Cutting sheet metal

Has anyone tried cutting sheet metal? Did it work? Did it fail? What was your setup like?

I’m trying to cut a piece of 26 guage zinc coated steel but so far I’m getting too much chatter.


Plasma cutter on your machine makes that easy. Have a look through the gallery.

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I would love to do that one day but for now the machine is in the spare bedroom of my apartment so I’m just looking at milling options.

Steel is probably not an option for milling at this point. I haven’t proved that but I would assume it can’t be done.

Just throwing a WAG, but you’d probably need down cut end mills and through cut into a wooden spoil board. It’s still going to screech like a banshee though.

Aside from milling (which probably cannot work on such hard materials) or plasma (which works well but you need some kind of torch height adjustment), the only option I can think of would be electro erosion.

But I don’t know anyone who tried that before on the MPCNC, so you’ll have to be a pioneer. Good luck!

After some experimenting I managed to get a nice result with reliable reproducibility. I used a 1/8" 4 flute down cut carbide end mill. I ramped into the work at 3 degrees. I initially thought that since the sheet was less than half a millimeter thick, I could plunge straight down into it. I destroyed a few end mills learning this lesson. To eliminate chatter I enabled trochoidal milling. This let me run at a high feed rate of 36mm/s without issue. Trochoidal milling by itself left a very slightly rough finish, so I added a finishing pass of the default value of 5% tool diameter and all cuts were then very smooth. Looks like it can cut steel after all.


DUDE, SERIOUSLY??? What, oh please get some video of this. You have just utterly blown my mind!

New gallery just for you.

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Okay, this is too good. You even have smaller steppers on there. I love it. There has been a bunch of giant nema 17 and nema 23 questions lately and I keep telling them it isn’t needed. Proof. You have absolutely made my day, I have to share this.

Oh how I love being wrong sometimes, I thought it could not be done, just wow.


Wooo! Looks like it’s going to be an enclosure of some kind, what-cha-making?

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This is awesome. Now it’s time to make some sweet rims :D. How many sheets would that take?

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Here's a video of the cut:

Some more notes I thought of: To secure the sheet to the spoil board I sprayed the back of the sheet with super 77 adhesive so no holding tabs were necessary. As the steel is conductive it was easy to do a z height measurement across the whole sheet at 100mm intervals to adjust the cut depth along the piece. I was able to use pretty aggressive trochoidal settings. I think it was 20% step length and 25% width. I used 0% oscillation because the bottom of the tool was just cutting soft plywood. After I peeled the finished part off I wiped the adhesive off with mineral spirits. No adhesive remained on the bed.

The part is indeed an enclosure. I've since bent it in a brake and attached it to the bottom of a longboard. I've already made some rims for it but they're 3D printed parts to attach gears to the wheels.

I agree that larger steppers are unnecessary. Before I had worked out proper settings and I was getting violent chatter, the steppers were holding fine, the spindle was just vibrating too much.


Oh man, that was perfect. No chatter, the router RPM didn’t budge, seems like you easily had that cut. Way more smooth than my old Aluminum video. Looks like I have some catching up to do.

Thank you so much for the video, the inspiration, proving me wrong, I am stoked! I want to go cut some metal but I am going to be busy making LR2 parts for a while longer.

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That’s insane.

I never thought it would be possible, and now I feel the urge to try that!!

I think that was the last really hard challenge this machine had to pass, and you passed it with style, with a big machine and a large part perfectly milled.

Congratulations, bravo!

(please make us a little tutorial on how you set it up and the modifications you made to the machine/software to get this result…)

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This is awesome! I’m still building my MPCNC, but I have a project to do where I need to cut some sheet metal to fabricate a rounded nose for a stock trailer. I was NOT looking forward to doing all of that by hand! So now I’m moving the MPCNC ahead of it on the project list. Your cuts look a LOT better than I was going to be able to do (and redo after I messed up…LOL). Now, I’m wondering what the upper limit on thickness might be?

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I’d bet the upper limit will be determined by a mix of cutting length of the bit and depth of cut, unless your Z isn’t completely vertical. It’s just going to take time…

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I did it! I did it!!! Steel baby!

wbendick, Thank you so much for the inspiration. So freaking cool! Kevin Messaged me today and he milled some steel with his LowRider a that really lit a fire under my butt. So cool I am putting together a tiny video to show off.

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I watched the above video to educate my self.

So if i understand this correctly, When using a 1/8" cutter, the actual cut out line is more like 3/16? because the cutter is not going in a straight line, but is actually making tiny little cirlces as it moves along the cut out path? did you use F360 like the video above?

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I really think it’s the trocodial milling that’s the secret here.

Again I really like mold making. The first time I saw it used was on a tormach 440. I’m really impressed it worked here. It gives me hope I can do a few more advanced things I have in mind on this machine without outgrowing it.


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CAM is still pretty new to me. Is trochoidal milling the same thing that Fusion 360 calls Adaptive Clearing? I was just learning about AC the other day and the motion looks very similar.

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