1. Read the upper half of the sleeve line and count
the number of lines visible. Each upper line equals 1
mm.
2. See if the half-millimeter line is visible on the
lower sleeve line. If so, add 0.50 to the reading in
Step 1.
3. Read the thimble mark that aligns with the
sleeve line. Each thimble mark equals 0.01 mm.
NOTE
If a thimble mark does not align ex
actly with the sleeve line, estimate the
amount between the lines. For accu
rate readings to two thousandths of a
millimeter (0.002 mm), use a metric
vernier micrometer.
4. Add the readings from Steps 1-3.
Adjustment
Before using a micrometer, check its adjustment
as follows:
1. Clean the anvil and spindle faces.
2A. To check a 0-1 in. or 0-25 mm micrometer:
a. Turn the thimble until the spindle contacts the
anvil. If the micrometer has a ratchet stop, use
it to ensure the proper amount of pressure is
applied.
b. The adjustment is correct if the 0 mark on the
thimble aligns exactly with the 0 mark on the
sleeve line. If the marks do not align, the mi-
crometer is out of adjustment.
c. Follow the manufacturer’s instructions to ad-
just the micrometer.
2B. To check a micrometer larger than 1 in. or 25
mm, use the standard gauge supplied by the manu-
facturer. A standard gauge is a steel block, disc or
rod that is machined to an exact size.
a. Place the standard gauge between the spindle
and anvil, and measure its outside diameter or
length. If the micrometer has a ratchet stop,
use it to ensure the proper amount of pressure
is applied.
b. The adjustment is correct if the 0 mark on the
thimble aligns exactly with the 0 mark on the
sleeve line. If the marks do not align, the mi-
crometer is out of adjustment.
c. Follow the manufacturer’s instructions to ad-
just the micrometer.
GENERAL INFORMATION
17
1
31
STANDARD METRIC MICROMETER
Anvil
Spindle
Locknut Sleeve line Thimble
Rachet
Thimble
marks
Sleeve
marks
32
5.00 mm
0.50 mm
0.18 mm
5.68 mm