Tubing diameters

Hello, I want to start buying parts for the MPCNC primo, but I literally can’t seem to find the pipe diameters. Anyone know where I can find them?

You’ve got 3 options for tubing, 23.5mm, 25.0mm and 25.4mm. In North America, the most commonly used is the 23.5mm, that’s the outside diameter of 3/4" emt electrical conduit, it’s widely available in 10 foot lengths at any hardware or big box store. Whatever size of tubing you decide on, make sure that the printed parts you use are the ones intended for that size of tubing. If you got to to printables.com, you’ll find the files for each of the three sizes.

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You may need to slightly adjust your shopping parameters. Conversationally, “pipe” and “tubing” are generally interchangeable. When shopping for them as engineering components they are not. Pipes (and conduits) are generally specified by inside diameter because what’s important is how much fluid/gas/wiring you can fit into/through them. Structural tubing is specified by outside diameter and wall thickness. Manufacturing method may also factor in e.g. welded or Drawn Over Mandrel (DOM).

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I already found 25mm aluminiun tubes for cheap, so I think it’s fine

I wouldn’t suggest aluminum. The bearings will wear into it easily

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Millennium metals
If your in Canada these places can get you what you need. I went 1”od ss.

EMT is fairly easy to find at local hardware stores. Or electrical supply places. Maybe even ask a electrician buddy.

But I highly recommend the 1”ss if you can get it.

Metalsupermarkets will definitely have 1"ss but they charge a pretty good premium on their stuff, if you’re near a large city, there will almost certainly be other metal suppliers there that will beat supermarket’s prices. Locally, I can get 1"ss for about $75-80 for a 20 foot length.


Consider calling your local Metalsupermarkets, don’t just trust the online web pricing. Multiple community members shared that they get better pricing when talking to folks at their local store.

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I’m from Romania, so any US/CA shops are out of reach for me. I do have a plumbing shop right next to me, I should (?) be able to find a good piece of plastic conduit.

Not from US/CA, but I’m sure conduits are an univeral thing, not only in the west.

Yes I agree
This is what I paid for mine at millennium
That’s CAD as well

Dang it sorry I just saw that your in not usa/cad.

Sorry I don’t have any connections there. Maybe just go to local shop and bring some calipers. Calipers and doughnuts that a universal extra helping tool.

Yeah, I assumed you couldn’t know. Wouldn’t it be good if I just brought one of the prined feets and see if it fits? I have personally never ever saw a caliper in my life, so I am not sure if I can Find one…

No!!! Plastic is not suitable, steel conduit or steel tubing is preferred.

I think that 25 mm (25.0) tubing is the European standard.

FWIW, I also checked with my local branch of the Metal Supermarkets, they were asking $120 CAD plus sales tax for 20 feet of .065" wall 1" stainless tube.

My aluminium rail MPCNC Primo is holding up pretty well. The bearings wear a flat spot pretty quickly but not enough to loosen anything.

I wouldn’t recommend it due to the relative lack of stiffness of even the heaviest walled aluminium tubing, but it does work well enough otherwise.

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Plastic conduit is not suitable for this use. Galvanized steel electrical conduit is readily available in the US. That’s the type of conduit referenced for MPCNC rails.