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Blowing holes in my butt welds...

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  • Blowing holes in my butt welds...

    I am patching some rust in the floor pans of my 69 Camaro and I am trying to butt weld the patch panels.

    So if I am blowing a hole in the sheetmetal what am I doing wrong with my butt weld? Here is what I am using....

    Miller 180 Autoset
    20 gauge metal
    .030 wire

    The voltage is set at #2 and wire speed is set for the .030 wire size.

    I tried adjusting the wire speed to 50 or 60 with the voltage still set at 2 but the wire seemed like it wanted to "kick" back the gun.

    What am I doing wrong?

  • #2
    You can't run a bead on that thin'll have to do a series of squirts till you complete your bead. and it sounds like your wire feed is too fast.


    • #3
      Originally posted by Rocky D View Post
      You can't run a bead on that thin'll have to do a series of squirts till you complete your bead. and it sounds like your wire feed is too fast.

      Nope,wasnt trying to weld a bead just trying to do some quick tacks here and there but was still blowing through.

      The more I turned the wire speed down (around 50-60) the wire seemed to want to make the gun "kick back" and be jumpy when I pulled the trigger to weld.


      • #4
        That could also be a bad ground...will it work on tap 1? My machines usually run around 40 WFS


        • #5
          If you can get to the back side of the panel, use a piece of brass or copper as a backer.

          Also - for the thin stuff you basically spot the whole seam together bouncing around to minimize the warping.

          Take a look through these threads. A few years back I went back and forth with a member, trying to convey my experiences with welding autobodys. Take a look:

          Last edited by MXtras; 11-13-2008, 08:40 AM. Reason: Added links
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          MXtras' Storage Cabinet thread -

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          • #6
            Hey 1320,
            I do restorations on 3-6 classics a year which are generally frame-up projects. I use a spoolgun now since I have to change wire sizes for the different thicknesses of applications. For all the sheetmetal, I use .023, ER70S-6, and C25 and generally run 30-40A & 250ipm WF. I have several pieces of 1.5" X 1.5" aluminum angle from 3" to 12" in length to use as a backing strip & the angle makes it easy to clamp in odd locations/configurations. You will get much better results by insuring the weld joints are clean, bare metal, and I would suggest a small 1/16"-1/8" lap joint and it will be stronger. Once I have the part tacked in place, I weld small 1" beads, and vary location allowing at least 5 min. separation time for cooling and reduced warpage. It takes practice and you should do all your setup heat/WF with some scrap pieces of the same material and the use of a backing strip. Stay with .023 and you will have a much better success ratio and eliminate burnthru. Be sure you have a really good ground connection and cut the end of the wire with each start to insure a good contact. It is quite easy once you do some practice to get the "feel" of welding the thin sheetmetal in auto floorpans, kickpads, fenderwells, & exterior panels. If you can't determine WF by the setting on your dial, simply pull the trigger & count to 5, cut the wire & measure length, and multiply length by 12 to get IPM for that setting. It's not hard.... don't make it hard.... practice.... it will come.... Denny
            Complete weld/mach./fab shop
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            "A man's word is his honor...without honor, there is nothing."

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            • #7
              I took a beginner auto body mig class. A buddy asked me to weld some panels under his '49 Ford. The dang thing was kicking back something terrible. It turned out to be the 'right knob' on the Lincoln 135. It was set 'about 2' IIRC. I turned it up from 'about' 10am to 2pm (sorry, don't remember) and away we went. Sometimes being a beginner, sucks.

              I learned to always point the gun at a test piece, pull the trigger, listen, turn knob, listen for 'bacon', weld piece.

              Edit: As Yorkiepap said, we used .023. Also, don't try to run a bead; lots of bzzt....bzzt....bzzt.
              Last edited by Craig in Denver; 11-14-2008, 12:32 AM.
              9-11-2001......We Will Never Forget

              Retired desk jockey.

              Hobby weldor with a little training.

              Craftsman O/A---Flat, Vert, Ovhd, Horz.

              Miller Syncrowave 250


              • #8
                Are you using flux core wire? It tends to blow holes in thin body metal.