Free calculator
CNC feeds and speeds calculator for wood and acrylic
Choose your material and bit to get a starting feed rate, plunge rate, depth per pass and ramp angle for a hobby or desktop CNC router — worked out from chip load, with the formula shown.
Tracing is free in your browser. A free account exports files of up to 40 shapes; paid plans from $2 a month export without limits.
Calculator
Pick your material and bit. Every number is worked out from chip load, and the formula is shown underneath so you can check it.
- Spindle speed
- 18,000 RPM
- Feed rate
- 1,440 mm/min · 56.7 in/min
- Plunge rate
- 480 mm/min · 18.9 in/min
- Depth per pass
- 1.6 mm · 0.063 in
- Chip load per tooth
- 0.040 mm · 0.0016 in
- Ramp angle
- 5°
How it is worked out
Feed = spindle RPM × flutes × chip load. Chip load = material factor × bit diameter. Plunge = a third of the feed.
Starting values for a hobby or desktop router. Every machine cuts differently: run a test on scrap and adjust from there.
How it works
Choose a material
Softwood, hardwood, MDF, plywood or acrylic.
Choose a bit
Flat end mills from 1/16" to 1/4", a ball nose, or a 60° or 90° V-bit.
Use the numbers
Copy them into your CAM software, or open the Studio where they are applied to your toolpath automatically.
Why woodworkers use Magic Carve
Worked out from chip load
Feed = RPM × flutes × chip load, with chip load scaled to the bit's diameter and the material.
Capped for hobby machines
Depth per pass is limited per material, so a 1/4" bit is not asked for a cut a desktop gantry cannot hold.
V-bits handled properly
A V-bit works at its narrow tip, so its feeds are set from the tip, not from its widest diameter.
Straight into a toolpath
The same presets fill in the Studio, where you trace a design and cut it with these settings.
Questions
What is chip load?
The thickness of material each cutting edge removes per revolution. Too small and the bit rubs and burns; too large and it deflects or breaks.
How do I calculate feed rate?
Feed rate = spindle RPM × number of flutes × chip load. For example, 18,000 RPM × 2 flutes × 0.04 mm = 1,440 mm/min.
Why is my bit burning the wood?
Usually the feed is too slow for the spindle speed, so each edge takes too thin a chip and rubs. Raise the feed or lower the RPM to bring the chip load up.
Are these values safe for my machine?
They are conservative starting points for hobby and desktop routers. Every machine differs: test on scrap first and adjust.