A downcut or compression bit, in carbide
Downcut or compression geometry keeps the top edge clean, and carbide holds up in dense species that dull a cutting edge faster than softwood.
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How to cut hardwood on a CNC router
The three things that matter most:
- Use a downcut or compression bit for clean top edges, and carbide for edge life in dense species.
- Grain direction and species density change everything - maple and cherry cut differently from oak - so treat feeds as a starting point and adjust to the wood in front of you.
- Burning means the feed is too slow, not too fast: a thin chip rubs and scorches. Feed faster or drop the RPM to thicken the chip.
Feeds & speeds calculator, pre-filled for hardwood
Set your cutter diameter, flutes and RPM and read the feed rate and chip load. This is the same tool as the hardwood feed & speed page, which carries the full chip-load reference table.
Recommended feed rate
396.1IPM10,062 mm/min
Plunge rate
130.7 IPM
3,320 mm/min
Chip load
0.2795 mm
0.0110″ / tooth
Chip load bandIn range
0.229 mm0.330 mm
Your chip load is 0.2795 mm per tooth, which is within the recommended 0.229–0.330 mm range for hardwood with a 6.35 mm upcut spiral.
Table range for hardwood at 6.35 mm0.229–0.330 mm
Depth factor (cut is 0.47× diameter)×1.000
Geometry factor (upcut spiral)×1.00
Feed = 18,000 × 2 × 0.2795 mm10,062 mm/min
Hardwood. Hardwood is the material where too slow a feed shows up fastest: the cutter rubs instead of cutting, heat builds, and the edge scorches. Burn marks mean feed up or RPM down, not the reverse.
Upcut spiral. The baseline the published charts assume. Chips are lifted clear of the cut, which keeps heat out of the workpiece at the cost of tear-out on the top surface.
Which bit to use
For clean top edges use a downcut or compression bit; for roughing where finish matters less, an upcut clears chips fastest. Carbide is worth it in dense hardwoods, which dull a cutting edge faster than softwoods. Match the bit to the finish you need on the visible face.
Feeds, speeds & depth of cut
Hardwood punishes a slow feed hardest - it conducts heat poorly, so the instant the cutter rubs, the heat stays in the cut and scorches. Researched starting feeds for hardwood often sit in the region of 100-200 IPM with a downcut or compression bit, but density varies enormously by species, so use that only as a bracket and take the exact chip-load figure from the calculator, pre-filled for hardwood below.
Workholding
Solid hardwood is heavier and holds well with clamps or a vacuum, but internal stresses can move a board as you cut it. Keep it clamped along its length, mind the grain direction so the cutter isn't fighting to lift fibres, and support thin stock fully.
Reading your results
A good hardwood cut throws real chips and leaves a clean, un-scorched edge. A burn mark - usually on the inside of a curve or where the machine slowed - is the signature of a chip too thin to carry heat: feed faster or lower the RPM. Fuzzy fibres instead of chips point to a dull bit or the wrong geometry.
Common mistakes
- Slowing down when you see a burn - that makes it worse. Feed faster or drop RPM to thicken the chip.
- Ignoring grain direction, so the bit lifts and tears fibres.
- Using one feed for every species - oak, maple and walnut differ enough to matter.
Tooling & parts for hardwood
The consumables a fix like this usually calls for. Prices are live; we may earn a commission on a purchase, which never affects what we recommend.
In stock
Frequently asked
- Why does my CNC burn hardwood?
- The chip is too thin, so the bit rubs instead of shearing and the heat has nowhere to go - hardwood conducts heat poorly, so it scorches. The fix is counter-intuitive: feed faster, or drop the spindle RPM so the same feed makes a thicker chip that carries the heat out. Slowing down, the common instinct, burns more. See the burning-wood troubleshooting page.
- Does wood species change the feeds and speeds?
- Yes, substantially. Density varies widely - maple and hard oak resist the cutter far more than cherry or walnut - so a feed that is perfect in one species rubs or overloads in another. Use a starting range, watch the chip and the edge, and let the calculator set the chip load for the cutter you are running.
Related
Feed & speed for hardwood (the tool) →Burning & scorching →Tearout & fuzzy edges →All material guides →
Tooling and technique are drawn from manufacturer documentation and established references; starting ranges are exactly that - the exact feed and chip load for your cutter come from the calculator above, never invented here.