How to calibrate a digital micrometer caliper

Tight, critical cuts make or break many of the more detailed home repair jobs, and accurate measurements can mean the difference between a pipe that works and a pipe that leaks.

For jobs needing the type of accuracy a tape measure just can't achieve, homeowners can turn to micrometer calipers, more commonly referred to simply as micrometers. Digital micrometers feature an accuracy and resolution as tight as 0.0005 inch, on an easy-to-read LCD display. Prior to using a digital micrometer caliper, homeowners should calibrate the tool to ensure it is measuring correctly.

Examine the physical condition of the micrometer. Inspect the micrometer's body for signs of visual damage. Check the flat, parallel faces on the micrometer's anvil and spindle for any pitting or other signs of wear. Open the micrometer fully, then close it, feeling for any odd tension or grittiness as it moves. Do not use the micrometer if not fully confident in the condition of the tool.

Open the micrometer and wipe the flat, parallel faces of the micrometer's anvil and spindle with a clean cloth to remove any residue or debris. Wipe down the contact surfaces of the gauge blocks being used to calibrate the micrometer, as well.

Shut the micrometer firmly, but without force. If the micrometer has a ratcheting knob at the top, use it when making contact to avoid over-tightening the micrometer.

Press the "On/Off" button to turn the micrometer on. Check that the display reads "0.0000" with the micrometer closed. Press the "Zero" button to reset the display to "0.0000" if needed.

Measure gauge blocks valued at 1 inch, 0.500 inch, 0.250 inch, 0.125 inch and 0.0625 inch to determine if the digital micrometer is reading accurately over the length of the tool. Place one end of the block firmly on the flat face of the stationary anvil. Lower the spindle until its face contacts the other end of the gauge block, using the same firm yet gentle touch used when closing the micrometer earlier. Compare the readings on the micrometer's LCD display to the known value of the gauge blocks.

Stop using a tool whose readings fail to match the known values of the gauge blocks. Press the "On/Off" button to power down the micrometer when you're done using it.