Technical Unbend tubing?

So say that you're making some tube bends, matching side to side. And you bump the pointer and don't notice. Now you have 2 tubes but 1 bend (the last one of course...) is just a degree or so, maybe 2, overbent. And don't want to start over, wasting 1 section of tubing.

What do you do to get it a tiny bit less bent? Suggestions, please, and don't worry about hurting my feelings, I've already called myself a couple of bad names over it!

 

Dave, I over bend tube all of the time. I have a couple 900 lb Welders that I can stick one end under, and slip an early Ford solid drive shaft into the other end, and pull. Depending on the tube size and thickness, you can normally take a little of the bend out.

 

Brake lines, roll bar/cage, frame, exhaust, round or rectangular?

 

Tubing for what ?

 

So basically just muscle a little bit out. Okay I can do that! Yeah I've got heavy stuff in my shop. And there's always a tree out back with 2 big trunks (a bifurcated tree, yup $10 word...), that I could stick it between and tug.

FYI Paul, it's 1.5 od .095 dom about 4 feet worth with 3 bends to shape it to the curvature of the body. Once I get the fit I'm shooting for, I'll be posting pictures to the Whatever project. Just have to mind the back...

 

Used to do this all the time when bending larger conduit...

It's funny, you do have to 'overbend' a bit to allow 'spring back' but things like ambient temps and slight material differences from piece to piece could cause variations in how much spring back you'd get. If it's not too much, say under 3 degrees, whacking the bend against a wood surface that's sturdily backed will generally remove the extra. Use wood so that it doesn't 'flatten' or scar the tubing. More than that gets a bit trickier, then you go looking for something heavy or a tree. But the 'whack' method gives better control for small changes. Try not to whack the same place each time, spread them out on the bend if possible.

 

Yeah, and of course mind the pressure points on the rebend, don't want to leave the over bend and create a new bend on the straight sections..

 

You probably will never get it straight again but like Marty here I have tweaked them a little bit when I have gone too far.

 

I remember using the whack it on a telephone pole method for a quick and dirty way to straighten bent tie rods to get the race car back on track by feature time, but that was a get it good enough to be able to set the toe quickly. Never thought to use it today for this proble... opportunity to save the tubing.

I'm going to try Marty's suggestion first tomorrow, when the back is willing.

 

Used to have a welding bench that was perfect for hooking overbent tubing under to straighten.

You want to get what I would call the anchor point as close to the bend as possible so the bend relaxes rather than bowing a straight section.

Throw a block or scrap of plywood on the floor where the bend is going to be if you're going to hook it under a bench or something. It's pretty easy to leave a divot in .095".

 

My welding table has a 2x4 steel channel horizontal crossbrace that can hold a multi bend bar. I let only the offending bend and it's tail stick out, and I slip a cheater bar over or inside all the way to the bend. I'm only 165 Lbs., but by bouncing a few times, I have taken out up to 2 degrees more than once.

 

Just curious, would heating an area on the outside of the bend shrink it?

 

Had to tweak some conduit when I was doing an electrical project in the garage. The tractor sure came in handy for that! Used the bucket and some wood to hold one end down, then drilled a hole in a length of 2x4 to slip over it for leverage.

 

I have done that as well as the bendy method Marty mentioned. Those old ford driveshafts are tough!

 

They are long, for leverage as well.

 

If you have nothing better to do, watch this. Pretty impressive.

 

These are my kinda folks. I enjoy these videos. Reminds me of all the stuff we had to fix growing up.

 

I’ve used heat.
I’ve whacked em on the floor.
Whatever it takes.

 

Next time you feel your life is difficult and are feeling conditions at work sucks, reflect how others get things done, No dial indicators, welding hood, mics, calipers, or some work boots/ shoes... Oh how those dingle balls hurt that role down the tongue of your shoes.

 

Love those safety shoes they wear and the ingenuity in their work.
Thanks for sharing!

 

Thanks guys. Yes it is just a wee bit of adjusticating to do. I'm going to use a heavy object (me) on one end, and like many mentioned, wedge the other end under something heavier. And I've got a lot of crap heavier than me in the shop

 

I stick one end under the Haas and correct as needed.

 

Thank You. The gears are turning in my head, have a 5'x 10' steel table, I can weld a few tubes across the center support for leverage bar using the table.

 

You know, when I strted this thread, I thought I had only overbent the one end. Ready for the next installment of "As the Tubing Bends"?

Yeah, Dumas me, when I put it in the bender working out from the center bend, my mind got wrapped around bass ackwards. So both outer bends were actually wrong from the point of view of my layout. But it fit better that way!

So I made a 2nd one to match, carefully bending it, checking the springback each time, and it worked!

So I also needed two tubes 14 inches long for another part of the fabrication, which I was able to cut off the ends ot the 1 I thought was correct (it was, BUT the other... see above). So only 12-13 inches of tubing was wasted due to the bends in it. I'll use them to mock up something else, maybe...

So no debending...

Lemonaide from the lemon.But now I can save slight overbends if need be.

 

No, he's not referring to Gene either!

 

I've found that a 5 degree or less bend on round tube up to 3" diameter will not look too terrible if you try to bend it back. i have made a few goofs on our tubing bender at work. Anything more, & the pipe looks ( & will be ) distorted

 

Heat shrinking can probably be used to do that. Although you may want to research what heat does to that type of tubing forst, I'm sure some won't be affected while some will be.

 

Your avatar is my kids favorite book, lol.

 

Go Dogs, Go!

 

Exhibit A.