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How to Cut a Groove on a Lathe
Guide · Updated October 28, 2026
Grooves on a lathe hold snap rings and O-rings or give thread relief. A grooving tool plunges straight in, so rigidity, tool height and steady feed matter more than in turning.
Measure the groove
Check groove width with gage blocks or pin gages. The free Gage Block Calculator builds the width stack.
Step by step
- Pick the tool: Use a grooving insert or ground tool at or under the groove width.
- Set height: Set the tool exactly on center and square to the work.
- Locate: Touch the face, zero the carriage and move to the groove position.
- Set speed: Run about 60–70% of the turning speed for that material.
- Plunge: Feed in steadily, about 0.001–0.003 in/rev, with coolant; peck if chips pack.
- Widen: For wide grooves, plunge at each end, then clean the middle.
- Finish: Take a light finishing pass on the walls and bottom, then check size.
Worked example
A 1/2 in shaft needs a snap ring groove 0.039 in wide and 0.464 in diameter at the bottom (check your ring maker chart). With a 0.039 in grooving insert on center, touch the face, move 0.75 in along, and at about 500 RPM in steel feed in 0.018 in on the radius at 0.001 in/rev. Measure the groove diameter with a mic or calipers and the width with a 0.039 in gage block or the ring itself.
Chatter
Grooving chatter comes from tool overhang, too much speed, a tool off center or a blade that is too wide for the machine. Shorten the tool, slow down, feed firmly and use coolant.
Grooves near a shoulder
For thread relief, groove to just past the minor diameter so the threading tool runs out cleanly.
Tips
- Parting: parting off.
- Height: setting tool height.
- Threads: cutting threads.
FAQ
What speed for grooving?
About 60–70% of normal turning speed.
What feed for a grooving tool?
Roughly 0.001–0.003 in/rev depending on width and machine rigidity.
How do I measure a groove?
Width with gage blocks or pins, depth with a groove mic or calipers.
Grooving vs parting?
Same tool family; parting goes all the way through.
Why does my grooving tool chatter?
Overhang, speed too high or the tool is off center.
Related guides and calculators
- How to Part Off on a Lathe
- How to Set Tool Height on a Lathe
- How to Cut Threads on a Lathe
- How to Measure a Groove or Recess with Gage Blocks
- Carbide Insert Basics for Turning
- Turning Speeds and Feeds
- How to Use a Steady Rest
- How to Cut a Face Groove on a Lathe
- How to Cut Left-Hand Threads on a Lathe
- All free machinist calculators
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General shop information only — follow your machine and tooling manufacturer's instructions and your shop's safety rules.