Milling aluminum with the Shapeoko 2

We get a lot of questions asking whether one can mill aluminum with the Shapeoko 2. I'd like to definitively answer that with a resounding "Yes!"

If you'd like to make it yourself, the files and instructions are here. In this blog post I'll be discussing more of the technical details and issues I encountered. Here's a brief video documenting the process:

 The inspiration: I saw some designs online for a bottle opener with nice wood cutouts on the handle and thought I'd make my own using the Shapeoko.

I drew the outlines using Adobe Illustrator and used to generate the toolpaths. Here are the settings I used:

We had some of this 1/8" aluminum plate in stock that works well for milling. I also selected some 1/8" walnut for the handle.

For the milling bit, I used the single-flute spiral upcut bit that comes in our end mill bits starter pack. That's what everyone who pre-ordered a Shapeoko will be using so I thought I'd put it through its paces to see how well it works.

One thing I highly recommend right away is: use a bit of plumber's silicon thread tape on the collet of your rotary tool, especially if you're using the one that comes with the Shapeoko. I had a number of failed jobs that I finally tracked down to the bit coming loose in the collet from the vibration. When I applied ~3 turns of thread tape, the bit stayed put and I got all the aluminum milled in a single pass. This probably wouldn't be a problem if you're using an official Dremel or a more advanced spindle.

As long as we're talking spindle speeds, I also recommend just cranking the speed all the way up if you're using the default spindle. It isn't really designed to operate at low speeds and will lose power (and torque) as you turn it down. I didn't have any issues with the aluminum gumming up the threads of the bit so you'll probably be ok.

Other protips for cutting aluminum:

  • Put a piece of thin scrap stock underneath your workpiece so you don't tear up the wasteboard when you cut through. I know that's what the wasteboard is for, but it's way easier to use up scrap and keep your wasteboard looking nice, especially if you sink in the threaded inserts to use screw-down clamp.
  • Clamp down your material really well. I know everyone says this, but it's worth reiterating.
  • Use a very small stepdown. Bart Dring recommend no more than 15 mils, I work in metric a lot and I found that 0.1mm was plenty.
  • Go slow. I ran at a feedrate of 500mm/min or ~20 inch/min. The plunge depth I used was 300mm/min or ~12 inch/min.
  • Use cutting fluid. We had some nice cutting fluid in the shop, but if you don't have any of that, mineral oil or even water (since we're cutting aluminum) will work. Be careful about getting it on surfaces that you want to keep nice (like your nice walnut), it'll stain and won't come out.
  • Make sure your bit is sharp. Use a fresh one.
  • Keep a steady hand on the e-stop.
  • Wear eye protection. Aluminum shards in your eye are no joke! (No Inventables employees were harmed in the milling of this aluminum).

Once your piece is cut out, I recommend going over the edges with a burnisher or de-burring tool. The edges can be very sharp, so be careful.

The piece turned out really nice!

I think I pretty much covered the bases here, but if you have any other questions or want to share your own aluminum projects, hit us up in the comments below!

-Michael Una


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