CNC Machinist how-to
How to Measure a Part with an Outside Micrometer
Micrometers are essential for holding tight tolerances.
Quick answer
Micrometers are essential for holding tight tolerances. In short: clean; check; hold, then complete the remaining steps below.
Step by step
Clean the anvil, spindle and part.
Check the micrometer’s zero with the anvils closed or with a standard.
Hold the part square between the anvil and spindle.
Turn the ratchet stop until it clicks two or three times for consistent pressure.
Read the sleeve, thimble and (if present) vernier scale.
Measure in more than one location to check for taper or out-of-round.
Record the measurement and compare with the tolerance.
Safety reminders for CNC machinists
- Wear safety glasses and keep loose clothing, jewelry and hair away from spindles
- Never reach into a running machine or clear chips by hand
- Keep machine doors and guards closed during operation
- Handle sharp chips and parts with gloves only when the machine is stopped
Key terms
CNC · G-code · M-code · Work offset · Tool length offset · Feeds and speeds: see the full CNC machinist glossary.