I'm ready to give up on machining aluminum kinda.... maybe?

It shouldn’t be this hard. I watch everyone else do it with no issues. Tons of YouTube videos not only of the mpcnc but cheap desktop cnc routers doing it with no issues.

I cant for the life of me get a 2d contour path to work.
Things I’ve tried:

  • single flute, 2 flute, 3 flute
  • .2mm .5mm .75mm 1mm depth of cut
  • travel speeds from 300 to 1500mm/min
  • built a 2nd machine

I’ve tried every combination of the above. I’ve broken at least $150 worth of bits at this point. I cant get anything to work. Soon as I find a setting that cuts a test part, it fails the next part almost immediately. I get a vibration in the cut that eventually causes the tool to either break or go off path. Its in every tool, every depth of cut, every speed, and every spindle speed. It always vibrates as its cutting. It has to be something that I am doing because It happens on both of my machines now.

I will attempt a video tomorrow, im too frustrated right now to continue tonight. It shouldn’t be this hard.

What spindle and spindle RPM have you got?

Keep on trying, you’ll make it work eventually!

I suggest you to read this thread: Lionkev's Aluminum Attempts

Kevin was arguably the one who got the most experience here cutting aluminum (at least the one who shared his experience the most). He got really good results so I suggest you to try to copy his setup as much as you can.
He too was on the verge of quitting his attempts at first, but he persevered and finally mastered aluminum [insert montage here] Next one might just be you, grasshopper!

Also, you should make sure that the aluminum you try to cut is good for machining, some grades are not designed for that, they get soft and gum up the bits.


I’ll also suggest to get the short single flute endmills Ryan sells. You can also find them on eBay, maybe Amazon if you’re already placing an order there that can save shipping. Kyocera I think they are. The open flutes are great at evacuating chips, and they are STRONG. I’ve packed them full of welded aluminum chips so badly that they stalled my machine and never broke. Pry the alu out and set it back to work cutting like nothing ever happened.
You didn’t mention air, but it helps a lot. Also, for 2d contour, I like to add a roughing pass (2 if you’re only finishing at final depth). This puts an extra pass on the perimeter to widen it up. That helps a lot with chip evacuation as well.

I have the same results with the single flute Kyocera.
I’m using air for evacuation
I’ve tried roughing passes. It will be moving along nice and smooth, then it digs in and breaks so fast you have no warning its going to do it.

First post says what I’ve tried. I’ve also tried every rpm in between. When it starts to vibrate ive tried increasing/decreasing speed. Increasing/decreasing rpm. Nothing works.

I have. I’ve been attempting aluminum for 6months now. Just when I think I get it sorted out, the next piece I cut doesn’t work.

6061 is all I use.

No, you did not mention any rpm or any spindle name/brand.

That matters a lot, for instance I was using a 500W brushless spindle and it had not enough power to do the job.

If you want some help you shouldn’t be too greedy with the information, we don’t know what part you’re trying to attempt cutting, what bit diameter, rpm, trochoidal or not? climb milling? conventional?
I understand your frustration but it’s hard to help if we have very little clue of what you’re doing :slight_smile:

Pictures and videos would also help a lot.

I am sure I will get the spelling wrong but I understand that trochoidial milling helps instead of conventional.


I thought i did. Late night and frustration.

I have both an 800w and a 1.6kw that have the same behavior on 2 machines. I’ve gone from 10k rpm to 24k rpm and everywhere in between. All trying to match the travel speed with the calculators.

Whaaaaaaaaaat? Dui is right… Time for pics and video.

Travel speed ≠ rpm.

What is your z height? Keeping the piece as close to the gantry as possible is crucial.

We are trying to help you here, don’t lose spirit!

Ok here you go. I’ve already given up on this nonsense. 6 months and 2 machines is enough to make me quit.

This in particular is a 2 flute bit, however the behavior is identical whether its a single, 2 , 3, or 4 (adjusting feeds and speeds for each)

You can see that changing travel speed and rpm does nothing. This also happens regardless of depth of cut. I have tried .14, .2, .25, .5, .75, 1 mm depths. I get identical behavior.

I also went through just before this video and got the bit as square as my tools will allow.

The gantry is as low as I can make it and still be able to machine the .75in and 1" aluminum pieces.

There really is no play in the spindle compared to my other machine, everything is nice and snug.

I’m having a hard time grasping how it doesn’t matter how fast, slow, what bit I use, what machine I use, and how deep I cut. This happens every time. Yet I see videos on YouTube of shapeokos cutting like 5+mm doc.

Move the material up, choke the end mill as high up as it can go, verify your speeds.

My vid is showing a single flute, 1mm DOC (min I would say is 0.5mm), 4mm/s (240mm/min), ~20k rpm at 600W and you hear it struggling. This is pushing it at this power and speed. https://youtu.be/FF1k24-HzpU. Notice how high up my Z axis is. You have not mentioned how large your actual machine is but mine has a foot print of 22x24" minimum Z (legs are not visible locks touch the feet).

I feel these numbers you want to shoot for, Slightly slower, slightly shallower. If your machine is reasonably sized, if you have a 3’x4’ good luck. Some have gone far and above this but that is a different topic.

Your 15000/500 and /300 don’t seem too bad. A little slower or tweak the RPM a bit and I think you have it.

Are you slotting in that video? Notice I am not (I use peel whenever possible), slot very slowly if you have to then use a finishing pass, trichodial is slow but is a better option for learning.

2 flutes=twice the load on the machine and half the chip clearing capacity (or less). Use a single flute for this for sure.

Why, you just asked for help. No need to struggle in silence, look at all the people that sprang into action and are ready to help!


I only have 3/4in z travel where it is. Im cutting .5" aluminum.

Machine is 24x36 as I make a part that is 32" long.

I did the same test with the single flute and have the same results.

The slower I move, the worse the chatter. And that is on all flute count bits.

Trichodial is difficult on some of the parts I make, unless I want to increase my material costs a lot. Trying not to do that.

Your comment about 1500/500 not being bad, that is until you’re over 1/4in deep and it breaks your bit without warning.

I keep trying, but im running out of money just to test cutting bits.

I did notice that with the spindle engaged but the feed paused while its in the channel, I can hear it contsct the sides just tapping the touch screen on the control box. Im going to go get some large nuts and bolts and weld a nut inside the support legs that will bolt through under the table to a large washer. Maybe that will stiffen the legs up a bit more

I still have the least amount of chatter with those 3 flutes I use. At least up until they break as well.

If you are done, then I won’t keep looking into this. Just let me know, I can’t be sure if you are frustrated and want some help or just here venting.

I cant tell either.

I have 1 single flute left. I will get some video. I