Why does my cutter grab or dig in when cutting brass?

Brass has a tendency to pull a sharp, high-rake cutter into itself - the edge self-feeds and digs. The fix is tooling with near-zero rake, ground specifically for brass, which shears the material without grabbing. Combine that with light cuts and controlled engagement, and be cautious with climb-milling.

Is cutting brass harder than aluminium?

Different, and generally more advanced. Aluminium's challenge is heat and chip welding; brass's is its grabbing tendency and the need for near-zero-rake tooling and careful engagement. Both demand a rigid machine, but brass is less beginner-friendly and rewards conservative, test-first cutting.

How to cut brass and non-ferrous metal on a CNC router

The three things that matter most:

Brass is the advanced one: it grabs the cutter, so an aggressive-rake bit can self-feed and dig in. Use near-zero-rake tooling made for brass.
Watch climb-milling - the grabbing tendency makes it more prone to pulling in, so control engagement and take light cuts.
Rigidity is the real limit, as with all metal; a flexible machine chatters and grabs where a rigid one stays controlled.

Feeds & speeds calculator, pre-filled for brass

Set your cutter diameter, flutes and RPM and read the feed rate and chip load. This is the same tool as the brass feed & speed page, which carries the full chip-load reference table.

Material

Bit type

Bit diameter

Flutes

Spindle RPM

Cut depth (mm)

Recommended feed rate

111.9IPM2,842 mm/min

Plunge rate

28.0 IPM

711 mm/min

Chip load

0.1015 mm

0.0040″ / tooth

Chip load bandIn range

0.076 mm0.127 mm

Your chip load is 0.1015 mm per tooth, which is within the recommended 0.076–0.127 mm range for brass with a 6.35 mm upcut spiral.

Table range for brass at 6.35 mm0.076–0.127 mm

Depth factor (cut is 0.47× diameter)×1.000

Geometry factor (upcut spiral)×1.00

Feed = 14,000 × 2 × 0.1015 mm2,842 mm/min

Brass. Brass machines cleanly but grabs. It cuts better at lower RPM than most people expect, and a cutter with no rake will resist snatching into the work.

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

Brass is 'grabby': a sharp, high-rake cutter can hog into it and self-feed. The classic answer is near-zero-rake tooling - bits ground specifically for brass - which shears without pulling in. Carbide for edge life. Other non-ferrous metals (copper, bronze) behave similarly but each has its own character.

Feeds, speeds & depth of cut

Take light cuts and keep engagement controlled - the danger in brass is the cutter grabbing and digging, not heat. Use the calculator's brass settings below as a starting point, favour shallow depths, and be conservative until you see how the specific alloy behaves. This is advanced material; treat early cuts as tests.

Workholding

Rigid, secure workholding matters more here than almost anywhere: a grabbing cutter puts sudden loads into the part. Clamp hard, back the work, and make sure nothing can shift when the cutter bites.

Chip evacuation & cooling

Clear chips so they don't recut, and a little lubricant helps in the softer non-ferrous metals. Brass chips are small and break easily, but keeping the cut clean protects both finish and tool.

Reading your results

Controlled brass cutting gives small, clean chips and a bright finish. A cutter that suddenly grabs, chatters, or pulls into the work is telling you the rake is too aggressive or the engagement too high - back off the depth, slow the feed, and consider brass-specific near-zero-rake tooling.

Common mistakes

Using aggressive high-rake tooling - brass grabs it and self-feeds. Use near-zero-rake bits.
Climb-milling without control - the grabbing tendency makes it worse.
Cutting heavy on a light machine - metal exposes rigidity limits fast.

Tooling & parts for brass

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.

Near-zero-rake / carbide tooling

Brass grabs an aggressive-rake cutter and self-feeds; near-zero-rake tooling shears without pulling in, and carbide holds its edge.

Genmitsu 10pc Nano Blue Flat Nose End Mills · or browse all options

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Frequently asked

Why does my cutter grab or dig in when cutting brass?: Brass has a tendency to pull a sharp, high-rake cutter into itself - the edge self-feeds and digs. The fix is tooling with near-zero rake, ground specifically for brass, which shears the material without grabbing. Combine that with light cuts and controlled engagement, and be cautious with climb-milling.
Is cutting brass harder than aluminium?: Different, and generally more advanced. Aluminium's challenge is heat and chip welding; brass's is its grabbing tendency and the need for near-zero-rake tooling and careful engagement. Both demand a rigid machine, but brass is less beginner-friendly and rewards conservative, test-first cutting.

Feed & speed for brass (the tool) →How to cut aluminium →CNC routers ranked for metal →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.