Large mpcnc builds

How many large builds are still in use? I am talking like 4’ x 4’ or bigger. Would you do it again?

I would like to make mine larger. I am thinking about maybe 2’ x 4’. I think that with bracing on outside 4’ side the shorter side would make things more rigid. I never plan to do metal. (plan being key, no needs now, lol).
i thought about 4x4 but not so sure that it would be rigid enough. I am using emt, not stainless.

4x4 working area or overall? I have a 2’x3’ working area currently. It will be expanded either this weekend or next to 2’x3-1/2’. Might go a little wider on the y axis too, at same time. No issues so far.

Oh yeah, using 3/4" emt.

Update, after doing more heavier cutting on bigger projects, i will now be reducing the size down to 24x24. There was too much flex in the mid spans with 3/4 emt. No fault of the design, i had built it bigger than what is recommended and probably should have built a lowrider instead.


Before downsizing, if you haven’t already, did you already consider adding midrail supports to outer rails, e.g.

Note, am not a MPCNC owner, have only printed parts for a friend. Only built a LowRider 3.

The midspan supports help, but not as much as you’d hope. Because the gantry XY pieces are still unsupported.


Been a couple months since I shared this, lol.
This is the gantry tube on the long direction of my 2x4 primo bouncing around during a cut, and this is with 1inch DOM 0.12" wall.

That looks rock solid compared to 3/4 emt… honestly, most of what i have been doing, except for cabinet doors, will fit in the smaller footprint.

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Hey Matt,

Just curious. Did you end up shrinking it down and did you do an overall 24x24 or a cutting area of 24x24? Ideally I wanted like you had 2’ x 3’ but I’m not sure if the added size is worth the added complexity of a low rider.

Vaguely recall someone sharing they reduced their EMT flex with, more EMT. Think they inserted 1/2" EMT into their 3/4" EMT, along with a bunch of epoxy. I don’t have have any stats/data on how much this helped. Seems quick/cheap enough to have a go if you have an existing build to tinker with.


I’ll be shrinking it down to 24x24 overall after my new machine is up and running. I’d definitely suggest a lowrider, but if you do 2’x3’, go with at least 1" tubing.

I remember, too. Motivated me to epoxy 1/2 emt into my 1 inch tube (0.12 wall made it a very nice fit).

That sounds like a messy pain in the ass.

These days the Lowrider is not all that much more complex, just having to cut your own strut plates, maybe. Other than that, squaring and leveling is probably easier.