Hi Everyone, I have just finished building my second Home CNC Router and need to cut

Hi Everyone,

I have just finished building my second Home CNC Router and need to cut automotive grade sheet metal. Approximately 26 AWG. What type of end mill do you guys recommend I use?

I have successfully cut aluminum plate with my previous machine using 2 flute aluminum cutting carbide end mill but not much experience with steel sheet mental.

Any recommendations will be greatly appreciated.

By the way, I am using a DW660 for a spindle, but can reduce RPM some what using a router variable speed controller.



4 flute with coolant would be best, but it all depends what the lowest RPM you can get that 30,000 Dewalt to go down to.

Thanks! Do you think that a pneumatic mister would be good enough for cooling? or should I build a motorized cooling tray?

Also, do you think that the DW611 variable speed router would be more ideal?

I don’t have any experience with cutting metal but I don’t think you will get low enough cutting speeds from a router while maintaining the torque needed.

I think your rpm will need to be in the hundreds not thousands… A router can’t go that low.

About 3000 rpm with a 4 flute end mill, start at 5ipm and work up from there. Use the biggest end mill you can fit. Full flood coolant is best.

Is not speed determined by chip load? There is a guy with a youtube channel that talks about using single flute cutters with his “trim router(?)”.

I think sheet metal is what they make plasma cutters and water jets for.

Thank you guys! I realize that cnc router is not the ideal tool for this job, but i have faith that it can be done with good results. I have just purchased a 1.2hp variable speed router and plan on using that for my experimention. I agree with you guys that low rpm and low feeds would be best.

I have a hand full of 4 flute carbide end mills and just a couple of 1, 2 flues. Do you guys know a specific end mill type which would work best for me in this sheet metal situation?


If you’re really careful with your G Code I think you might be able to use something called a nibbler. Although good lord those things make a mess when they run. They shoot these horrible little half moon slivers of metal everywhere! A nibbler can cut in any direction though. So they’re nice like that. Nibblers are sort of like spastic hole punchers in a way.

@Krzysztof_Foltman like you say, the game does indeed change when you step up to ferrous materials. Then feeds, and speeds, become critical. At least that is my experience on my lousy imported bench top milling machine. Which for all of that is still a lot more rigid than any homemade CNC machine I’ve ever seen. It will mill steel, if I am extremely careful about it. But I have to feel my way through a cut. Which is part of being careful I suppose. I also have to run as close as I can to the optimal surface speed for the tool I am using too. Which on my mill for a HSS cutter is 100 surface feet per minute, or a little over that.

For everyone here that doesn’t know, there is a formula to calculate surface speed:
(π * DIA. * RPM ) / 12 = SFPM

A worked example:
3.1415927 * 0.25 * 1740 = 1366.5928 / 12 = 113.88

That would be spot on.

I cut 303 stainless steel on my CNC. A part I am doing now is using a .250 e.m. 4 flute, 3500 rpm .025 deep per pass at 10 ipm. Full flood coolant. This is a very conservative approach. I could easily double the DOC. My CNC is extremely rigid though, weighs 2200 lbs.

Not in my country it isn’t. The Moon is still a quarter of a million miles away too, until some of you other savages get there.

If you ran a bit about two millimeters in diameter then 6,000 RPM would be about right for that. Your feed would be really slow though. A 2mm diameter bit cannot take much side loading. heh