A rough machined surface usually comes from too much per-tooth load, a worn tool, or vibration. Improving it is about taking a light, clean final pass with a stable setup.
What improves finish
- Take a finishing pass — leave a few thousandths and remove it in a light, fast pass dedicated to finish.
- Reduce stepover — on contoured surfaces, a smaller stepover leaves shallower scallops.
- Tune feed per tooth — too high leaves tool marks; very low rubs. There’s a sweet spot.
- Use a sharp tool — a worn edge tears rather than shears.
- Climb mill — usually a better finish than conventional.
- Maximize rigidity and use coolant — less vibration and cleaner chip evacuation show up directly in the finish.
Counterintuitively, both too high and too low a feed hurt finish, so aim for the tool’s recommended chip load rather than just slowing down.
Frequently asked questions
Easiest way to a better finish? A dedicated light finishing pass with a sharp tool.
Does stepover affect finish? Yes — smaller stepover means smaller scallops on contours.
Climb or conventional for finish? Climb milling typically finishes better.
If you can change only one thing, leave a dedicated finishing allowance and take a separate light pass — trying to rough and finish in a single heavy cut is the most common reason parts come out rougher than they need to be.