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  • Newbie - tips on sheet metal repair

    Hey Guys,

    Have only been welding for a couple of months. I've got a Millermatic 180 mig welder. My project is 1969 AMC Javelin that I'm restoring/customizing. The body is in pretty rough shape, and new panels for these old AMCs are tough to come by, so I'm getting lots of welding practice! I've gotten decent at patching in new metal here and there, and plugging small holes. I've used copper to back the holes and have had good results at plugging the, and grinding down the excess. However, there are a few areas with rust holes that are inaccessible from the back, so I can't get any copper behind them. These also tend to be areas where the metal is fairly thin, so when I've tried to weld them w/o anything behind them, I'm just blowing through the metal, making the holes worse. The areas I'm struggling with are all areas that would be a ton of work to cut out and replace, so I'm hoping for a solution to plug the holes instead of having to cut out and replace.

    Here are some pics - some of the holes are tough to access directly because of the drip rail above the windows. Any suggestions are much appreciated!

    Mike
    Rust behind drip rail Rear window trough

  • #2
    You ask for suggestions without telling us what process and wire size you're currently using. What is the actual thickness of the sheet metal in question?

    For best results, you will want the GMAW process and .024" solid wire with a C25 (or similar) shielding gas. Everything different from those adds to the difficulty. After that, practice. Do not wait for the blow-through before getting off the trigger of the gun. Try a series of short-time spot welds, letting the puddle cool before adding another one.

    ESAB EasyGrind is a wire that is made for that kind of work, but will only help the finishing, not the actual welding.

    Comment


    • #3
      MAC72,

      Sorry about that....first time here. I'm using GMAW, and have tried .024" and .030" solid wire (ER70S-6). The sheet metal is about 19 GA (I've gotten slightly different thicknesses, depending where on the car I've measured it). And yes, I am using C25 shielding gas.

      I was looking for advice with the actual welding, but will check out that ESAB product, as it sounds like it would be a bit easier to grind down and finish. I didn't know if there was a method or product that I'm not yet aware of that might help with this project.

      Thanks,
      Mike

      Comment


      • #4
        I like .024 Silicon Bronze and Argon for thin sheetmetal. Pricey but works great...Bob
        Bob Wright

        Spool Gun conversion. How To Do It. Below.
        http://www.millerwelds.com/resources...php?albumid=48

        Comment


        • #5
          Originally posted by aametalmaster View Post
          I like .024 Silicon Bronze and Argon for thin sheetmetal. Pricey but works great...Bob
          Hello Aametalmaster, I would like place a question about this matter to you please. I am trying silicon bronze on TIG welding, the mother material is thin steel sheet of 0.5mm thick, butt welding/joint. The electrode I use for this is a 2.4mm 2% ceriated tungsten rod, and the current is DC electrode negative with pulse. Pulse on time duty ratio, or the welding pulse ratio, is 10% with 35A, while the base current or the off-time pulse current is 4A(minimum for this machine, Hitachi Inverter-Pair 300GP).

          The welding/brazing starts mostly good and can go several inches ahead, but the electrode easily get contaminated with some red-colored stuff on its surface. It seems like some copper-like stuff out of the filler rod.

          As far another thread tells they seem to use AC for this sort of jobs;
          http://www.millerwelds.com/resources...888#post315888
          but in these cases they do on bronze as the mother material.

          Should I use AC instead of DC in my case?
          Appreciate your tips please. Thanks in ahead.

          Chy
          Last edited by chy_farm; 09-15-2017, 04:48 PM.
          Oxy-A (Koike, Sakaguchi)
          HITACHI Inverter Pair 300GP(AC/DC TIG)

          Comment


          • #6
            Did this for 40 years. Pull way back with the mig gun and melt off pieces of wire red hot. When you have enough pieces stuck around the hole move the gun in and make your weld, repeat and repeat. I'm sure they exist but I never met my rival on automotive rust repair.

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            • #7
              He's doing TIG but that is an interesting approach you have there. Thanks.

              Comment


              • #8
                Originally posted by shootist2 View Post
                Did this for 40 years. Pull way back with the mig gun and melt off pieces of wire red hot. When you have enough pieces stuck around the hole move the gun in and make your weld, repeat and repeat. I'm sure they exist but I never met my rival on automotive rust repair.
                Hello Shootist2, I am sure you are talking about the original post of this thread, aren't you? Thanks.

                Originally posted by Aeronca41 View Post
                He's doing TIG but that is an interesting approach you have there. Thanks.
                Yes, my project is silicon-bronze welding/brazing on steel sheet with TIG welder, thanks.


                Chy
                Oxy-A (Koike, Sakaguchi)
                HITACHI Inverter Pair 300GP(AC/DC TIG)

                Comment


                • #9
                  I don't see any benefit to using AC for your application. If you were using aluminum bronze, maybe. Red colored stuff on the tungsten? Might be sucking air somewhere in your argon supply.

                  But if someone suggested AC as a cure to your red stuff, try it and see what happens.

                  Comment


                  • #10
                    Originally posted by chy_farm View Post
                    Hello Shootist2, I am sure you are talking about the original post of this thread, aren't you? Thanks.


                    Yes, my project is silicon-bronze welding/brazing on steel sheet with TIG welder, thanks.


                    Chy
                    Yes, the original post is mig.

                    Comment


                    • #11
                      Originally posted by chy_farm View Post

                      Hello Aametalmaster,



                      Should I use AC instead of DC in my case?
                      Appreciate your tips please. Thanks in ahead.

                      Chy
                      Can't help you there either as I use MIG with Argon, sorry...Bob

                      http://crownalloys.com/TechSheet/COP...White)_PWP.pdf
                      Last edited by aametalmaster; 09-16-2017, 07:06 AM.
                      Bob Wright

                      Spool Gun conversion. How To Do It. Below.
                      http://www.millerwelds.com/resources...php?albumid=48

                      Comment


                      • #12
                        Originally posted by ryanjones2150 View Post
                        I don't see any benefit to using AC for your application. If you were using aluminum bronze, maybe. Red colored stuff on the tungsten? Might be sucking air somewhere in your argon supply.
                        But if someone suggested AC as a cure to your red stuff, try it and see what happens.
                        Thanks Jones, will give it a try on Monday.

                        Originally posted by aametalmaster View Post
                        Can't help you there either as I use MIG with Argon, sorry...Bob
                        Good evening and thank you Aametalmaster for this informative copy, appreciate it very much.
                        Oxy-A (Koike, Sakaguchi)
                        HITACHI Inverter Pair 300GP(AC/DC TIG)

                        Comment


                        • #13
                          There is always more than one way to do things. Sometimes when metal is very thinned out due to rust anything you try with a welder will blow out and make the hole even bigger.If you can't cut it out and fix it "right" and if it is not going to be a show car with a 10k $ paint job, then here's what I do. I grind , sand ,and by any means possible remove all the rust possible mechanically then I use rust neutralizer liquid . After that I use Dynaglass and fiberglass . It will last many many years . Not exactly " first class" but very good. No car will be ver be perfect no matter what you do.imho.

                          Comment


                          • #14
                            I have found looking back at repairs that I did decades ago, welding on rust thru areas causes some transformation and it lasts much longer afterwards.
                            A lot of that was oxy-acetylene and remainder mig. In my opinion, it is worthwhile to fill holes before filler is applied.

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                            • #15
                              Originally posted by FusionKing View Post
                              I have found looking back at repairs that I did decades ago, welding on rust thru areas causes some transformation and it lasts much longer afterwards.
                              A lot of that was oxy-acetylene and remainder mig. In my opinion, it is worthwhile to fill holes before filler is applied.
                              Interesting. Now that you mention it, I've noticed the same thing but never thought enough about to draw a conscious conclusion. My guess is that no amount of grinding or chemical treatment is going to get rid of microscopic corrosion pockets like welding heat will.

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