Bending tube with a TIG torch

[joshuabardwell]

If you can heat these areas red hot, and use a spray bottle of water to cool the heated zone. The material must be cool to the touch before re-heating. Remember if you can feel heat with your hand, the material is still moving!

I think the rapid cooling is another component that I was missing. But I don't spray cold water on my welds, and they still warp the metal. I can't figure what's different between the two examples. Is it just that the welds are so much hotter?

 

[CNC Dan]

I think the rapid cooling is another component that I was missing. But I don't spray cold water on my welds, and they still warp the metal. I can't figure what's different between the two examples. Is it just that the welds are so much hotter?

When welding, you're moving. So while the whole area may be hot, one spot is very hot(the puddle). And that spot isn't in one place for very long. When welding you have to keep moving at a good pace. But when heat bending/straightening
you can stop and take your time. Let it cool, check results try again.
Also, try to move around to heat a wedge or pie slice area(not all at once), with the point at the pivot point of the bend. Think of the area that you would remove if you were going to cut out and reweld.

 

[Shield Arc]

Heat shrinking is very easy to learn once you get around someone who knows how to do it. I learned from a guy who learned from the guy who did the beams on the Seattle Space Needle. I'm really good with shapes, little weak with plate.
Here is an example of the wedge technique.

 

[Yellowhair42]

I have done lots of heat straightening.Some pointers are:use OA torch,lots of heat quickly,for your square tube you want to heat a strip in the middle of the bend in the middle of the tube itself parallel to the tube,once an area has been heated for straightening you have to get it hotter in a lager area and if you do multiple heatings eventually it wont work in that spot anymore,for difficult ones clamp to something straight and heat the whole area hot

 

[joshuabardwell]

Pleased to report that 160 amps applied for about 1-2 seconds, followed by a spritz from a water bottle until cool seems to have worked, at least on a scrap piece. I did it first in a quarter-sized spot, which had little effect, then did it on about an inch-long spot on the corners, and that worked better. Now to try it on the actual work piece!

 

[Shield Arc]

The technique isn't hard to learn, now the amount of heat to apply is the trick! And that part only comes with experience!

 

[joshuabardwell]

Well, it's clearly a matter of my technique, but I couldn't get it to work on the actual piece. Maybe it was the welds that caused the warp holding tight. I also tried clamping the piece straight and then heating a V on the side of the tube, followed by water. No dice.

Finally, I but the bullet and put a few beads in on the back side of the tube, perpendicular to the tube. That did it. Silly me trying to be creative... I'm going to be sure to clamp the remaining stuff down until it cools to try to prevent further trouble.

 

[joshuabardwell]

Ultimately, I'm sure the difference was the amount of heat applied, which I could tell from how many spritzes it took to cool the piece. No matter what I did, any amount of heat that didn't melt the base metal was inadequate. I know that heat bending can be done with an oxy fuel torch, so clearly melting is not required. Maybe it's just how focused the TIG torch heat is.

 

[Shield Arc]

I think you really need an O&A torch! I just can't imagine doing this with a Tig torch. When I built this gooseneck adapter for my trailer, one of the uprights, (12" x 19-pound S-shape) pulled out of plumb, little heat in the correct spot, bingo perfect.

 

[Arc weld]

Don't reheat your weld. Clamping before welding and moving your welds around makes a big difference. That's why a lot of projects with small tubing, everything is tacked together first and then you weld a little here, a little there and move all over so all the heat isn't in one place. Type of welding process makes a difference too. TIG torches aren't made for heating. Also when straightening tubing, heat just the corners(edges) of the tube. If you heat across the width make cause a bit of a "crimp" in the tubing.