3/4 EMT Conduit Frame

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3/4 EMT Conduit Frame

Postby ferbal » Sun Apr 01, 2018 8:58 am

Forgive me if this has been covered before but I thought I was pretty thorough in my research and have not come across any practical data on this.

3/4 EMT conduit is inexpensive and easy to source. It cost slightly more than 1/2 inch and significantly less than 1 inch, and any big box hardware store has it.

The only cons I see to it are it’s galvanized so welding can be an issue. But aside from that it’s cheap and light weight.

I have found people building roof racks, green houses, bikes and many other things with it but every discussion about it inevitable ends with “its great stuff but I don’t trust it use real metal stock”.

Has any one used it for framing a shell? I can not find any good info or data on this. Specifically the strength characteristics of 3/4 EMT in a structural application.


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Re: 3/4 EMT Conduit Frame

Postby Karen Clancy » Sun Apr 01, 2018 9:40 am

I have worked with Conduit my entire career and have seen it split along the seam while bending at times . I would contribute that to the manufacturing process & not the means of bending . As far as welding the galvanizing coating I suppose could be removed by a chemical or mechanical procedure I would think ( etching , or lite grinding ) . I'm not a engineer or a metallurgist by any means but do understand that it would gain strength by the curve .
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Re: 3/4 EMT Conduit Frame

Postby ferbal » Sun Apr 01, 2018 11:40 am

The split in the seam happens at the time bending, not spontaneously a week later right? So if survives the bend it should be good as long as I am not putting a load on it. Aside from the roof skin the stress on curve would be minimal. Or is my thinking flawed?


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Re: 3/4 EMT Conduit Frame

Postby QueticoBill » Sun Apr 01, 2018 2:42 pm

Fastening things to a round member has some chalkenges, as dose cutying for joints, where as square tubing is easier, though maybe 4 times the cost.

I assume thinking of framing the cabin, not the chassis?
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Re: 3/4 EMT Conduit Frame

Postby ferbal » Sun Apr 01, 2018 3:16 pm

Definitely just the cabin I would have a hard time believing 3/4 EMT would make it as a trailer frame, even my optimistic imagination has some limits. As far fastening to a round frame I was thinking corrugated tin attached with u bolts on the outside and interior panels attached using round spring clips.


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Re: 3/4 EMT Conduit Frame

Postby Karen Clancy » Sun Apr 01, 2018 5:57 pm

Yes at the time of the bending . I should have made that clear
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Re: 3/4 EMT Conduit Frame

Postby M C Toyer » Sun Apr 01, 2018 8:44 pm

I used 3/4" EMT for a teardrop shape frame for a canvas cover. T joints and X joints were made from short lengths of welded 1" EMT; standard 3/4" EMT couplings used for linear joints. I later replaced the canvas cover with FRP (fiberglass reinforced plastic) attached directly to the EMT with 3/16" pop rivets. Held up well.

The large radii were hand bent on a jig made of wood blocks attached to OSB; the tight radii bends with a standard EMT bender.

The entire framework was hinged at the front of the trailer to form a clamshell to allow loading a dual sport motorcycle in the trailer bed.

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Re: 3/4 EMT Conduit Frame

Postby ferbal » Mon Apr 02, 2018 11:30 am

Do you have a close up of one of you T connectors? Because the inch sleeve idea for tees sounds like a great idea.


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Re: 3/4 EMT Conduit Frame

Postby QueticoBill » Mon Apr 02, 2018 12:33 pm

ferbal wrote:Do you have a close up of one of you T connectors? Because the inch sleeve idea for tees sounds like a great idea.


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Google "canopy fittings" - here's one link with close ups of the fittings for sale. https://www.a1tarps.com/flat-roof-fittings.html Our Scout troop uses these for dining flies.
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Re: 3/4 EMT Conduit Frame

Postby M C Toyer » Mon Apr 02, 2018 6:13 pm

Ferbal -

Very similar to QueticoBill's link but without the set screw. I wrapped the 3/4" EMT with some thick rubber electrical tape to take up the slack of the 1" EMT then pop riveted all pieces since the joints were more or less permanent. I bought mine from an online greenhouse supply company for about $1.50 each but the finish was not as high as in the link.

I had also used 3/4" EMT for roof spars for the plywood sided shell which replaced my semi open canvas then FRP model.

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Re: 3/4 EMT Conduit Frame

Postby low277 » Sat Apr 07, 2018 8:54 pm

Another option might be aluminum rigid conduit, I have seen people use it for ice fishing houses. Can be bent with standard conduit benders, one size over, use a 3/4 bender for 1/2 rigid. Never tried to weld it.
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Re: 3/4 EMT Conduit Frame

Postby John61CT » Sun Apr 08, 2018 5:52 pm

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Re: 3/4 EMT Conduit Frame

Postby ferbal » Wed Apr 11, 2018 6:59 pm

Now that I decided on 1 inch conduit the cost is similar to 1/2 black iron. Because I plan on welding the 1/2 black iron may be easier to deal with but weight wise I still like the idea of 1 inch conduit. Any thoughts?


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Re: 3/4 EMT Conduit Frame

Postby John61CT » Wed Apr 11, 2018 8:21 pm

Plain stock mild steel tubing then, shop hard for a good price, especially if you can pick up.
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Re: 3/4 EMT Conduit Frame

Postby GPW » Thu Apr 12, 2018 6:01 am

We’ve used electrical conduit for making bicycle chopper parts … Just avoid the white smoke when welding ( outdoors and upwind)… Never a failure …
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