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Thread: Fusion welding sheet metal

  1. #1
    Registered Member MP&C's Avatar
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    Fusion welding sheet metal

    This evening I tried some more Fusion welding using the Tig.. To review my previous attempt:

    Some practice at fusion welding using the Tig, here's the front showing some slight undercutting..



    The rear side shows some good weld penetration in some areas and needs more practice in others..



    Just to show that slight undercutting on fusion welding was not an issue in the joint's strength, the seam was clamped in the apron brake and bent to 135 degrees, with no detriment to the weld..



    When using the Tig torch on that pass, I had set the amperage, mashed the pedal, and used the speed of the pass to control the heat. The slight undercut in the center is likely due to the fact that I made a straight run from one end to the other. I wanted to try this again, giving the torch a circular motion to see if it helped. Here's our sample pieces..



    For tacking purposes, I set the electrode depth so it was just sticking out past the cup. The electrode is fairly easy to position using this method, drag it side to side and it will find the exact joint between the two pieces. Then rotate the torch backwards just enough for the cup to pick up the electrode off the metal, and give the pedal a quick push. These "tacks" were about 1/2 second in duration, amps set at 82. This shows the front:





    And the rear side weld penetration:





    For the weld pass, the sample is raised above the "table" to simulate welding the panels on a car in free air...



    In order to maintain consistency for the test, the cup is modified so as to use it as a "glide" (think plasma cutter guide) and the electrode is now moved just inside the low point on the cup. This should hold our electrode height exactly the same, to limit one of the walking, talking, chewing gum factors.





    This was welded using a circular motion with the torch while making the pass:



    Rear shows some undercutting



    Planishing to bring the weld proud down flush with the front surface
    Front:



    Rear:



    Now to test the weld to see how structurally sound it is with the undercut....

    Here's the front side with the weld pass...



    This is the rear side with the undercut..



    This was bent approx. 150 to 160 degrees and the weld held..



    I definitely need more practice to build up my "comfort level" with using this process, but sure beats all that grinding with using the Mig!
    Robert



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  2. #2
    Registered Member carls 56 (RIP 11/24/2021)'s Avatar
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    thanks for sharing Robert.
    ARMY NAM VET, very proud!

    56 210 4dr

    drive and enjoy them while you work on them, life is to short.

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    Robert, does your machine have a pulse feature?

    It is very easy for me to tig weld 20 gauge steel without filler metal using the pulse and do a near perfect job. At least at the bench.

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    What gauge metal did you use Robert?

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    Registered Member MP&C's Avatar
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    Quote Originally Posted by Rick_L View Post
    Robert, does your machine have a pulse feature?

    It is very easy for me to tig weld 20 gauge steel without filler metal using the pulse and do a near perfect job. At least at the bench.
    Rick, it does but I don't think it was turned on at the time.. Thermodynamics 185


    Quote Originally Posted by LEE T View Post
    What gauge metal did you use Robert?
    Lee, this was using 19 ga CRS
    Robert



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  6. #6
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    [QUOTE I don't think it was turned on at the time][/QUOTE]

    You'd know if you had it turned on. Give it a test drive - it's interesting and effective. Try it on some aluminum too if you ever weld aluminum. The biggest thing it does is allow you to slow down your welding if you want to lay a pretty bead.

    The manual or the laminated cheat sheet will get you started with the settings.

  7. #7
    Registered Member MP&C's Avatar
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    I could see it if adding filler, but for the no-filler fusion weld I would think everything consistent would be in order. Same heat, same speed, etc. to produce same bead from start to finish. Of course, I'd say I'm in for quite a bit more practice before this is over...
    Robert



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    Robert, if you pulse fairly slowly, like 1-2 Hz, it lets you build up a slower rhythm for adding filler and moving the torch. That works better for me with aluminum. The reason for that is the heat required to melt a puddle but once it's melted you need to time the filler and move on. The pulsing lets you move on more slowly.

    I forget what setting I used for the steel sheet - it was a much higher frequency. I move the torch in a circle but also forward at the same time. I didn't write down the settings but I'm sure I can figure out what I did again and I will post back.

    The other variable with pulse is that you can set the minimum amperage. It's not just 0 to maximum.
    Last edited by Rick_L; 07-19-2014 at 06:36 PM.

  9. #9
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    Robert, on the 20 gauge sheet that I welded with pulse, I used the following:

    high amps - 45A
    low amps - 20A (I think)
    balance - 50%
    frequency - 20 Hz

    This produced a nice smooth weld on the torch side, and the back side was almost the same (I was very impressed with that!) The reason that I think the low amps was 20 was apparently I changed it inadvertently after welding the sample so I am relying on my poor memory (it was set real high when I checked it today). I'm still getting used to which button to push to set what.

    I also did some .062 aluminum at 1.0 Hz and 0.75 Hz. I also tried some steel at 1.0 Hz before trying the 20 Hz.

    Try this out, especially the 20 Hz, I think you will be impressed.

    I also recently replaced my torch and torch lead with one that's sold by HTP for the Thermal Arc welders. The torch that comes with the TA is a 26 (I think), and the HTP kit is a 17 (a bit smaller). The main thing about the new torch is that the gas and electrical are all in one lead, and it's very light weight and small in diameter. It makes torch control MUCH easier. The 17 torch uses the same collets, cups, etc. as the 26 torch, so you won't have to buy any of those.

    I would post a photo but I let my picturetrail upload s/w lapse. Maybe I can renew that and post a photo in a day or two.

    Edit: I used a 10A low amp setting rather than 20A. Found it in a post I made on another site.

    Your welds look good. But they will be better with pulse. If I can do it, certainly you can.
    Last edited by Rick_L; 07-20-2014 at 05:44 PM.

  10. #10
    Registered Member MP&C's Avatar
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    I'll have to give that a shot. I'm not using any filler, did you use filler on the steel?
    Robert



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