I would like to use a little stronger tubing than the EMT conduit, and was hoping to get some DOM tubing here in town. The shop I normally get my materials from doesn’t carry 1" .065 wall DOM, but they have HREW. I know it’s not a strong as DOM, but wondering if in this application if it really matters. Any one have any experience with it? Upside is I can get 20ft for about $25.
No personal experience but I did find this:
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Thanks! I know that the “common knowledge” is that ERW has less tensile strength so isn’t preferred in chassis construction, but that video definitely makes it look like it would be more than enough for a 24" x 24" MPCNC, possibly even better than DOM. Which is definitely nice since it’s cheaper!!
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I haven’t tested both, but I’ve handled both and I’d bet a dollar you’re going to see much more variance based on the thickness than whether it got a little extra processing.
Hi i am using ERW in my build, its a fair bit smaller than yours (500mm x 350mm) and its not finished yet but it feels very solid. As I understand it they use ERW as the base material for manufacturing DOM. The main issue with ERW is it does not tend to be as dimensionally accurate as DOM, rigidity i think is not that different.
Don’t forget that ERW also has a seam so I’ve avoided letting the bearings run on it just in case. My thinking at the time was its better than conduit and cheap enough that I can replace with DOM if I hit problems.
I did compare some 1 inch 0.065 erw to conduit. I’d expected the larger diameter to be stiffer, but since it was only a LITTLE bigger and the conduit had a thicker wall, it pretty much washed out even over the 4ft sections I tested.
Hmm, well that makes me just want to go with the conduit then if it’s a wash. I’m not going over 24" square so I’m guessing it won’t be too much of an issue.
Upside of the erw is that if you WANT more rigidity out of the tubes later, 1 inch is easier to source. I think conduit is the only thing that fits in the conduit OD. Plus, I was talking about the 0.065 wall specifically. You can also get 1 inch in 0.08, 0.095, 0.120 etc, at least out here in AZ. The price scales with weight, so we can pick a sweet spot for our wallets.
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Is there any perceived benefit or downside to to having the extra mass that a heavier pipe (DOM or Stainless) would offer or does the MPCNC not generate that much inertia when changing directions?
That would depend on whether that extra mass is accompanied by extra stiffness, and if it’s already ‘stiff enough’ for what you’re doing, the only benefit I could possibly see from extra mass would be vibration damping.
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