Heavier Conduit?

Has anyone ever tried to use a heavier conduit or a regular scheduled pipe for more strength? I am trying to decide whether this would be a good option to try for the support frame, and maybe using the lighter conduit for the gantry part of the build. Any thoughts?


As far as I can tell in my area this conduit is the most rigid. Pretty easy to test, I went to the hardware store and flexed all the 10’ lengths. Conduit was the clear winner for me, but you might have something better in your area.

Is your frame flexing too much?

I am getting ready to build one, and was just wondering about the metal rigid conduit instead of the metal EMT. The metal rigid has threaded ends which are not really needed, but this means that the wall thickness is heavier than the metal EMT, so more rigid and less flexing if I wanted to build a bigger cnc work platform.

The rigid is more expensive, but if it makes it much more rigid, maybe worth it?

Just trying to research which way is the best way to build without the need to add support under the frame.


Actually the OD for the 3/4" rigid is (1.050" / 26.7 mm), so thicker compared to 23.5 mm OD, which would mean more rigid without the worry of flexing. See attached chart where the thickness of rigid would be more than double of the EMT.

Any ideas on this to strengthen the frame up for maybe a 48" x 48" build area?


That size is not even in the ball park of working and heavier can also mean is flexes under its own weight. Have you tried flexing it at the hardware store?

Yes I did compare the flexing at the hardware store between them, and rigid does not flex at all compared to EMT. I edited the above post to show the chart comparison between them both.

Why would this not even be in the ball park of working? I am not proposing to making the gantry out of this this heavier material, only the frame that supports the gantry.

Thanks you for your fast responses to these posts! I am just thinking out loud here to see if this might be an option.


we have 23.5 and 25mm od thats it.

If you are worried about flexing along the outside rails just use supports mid way. I have done that on my build and its 5’ square. I can put a lot pretty much all my body weight on the unsupported half section with out flex. That in combination with the new V2 center I am confident I will have few problems cutting.

Oh, I understand that. Is there anyway that us users can modify the needed parts to accommodate the larger conduit? As I see it, the only parts that would need to be modified are the Foot_Bottom, (Bottom_CornerF and BottomM_CornerF), (Lock_CornerF and LockM_CornerF), (Top_CornerF and TopM_CornerF), Spacer_CornerC, and the Roller_F. To me it seems as though a most of these parts only need to probably be scaled up a little bit to make changes. I only can imagine that the Roller_F part would need modifications to make it work properly and still be able to attach the Roller_Motor_Mount without any issues.

Is there a way to get the native file for any of these parts like the Roller_F so that I could easily modify it to make it work?


Thank you Jason! This was my other option to be able to get bigger build area.

Nissan supports offer a 4x increase in rigidity, different conduit probably doesn’t even come close.

Can you tell me what Nissan supports are? Sorry, I am not sure what that is? I am happy to check it out.


Sorry I’m driving. Mid-span supports. Everytime you half the unsupported distance you increase rigidity by 4. Try the supports it is much easier than trying scale my parts the exact right amount and not cause other issues, which it will.

Cool, Thanks! I am guessing that someone already has some supports made for this on thingiverse?

Yup search mpcnc

First time poster here and first of all thank you to Ryan, team, and fellow hobbyists! I was hoping folks would consider revisiting this very old thread on utilizing rigid conduit instead of flimsier EMT or the drastically more expensive Stainless Steel tubing that it seems most everyone (including Ryan) have gravitated toward over the past 5 years of experience to improve rigidity/performance… Wouldn’t this be an optimal performance/value solution at $2.90/ft from Lowes/HomeDepot for both the MPCNC and the LowRider? I understand this would require a significant effort to update the print models to also accommodate 26.7mm tubing, but wouldn’t this be a huge win for the MPCNC’s success as it captures the value/performance segment of the DIY CNC market? Perhaps I am over estimating the importance and impact of the many comments I’ve read on the forums here about those that have evolved up to SS tubing, IDK… At any rate, would really like to hear from those of you that have been at this much longer than me! Thanks.

Ryan tested it when he was designing the primo. I don’t remember why now.

The common DOM tubing is a good choice too (and not as expensive as SS).

If you want a good machine, at a low price, the regular EMT is good.

If you want to push the limits, or you want the best or live outside of North America, pick DOM or Stainless tubing.

Oops… A change of search terms yielded some posts that I had never seen where you all were looking at this idea in 2019… I’m guessing in support of the Primo. Never saw any conclusions on this and just curious even if it is seemingly dead at this point… Was it the surface imperfections of the Rigid Conduit or maintaining yet another dimensional model that killed the idea? It seems like 26.7mm pops up a lot. Lastly, before I go out and buy any rails- any advice on the current wisest approach on rails where a little more money or effort will reward me with improved performance (beyond the current FAQ)? I thought the guy that tired the 1/2"EMT inside the 3/4" EMT was clever… I haven’t had much luck sourcing DOM locally, and interested in doing what I can to build the best performing MPCNC with a 24"x24" workspace. Thakns

Ah, thanks for the reply Jeffeb3. I actually hit reply the instant your reply posted- LOL. Appreciate the responses and trying to both learn and do what I can to make the most worth-while build the first time without getting too carried away.

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My first MPCNC was using conduit, and built over the recommended size. I had a blast and got within a little sanding on all my projects. That was 3 versions ago and each one is much more rigid. Don’t stress too much about it. You are opening a door, and hopefully enjoying the process.

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