Bit type for milling aluminum?

Using an 1/8" bit, which type should I use: straight cut, upcut or fishtail?

Always use upcut for aluminum. If possible use a single flute end mill, with your router at the slowest rpm setting. Try to keep the chips out of the cut path as well (dust shoe, air blast, etc). This prevents the bit from “recutting” chips.

If you can, get bits with a ZrN coating (but these cost probably 2-4x more than plain carbide bits but will leave a better surface finish)

I’ve been doing a lot of cutting with the dewalt 611 and 1/8" single flute recently and have gotten excellent results with the following speeds/feeds:

45 in/min
.01" depth per pass
router rpm at “1”
dust shoe (to extract the chips)


I bought a bit made for aluminum machining with a higher helix (45 vs 30 degree) and ZrN coated. It was 2 flutes but at the recommended chipload, it was 48 ipm which seemed doable. I had good success with the bit. I had other machine issues but the bit performed flawlessly. It was $15 for the bit.

Welp, I just broke the 3 1/8" upcut bits I had. :disappointed:

Feed: 750 mm/min
Plunge: 25 mm/min
Depth per pass: 0.1 mm

I started at a higher feed rate (1200 mm/min) and kept lowering it…broke my last 1/8" bit at the 750 mm/min feed rate.

I guess I could have gone down to something like 250 mm/min but my hunch is I need stronger bits…I was just using the 1/8" upcut bits that came w/ my X Carve.

If you go too slow the bit will rub instead of cut => heat up, aluminium will gum up the surface of your bit.
You may be in that territory.

Quality of bit / number of flutes will affect things aswell, I use 3mm 3F 45deg Helix upcut with good success (min. rpm 10k) It can go 1400mm/min all day long dry.
Cooling/lubrication? Try using a syringe to add denatured alcohol to the bit carving area when running. This will help a big deal.

Cutting strategy also play a big factor, also how rigid is your system.
I have tested up to 10mm depth per cut when running adaptive clearing path, I have also cut 1mm alu sheet with a single pass. Get good bits, make sure you have a decent chip thickness and you should be getting improvement :slight_smile:


Hey Josh

So it really depends on what material that you are cutting thickness and grade of aluminum matter

could you give me some details on that?

also I would look into using high quality tools like onsrud or amana or vortex

also are you using coolant? WD-40 is a great coolant for aluminum

It aint bad, but it will leave oil residue. Denatured alcohol is better and leave none :slight_smile: