Printed parts are too small to fit 1" conduit

I just got done printing all of the parts for the MPCNC Primo-J 25.4mm and got done cutting all of the 1" diameter pipes. I went to begin assembly only too find that the pipes are too big to fit any of the printed parts. The pipe that I used is 1" diameter steel conduit. Did I purchase the wrong pipe or what did I do wrong? I would rather find that I used the incorrect pipe instead of having to reprint all of the parts. Please give me some help and feedback! Thanks!

Oh no. Sorry. But you’ve made a mistake. The 25.4 is the outside diameter of the tubing. 1" steel pipe (from a metal supply store) will fit. 1" conduit is meant to fit 1" of cables inside of it. It has an outside diameter more like 29mm. Those parts will not work with any size of the cheaper conduit. You either need to make 23.5mm parts to fit 3/4" (ID) conduit or buy 1" (OD) tubing.

Tubing = measured by OD
Conduit/pipe = measured by what it can hold, or ID

1 Like

If you use Stainless Steel pipe then I believe 1" is 25.4mm outside diameter (OD).

Bottom line it is 25.4mm OD you are looking for. I don’t believe any of the EMT is 25.4mm.

Hey look at the bright side. Stainless Steel 800 grit is nice and shinny. In my neck of the woods it wasn’t horribly priced and while more expensive it is a lot easier then spending all those hours reprinting.

I’m only suggesting Stainless Steel as that is what I used. I think there is also 25.4mm OD regular pipe (not EMT) but I’m not familar with the specifics of it as I haven’t used it.

Just to be clear.

1" Stainless steel tubing is 1"OD or 25.4mm nothing in home depot is that size.

1 Like

So if they don’t carry the correct stuff at Home Depot or Lowes what type of place should I look at? I’ve never needed to purchase anything like this before and could use a little bit of guidance. Thanks!

Just like every town has a mechanic, any town big enough for a home depot will have some kind of metal supply. google maps should find something. There are chains, like metal super market (these folks, specifically have cheaper prices in the store than their website). If you are really stuck, you can probably call a mechanic and they will tell you where they would go. There are also some online shops. I don’t keep them straight, but there have been a few recommendations here.

The steel can be stainless, which is more $$, or DOM, which is usually cheaper, and actually more rigid, but depending on where you live, it may rust. I live in Colorado, and I swear rust disappears here.

1 Like

Also I recommend getting quotes from a few places. Some places want to charge you outrageous prices(I think I had one quote for over $200 for 20ft of stainless). But you should be able to find 20ft for around $70. 100 would be on the high side but at least reasonable.


If you are going the DOM route I picked mine up at Summit Racing. I’ve seen other posts here in the forum saying that Menards and TSC (Tractor Supply Co.) both carry 1"DOM. If you have any of those near you.

1 Like

I got my rails from Amazon and I don’t think it was too expensive:

DOM (mill) 1" Tubing