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Thread: Warpage...argh.

  1. #1

    Default Warpage...argh.

    OK, I thought I read and learned about controlling warpage. I welded a lip lengthwise down an 8' long square tube with my Millermatic 250. I welded two inch long beads every eight inches or so and even started at opposite ends. Well, it looked really nice, then I realized it warped like crazy.

    The warping is done. Does anyone know how to un-warp it? Probably not easily done. The tube is 1.5 x 1.5 .120 wall. Standing on it has no effect. I heated it with a torch and stood on it to no avail either. I'm afraid to give it too much umpff for risk of kinking it.

    Here's the kicker: My wife says I should just weld a bunch of beads on the other side and warp it back.

  2. #2
    Join Date
    Sep 2002
    Clark County, NV


    Quote Originally Posted by drewworm
    Here's the kicker: My wife says I should just weld a bunch of beads on the other side and warp it back.
    That can be an easy option if it works for the weldment.

    WHERE did you apply the torch heat? That matters, too.

  3. #3
    Join Date
    Jan 2006
    Albuquerque, NM


    I have used the method your wife proposed with great success at times. Just weld some well placed beads and grind them off after you get it stright again.
    Regards, George

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  4. #4
    Join Date
    Sep 2005
    Salem ,Ohio


    Your wife is pretty smart. The whole idea is to put the same amount of heat on the backside as you put on the front. It will bend like a big bananna but should pull back flat when cool. I used to straighten 40' parts after welding with a torch and lots of hours...Bob
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  5. #5
    Join Date
    Oct 2005
    Bulverde, Tx


    I have done this too many times with pipe, but never with sq. tube...Heat the opposite side with your torch and when you get it hot enough, quench it with a wet rag or dump water on it. I have taken some big warps out with three or four passes like that.

    I've always wondered if it would work on sq. tube...........anyone know?

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  6. #6

    Default Fix'in the warp

    I think the overwhelming majority agreed on applying some weld beads, or heat to the opposite side of the sq. tube. I wll get back to everyone after I try it.
    Thanks for the help.

  7. #7


    Just to be fair, I took a very stout tube of 2" sq. .250 wall and layed it over the warped tube with 2 X 4 blocks between them. I then grabbed every "C" clamp I could find and spaced them over the 8' length. I put some serious clamping force on the 1 1/2 piece and left it like that while I did some other stuff. When I removed the clamps, the warped piece was about half as warped. Since I don't do this often and I'm learning as I go, I thought it necessary to see if the piece could be brought straight mechanically. I still plan on welding the opposite side of the warp and see if that works.
    Stay tuned.

  8. #8
    Join Date
    Apr 2007
    Kansas City

    Default Unwarping 1/2 Plate

    My First Post Here!
    I bought some 1/2 plate for my welding table. I knew it had a slight warp at the scrap yard but didn't realize how much till I got it home. I've heard that I need to heat it to reduce. I have it placed on my frame with the high side in the middle. Do I heat the underside to bring it down?
    Millermatic 200 w Spool
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  9. #9
    Join Date
    Mar 2007
    Fraser Valley, BC

    Default Back breaking

    Warping can be a little bit of a problem, (or not so little ) on some weldments. I learned a little trick at work from my welding supervisor called back breaking. Basically you take a piece of metal as long as your weldment, and preferably thicker. Insert two spacers about 1/3 from the center from each side and clamp the ends until the weldment bows. Take the "back break" off after the metal has mostly cooled and it should be pretty close to straight. Coincidentally, you can use this same technique on a warped piece. Clamp the "back break" on the side you want to straigthen it to and tighten down the clamps. While you tighten down the clamps apply heat to the weldment. Keep going till you bend it past straight then unclamp it when it is half cool. It work for us at work while trying to straighten a 25'+ garbage can wall, so it's worth a try. I've been told that to bend a piece straight without an heat you have to bend it twice as far the in the opposite direction of the bend, but I imagine this would break or crack you tubing. Just my .02$, hope it helps.
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  10. #10


    If you have access to a press you can straighten this without heat by overbending and allowing it to spring back. If you do not have a press then put a 4"x4" under each end and put some weight or force in the middle. My point is if you use inginuity, it can be straightened without heat. Even if a strongback was used, you will almost always have to deal with warpage.

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