CNC Feeds and Speeds for Aluminum 6061 (Desktop Routers)
In short, Never use a 3-flute or 4-flute end mill on a desktop CNC router cutting aluminum! The tiny flute gullets cannot clear hot chips fast enough. Aluminum chips melt, weld themselves to the carbide flutes within seconds, and snap your bit instantly. Always use a polished single O-flute upward spiral cutter.
Why Aluminum Requires Single-Flute Tooling
Aluminum has high ductility and a relatively low melting point compared to steel. Desktop CNC routers (Shapeoko, X-Carve, Onefinity, Genmitsu) spin at high RPMs (10,000 to 24,000 RPM) with limited frame rigidity.
A single-flute end mill gives you one massive open pocket for chip ejection. At 18,000 RPM, a single-flute cutter only takes 18,000 cuts per minute instead of 54,000 cuts on a 3-flute bit. This allows you to run reasonable feed rates without your machine flexing or chattering.
Baseline Settings for 6061-T6 Aluminum
| End Mill Size | Flute Count | Spindle RPM | Feed Rate (mm/min) | Feed Rate (IPM) | Axial DOC (Pass Depth) |
|---|---|---|---|---|---|
| 1/8" (3.175 mm) | 1 Flute (O-Flute) | 20,000 | 900 – 1,100 | 35 – 45 IPM | 0.50 mm (0.020") |
| 1/4" (6.35 mm) | 1 Flute (O-Flute) | 16,000 | 1,400 – 1,800 | 55 – 70 IPM | 1.00 mm (0.040") |
| 1/4" Roughing | 2 Flutes (ZrN Coated) | 14,000 | 1,200 – 1,500 | 48 – 60 IPM | 0.75 mm (0.030") |
Lubrication: Isopropyl Alcohol or Air Blast
You don't need a heavy flood coolant enclosure to machine aluminum on a desktop CNC. The easiest setup is a simple continuous compressed air blast aimed directly at the tool tip to evacuate chips, combined with an occasional squirt of 91%+ Isopropyl Alcohol (IPA) or WD-40.
Alcohol evaporates immediately, leaving zero oily residue on your spoilboard while keeping the aluminum below the temperature where chip welding occurs.