No need to know the vocabulary first
A few words, explained
- Stepover
- The sideways spacing between neighboring cutting passes.
- Spindle
- The rotating assembly that turns the cutting tool.
- Veneer
- A thin layer of wood, often bonded to another material.
- CNC
- Computer numerical control: a computer directs a cutting machine.
- Workholding
- The way you keep a piece securely in place while working on it.
- Feed rate
- How quickly a cutting tool moves along the material.
3 more words used on this page
- RPM
- Revolutions per minute: how many full turns a tool makes each minute.
- Chip load
- The calculated forward distance per cutting edge; one way to understand how much each edge cuts.
- Grain
- The direction and pattern of the wood's fibers.
Begin with the tool and material
Identify the bit type, diameter, flute count, coating, material, and operation before choosing a setting. A compression bit in plywood, an upcut bit in solid wood, and a small engraving bit do not share the same safe starting point.
Watch chips, sound, and edge quality
During a test cut, inspect chip size, heat, chatter, fuzzing, tearout, and the machine's sound. Make one controlled adjustment at a time so you know what improved or damaged the result.
Record proven settings by setup
Keep a shop record for material, bit, machine, workholding, RPM, feed rate, depth of cut, stepover, and finish quality. Those records make future quoting and production more repeatable.
Advanced practice
Compare CNC settings on matching stock
Start with tooling guidance, change one setting at a time and record how it affects the cut.
- Use a known bit and matching scrap material.
- Run a labeled test that changes only one variable at a time.
- Inspect edge quality, chips, heat, sound, and hold-down before choosing the next trial.
Try it with your own numbers
Common questions
What should I change first when a CNC cut burns?
Review chip load, RPM, feed rate, bit condition, dust extraction, and whether chips are clearing the cut. Test carefully and adjust one variable at a time.
Why does plywood tear out on a CNC?
Tool geometry, grain direction in face veneers, hold-down, chip load, bit condition, and the entry or exit strategy can all affect tearout. Test on matching scrap before running finished sheets.
Can one speeds-and-feeds setting work for every machine?
No. Machine rigidity, spindle power, workholding, tool length, material, and dust collection change the safe and effective range.