Materials · Other materialsadvanced~2 min read

Aluminium on a hobby router

Short answer

Many hobby routers can cut aluminium if you drop the RPM to where your machine's feed can still keep a real chipload, take very light passes, use a bit meant for aluminium, and keep the cut lubricated. The two ways it goes wrong are chip welding at high RPM and tool breakage from too much engagement.

Can a hobby router cut aluminium?

Often yes, within limits. A router is not a mill: it is less rigid, the spindle runs far faster than metal cutting wants, and the frame is not designed for the forces. What you can realistically do is light work in soft alloys. What you cannot do is treat it like a milling machine.

The two things that go wrong

1. Chip welding

Aluminium is soft and it has a strong affinity for the carbide of the tool. At wood RPM the cut gets hot enough that aluminium welds to the cutting edge. Once that happens the tool is no longer sharp, it is a lump of aluminium dragging through more aluminium, and it fails quickly. The fixes:

Much lower RPM than wood. Metal cutting speeds are a fraction of wood cutting speeds.
Lubricant. A mist, a drip, or even a periodic spray of a suitable cutting fluid or WD-40 makes a dramatic difference. It is the single highest impact change for most people.
Bits meant for aluminium. One or two flutes, high helix, polished flutes, often ZrN coated, designed so chips do not stick.
Keep chips out. Recut aluminium chips are what weld. Air blast and extraction.

2. Tool breakage

Aluminium takes far more force than wood, and a hobby gantry deflects. That deflection increases the load, which increases the deflection. The answers are all about reducing engagement:

Very light depth per pass. Much lighter than you would ever use in wood.
Light radial engagement. Adaptive or trochoidal clearing, where your CAM offers it, is genuinely the right tool here: it keeps the engagement low and constant while allowing deeper axial cuts.
Short stickout. Every millimetre matters.
Do not slot if you can avoid it. A full width slot in aluminium is where hobby machines break tools.

Alloys

Alloy	Behaviour
6061	The usual choice. Machines well, chips break up nicely.
7075	Harder and stronger, machines well, more expensive
5052	Gummy. Sticks to tools. Common as sheet, awkward to machine.
Cast aluminium	Varies hugely and may contain hard inclusions
Unknown extrusion	Usually a soft alloy. Test cautiously.

Safety differences from wood

Aluminium chips are not sawdust

They are sharp, they are hot, and fine aluminium dust is flammable. Do not run aluminium chips into a dust collector that is full of wood dust. Use eye protection without exception, and be aware that lubricant plus chips makes a slurry that is unpleasant to clean and hard on some machine components.

Expectations

Cutting aluminium on a router is slow. A pocket that would take two minutes in pine can take twenty. That is the correct outcome, not a sign you are doing it wrong. If aluminium becomes a regular part of your work rather than an occasional part, the honest answer is that a small mill will do it better, faster and with less risk to your router.