How to Read a Millimeter Micrometer

Micrometers precisely measure distance.

Determining the lengths of objects with a millimeter micrometer allows precise measurements up to one-hundredth of a millimeter and is often used by engineers and machinists. The precision offered by these devices depends on the skill with which the device can be used and read. Measurements are read on the micrometer using the markings on the sleeve and thimble. The sleeve is a horizontal bar that does not move as the thimble rotates around the sleeve.

Things You'll Need

• Millimeter Micrometer
• Small Object

Instructions

1. Place an object in the gap of the micrometer. The side of the gap that is stationary is termed the anvil while the rod that extends across the gap is called the spindle. Rotate the handle until the spindle is gently holding the object against the anvil. Lock the spindle in place using the lock nut or lock ring located between the sleeve and the spindle.

2. Read the measurement on the sleeve where it is crossed by the thimble to determine the distance to the nearest half-millimeter. The sleeve is marked with a horizontal line with graduated markings on each side of the line. The side with numbered markings indicates whole millimeters while the opposite side measure half-millimeters.

3. Read the measurement on the thimble where the markings are crossed by the horizontal line on the sleeve to determine the distance to the nearest hundredth of a millimeter.

4. Add the sleeve and thimble measurement to determine the total distance. For example, if the sleeve reads 9.50 millimeters and the thimble reads 0.27 millimeters, the total distance is 9.77 millimeters (9.50 + 0.27 millimeters = 9.77 millimeters).

References

• University of Tennessee-Chattanooga: How to Use a Metric Micrometer
• University of Toronto: The Micrometer
• Linn Benton Community College: How to Read a Micrometer