Typical procedure for reading a micrometer
�?Tools required to perform this task are a micrometer set and a
clean shop towel.
�?Select the correct micrometer. If the component measurement is
less than 1 inch, use the 0-to-1 inch micrometer.
�?Check the calibration of the micrometer.
�?Locate the component between the anvil and spindle of the
micrometer, and rotate the thimble to slowly close the micrometer
around the component. Tighten the thimble until a slight drag is
felt when passing the component in and out of the micrometer. If the
micrometer is equipped with a ratchet, it can be used to assist in
maintaining proper tension.
�?Lock the spindle to prevent the reading from changing.
�?Remove the mocrometer from the component.
�?Each number on the sleeve is 0.100 inch, and each graduation
represents 0.025 inch. To read a measurement, count the visible
lines on the sleeve.
�?The graduations on the thimble define the area between the lines
on the sleeve on 0.001 increments. To read this measurement, use the
graduation mark that aligns with the horizontal line on the
sleeve.
�?Add the reading obtained from the thimble to the reading on the
sleeve to get the total measurement.
�?Since the 0 on the thimble scale aligns on the reading line and
the last sleeve graduation is 5, the reading is 0.500 inch.
�?If graduation marks are visible after a number on the sleeve
scale, add the graduation value to the number in this case, the
micrometer reads 0.375 inch.
�?Use the thimble scale to determine the thousandths to the sleeve
scale. This micromter is reading 0.311 inch.
�?Some micrometers have vernier scales that allow
ten-thousandths-inch readings. The 2 on the vernier scale is the
only one that aligns with a thimble graduation mark. The reading is
0.3112 inch.