Hey all, what is our capacity for bending 1/2" steel tube? It needs to be a fairly tight bend, making a 90 degree turn within like 3".
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Yeah, I think that’s the Harbor Freight bender & from what I read it doesn’t go down to 1/2". 
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Condiut benders don’t bend that short do they?
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Is it tube or pipe? There’s a difference. I have dies to bend 1/2" tube with a (iirc) 1.5" CLR. I think we have a general purpose bender that they would fit in. What’s the wall thickness, assuming it is really tube?
I also just remembered I do have aa actual tubing bender, but the only die I have for it is 1.5" round tube. A die for 1/2" in whatever CLR could be made for it though.
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Fyi, many folks think the pipe bender will bend anything round, and truth be told, it will. But the dies are sized for pipe. Trying to bend tube that has a different OD will result in, at best, flattening of the tube, but depending on the tube thickness, more likely it will kink. If you need to bend pipe, have at it, but for bending tube, you really need a machine made for tube.
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Yeah, this is actual 1/2 OD tube with 16-gauge walls. I went ahead and ordered a bender off Amazon last night, to see if it’ll cut it.
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Let us know how it works out.
I have played with burnout mandrels befote on very thin tubing. But it still has “kinks” and imperfect bends where the wood or cardboard mandrel fails. If reaching just for flow thru capacity, this CAN be an option. But we were reaching for structural integrity and nearly perfect radii were not reached in this fashion. And our Midas guy advisor on this student project knew we needed a support mandrel inside while bending. he showed us his mandrels so we understood. But we never quite got structural bent corners on our thinwall tubing.
Ya gotta respect students who dont know “it cant be done that way”, and will just keep trying creative ways like pressurized tubing. They taught us to not give up too easy just coz a pro said it cannot be done. But they still listened to the available experienced guy.
What is a burnout mandrel? Mandrel bent tubing is nothing new. It is used for everything from structural members to fluid carrying. There are several methods of achieving a kink free bend, limited often by the material itself. Pulling a mandrel through the bend as it’s occurring is usually the most effective and easiest, assuming you have the right equipment.
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Next time talk to the Metal Shop Leed , 50 years making tube bending dies and fabricating equipment they say cant be done!
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Burn out mandrel is material that melts at low temperature you fill the tube with it hardens
to support the walls while bending then you heat it and it and it melts out and you use it again!
CERRO BEND Filler for tube bending.
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It was a naive attempt but worthwhile learning for student builders.
A cardboard and glue mandrel didnt work so well… we switched to a carbon fiber /vinyl ester rod inside the thin aluminum tubing. This was used in deep dual bends to make a u-shaped wing frame… and then a propane grill or brushy flame on propane torch… used to heat it until a [coathanger wire] could push [most of] the half ashed leftovers out. The result still wasnt smooth enuf as it couldnt control the wrinkles on the inner curve. Nor fully prevent flatting on the outer bend of a 90 degree 1 inch radius… it worked for very gentle bends only. Which wasnt interesting to the students. We did build a U shaped hobby plane wing almost as light [and far more resistant to crash damage] almost as light as the balsa frames in general usage. But it was just … interesting.
The students had access to a guy who knew how to bend trombone tubing. He couldnt help with our tiny tubing fabrications. He showed them his mandrel kit.
I was the team mentor for wood bending, but [slow] deep bends require ammonia soaks [chem hazard for students… gong] and steam and oven soaks helps. But ammonia seriously reduces woods strength. And we just wound up building glued balsa structures for the planes. But we learned a lot along the way. Some of our students planes placed at nationals, 3rd or 4th place maybe.
Bridge builders used our wood bending more than plane builders.
Talk about fun building and mentoring youth. They always amazed us with creative trials. Like burnout mandrels.
This was late 90s, early 2000s Science Olympiad. Our team went to nationals ten times. Then the parents got tired of the national travel expense and placing 3rd or 4th at State was… enuf.
One of my employers involved me in a washout mandrel. A foam used as a layup form for a carbon fiber epoxy crash bar tubing frame. And they used a steam nozzle to remove the foam. Patented. Still utilized today i think … altho that model airframe isnt in production anymore.
Did you find a good method to bend the tube? I also need to bend some 1/2" OD, thin-walled steel tubing to a bend radius of about 1.5".
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Larry Meeks metal shop Wednesday 4 o’clock i have 1/2 in with 1.50 bend radius hand bender will be at make for leeds meeting to-nite room 4, this is my second try to reply to this need to swap phone numbers! Forum does not like to work for me!
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Will be at makeict for cad meetup starting at 5 o’clock Thursday !
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Don, I never did come up with a viable solution. All the hand-benders I found were for pipe, not tube (I think, but I might have it reversed?) and so the OD was off. It became a non-issue in my case & if I have to do it in the near future, I found I can buy pre-bent tube on Amazon & just weld it in place.
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Ian, Thanks for the update. Larry Meeks loaned me a tube bender, and I was able to make it work for me.
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On Fri, Jul 12, 2024 at 3:45 PM Ian Cazabat via MakeICT Forum <noreply@talk.makeict.org> wrote:
| iancaz MakeICT Member
July 12 |
- | - |
Don, I never did come up with a viable solution. All the hand-benders I found were for pipe, not tube (I think, but I might have it reversed?) and so the OD was off. It became a non-issue in my case & if I have to do it in the near future, I found I can buy pre-bent tube on Amazon & just weld it in place.
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