IDEA: 3D printer with the MPCNC body

I know this is probably stupid, but I was thinking about the issues with the MPCNC ( plan to build one to mill signs and art, etc). the issue of height is the z axis, correct? so, my thought is to use the MPCNC with a CoreXY style bed. the hot end can move around freely (24" x 24" is HUGE for a printer!), but the z would not be an issue like on the MPCNC. the Z axis would be on the bed, and it would move independently of the conduit. If you added a BL touch, then the current z axis could be used for leveling and micro adjustments.

Has anyone tried this? It would pretty much just be a coreXY Printer, but you could just replace the ‘bed’ with MDF when you are done, change the hot end for a spindle, and go back to milling. In my head it SOUNDS good, but a lot of things sound good in my head…

I had this idea when I first got here… its possible but a 24x24 bed is heavy, large and difficult to level (keeping in mind auto leveling only works in for small Differences) also you need z movement for the mill to work so you would be limiting your maximum milli level item to the size of the bed. And wood gets heavy quick, so you would need to slow down your plunge speeds and need some really good steppers in the bed… at least that was what was explained to me when I asked the same question… and no it hasn’t been done to my knowledge.

All that said, if you want a combo unit o do think its possible… but I think youbwould want to set it up different… have a very short z axis on the rails for milling that gets locked for 3d printing. Then use a stepper controlled drop table for 3d printing… you would want to use klipper on a pi so you could easily switch between z steppers. When milling you could lock a spoil board in place level with the top of the table…

it would work, but unless your really limited on space, probably not worth the effort when you could just make a large format printer and have your cnc mill separate. I have a SM2 3 in 1 machine now and let me tell you. Having all three in one machine causes more limitations then advantages.

yeah, that’s kinda similar to what I’m building right now, but mine evolved quite far of the original MPCNC.

It’s totally doable with a regular MPCNC, though, to be honest with you, the MPCNC prints really fine as it is. On my previous machine I was printing with a gigantic 50cm long Z axis and got really great results, so I suggest you to not burn the steps, try the standard machine first, and then maybe, upgrade if you feel that it’s necessary.


maybe i’m mistaken but the current MPCNC design is good at printing or good at milling but not good at both. meaning you have a trade off between Z Hight that is needed for the 3dp and rigidity that is needed for the Mill. i could be wrong but i took his question and approach as a way for it to be good at both at the same time. i do still think it is possible, just seems like maybe not the most practical thing, but it could be fun.

Dui has shown it is possible to straddle that edge. His first build had a wood based drop table and a big Z. When printing he would drop the work table way down and use the long Z for printing. For milling, he would move some dowels and the table would be just a few inches from the bottom of the MPCNC. This isn’t perfect, since you have a huge Z with a motor on top, but it is pretty good. You could also have two Z assemblies (many people do that any way for multiple tools).

I will say that this kind of printing isn’t for a beginner.


Yeah, just as Jeffe said, you can have both good printing quality and good milling ability if you use a drop table like I did on my first build (see here).
I was able to 3D print really well and also to mill wood and aluminum. I didn’t have great results with aluminum, but that was mostly due to my spindle motor which wan’t powerful enough (and my CAM skills that were bad).

I had two Z axis, I was using the long one for 3D printing and a super short one for milling.
The drop table wasn’t difficult to build at all, so I guess you should not be afraid to try it :slight_smile:


Yeah I’m sure switching out the z rod lengths would go a long way. I personally feel like its to much work constantly swapping between functions. I would rather have a dedicated mill and a dedicated large format 3d printer (even if they are both MPCNC designs)

It takes 5 minutes: unplug the Z axis, remove it, drop in the other one and lift the table.
But yeah, if you have space (and money) it’ll always be better to have several machines.

Sounds simpler then my SM don’t you need to run calibrations with each tool change? And how are you handling the firmware differences?

Edit: I mean are you running 1 firmware version that is handling both milling and 3d printing?

For the calibration I had a probe sensor on the Z axis, to I was just running the autoleveling routine before each print, which is what I do on all my other printers anyway.
I was using Marlin as a firmware, it was fine for both printing and milling.

Ahh, I only calibrate like once a month on my printers. I assume you had to modify the firmware though, as Ryan’s marlin versions remove the 3d printing stuff. And from my understanding the full marlin 2.0 release needs some settings changed to work with the mill… for example when you don’t have the extruder attached how do you keep it from registering a thermistor read error?

I’m not sure since it was a very long time ago so I kinda forgot, but I think it wasn’t a problem since you don’t need to heat anything while milling, so there is no heater gcode.

If you have a copy of the firmware laying around I would love to take a look at it.

Thanks for all the replies, and linking your build Dui! I think I might make it normal for now, and when I NEED the extra print size (for cosplay helmets and whatnot) I could just modify it when that comes up. I have a lot to think about…


yeah i’m in the middle of a build and there is alot to consider, and so many other options, like duel endstops and speed control and PI control and wasteboard layouts… its almost never ending :slight_smile: i look forward to seeing your cosplay prints (whats your fandom?) and anything else you end up making.

I think corexy cube type build in aluminum extrusion is the best approach for big beds. Voron 2.4 with the orbiter ultra lightweight head can get crazy print speeds

I have never even HEARD of the Voron! their website looks pretty cool. Might have to look into building one for my next printer

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