Speeds and Feeds for Beginners — Understanding the Math
Speeds and feeds sound intimidating. Here's the simplified version that's actually useful for a desktop router like the Wolfpawn.
The Three Numbers
RPM — how fast the spindle/bit rotates Feed rate — how fast the machine moves (mm/min) Depth of cut (DOC) — how deep each pass goes
These three interact. Get them balanced and the bit cuts cleanly. Get them wrong and you either break the bit or burn the material.
The Simple Rule
Each flute of the bit needs to cut approximately 0.01–0.05 mm of material per revolution.
This is called chip load. Too low = rubbing, heat, burning. Too high = bit snaps.
Practical Starting Points for Desktop CNC (Wolfpawn)
| Material | RPM | Feed | DOC | Bit |
|---|---|---|---|---|
| Softwood | 8000 | 1200 | 3 mm | 1/8" 1-flute |
| Plywood | 8000 | 1000 | 3 mm | 1/8" compression |
| Hardwood | 9000 | 700 | 1.5 mm | 1/8" 2-flute |
| MDF | 8000 | 1500 | 4 mm | 1/8" 1-flute |
| HDPE | 8000 | 1200 | 2 mm | 1/8" O-flute |
| Acrylic | 8000 | 800 | 1.5 mm | 1/8" O-flute |
Reading the Signs
Cut sounds right (crisp, confident): Good settings High-pitched whine or squealing: Feed too slow or RPM too high — increase feed Loud rattling: Feed too fast or DOC too deep — reduce Burning smell, smoke: Too slow or dull bit Bit snapping: DOC too deep or feed too fast — reduce both
The Tuning Process
- Start with conservative values from the table above
- Run your first pass — listen and watch
- If chips look like powder = feed too slow, increase by 10–15%
- If chips look like large chunks and bit rattles = slow down
- You want small curls or chips of consistent size
Flute Count Matters
1-flute: larger chips, better chip clearing, lower RPM needed 2-flute: smoother finish, higher feeds possible O-flute (single): designed for plastics — wide chip slot
On a desktop CNC with a 300W spindle, 1-flute bits for soft materials are often better — they require less torque.