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Very Small Welds Advice

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  • Very Small Welds Advice

    Hi,

    I need to weld a new tab onto a small steel part where the original one broke off. The piece is about 1.5 in square and is about .025" thick. There are 4 tabs that stick up vertically off each side of the square. Tabs are about 3/16" wide by 3/8" tall, also about .025" thick. The piece was originally stamped out, and then the tabs were bent up vertically. I cut a new tab, and the plan is to weld it on.

    So I'm going to TIG it. I tried some experiments on similar thickness stuff, and melted the crap out of it. Any tips on how to approach this? I'm really doing it for the challenge and the learning. How much current should I be using? My machine goes down to 5 amps. Tungsten size? How about .040", Ceriated?

    Thanks.

  • #2
    Hi ParisDakar,

    I am not an expert at this but I often come across small things which I want to TIG. (If they were large I would burn some flux core in my wire welder :-)

    I have found the trick to these sort of welds to be a good HEAT SINK. My approach to the weld you describe would be to get a piece of copper (aluminum will do but copper is better) which I could clamp against the tab side of square piece. I would make sure I had a nice square corner on the edge of the copper where the new tab is to be welded. This will allow the copper to align the tab to the base at a 90 degree angle as well as to remove excess heat. I would also cut the new tab a little long so that it could extend beyond the base. That would allow a simple fusion weld to make the joint. No filler needed.

    As to the tungsten... .040 with a sharp point is probably fine. If you were manufacturing these parts a .020 tungsten might be worthwhile. For a single weld - use what you got! If you have an inverter power source Ceriated or Lanthanated should be fine.

    As to the amperage... put together some scrap pieces of similar size with the heat sink and experiment. It will not take much current but only some testing with your setup can truly answer the question.

    Good luck,

    Ken

    Comment


    • #3
      FOOT PEDAL! do you use a foot pedal ?? Makes life a lot easier!

      Comment


      • #4
        Heat sink. Makes sense. I have some copper I can shape to fit. The tabs don't come off the main piece at exactly a right angle, there's a small 45 degree edge around the perimeter.

        Yep. Using a foot pedal. I have a 330A/BP. Lowest range is 5-50 amps DC, but it also depends on what the main current control is set on.

        Thanks for the tips. I'll fool around with it and see what works.

        Comment


        • #5
          You might take a look at this thread from a few weeks ago.... that should help with some background

          http://www.millerwelds.com/resources...uot-)-possible

          also an internet search of "Micro Tig" will yield a boatload of info... it is very common in the repair of dies and in the jewelry industries as well as gunsmithing an aerospace...

          the real trick is controlling heat input precisely.... if you have to heatsink it... you are probably applying too much heat to begin with...

          Comment


          • #6
            Originally posted by ParisDakar View Post
            Hi,

            I need to weld a new tab onto a small steel part where the original one broke off. The piece is about 1.5 in square and is about .025" thick. There are 4 tabs that stick up vertically off each side of the square. Tabs are about 3/16" wide by 3/8" tall, also about .025" thick. The piece was originally stamped out, and then the tabs were bent up vertically. I cut a new tab, and the plan is to weld it on.

            So I'm going to TIG it. I tried some experiments on similar thickness stuff, and melted the crap out of it. Any tips on how to approach this? I'm really doing it for the challenge and the learning. How much current should I be using? My machine goes down to 5 amps. Tungsten size? How about .040", Ceriated?

            Thanks.
            If you can't dial it down enough you have to put your filler rod between the part and tungsten. Or you can box it up and ship to me.

            Comment


            • #7
              ive used .035 mig wire for filler on small stuff.

              Comment


              • #8
                if your machine goes down to 5 amps... it is not a machine problem... is a matter of developing the technique and skill to do it..... I do little stuff with a Dynasty 350... no probs.....
                take some time and study the links I previously posted... and google "Micro TIG" it is not magic... there is just a bit of a learning curve.....

                practice on stuff that does not matter first... then when you have developed the skill and confidence to do it... give it a try...

                am always amazed at those that dive in clueless and are shocked that the job gets muffed up... develop the skills first...

                Comment


                • #9
                  This all sounds good. Thanks. Practiced a bit and I'm to the point where I can pop off an arc and hold it at the minimum the machine will do. Almost need a magnifying glass to really see it well.

                  Probably make another new tab that has a bottom leg, like an "L" so I can do a lap weld, rather than an edge weld, plus more metal in the vicinity. Pretty confident now that I can do it without ruining it

                  Don't have any ER70... filler rod that small. What else could I use? A strand of wire off a wire wheel seems like stiff stuff. How about that?

                  I'll post a pic when I get it done.

                  Comment


                  • #10
                    .023 MIG wire works fine for TIG.... just about any hardware or home center carries it

                    regular steel MIG wire in 2lb spool is usually ER-70-s6

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                    • #11
                      Check with Miller

                      These guys have a weld calculator for everything. Even an app for your phone.

                      Comment


                      • #12
                        Try dc+

                        Comment


                        • #13
                          Use the correct filler. Either go buy it or use the mig wire as suggested.
                          Trying to guess the composition of some random junk, will only cause you to have to redo the job after it fails.

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