|The metric micrometer looks very similar to a standard inch
micrometer until you look at the graduations on the sleeve and the
barrel (Figure 1).
Figure 1 0-25 millimeter
|There are two separate rows of lines on the sleeve of the metric
micrometer (Figure 2).
Figure 2 When reading a metric
micrometer you have to remember to add the half-millimeter
graduations of the upper row to the reading.
The lower row represents whole millimeter graduations. The upper row
represents one-half millimeter. Each complete turn of the thimble moves
the spindle ½ millimeter (0.5 mm). The circumference of the thimble is
separated into 50 equal divisions (Figure 2) or .01 mm.
Reading the Metric Micrometer
To read the metric micrometer, first read the number of whole
millimeters on the bottom row of the sleeve of the micrometer (Figure 3).
These are the whole millimeters. If there is an additional line uncovered
on the top row, this is equal to one-half a millimeter (Figure 3). So 0.5
mm would need to be added to the measurement. Then add the thimble reading
to whole and half millimeter sleeve readings. Refer to figures 3, 4, and 5 and
try to read the measurements before looking at the answer in the figure
Figure 3 Metric micrometer reading
equals 23.15 millimeters.
|23 whole divisions are uncovered = 23 millimeters.
0 millimeters divisions are uncovered = 0.0 millimeters
15 0.01 millimeter divisions line up on the thimble = 0.15
|18 whole divisions are uncovered = 18 millimeters.
0.5 millimeters division is uncovered = 0.5 millimeters
10 0.01 millimter divisions line up on the thimble = 0.10
Figure 4a Metric micrometer reading
equals 18.60 millimeters.
Figure 4b Metric micrometer
reading equals 15.63 millimeters.
|15 whole divisions are uncovered = 15 millimeters.
1 0.50 millimeters division is uncovered = 0.5 millimeters
13 0.01 millimter divisions line up on the thimble = 0.13
Note: Some manufacturers of micrometers may reverse the
position of the whole and half millimeter graduations. The order in
which you read the micrometers will still remain the same i.e.,
whole-millimeters, half-millimeters and hundredths of a millimeter.
Reading the Vernier Metric
The vernier metric micrometer has the ability to measure to two
thousandths of a millimeter (0.002-mm). 0.002 mm is equivalent to
approximately 0.00008 of an inch.
The vernier is graduated in increments of 0.002 mm starting and
ending with 0 (Figure 5).
If either 0 on the vernier graduation scale lines up with the
thimble reading, no additional thousandths of a millimeter are added
to the reading.
Figure 5 The two-thousandths vernier scale line that lines up with the
graduated line on the thimble is added to the reading. In this case 0.006 mm
must be added.
The reading of the vernier metric micrometer is accomplished by
adding the whole millimeter, the half-millimeter, and the hundredths
of a millimeter just as before. To this reading is added the number of
two-thousandths of a millimeter, which is read off of the vernier scale
Figure 6 Metric micrometer
reading equals 15.584 millimeters.
|15 - whole divisions are uncovered = 15 millimeters.
1 - 0.50 millimeters division is uncovered = 0.5 millimeters
8 – 0.01 millimter divisions line up on the thimble = 0.08
4 – vernier divisions line up on the vernier scale = 0.004