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2" square 1/8" tubing square but sprung

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  • 2" square 1/8" tubing square but sprung

    So I welded this frame together as a rectangle for a top and bottom of a table. Each box is welded square but when I sit it on a granite table it rocks on two corners about 1/4". I assume this is caused by stress from welding.

    How can I fix it and or prevent it ??
    Miller Syncrowave 350 LX

  • #2
    Square. NOT flat. oops!!!

    I assume you are checking square by the diagonal measurement? Distance from top left corner to bottom right corner is identical to measurement from top right corner to bottom left corner (at least relatively close as 1/16" or less difference).

    If you redo the frames, lay out material on a relatively flat work surface, use1/4" steel tabs between the work surface and material for frame at all 4 corners and every 12"-20" along the tubing between each set of corners. This will help get the frame flat. Clamp at least 2 corners at a time-preferably all 4 corners if possible, tack along the top of each corner, check square and flat after each weld. Check square by measuring diagonal as above and check flat by left to right and diagonally trying to rock the frame on the tabs. Do not remove clamps the tubing until the welds cool. If you need to redo, cut the tacks. When re-tacking you may want to tack weld the inside corners. These tacks will be more secure and harder to cut out if necessary. A square flat frame sounds simple and can be a pain in the assz!!! BE SURE TO TACK OPPOSITE CORNERS TO ALLOW FOR EVEN HEATING, COOLING, AND METAL DRAWING. WELD THE SAME WAY. I tack and weld the top first, inside corners second, back side last. Don't forget to clamp. Stop often and check for square and flat.

    I PROMISE THIS PROCEDURE WORKS. I have welded many a square and flat frame that must fit within 1/32"" left to right and slide 12' in a saw gantry without rocking.

    By the way: I have never had good luck in heating and drawing the frames flat. Your best bet is cut out your mistakes and do it over. A cut off wheel on a good electric or pneumatic grinder works best for cutting out your welds. A die grinder with a cut-off discl does not have the guts to do it very well. Be sure to wear a face shield or welding helmet you can see to grind in. If the cut-off wheels fly apart, your most likely going to be hit in the face. I also wear ear protection.

    Good Luck!!!!
    Last edited by HAWK; 04-13-2011, 12:31 PM.


    • #3
      As far as fixing it goes you need to bend it back. If you have a table large enough to fit the whole frame lay it on the table. Put a shim (maybe 1/4" to start) under the two corners that touch the table & clamp them to the table. Now the other two corners should be up about 1/2"? Draw them down to touch the table with clamps. Now unclamp & check it for flatness. If it still needs more tweaking then add more shims & repeat.
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      • #4
        Thanks guys.

        Yeah, its square by measuring corner to corner.

        I didn't bother clamping it to the bench the first around b/c the bench isn't the flatest surface I've ever had at work. This in-house project is a roller table for in front of the heat treat oven. If it were a customers' job I would definately redo it.
        Miller Syncrowave 350 LX


        • #5
          I weld frames up all the time and even though they come out square they may still rock once put where they are going to live because whatever they are sitting on is untrue, Fact of life. Put on adjustable feet, or at least weld a gusset across each corner 1/2" off the floor and drill and tap for a bolt that you can run down to level it.


          • #6
            Good point Walker.

            I usually build jigs for any repeat work where mating parts must be square and flat. This precludes sloppy fits and rocking. Most folks think "square" is adequate when "flat" is a necessity with sets of mating parts.

            If the mating part is not fabricated by "you" (the welder), then flat is a relative term.

            Good Luck