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no penetration on back using 20 ga sm

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  • no penetration on back using 20 ga sm

    Im practicing with my Hobart 140 using .023 wire and 75/25 argon co2 mix. Welder is brand new. Im practicing on 20 ga sheetmetal to get ready to weld in patch panels on my 54 merc. I get nice flat circular tacks using the reccomended #2 voltage 30 wire speed on my scrap piece but i dont see any penetration on the backside. My Boss at the body shop says when he welds in patch es he leaves NO GAP. What am i doing wrong. Thanks Mike

  • #2
    When you replaced the flux cored wire with solid wire w/ gas, did you reverse the weld polarity?

    The positive weld terminal should be connected to the gun block while the negative weld terminal should be your work lead.


    PS Check the door chart on the 140 for this info as well.


    • #3
      Yup, there are lots of methods for welding panels, there was another thread about how much gap and I hesitate to comment as everyone has their own techniques, some good, some poor but with a butt on light sheet you need little to no gap. I don't even like doing them that way, personally I make the patch slightly larger, very slight, less than 1/8 and put the patch behind. I know what will be said about water etc but if done right the overlap is almost all consumed in the weld, keeps some shielding behind the weld and is at least as good as something noodled over a crack.