One of the things I wanted to try with my CNC router from the start was cutting metal. I’ve been building up to it as I learned the limits of my machine and got a sense for what it can do. This weekend I decided to try engraving my blog logo onto a piece of metal. I don’t really know what metal it is, possibly its aluminium but I don’t really remember where I got it from. In any case….I selected one of the diamond burrs for engraving from the original kit my rotary tool came with. It is pointy, and the idea was that for a shallow engrave of just 0.5mm. At this depth just the narrow tip is used so I can get some pretty good detail.
I am very happy with how things turned out The detail could be a little sharper I guess. I’m not sure how much smaller than this I would want to go without an even more pointy bit. perhaps another bit purchase in my future…
I then needed to actually cut the piece out of the metal sheet. For this I switched to the 2mm tilan covered bit that I bought and just lined up a simple square cut around the words. For this I was a little too optimistic. I had the speed still up at 200mm/min and I was going for 0.5mm cuts.
A couple of things went wrong here.
1) that was way too fast, and
2) the levelling wasn’t quite right and it wound up trying to make an even deeper cut.
It is times like this when I really ought to fit an emergency stop button to the machine. I could hear as the router speed started to stall out attempting to push too hard into the metal. I had to rush to hit the reset. And due to the way commands are being streamed to the arduino, I also have to abort the run else it just resumes after the reset. It would be handy to have something that just drops the power and resets the arduino to ensure I minimise the risk to the bits and the motors. As it was I was quick enough and prized the bit back out of the metal. Backed everything off and reset for 60mm/min 0.5mdepth cuts.
I decided to manually triggered each command since it was just a simple square. When I got down to mostly cut through I reset the clamping to hold the now mostly loose piece. As I’ve seen before with my machine, I had an issue when going backwards on the x-axis and the bit pulling off course. So I switched tack to just running that side forwards at depth, then returned without a drop, then forwards at next depth. And here is the final result:
The cut out isn’t as straight and square as it could have been due to a couple of issues, but in general it worked great. Certainly well enough that I think I can machine metal in the future, being careful with shallow depths and slow cuts. As ever here is a timelapse. The beginning of this you can see me doing some investigation of the electronics with my awesome multimeter. Somewhat overkill for this use, since I was just checking connections. I have a bad solder joint on one of the switched I’ve got for the y-axis. The switches control the level of micro-stepping so when its not reading right, the y-axis was not running correctly. I managed to get things sorted but I should probably properly resolder the connections.
Disclaimer: the very nice multimeter I mentioned above was a gift I received via the RS-online tech outreach team. I receive a lot of random offers to place ‘sponsored posts’ for completely unrelated products to which I always say no. In this case i would be happy to promote RS as a very relevant supplier to my hobbies and in particular their CNC safety information is very pertinent to me. Also, far from a faceless PR agency just interested in advertising, Tatiana who contacted me, is very nice and genuinely interested in her own projects, so has a good understanding of the joys, and trials, of trying to make things. All in all it was nice to finally be approached by someone actually interested in the specific content of my blog. So if you find me suddenly quite pro- RS-online, it is mostly because they really seem to understand the independent maker, and only party because they sent me a nice multimeter.