help bending 1 1/2" tube in a very large arc

[kdouglas]

I am looking to bend some 20 ft sticks of 1 1/2" OD tube into a very large arc.....say 40 ft diameter. Any suggestions on how to accomplish this with little to no tooling? It will be supporting some lights so no a heavy load ...aka : material thickness can be pretty thin. Accuracy of bend not critical, basically needs to just be aesthetically pleasing

Thanks in advance for any suggestions

 

[PT Doc]

pipe bender. hf has a good one reportedly. look at swag off-road video on YouTube. they have an adapter I think for the hf electric pipe bender and does as well.

 

[Jere]

Sand tubing capped heated and bent over a hardwood curve. You would have to have curve bolted to something that wouldn't slide around.

 

[IOWNJUNK]

Sand tubing capped heated and bent over a hardwood curve. You would have to have curve bolted to something that wouldn't slide around.

This would work without heat too, OP said material wasn't very thick. Sand it and two people could bend it together around the appropriate object to get the size needed.

 

[readhead]

We roll pipe and tube just about everyday. You want it rolled, not bent. The lighter the material, the harder it is to roll. I know, that sounds strange but the lighter material deforms easily. 20' is a pretty large radius. As mentioned above you could build a form at about a 18' radius to allow for spring back. It should be fairly long , say 3', and have a top to capture the tube.
Just for perspective, I could roll five of them for $75.00 not counting the material.

 

[Graham08]

Best bet would be rolling, especially since it needs to be aesthetically pleasing. This should be cake for anyone with a tube roller.

Another option that would require no tooling would be heat shrinking. If you have access to an oxy-acetylene setup, you could heat and quench a series of small spots on the inside of your radius. The heated spots will shrink and draw the tube into a curve. This will take some experimentation to get the size of the spot you're heating and the interval correct. This technique has been used quite a bit to introduce camber into beams and other structural steel for years. Tom Lipton's book, "Metalworking: Sink or Swim" has a chapter on how to do this.

 

[csp]

Another vote for a roller, not a bender. Especially not one of those harbor freight pipe kinkers. Their roller can be turned into a fine piece of equipment though.

 

[zkling]

You need a tubing roller. How critical of a tolerance do you need on the arc? What is "pretty thin"? One thing you may want to consider is self weight. Rolling an entire 20' stick by hand is pretty tedious, as you have to fight to keep it from corkscrewing. HF and a few of the off road fab outfits produce a tubing roller pretty cheap. But, if I was in need, I'd contact someone like readhead.

 

[NASTYZEN]

Cave man style:
Lay out your arc with a felt marker on a concrete floor.
Space out 2 pieces of 2x4 and use the marker to mark there place on the floor so you can put them back in place when they move. Space them somewhere in the 3 ft apart.
3 guys preferably... One to hold the tube. One to hold the 3rd 2x4 perpendicular to the tube, in between the 2 other 2x4s and one guy with a sledge hammer....
Check the tube with your floor arc to see what your bending did..
Now do this at regular intervals and you will eventually get an arc'd tube.
How well this works for you will greatly be affected by wall size and quantity of drincks you have with your buddies while performing this task.

You could also have it rolled, then have a flatbed tow truck deliver it to you.

 

[RoosterBooster]

this :

http://www.metalgeek.com/archives/2005/05/01/000047.php

your welcome

 

[FMC]

depending on weight of fixtures and type and placement of suspension you may not need to bend anything, a 20' length of thin wall is plenty bendy on its own, I would dry hang and mount the parts and see where its at, any holes in the tube will be weak spots if you try to bend it after drilling.
Soft arcs... the ends are hardest to achieve the middle bit is easy, its easier to unbend than too bend, in the past I have supported both ends on block and just walked on the tube from center to block, it really dosent take much for what you want.

 

[metal1313]

most green house frames are hand bent. build a large die/form with a radius slightly smaller with plywood. have a block at one end to capture the tube, and carefully walk the tube to the form, then slide the tube down and bend the next section.

 

[EdT]

Check out Jack Olsen's 12-Gauge Garage thread around post 2925. He did just about exactly what you're talking about and there is a fair amount of detail on how he did it.

 

[cwh]

this :

http://www.metalgeek.com/archives/2005/05/01/000047.php

your welcome

Thanks! Great link.