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Micrometer:

               
A Micrometer is a precision measuring instrument. Also called a "Mike" by Pundits. There are
many different styles and sizes of micrometers. This information will pertain to the common 
micrometer caliper. It consists of only a few parts. The Frame, Anvil, Spindle, Cam Lock, Hub, 
Thimble, and Ratchet Cap.
The measurement is taken by placing the item you want to measure between the Anvil and
Spindle. Tighten the Ratchet Cap with the thumb and index finger until it slips. Then lock the  
Cam Lock and slide the micrometer off. With the micrometer off you can now take the readings.

Mircometer Mircometer

Mircometer Scale   Mircometer Scale

The first reading would be the tenths and hundredths on the Hub. Figure 1 reads .475.
Pronounced: Four hundred seventy five thousandths of an inch.

A Second reading is taken from the Thimble. Figure 1 reads almost .019, so we use .018.
Pronounced: Eighteen thousandths of an inch.

Next add the Hub reading to the Thimble reading. (.475 + .018= .493)
Pronounced: Four hundred ninety three thousandths of an inch.

For accuracy of ten-thousandths of an inch (.0001) take the reading from the
Vernier scale on the Hub (Figure 2). Look for the Thimble graduation that lines up 
with the Vernier scale. Add that Number to the previous reading of .493.
(.493 + .0009= .4939) 
Pronounced: Four thousand nine hundred thirty nine ten-thousandths of an inch.

.1 = one tenth of an inch.                      .10 = ten hundredths of an inch
.01 = one hundredth of an inch.              .010 = ten thousandths of an inch 
.001 = one thousandth of an inch.           .0010 = ten ten-thousandths of an inch
.0001 = one ten-thousandth of an inch.    .0100 = one hundred ten-thousandths of an inch

Cleaning: 

Wipe with a clean rag and always keep it well oiled.
This well prevent rust and premature wear.

Calibrating:

Calibrating is usually performed by measuring a Calibrated block. Then the hub is
usually turned with a spanner wrench to match the blocks dimensions.
(See your specific manufacturers instructions) 

It's that simple!