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Burning thru metal on body panels

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  • Burning thru metal on body panels

    I hope somebody can help me out here. Iím trying to weld up some cracks and holes in old body panels. The metal (22ga) is very good but all I seem to do is burn through when I try to weld it.

    Iím using my MM 250 with .023 wire with 25/75 gas mix set at 25 psi. My gun is a Bernard T3 that I just put a new .023 liner in. The suggested settings are 16.5 volts and wire speed at 38 (low). Iíve tried settings all over the board with no success. Canít experiment too much as I donít need any more holes than I already have to deal with.

    Thanks so much,

  • #2
    Are your Stitch welding it or trying to do a continuous weld ?

    Comment


    • #3
      Originally posted by californiakid21 View Post
      Are your Stitch welding it or trying to do a continuous weld ?
      If you mean welding a small section at a time, even when I try that the wire burns throug. It's like I've got the voltage cranked up too high. Could it be the machine, or is it me.

      Comment


      • #4
        I have not had very good results with a MM250 on auto body stuff. Mine just doesn't seem to be great at the low end. I have had better luck with .030 wire.

        If you can back up the weld area with a copper bar or even a flattened copper water copper pipe it will be much easier. You just need to tack & let cool using multiple tacks to fill in.

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        • #5
          If they are not structurally significant then just stitch it up, or "nickel bead" it, instead of maintaining an arc, you just lay down a series of tacks , one slightly overlapping the last until your crack is welded up

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          • #6
            Burning thru metal on body panels

            Do as S.A.W. said and stitch it. What you are doing is more difficult than it seems. When you get the hang of it things of that nature are like riding a bike. That thin of material will probably warp on you if your heating up too much at a time. Slow and spot w/ overlap and heat shouldn't be too bad.

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            • #7
              Use a copper backing tool, you can pick one up at harbor frieght for like 10 bucks ( welders spatula I think its called)

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              • #8
                Do as s.a.w said. That's where I was headed with my question.
                There nothing wrong with stitching it. That's how I-car has you do the butt joint with no backing test. Stitch it.
                A crack is basically the same thing.

                .

                Comment


                • #9
                  Doing a fair amount of body work, agree 22 is tough. For the holes as suggested make up a the copper backer out of some flattened copper water pipe. If the machine has spot or stitch settings- experiment on some scrap and find a setting that allows a weld but turns off the welder before it burns thru. Other wise make short tacks- and allow it to cool between tacks. A good method is say a tack at 0 then one at 6" and one at 12". Let cool-cool means you can put your hand on the panel (and dont' force it with blast of air to cool!) then tack at 3" and 9" -let cool again and keep reducing the distance between tacks by 50%.
                  You might want to tilt the gun more towards horizontal since the need for penetration is not an issue and the 'flatter' you make the torch the less penetration you will get and what you need here. And push the gun don't pull.
                  Harris used to make a wire called 20 Guage which was ideal for thin work but it seems to no longer available.

                  Comment


                  • #10
                    Originally posted by 131RE View Post
                    Doing a fair amount of body work, agree 22 is tough. For the holes as suggested make up a the copper backer out of some flattened copper water pipe. If the machine has spot or stitch settings- experiment on some scrap and find a setting that allows a weld but turns off the welder before it burns thru. Other wise make short tacks- and allow it to cool between tacks. A good method is say a tack at 0 then one at 6" and one at 12". Let cool-cool means you can put your hand on the panel (and dont' force it with blast of air to cool!) then tack at 3" and 9" -let cool again and keep reducing the distance between tacks by 50%.
                    You might want to tilt the gun more towards horizontal since the need for penetration is not an issue and the 'flatter' you make the torch the less penetration you will get and what you need here. And push the gun don't pull.
                    Harris used to make a wire called 20 Guage which was ideal for thin work but it seems to no longer available.
                    Thanks for the suggestions. I'm headed back to the shop to give it another try.

                    Comment

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