MPCNC Over ambitious first build?

I’m new to CNC’s, other than feeding files to a wood worker in house within a design studio I worked at. Now I want to start a side business, and I’m really weighing the benefits of having a larger machine off the bat. I don’t plan on doing anything other than wood at this time.
I originally bought the parts for a 2ft x 2ft setup for MPCNC, but am now leaning towards a 4ft x 4ft setup.
Is there any blaring difficulties I should be considering with this build?
Calculator is telling me roughly ~32ft of EMT is required - correct?
Does a 4ft x 4ft build require anything different in terms of belts? I already bought additional belts just in case.

I appreciate any/all tips and suggestions.

4 feet is on the large side, which is going to affect stiffness, but if you only do wood it can work. The conduit quantity sounds right – there are three rails each direction, and 4 feet of working space is roughly 5 feet of external dimension, so 5x3 for X and 5x3 for Y, plus legs.

The lowrider was made specifically for the larger scenario so thats definitely recommended over a big mpcnc. I think all the electronics are compatible between them, so you wont need to invest too much more to switch to lowrider.

I have a 2’x2’ MPCNC and feel it’s about as large as that machine should go. Anything larger and I’d be looking really strongly at the Lowrider.


I made my MPCNC with dimensions of 600mm x 900mm as a working area. so the final dimensions were slightly over these measurements. I have had zero issues but I must say that I did insert supports midway along each axis to prevent the conduit from any intention of bowing. so far I have cut wood, acrylic and some aluminum. Using a laser to make RC aircraft parts cut from balsa mainly and the router for ply parts. One thing I have done is make the router / laser interchangeable quickly.


regards Stuart

I’d like to note that I have every intention of using a tubing more rigid than EMT/Conduit. I’m still searching, but I’m fairly certain I can source some steel tubing at the same diameter. The size bonus would offset the added costs for sure.

Otherwise, I’d always be able to cut the tubing down to a 2x2 format down the road when problems arise, but I at least want to try to make the 4x4 work before throwing in the towel.

I think several of the questions that have been left unanswered will answer themselves when I finally get all the pieces in my possession. I have someone 3D printing me the parts, and I just ordered the kit yesterday. Just a little anxious/eager to start digging into this project. I still haven’t built a table to put this on, nor cleared a spot in the garage for it haha.

I recommmend that until you know for certain the exact diameter of the tubing you will end up using, hold off printing parts. This mistake as been repeated many times by various builders, it’s painful to see it again (I am one of those victims).

If you bought the kit, I’d suggest you just build it as a 2x2. If you’ve never dealt with anything CNC before you’re already going to have a lot on your plate. Machine rigidity is just one more thing fighting you. You can buy all the conduit for a 2’x2’ machine for $20 anyway, learn the ropes, then go up to a 4’x4’ machine by simply getting new tubing (you said you were going to use steel, so to me it makes more sense to just spend less money on conduit, find out if you actually LIKE this stuff/machine), getting new belt (a couple of bucks) and extending stepper wires (you’d have to do this anyway as the kit only comes with wire long enough for a 2’x2’)


But that’s just my 2 cents. Also, these machines are kind of slow to be working on 4’x4’ material. So you might built it and think “wow, it takes 8 hours to do what I want to do on a 4’^2 piece” then decide to go with a larger, faster, more rigid, more expensive machine.

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I built my first mpcnc oversize, against the usual recommendations, and I don’t regret it.

Everything people have said above is true, but as long as you have the right expectations, you will be okay. Certain aspects might be worse than the standard build, but what fits your need can only be decided by you.


I’ve done a lot of thinking, and I plan to go forward with a 4’x4’ build, with this exact mentality in mind. It may be challenging for my first build, but the pros vastly outweigh the cons for what I plan on using this CNC for. I can’t stomach the regret I may have down the road when I finish a 2’x2’ build, and am unable to complete some of the projects due to size restraints.

I would appreciate any suggestions for mid supports - is that an additional printed part? Is it available for purchase? Any alternative options?

EDIT: Also, I’ve got a 5x5 table planned out. I can’t haul full 4x8 sheets, thus, I’ve broken the top into a 2.5x5 piece that’d be supported by joists underneath. All boards are 2x6, with 1/2"+ Plywood. Thoughts on this table build?

There are mid span support designs on Thngiverse. You basically use a threaded rod under the center or each span and adjust the height by turning the rod. Your big thing to watch for with that large of a design is sagging in the two center tubes.

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How would I go about extending the stepper wires? I’m guessing just buying same gauge wire and wire nutting ends to existing steppers?

I would either solder them up, or use a pair of these (then ziptied):




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Would you be able to provide me a link to these supports you mentioned? I’m not finding them on Thngiverse, unfortunately :frowning:

Here is the first one I got in a search for MPCNC Support. Mine isn’t big enough to need them so I can’t really tell if these are the best…

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I know this isn’t the way to ask but I have a 4ft by 4ft build and I have three supports along the side so there is only 15in span without support but i’m wondering how to set the build area in marlin software so my z height is 120mm above the standard height

5ft x 5ft Table is almost finished. Just needs mid supports to prevent the seem from bowing.

Would I just need to buy an extra set of these wires?

It says “Quantity” - is that an individual cable cost? Or would 1 quantity have 3-4 wire sets in it?