using EMT as tubing

[hooohaa2]

Just a quick question, is EMT conduit anywhere near as strong as the sorts of tubing (of the same size and thickness) used on buggy cages etc (I believe it's called DOM tubing)? It is not terribly expensive, and I was thinking of doing a few projects using it in the 2-2.5" variety to get my feet wet in tubing notching with the old harbor freight chop saw. Just wondering how it compares.

[Timinmb]

Not at all comparable to DOM. I've made stuff out of it, but it splits, cracks and is brittle. Plus its galvanized. I sure as heck wouldn't build a roll cage out of it, unless there is some other kind than what I've fooled around with.

[MadMax]

Just a quick question, is EMT conduit anywhere near as strong as the sorts of tubing (of the same size and thickness) used on buggy cages etc (I believe it's called DOM tubing)? It is not terribly expensive, and I was thinking of doing a few projects using it in the 2-2.5" variety to get my feet wet in tubing notching with the old harbor freight chop saw. Just wondering how it compares.

Umm, not sure, but if you're just practicing then go for it. I can almost 100% gaurantee that it isnt, as it is conduit. And you are correct about it being called DOM tubing. DOM stands for Drawn Over Mandrel. It's just a better forming process, but is still mild steel. When people compare Mild to DOM, its really the same metal, but when they say 'mild' they mean ERW (electronic resistance welded).

Well then, sorry I went off topic. But yea, what kind of projects do you plan on doing?

-Max

[TOMWELDS]

Im an electrician and i would not use EMT for a frame. If you look closely, you will see a seam in the tube that will open up with stress. the galv. doesnt help.

[david_r]

hooohaa,
Check out the ERW tubing at your steel supplier. No galvanization to grind off and it should be cheaper than conduit. FYI, most racing the average joe could get into only requires ERW tubing for the roll cages and DOM started life as ERW before it got thinned and smoothed by a mandrel.

[kevbo]

If you had something TOTALLY non-structural that was to be in the weather, then it might make sense.

I've seen it used as a frame for a tarp as a sunshade at flea markets and such....doesn't stand up to the first good gust of wind from what I've seen...but is easilly straightened or replaced when it breaks.

[Sberry]

A former girlfriend looked around my place and said "I see many creative uses for conduit" Lots of hangers and brackets and she really liked the towel holders from emt. I have built a LOT of stuff from it but frame parts of a buggy wouldnt be one of them.

[david_r]

After re-reading hooohaa's post, I wonder if he's actually talking about EMT or rigid?

[hooohaa2]

After re-reading hooohaa's post, I wonder if he's actually talking about EMT or rigid?

Well, I was talking about EMT since it is much cheaper than rigid. How much different would the answers have been if I were talking about rigid?

[david_r]

I'd have told you that there are lots of mini-bikes and carts out there made with that stufff. However, I'd not recommend it be used for a roll bar since I don't know if there is much material science behind it. Than again, maybe there are specifications for the mfg of it?

I'd have no problem using ERW tubing in the proper sizes. Search on SCCA, NHRA, CORE, etc. rollbars and see how many have to be made from DOM.

Funny thing about a rollbar is you don't actually know the exact application it'll be used in when it is used.

[Sberry]

Ridgid will cost as much as bare structural tubing and I doubt if the steel is QC very well in it. Its galvanized so thats not good either.

[darelldd]

Neat. Was just meaning to start a topic on welding this same stuff. I'm just making some vegetable growing cages out of it - so no worries about life and limb! What's the real deal with welding gavanized metal? I know the fumes are to be avoided - and I know it is best to first grind the stuff off - but is it possible to just weld to the galv? Any neat tips to share for same? Right now I have everything screwed together, and I hate all the rough edges, and the screws that are now rusing. I'd love to weld it all and remove the screws and then probably paint it.

Thanks for letting me veer this existing thread is a wee bit off course.

[Mike W]

You can weld over it but you want to avoid the fumes.

[darelldd]

Thanks, Mike. I have some good ways to avoid the fumes - I thought that it wasn't even possible to weld to it for some reason. Good news!

[hooohaa2]

Neat. Was just meaning to start a topic on welding this same stuff. I'm just making some vegetable growing cages out of it - so no worries about life and limb! What's the real deal with welding gavanized metal? I know the fumes are to be avoided - and I know it is best to first grind the stuff off - but is it possible to just weld to the galv? Any neat tips to share for same? Right now I have everything screwed together, and I hate all the rough edges, and the screws that are now rusing. I'd love to weld it all and remove the screws and then probably paint it.

Thanks for letting me veer this existing thread is a wee bit off course.

Don't worry about it, thats the way it was heading anyways.

Yeah, stay away from the fumes, no fun having galvi flu.