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whats wrong with my plug welds

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  • whats wrong with my plug welds

    I hear them popping, I drill through both pieces, put a copper spoon in the bottom and fill the hole. .25 wire set on D and about 2.5 wire speed on a lincoln 110v mig I also weld the back side. seems like not enough penetration. the steel is 15 ga and maybe 16 ga angle.

  • #2
    another picture

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    • #3
      Bert.
      Why are you drilling though both your attachment and base metal.??
      Just drill a hole in your attachment and fill with weld. This is what I do with out any problems.
      Your base metal looks dark what are you welding on.???
      sigpic

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      • #4
        its a truck bed, base is painted so after its welded I dont get rust behind the rail. Maybe the paint is contaminating the weld?

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        • #5
          Originally posted by bert View Post
          its a truck bed, base is painted so after its welded I dont get rust behind the rail. Maybe the paint is contaminating the weld?
          Remove the paint/coating on the bed.
          After welding go to a body shop supplier and get the same caulking that all pickup beds have used in the joints. Caulk only the top and sides leave the bottom open to drain any water that does get in. Then paint the whole thing.
          sigpic

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          • #6
            When I first started playing with plug welds I was getting cold welds because I was drilling small hole 3/16". Hole is drilled into only top metal which is welded to bottom metal of lap joint. Top hole 5/16" to 3/8" is better as MIG welder has cold starts and takes a little time to get up to temperature even with correct settings. Some companies sell plug weld nozzle that rests on work as your making plug weld with wire centered in hole in top metal. This might be ok if welder has plug weld timer but I feel better weld is made welding around edge of larger hole then filling in center manually.

            Larger holes for plug welds in thicker metal.
            Top metal in contact with bottom metal is needed for best weld.
            Slot weld is same principle used to weld thicker metal.

            First 3 links I opened after web search seems ok.
            http://www.i-car.com/pdf/upcr/procedures/we/we01s.pdf

            http://www.millerwelds.com/resources...articles8.html

            http://www.autobodystore.com/new_page_11.shtml

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            • #7
              Originally posted by Roger View Post
              I feel better weld is made welding around edge of larger hole then filling in center manually.
              I have exactly the opposite opinion - I think best plug weld is made by starting in the middle of the hole so you know that the arc is on the base metal and not bridging over. Then wash the weld into the edges of the hole, which tale a lot less less heat to fuse than a flat surface.

              That's the method I use for welding conventional screw-mount hinges to square tube gate posts:

              Last edited by Zrexxer; 07-03-2010, 03:46 PM.
              Trailblazer 302 * Millermatic 212 * Syncrowave 180SD * X-Treme 12VS Feeder * Spoolmate 3035
              Thermal Dynamics Cutmaster 52 Plasma * Lincoln 175 MIG

              Victor Superrange II * Victor Journeyman

              Hobart HH 125EZ


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              • #8
                Screw mount hinges often have tapered holes for counter sunk screws which are better for welding.

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                • #9
                  Thank you all . After reading all those links there are a few things I can see I need to correct. Shorter stickout for hotter starts, crank up the gas to 30 (working outside), maybe a little more wire speed, clean my work area. I;m going to do another round today see how it turns out.

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                  • #10
                    Originally posted by bert View Post
                    Thank you all . After reading all those links there are a few things I can see I need to correct. Shorter stickout for hotter starts, crank up the gas to 30 (working outside), maybe a little more wire speed, clean my work area. I;m going to do another round today see how it turns out.
                    ...you missed the most important one...Only hole is in the 'upper' piece, the bottom part is solid, and Zrexxer gave you a very important pointer...go back up and read it. Its easy to do it wrong and create a little ring of "weak-weld" around the edge if you wash from the outside in...and that edge is you primary interface between the two panels. Inside-out not only gives the better plug weld, but also results in smoother finished plugs.

                    I've also found these 'Plug Weld Pliers" handy in many instances...keeps the two panels squeezed together nicely...but often you can't fit them into place...I've considered making up a set using a long reach Locking C Clamp plier.,,



                    "Good Enough Never Is"

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                    • #11
                      Actually, I plug weld both ways. If I am plugging a small 3/8" hole I start in the center and work or wash outward. But if I am plugging 1" or 1-1/2" holes I weld from the out side in, this way I make sure I get a good root before filling in. And a lot of times it don't have to be filled in just a good root is all it takes. After all any more is just for looks. And 90% of the time that I do large plugs I am on my back under a trailer.
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