Steel milling

Hello everyone,

When I saw a video of Ryan machining steel with an MPCNC milling machine, I wondered: is it really possible with an MPCNC?

It seems to me that industrial machining centers use a permanent supply of cutting oil to prevent overheating, for example… Would it be possible to compensate for this, even if it means using extremely low feed speeds (after all, we’re less constrained by time when using a hobby machine…)?

Have any of you experimented with this?

Thanks in advance

I have not cut steel (yet) but I have cut tons of aluminum and it’s extremely capable. I run an air mist coolant with IPA to keep chips evacuated and everything cool. I’m sure you could do the same thing with the steel. Just going to take slow feeds and speeds and definitely trochoidal milling.

There are a lot of levels of difficulty in milling. Cutting through foam is easy. Cutting through MDF is pretty easy. Cutting 3D in MDF is harder. Cutting aluminum is harder. Cutting steel is really hard. It isn’t exactly on a line, but some things are just easier than others.

Once you figured it out, it would be pretty repeatable and the machine would survive fine with lots and lots of cuts. But the “envelope” of successful settings gets smaller as you increase difficulty. Finding that sweet spot of cutting before the work hardens is hard. Ryan is obviously an expert. If you paid $10k-$100k for your machine, the envelope gets wider, and it is less difficult to find success. Adding lubricant widens that envelope.

But Ryan wasn’t even the first to cut steel (and before that, we would say it wasn’t possible). It definitely is possible and the results have been repeated.

That said, if cutting thin sheets of steel is your goal, a MPCNC or LR plasma cutter is way faster and has a larger envelope of success. But it does require torch height control, which requires Linux CNC (at least, that is the common setup).


Cutting steel is definitely possible (I’ve done it, with mixed results) but it’s more complicated than just turning down the feed rate for lighter loads. Lowering feed rate does reduce the cutting load but the temperature goes up.

I haven’t gotten around to setting up mist or flood coolant but I would think it would be able to keep the temperatures under control and in that case you should be able to trade time for cutting load.


I have no idea what settings I used.


Interesting. I didn’t know about mist cooling, but only with cutting oil in a closed circuit. What kind of liquid do you use? Is it water? Anything other than water might make the working environment a bit dirty…

Do you have a photo of your installation?

I would like to machine parts like this: Flat Mount Dropouts | Paragon Machine Works
It’s fairly flat but with some relief.

For sheet metal, my MPCNC is equipped with a plasma cutter. That said, in retrospect, I don’t know if the THC is really useful:

  • when I’m cutting thin sheet (1mm), the deformation is so great and unavoidable (on large surfaces) that I don’t think the THC can correct anything, given the speed of Z movement. Even so, THC only corrects the Z trajectory and doesn’t prevent deformation.
  • when I cut thick sheet metal (I’ve tried 4 and 6mm), with the right feed speed and power, I don’t notice any sheet metal deformation.
    After all, I use a “top-of-the-range” plasma station (GYS), so maybe that has something to do with it…

Thanks for the information. Maybe I’ll practice on soft materials first.

Great job! Which milling machine and cutter did you use? With cooling?

Incidentally, I was wondering if you just want to engrave and not cut metal, what minimum laser power do you need (maybe with a specific wavelength or characteristics?).

I regularly cut materials at the fablab near me, but their laser doesn’t attack metal (only cuts/engraves plastics, MDF, leather…).

I use Isopropyl Alcohol. It evaporates about as fast as it sprays out. Works great on aluminum but I have never tried it on steel. I use just air on acrylic and it helps a bunch.

The latest MPCNC, no cooling, with carbide 2 flute endmill.

I’ve cut quite a bit of steel. It is slow but works ok. I only use my machine for steel in a pinch when I have the time or dont want to pay for laser or waterjet. Check out some of my posts and the community documents on Github. I use a mister to cool the cuts.


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Okay, but aren’t alcohol vapors flammable?

If you have enough sure. I wouldn’t use it in a basement. Some ventilation is required.