| The metric micrometer looks very similar to a standard inch
micrometer until you look at the graduations on the sleeve and the
barrel (Figure1). |
Figure 1 0-25 millimeter
micrometer
|
| 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.
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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 explanation.
|
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
millimeters. |
| 18 whole divisions are uncovered = 18 millimeters.
0.5 millimeters division is uncovered = 0.5 millimeters
10 0.01 millimeter divisions line up on the thimble = 0.10
millimeters.
|
Figure 4a Metric micrometer reading
equals 18.60 millimeters.
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|
Figure 4b Metric micrometer reading
equals 15.63 millimeters.
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15 - whole divisions are uncovered = 15 millimeters.
1 - 0.50 millimeters division is uncovered = 0.5 millimeters
13 – 0.01 millimeter divisions line up on the thimble = 0.13
millimeters. |
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 Micrometer
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 5).
|
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 millimeter divisions line up on the thimble = 0.08
millimeters.
4 – vernier divisions line up on the vernier scale = 0.004
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