MPCNC for Aluminum and mild steel

i am getting ready to pull the trigger and build my beasti. ( does a happy dance)
I plan on mostly using this for alu and some mild steel.

  1. After much reading i under stand that nema 17 is the way to go but i do not understand the ratings or which would be the best to order.

  2. I would like to use the Dual motors for X and for Y axis. Can this be done with a Duet 2 wifi board

  3. i have seen talk about 6MM GT belts and pulley size. (wife says size doesn’t matter) should i consider 10MM belt? 12T,16T, or 20T pulleys and where.

  4. Motor/Spindle? for mostly metal work, which is the best option for me.

  5. what size build yields a 600MMx600MM cut area?

I don’t want to turn you away, but I also don’t want you to be disappointed.

  • Mild steel is possible, but it’s pushing it, even for a small footprint.
  • A 600x600 cut area is fine for wood, but metals will suffer and particularly steel is likely to be disappointing.
  • The Z height must be kept as low as possible for best results with metals.

That said, if you are not too aggressive, aluminum should be ok at 600x600.

As for your specific questions:

  1. Ryan’s recommended motors are the simplest option. The torque is appropriate for the strength and stiffness of the other parts, and the current is within the range of the common stepper drivers. I don’t think it is worth ‘optimizing’ for stronger motors because you wouldn’t see much benefit given the stiffness of the other parts and you may fall outside the current range that the drivers can deliver.
  2. In principle dual endstops on the Duet 2 wifi should be possible since it has five drivers, but you may be somewhat on your own on the firmware side since it doesn’t run Marlin.
  3. 10mm belt will help slightly, especially as the work area gets larger, but the Z height is going to be much more critical and may swamp any differences in stiffness you would see.
  4. I’m not an expert in spindles but high power or low-speed high torque spindles are more likely to overcome the strength of the machine. If you can only take light cuts then there is no benefit to a high-power spindle, which is why they are generally not used on the MPCNC.
  5. The outside dimensions are about 11" to 12" larger in X and Y than the work area, for the standard DW660 router. A larger spindle will further decrease the work area relative to the outside dimensions.

Again it sounds like you have high expectations. You haven’t said anything about tolerances but that is another area where if you are hoping for 0.001" you might be unhappy with the outcome. Not to discourage you but your enjoyment is likely to be strongly influenced by your expectations.


I would add: it is not too hard or expensive to change a lot of things, including the size later. The control board is the exception, tht is obviously expensive.

Honestly, my recommendation is to start with it built to spec, with a much smaller footprint if you are looking at aluminium. Then you can answer your own questions on your own machine.

There is an “envelope” of useable settings in CAM. The envelope gets smaller with metals, especially steel, and smaller when your machine gets bigger. You will spend a ton of time learning CAM if you can’t find settings in that envelope.

I doubt 10mm belts will matter.

And for God’s sake, don’t watch the NYC CNC channel on YouTube. It’ll either give you insane expectations of your machine’s capabilities, or leave you weeping for lack of funding. :wink: AvE is OK, as he mangles the language and projects with equal facility, despite his industrial equipment…

Actually, NYC CNC is a great channel, they are some great videos, and as long as you remember that they have big, industrial machinery, and that you will never get those feeds and speeds with anything you print and build for under $500USD, it’s fun to watch what they do.

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Same with titans of cnc. Much less educational, imo, (at least for us small guys) but he has several videos that show his machines just MOWING through stock and finishing to 0.0001. I mean, he has a video where he explains why he bought a Tormach, and it was naively so he could communicate with people “just starting out” and I’m pretty sure John at nyccnc runs two of them for production, lol. Both are valuable to me for different reasons, but John is much more accessible, I think.

thank you all for your replies. I think based on that I will probably start with a 300 by 300 build area. I’m probably mostly going to be using aluminum, and once I get familiar with that and it pulled all my hair out and got older than I currently am oh, I’ll probably start to play with some mild steel. I think from what I can gather I will be fine with the duet 2 Wi-Fi and the DW660 router

How About this Spindle for aluimum

Is 12000 rpm enough or do i need the 24000 to 30000 rpm

You actually want a slower spindle for aluminium. Too fast, and the Al gets gummy… 12K RPM is probably (possibly?) more than enough. Just as long as you have the torque to make chips, you’ll be OK. Spindle speed is not necessarily your friend in this arena. We can’t push the bit fast enough to keep up with a high-RPM spindle.

In theory, the chips you take on your MPCNC should be the exact same size that Daddy YouTubeBux takes on his Haas. He just drives his spindle around about 10 times faster than we can…

That’s a very clear and firm NO.
I tried these, they suck.
Go for the Dewalt DW660, it has been proven to work extremely well.
I suggest you to search the threads and posts of @lionkev55 , which is one of the MPCNC users on the forum who is probably the most experienced on aluminum machining with the CNC, read everything you can from his experiences. He made hundreds of aluminum parts on a daily basis with his MPCNC so just try to get as close as possible to his settings if you want something reliable that works.


And I’ll step in and say that spindle is more money, for less power and less rigidity. Otherwise it’ll be quieter when you have it spinning but not cutting. :slight_smile:

Sidebar question for everyone here - On the question of RPM - does the torque of a Dewalt drop if you’re using a router speed controller to bring it down from the full speed?

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And, if I may, a related question. My Makita clone router has a speed control with 6 positions and some electronics to keep the router at a constant speed under varying loads. If I use a PID speed controller, does that interfere with the speed control on the router itself? Would it still work as expected with full torque at lower RPMs?

It will drop torque, which results in reduced speed, but without PID, it won’t be speed control, just torque/power control.