How To Read a Micrometer
Micrometers are precision measuring instruments used for accurately measuring very small distances. They are used when a standard rule or a slide caliper cannot get the precise measurement needed.
Micrometers use a calibrated screw to determine these small distances. The item to be measured is placed between a stationary endpoint, the anvil, and a movable metal post, the spindle. As the spindle is screwed in and out to touch the item, the number of threads covered up or revealed is used to calculate a measurement.
The sleeve resembles a ruler with ten numbers. The gaps between the numbers are divided into quarters. The sleeve does not move. When the thimble rotates around the sleeve, it covers up, or reveals the numbers marked on the sleeve.
There are three types of micrometers commonly used:
A couple of points should be brought up before you purchase a micrometer. First, there are now digital micrometers available where the measurement can be read directly from a digital display, negating the need to learn how to read a micrometer. Secondly, micrometers are available in metric and imperial measurements. We will discuss the Imperial, or inches, version.
Decimal numbers and their meaning:
Each digit is a different place value.
Here is an example: 0.4567
So, our example has four tenths, five hundredths, six thousandths, and seven ten-thousandths.
Reading An Imperial Micrometer
To read a micrometer, read the micrometer scale and add the fraction of a revolution.
To read this example:
Full Measurement = .300 + .050 + .017 = .367 inches
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