Spiral Bit

CNC Bit Reference — Genmitsu MC40A — Flat Downcut 2-Flute (Nano Blue)

Notes

Downcut pushes chips down into the cut — top face of the workpiece stays crisp and splinter-free. Trade-off is reduced chip clearance; chips pack into the slot if DOC is too deep. Feeds & Speeds (Wolfpawn 4040 Pro, 3.175mm cutting dia): RPM: 10000 Feed rate: 600–900 mm/min (slower than upcut — chip clearance limited) Depth of cut: 0.8–1.0mm per pass max Plunge rate: 200 mm/min Best for: Veneered plywood (top face must be clean) Painted or primed MDF signs Surface engrave operations where tearout ruins the job Not ideal for: Deep pocketing — chips pack in Through cuts on thick stock alone — combine with upcut pass

Tips

For through cuts: use downcut for first pass (top face), upcut for remaining depth. Shallow DOC is essential — 0.8mm or less per pass to avoid chip compaction and heat.

Details

Downcut pushes chips down into the cut — top face of the workpiece stays crisp and splinter-free. Trade-off is reduced chip clearance; chips pack into the slot if DOC is too deep.

Feeds & Speeds (Wolfpawn 4040 Pro, 3.175mm cutting dia): RPM: 10000 Feed rate: 600–900 mm/min (slower than upcut — chip clearance limited) Depth of cut: 0.8–1.0mm per pass max Plunge rate: 200 mm/min

Best for: Veneered plywood (top face must be clean) Painted or primed MDF signs Surface engrave operations where tearout ruins the job

Not ideal for: Deep pocketing — chips pack in Through cuts on thick stock alone — combine with upcut pass

Specs

Setting	Value
Shank	1/8" (3.175mm)
Flutes	2 — downcut spiral
Material	Tungsten carbide

Limits

Setting	Value
Max Rpm	30000 RPM

Applications

Setting	Value
Best For	Plywood top face, veneers, painted MDF
Not For	Deep pockets — chips pack in, risk of burning

Settings

Setting	Value
Rpm	8000-9000 RPM
Feed	700-900 mm/min
Doc	1.0-1.5 mm per pass

Tips

For through cuts: use downcut for first pass (top face), upcut for remaining depth. Shallow DOC is essential — 0.8mm or less per pass to avoid chip compaction and heat.