Warped Roof

Well my welder warped the roof of the Hummer. He made a continuous weld as opposed to multiple tacks (tack several spots, let cool, several more tacks, let cool, etc.). I wasn't there when he welded.

Anyway, whats done is done. Now I've search the forum on how to repair the warp, but found little information. I did find a technique on heating the warp and applying ice to the center. This sounds like a great trick. Has anyone used it? If so, how successful was it. Has it failed on anyone and made the warp worse?

The reason I am asking instead of trying is that I don't want to make it worse. I believe with the current warp, I can pop the warp and tack a piece of metal to the backside as support to hold it from popping back to the warped position. I don't know if welding a support in is a good technique, but it appears like it should work. I don't want to do this if the ice trick is normally successful though.

Any comments?

Thanks,

Scott

The heat from the welding shrinks the metal as it cools in the heat affected zone. You will have to stretch the material out by hammer and dollying the welds. What kind of welder did you use? If MIG, the welds will most likely have to be ground down. MIG welds are hard and can't take a ton of hammering, they will crack. Plus, grinding them down helps in flattening them out. I usually use a cutoff wheel on a highspeed air motor. I have lots more control on the amount of material being removed. So, I would stretch the weld area first before trying to shrink anything with a torch and water, ice or dry ice. Good luck.:CRY:

Heat, shrunk the metal? I thought it expanded the metal. Since all the sides were locked in by factory welds, shrinking shouldn't have caused a warp. At least by my thought process. This was a patch welded into an existing roof.

By the way, I don't know what welder the guy used. He had Arc, Gas, Tig and Mig available, but I think he used Arc.

Thanks,

Scott

shrinking with a torch is very tricky. i would set it out in the sun and let it heat up good and then hit it with a bucket of well water. if that does'nt help move on to the next step. buy a shrinking hammer from eastwood and try your luck. my guess would be that it's probly as bad as it can get. to torch it you need to mark th center of the warp and the outside edges. start close to the weld as this is where it started. do a fast cherry spot the size of a quarter and then hit it with water. use hammer and dolly to help relieve the warp. if you can bring the sides up the center will follow. good luck.

Thanks, I'll give it a shot.