Can a 3018 cut aluminium?

It can engrave and profile thin aluminium with a single-flute cutter, shallow passes and a slow feed. It cannot do it productively, and it will break tools while you learn. If aluminium is the point rather than an occasional job, start one class up.

Do I need a water-cooled spindle?

For metal, effectively yes. Air-cooled spindles hold temperature for short jobs and get hot on long ones, and metal jobs run long. The water loop is a pump and a bucket; it is not the complication it sounds like.

Router or mill for aluminium?

Either, if the router is rigid enough. Routers spin fast and suit shallow, fast passes; mills are slow and heavy and suit deep cuts. For aluminium specifically, a rigid router is often the more productive choice.

Mild steel on a rigid benchtop mill, yes. Mild steel on a desktop router, only in the sense that it is technically possible. Stainless and tool steel want a proper machine.

desktop CNC machines, tooling and upgrade parts / Buying guide

Desktop CNC machines for metal

Cutting metal on a desktop machine is entirely possible and routinely oversold. The machines that do it well are heavier, slower and more expensive than the ones in the photographs, and the ones in the photographs will do it badly enough to break tools and convince you the whole idea was a mistake.

This is the honest version: what each class will cut, at what rate, and what changes when you move up.

In this guide

Rigidity is the whole argument

Every problem people have cutting metal on a desktop machine traces back to deflection. The cutter pushes, the frame gives, the cutter unloads, the frame springs back and the cutter takes a double bite. That cycle is chatter, and it is what breaks end mills and ruins surface finish.

You cannot fix it with a better spindle or a smarter toolpath — only with mass and stiffness. Within a class, the heavier machine is the better metal machine almost without exception, which is why crated weight is the most honest single number in a machine specification.

What each class will actually cut

3018-class extrusion machines — engraving in aluminium, PCB isolation routing, soft plastics. A 1mm-deep profile in 6061 with a single-flute cutter is achievable and slow. Treat steel as out of scope.
4040 to 6040 on a steel or thick-plate frame with ballscrews and a 1.5–2.2kW spindle — aluminium as a normal operation, brass comfortably, mild steel in shallow passes with coolant and patience.
Benchtop mills with a dovetail or box column, 150kg and up — mild steel as a normal operation, stainless with the right cutter and a slow feed. This is where the machine stops being the limit.
Anything advertising "cuts steel" under 50kg — read it as "will scratch steel once before something bends".

Spindle: torque where you are cutting

Aluminium on a small machine wants a shallow cut at high RPM with a fast feed, so the chip carries the heat away rather than the tool. That means a spindle that still makes power at 10,000–18,000 RPM, which a water-cooled 2.2kW unit does and a trim router only approximately does.

Steel is the opposite: low RPM, low feed, and torque. A router spindle has almost none down there. This is the single clearest technical reason a mill and a router are different machines rather than different sizes of the same one.

Cutters and coolant

Single-flute or two-flute carbide in aluminium, so the chip has somewhere to go. Uncoated polished flutes or ZrN; the common TiAlN coatings encourage aluminium to weld itself to the tool.

A mist of coolant or even WD-40 on a brush changes aluminium from difficult to straightforward, because it stops the chip re-welding into the cut. It also makes a mess, which is why enclosures exist.

Workholding is the second limit

A rigid machine holding a part in a flexing fixture is a flexing machine. A proper vice, or a fixture plate with real clamps, is frequently a bigger improvement than the next machine up — and it is a fraction of the price.

It is also the cheapest thing to get wrong: double-sided tape holds thin aluminium well enough until it does not, and the failure mode is a cutter through your hand's worth of part.

Questions & answers

Common questions

Can a 3018 cut aluminium?: It can engrave and profile thin aluminium with a single-flute cutter, shallow passes and a slow feed. It cannot do it productively, and it will break tools while you learn. If aluminium is the point rather than an occasional job, start one class up.
Do I need a water-cooled spindle?: For metal, effectively yes. Air-cooled spindles hold temperature for short jobs and get hot on long ones, and metal jobs run long. The water loop is a pump and a bucket; it is not the complication it sounds like.
Router or mill for aluminium?: Either, if the router is rigid enough. Routers spin fast and suit shallow, fast passes; mills are slow and heavy and suit deep cuts. For aluminium specifically, a rigid router is often the more productive choice.
What about steel?: Mild steel on a rigid benchtop mill, yes. Mild steel on a desktop router, only in the sense that it is technically possible. Stainless and tool steel want a proper machine.

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