Hardware came today, Now if only I could figure out the right conduit size!

Mostly Printed CNC - MPCNC Troubleshooting
#1

Hey everyone, glad to have your support this afternoon!
I’ve been printing the 25.4mm (1 inch OD) scale parts for the last two weeks with the assumption that standard 1" conduit would fit…
Boy was I wrong! The actual outer diameter appears to be 1.32".

I just learned about nominal pipe dimensions here (http://www.atc-mechanical.com/tube-pipe-101/tube-pipe-size-overview/).
And think that I need 3/4" pipe to get closer to the right fit. Did anyone else struggle with this? I’d love some input and hope I’m not the only one!

I’ll update this post with my findings when I get back.

Note*
I live in NYC, so walking home with 20’ of the wrong material is a real Beach! I’m probably going to buy calipers to ensure that I don’t make this trip for the 3rd time!

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#2

For the 23.5mm parts we use 3/4" EMT. The 25.4mm parts are used with 1" OD stainless. I thought I had that in the description on all the links but I must have missed one. Sorry about the mix up.

#3

Buy stainless steel conduit, you won’t regret it. It’s way more rigid and it’s absolutely beautiful.

#4

Hey! Thanks for the replies! Here is my update:

1" US Conduit = True 1.315" Outer Diameter
3/4" US Conduit = True 1.05" Outer Diameter

I am considering ordering this steel tube after verifying that it is a true 1"! However, the price difference between the 3/4" conduit ($9.00) and this ($74.00) makes me want to give the conduit a shot first.

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#5

You might want to specify the brand you get those measurements from. Most of us have been using 3/4" conduit that measures 23.5mm OD. I have checked three brands I know wheatland is one of them.

Those numbers might be for rigid conduit which is not what we use. We use either EMT conduit (Sold by ID) or stainless steel tubes (sold by OD).

As for the stainless I recommend the .049" thickness. https://www.v1engineering.com/forum/topic/stainless-steel-quick-and-dirty-flex-test/

#6

Is stainless really more rigid? I spent a lot of money on it, so I hope so, but from what I’ve been reading the rigidity of stainless vs mild steel should be roughly the same. Is the standard EMT mixture just a particularly flexible variety?

#7
#8

There are more kinds of steel that varieties of chocolate chip cookies. It can be flexible or rigid.

#9

Can’t argue with the empirical test. I couldn’t even find any info on composition of steel EMT (Home Depot just describes it as “galvanized steel”). At least when you order the stainless tubes you have some assurances on the composition. I took a look at the ones they had, and they were more wobbly than the 304 I got. I just found it odd that most everything I can find online seems to claim that steel is steel, except when it’s either high carbon or cold rolled. I am neither a chemical nor mechanical engineer, so it’s likely I don’t even know enough to understand what to look for :slight_smile:

#10

I have been trying to figure out which printed parts set would be the correct one to order.

From the descriptions I was having trouble figuring out the correct set for 1" EMT.

If I understand the previous posts, there is not a set for 1" EMT (US). Is this correct?

Thank you.

S.

#11

No there is not.

You should really physically measure what you have locally available and buy/print the correct sized parts.