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How big of gap when butt welding quarter panels?

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  • How big of gap when butt welding quarter panels?

    I am going to weld some quarter panels on my 69 Camaro and I am wondering how much gap to set when doing a butt weld on this sheetmetal?

  • #2
    Butt welding auto body panels is very tricky, but is done all the time by experienced body men. I have used panel clamps, that have a thin (about 1/32") divider that keeps the seam spacing even all around the patch...but you have to have access to the back side...(Harbor Freight has these cheap!)

    Today's auto sheet metal is a different critter than the old 30's and 40's cars I used to mess with (and messed up a few). Its thinner and 'high strength', which sure seems a lot more like working with a Potato Chip instead of leather.



    But I prefer plug welding in a strip along the edge of the fender that overlaps the opening, so the new panel rests on it, and can be simply plug welded in, then the seam filled with a quality body filler. Space the welds out, don't over-heat any one weld...the panels distort very easily.

    Another method...and one widely practiced now, is to do it all with panel adhesives...you do the backing strip around the edges, clamping it (with the adhesive) to the car first, followed by applying adhesive to the exposed edge and setting the new panel on it...followed with a filler when set. No welding = no panel distortion from the heat.

    If you really want to "weld it in", use a gas torch and hammer weld it. This takes two, and is the technique body shops and custom car builders used for decades, but you don't see it used as much nowadays. It involves small welds, hammering the weld out against a 'buck', and quenching (to shrink) the metal. Its a two man job, if only for one to hold the torch, because you have to work quick. I have been the helper for a couple body men who could do magic with hammer welds on car bodies.
    Last edited by Hotfoot; 10-23-2008, 08:20 AM.
    "Good Enough Never Is"

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    • #3
      I've done quite a bit of O/A hammer welding solo. All you need is a good torch holder that you can set it in while lit. Mine is set up with the hammer next to it so I can heat, place the lit torch, grab the hammer and go.

      Not as quick as two persons, but doable.

      Jeff

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      • #4
        I've seen hammer welding done using MIG welder. Auto dark lens makes it easier.

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        • #5
          Originally posted by Jeffw5555 View Post
          All you need is a good torch holder that you can set it in while lit.
          Jeff, do you have a photo of your holder?

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          • #6
            Originally posted by Hotfoot View Post
            Butt welding auto body panels is very tricky, but is done all the time by experienced body men. I have used panel clamps, that have a thin (about 1/32") divider that keeps the seam spacing even all around the patch...but you have to have access to the back side...(Harbor Freight has these cheap!)

            Today's auto sheet metal is a different critter than the old 30's and 40's cars I used to mess with (and messed up a few). Its thinner and 'high strength', which sure seems a lot more like working with a Potato Chip instead of leather.



            But I prefer plug welding in a strip along the edge of the fender that overlaps the opening, so the new panel rests on it, and can be simply plug welded in, then the seam filled with a quality body filler. Space the welds out, don't over-heat any one weld...the panels distort very easily.

            Another method...and one widely practiced now, is to do it all with panel adhesives...you do the backing strip around the edges, clamping it (with the adhesive) to the car first, followed by applying adhesive to the exposed edge and setting the new panel on it...followed with a filler when set. No welding = no panel distortion from the heat.

            If you really want to "weld it in", use a gas torch and hammer weld it. This takes two, and is the technique body shops and custom car builders used for decades, but you don't see it used as much nowadays. It involves small welds, hammering the weld out against a 'buck', and quenching (to shrink) the metal. Its a two man job, if only for one to hold the torch, because you have to work quick. I have been the helper for a couple body men who could do magic with hammer welds on car bodies.
            Hey Hotfoot, I have just purchased a new Miller Autoset 180 and am practicing butt welding before i do it on my car. I need to learn it before I move on to "torching and hammer welding".

            I am not quite understanding your method of plug welding a strip along the edge of a fender. Is there another way to explain it so I can fully understand what you are meaning and how to do it? I would definitely appreciate it.

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            • #7
              Plug welding is simply drilling holes in one piece, placing the other behind it, and welding the two together thru the holes.
              *** Disclaimer ***

              As I have no wish to toy with anybody's life, I suggest you take this and all other posts with a certain amount of skepticism. Carefully evaluate, and if necessary, research on your own any suggestions or advice you might pick up here, especially those from my posts, as I obviously haven't the skill and experience exhibited by some of the more illustrious and more successful members of this forum. I'm not responsible for anything I say, as I drank toxic water when young.

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              • #8
                Originally posted by calweld View Post
                Plug welding is simply drilling holes in one piece, placing the other behind it, and welding the two together thru the holes.
                I know what a plug weld is but he mentions putting a strip on the fender. I am trying to picture what he is talking about and how it would make my quarter panel install easier and or cleaner.

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                • #9
                  You would plug weld the backing strip to the back of one side (existing on the car), say it's 2" wide, leave 1" sticking out. You would then place the new panel, where it overlaps the exposed part of the backing strip, plug welding it also. Sand everything , smear bondo over all seams, plugwelds, and imperfections, sand again, ready to paint Think of it like a piece of tape, covering the seam from the inside.
                  *** Disclaimer ***

                  As I have no wish to toy with anybody's life, I suggest you take this and all other posts with a certain amount of skepticism. Carefully evaluate, and if necessary, research on your own any suggestions or advice you might pick up here, especially those from my posts, as I obviously haven't the skill and experience exhibited by some of the more illustrious and more successful members of this forum. I'm not responsible for anything I say, as I drank toxic water when young.

                  Comment


                  • #10
                    Originally posted by calweld View Post
                    You would plug weld the backing strip to the back of one side (existing on the car), say it's 2" wide, leave 1" sticking out. You would then place the new panel, where it overlaps the exposed part of the backing strip, plug welding it also. Sand everything , smear bondo over all seams, plugwelds, and imperfections, sand again, ready to paint Think of it like a piece of tape, covering the seam from the inside.
                    Oh I see now! Kinda like the copper spoon trick but instead you use strip metal and actually leave the strip metal welded behind the seam....also like a piece of tape covering the seam from inside,GOTCHA! Just learned something this evening thanks!

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                    • #11
                      Calweld said it exactly! The little plug welds are dealing with two layers of metal, as opposed to trying to butt weld a thin-to-thin...plus the strip you pace behind gives the body filler some thing to adhere to, so future cracking isn't likely to occur, like it would straddling an un-backed seam. I also plug weld a strip behind when I am going to butt weld a seam all the way (like on a top chop pillar) because it give "more meat" to weld, and makes the task wayyyyy easier (for me, anyway).

                      I've got a VHS tape on hammer welding, but if you go to You Tube you see pretty much what is involved...put "Hammer Welding" in the search bar.

                      I still like the body adhesives, though...especially when combined with the backing strips,but now "stuck" in place with adhesive. Get it at professional body shop/paint supply stores. The guys at those place know their stuff, and are usually more than happy to explain the steps and products to use (and NOT to use).

                      Just like prep is everything in a paint job and in welding two pieces together, alignment of your panel before any welding or gluing is hyper-important. Make a template from the other side of the car that follows the exact curve of the body...heavy cardboard or thin plywood does great.
                      "Good Enough Never Is"

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                      • #12
                        panel clamps

                        Hotfoot -- do you know what harbor freight calls the panel clamps? I checked the web site and could not find them.

                        Thanks

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                        • #13
                          Butt welding clamps:

                          http://www.harborfreightusa.com/usa/...o?itemid=44751

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                          • #14
                            ...and I'm really surprised that the "word watcher" didn't didn't make that XXXX welding clamps!!
                            "Good Enough Never Is"

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