ZenXY v2 Rail Diameters

Hey everyone,

I hope the ZenXY community is doing great. A friend approached me and asked if we wanted to build a ZenXY v2 over the holidays. I certainly agreed to that and looked at the Bill of Materials. I could not figure out what diameter I need for the rails. I also searched the forum yet I could not find what I was looking for.

Now I wonder: I require some small and big diameter rail. But what diameter is it exactly I need? Can I just go for what the hardware store offers? I would greatly appreciate if maybe someone (possibly EU, ideally German) could point me to a part source for the rails and tell me more about the diameters :slight_smile:

Have a nice day y’all,

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I believe it’s designed using 1/2" and 3/4" EMT conduit, so 23.5mm and 17.95mm outside diameter. Ryan, please correct me if I’m wrong…

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That is correct, thanks Bill.

I tried to keep the instructions generic and the sizes on the printed parts links themselves. I assumed we would have another set or two.

Since 23.5mm is a very odd size over here (there are some MPCNC discussions around it as well, I think it’s one reason why there is a 25.4mm version of the MPCNC if I remember correctly since people couldn’t come by 23,5mm OD steel :smiley: ), I need to find the closest thing to it.

Are there any requirements on the rails? Certain thickness of wall? Don’t think they need to be uber rigid or something, so I might be able to use some 23.5mm aluminum tubing…?

Where you can’t get imperial sized conduit, it could indeed be tricky to get the required 23.5mm and 17.95mm tubing. The 17.95mm tube could even be solid dowel.

Fortunately, the wall thickness isn’t super critical with one caveat. There has to be enough room inside the 23.5mm tubing to fit the 10mm belt with a half twist in it.

Material strength is not critical. Aluminum would be fine for this application. There should be very little resistance to movement overall.

The 23.5mm diameter is common 3/4" conduit. The 25.4" is fairly common as 1" steel tube. The 25mm is more common outside of North America where metric sizing is easier to find.

Yeah I can get access to 18mm steel pipe and 23.5mm aluminum tubing. both have a wall thickness of 1.5mm so i have plenty of space to accomodate the belt :slight_smile:

Thank you, let’s see if we get it to work :slight_smile:

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If you get it to work, please share hoe you did it. I think a few EU zen builds would be great.

We don’t use aluminum parts on the MPCNC because the bearings are hard steel and chew on it. But with the rubber wheels, it should be fine. Nice idea.

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Can you send me a link to your countries common EMT conduit sizes. I have tried for years and can not find a decent link.

I can remake the model but I only want to do so once.

Something like this, Electrical Metal Tubing (EMT) - Conduits or this electrical metallic tubing

This should be readily available for tradespeople that use it, but in the US I can’t seem to find any other standards.

Hi Ryan,

thank you for your generous offer. That’s great.

There is nothing comparable to the electrical conduit here, since it is not allowed to put conductors (AC/DC) inside ungrounded metal pipes. So people would either have to ground all the conduit or just use plastic tubing for it (which is what they do).

But: It’s very easy to come by round aluminium tube here and it’s very cheap. If aluminum can be used for the ZenXY v2 then I researched the following aluminum tubing profiles (exact code: 3.3206, AlMgSi0,5) that are closest to the EMT measurements and also readily available for instant dispatchable mailorder in Europe, at least when I just checked:

  • The 1/2" conduit has an outer diameter of 17.9mm.
    So an 18mm x 1mm (wall-thickness) or 18mm x 2mm aluminum tube would be perfect as a metric replacement.

  • The 3/4" conduit has an outer diameter of 23.4mm.
    The two most common alternatives are both about the same difference away from that: either 22mm x 1.5mm or 25mm x 2mm. It’s up to you.

If you choose the 25x2 and the 18x1 they are about equal in price and total up to around 5€ per meter which is a reasonable cost I think.

Let me know if I can help you with something else. I can also test-print a part and try its fit if you want.

I would rather find a steel equivalent since we can use it for very large Zen’s and both CNC’s. Aluminum will work for a small table but it is many many times more flexible and is useless on the CNC’s with bearings. (I am about to start a new CNC so this info is double duty for me.

We have 25mm and oddly enough 25.4mm (but not standard in the US 1"??) that seems to be a standard, or at least commonly available everywhere in the world I just don’t know what the equivalent next size down is.

Both sizes (18 and 25) are also easily available in steel and stainless steel (I built a 800x400 MPCNC Primo with 25mmx1.5 Stainless steel).

Is aluminum going to work with a 800x400 ZenXY-table? Or is stiffness also an issue with these less intensive builds? Then I would opt for the steel tubings :slight_smile:

AWESOME, thank you for some numbers!!!

Aluminum will absolutely work for a small build like that.

Just for my planning purposes: how quickly do you actually work on these files? Is it worth the wait or shall I just go for the 18mm pipe and the 23.5 special pipe for this build right now? Takes the timing stress off your part and I don’t mind. But if you have the files ready within the next few days I could go for the standard equip directly :slight_smile:

Also, the mini v-wheels are hard to come by here. But I may have found a shop. Is this the correct sizing? The center hole is a 5mm diameter.

Thank you again for all the work, also for my awesome MPCNC :slight_smile:

Let try and take a look this afternoon. If the model explodes it could take a while…or it could be done this evening.

Same with the wheels.

I hate it when a model goes haywire after making a single dimensional change. I got my fingers crossed that all your implicit references work with the change in dims. :wink:

I am always trying to improve my modeling habits in general to use methods that are less likely to lead to avoid issues with adjustments to critical dimensions. The only thing I’ve come up with that always helps, is start with the stripped down fundamental basics… like “we have 2 pipes, 90” oriented in the horizontal plane"… instead of “we have 2 trucks that will hold 2 pipes on a horizontal plane”. Whatever details come after the fundamentals, are what they are and can be more implicit (like clearance between pipes, details of truck dims, etc… but starting with everything referencing generic pipes (arbitrary length/diameter) can prevent issues when those pipes get swapped out.

Anyhow, I’m sure you’re better at this than I am… would be awesome if there was a good read on good general mechanical design habits to follow. I didn’t learn much along those lines in the 1 semester of Autocad I took in 1998… it was Acad2000 and undergrads didn’t do 3d 1st semester… so no surprise lol.

I just opened the model fingers crossed.

When I modeled it I knew I would want to change the Rail sizes so in general that change is always easy. Chamfers and fillets always die so do those last, and do not do all of them in one operation split them up so the bad one is easier to find (fusion does a better job of this than SolidWorks).

I don’t think there are any tricks other than knowing what might change, hard code the rest. I do not bother doing universal sizes for screws and stuff.

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Seems good to go, I need to export and orient all the parts now.

One constraint error and 4 filet errors, not bad.

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Give this a go,



Whoa, awesome! I will have a go at it right away <3

Can I go with the wheels I posted above?


Yes, those are the ones you want.