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Bending Aluminum Tube

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rbrochey

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Need some advice. I am embarking on using aluminum tubing for the trike I am building plus 4130 tube bending for my 69 vw that i am converting into a trug which is a bug truck with some baja fenders so i guess its also part off road bug. Anyway I will be using various sizes of tubing. I have bent 1/2 in aluminum using the fill it with sand and a jig. That worked ok but this is bigger stuff. Most all bend will be 90 degrees or less.
 

rv7charlie

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Unfortunately, that pipe bender isn't going to work unless you're willing to accept collapsed tubing (ask me how I know). The dies are cut for pipe, so they don't fit tubing sizes, and the only die is on the ram. The two sides are simple bars, which will put dents in aluminum tubing. I haven't tried 4130, but I'd fear them denting thin walled 4130, as well.

I'd be carrying a couple dozen donuts to a well equipped muffler shop in your area. A lot of them have mandrel benders with dies for tubing. Another possibility would be speed (hot rod) shops that fabricate race cars. If you mark the tubing ahead of time, they should be able to get your bends done in just a few seconds per bend, without crushing the tube.

edit: for minor bends in 4130, a torch works fine.

Charlie
 

Jeff Liot

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Either you get access to a mandrel bender or you buy mandrel bends (lots of suppliers) and cut and weld to your desired angle. There is no short-cut. Raiding the cat's litter box for sand will not cut it.
Jeff
 

deskpilot

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If small imperfections can be tolerated, how about using a propane blowtorch and flux filled aluminium rods to fill the indentations on the tube? Wouldn't add much weight but would prevent further tube collapse when under stress.
Would the same system be safe to "weld" tube joints?
 

Marc Bourget

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I'm surprised that no one has mentioned filling the tubes with casting sand, packing tight sealing the ends and bending over a form. For 4130, you use heat. Ron Covell may have a YouTube Video. I attended one of his demos where he bent a roll bar hoop using thick wall 4130
 

don january

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Rob have you thought about filling the tube to be bent with expanding foam like used in making a plug for aircraft cowling ? Just a thought.🌤
 

rv7charlie

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OP mentioned sand in 1st post. Unlikely to work well enough with structural tubing. I mentioned heat for 4130.

Foam will just collapse under the pressure.
Mandrel benders....
 

Geraldc

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There is also a resin you melt in and melt out when you are finished.
But in my many years dealing with pipe you can't go past a mandrel bender.
 

Pops

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Have a hand crank binder that does a good job on 4130 up to 3/4" dia in 4130 with no kinks.
 

karmarepair

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Need some advice. I am embarking on using aluminum tubing for the trike I am building plus 4130 tube bending for my 69 vw that i am converting into a trug which is a bug truck with some baja fenders so i guess its also part off road bug. Anyway I will be using various sizes of tubing. I have bent 1/2 in aluminum using the fill it with sand and a jig. That worked ok but this is bigger stuff. Most all bend will be 90 degrees or less.
For ALUMINUM, Leonard Miholland talks about drilling a hole only slightly larger than the OD of the tubing itself in a firmly clamped chunk of 3/4" plywood, and pulling and bending a LITTLE bit at a time, to sneak up on the curve. The round hole keeps the sides of the bend from bugging out and kinking and collapsing the inside of the bend.

IF it's thick enough and heavy enough for your purposes, avoid bending the steel at all, and use "muffler moly" pre-bent exhaust tubing.

The people that sell tubing for roll cages, or sell bolt in roll cages, might be able to sell you bends in the Good Stuff.
 
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