrometer" Encyclopedia Americana 19: 500 {{ISBN|0-7172-0119-8}}</ref> It widely used in [[mechanical engineering]], [[machining]], [[metrology]] as well as most mechanical trades, along with other [[dimensional instruments]] such as [[Caliper#Dial caliper|dial]], [[Caliper#Vernier caliper|vernier]], and [[Caliper#Digital caliper|digital calipers]]. Micrometers are usually, but not always, in the form of [[caliper]]s (opposing ends joined by a frame). The spindle is a very accurately machined screw and the object to be measured is placed between the spindle and the anvil. The spindle is moved by turning the ratchet knob or thimble until the object to be measured is lightly touched by both the spindle and the anvil.