Welding sheetmetal

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I need some help to weld sheetmetal.  I started welding a few years back, and even took some classes to learn the basics of oxy-acetylene, mig, and arc.  So I know the basics, I think.  And I can weld up the backhoe on the tractor and not worry about breaking the welds...But I cannot for the life of my weld sheetmetal together (auto body panels).  I bought a Century 110V unit some years back, and was able to weld with that unit on sheetmetal, but I recently bought a Lincoln 175 and even with it turned down to the lowest setting (A) and fairly slow wire speed (1.5-2) I burn through the metal fairly regularly.  So I need some advice please...  Or just refresh my memory, what have I forgotten?ThanksKeith
Reply:Metal that thin needs to be spotwelded ie: just weld a small area w/o moving gun ahead or back,then move quite a way away from that one and weld another spot. Keep moving around as this will also lessen warpage.            HTH,                  MikeOl' Stonebreaker  "Experience is the name everyone gives to their mistakes"Hobart G-213 portableMiller 175 migMiller thunderbolt ac/dc stick Victor O/A setupMakita chop saw
Reply:Originally Posted by KG4ZRCI need some help to weld sheetmetal.  I started welding a few years back, and even took some classes to learn the basics of oxy-acetylene, mig, and arc.  So I know the basics, I think.  And I can weld up the backhoe on the tractor and not worry about breaking the welds...But I cannot for the life of my weld sheetmetal together (auto body panels).  I bought a Century 110V unit some years back, and was able to weld with that unit on sheetmetal, but I recently bought a Lincoln 175 and even with it turned down to the lowest setting (A) and fairly slow wire speed (1.5-2) I burn through the metal fairly regularly.  So I need some advice please...  Or just refresh my memory, what have I forgotten?ThanksKeith
Reply:You can increase the (wire) stickout too, this will preheat the wire, lessening the amount of heat deposited at the work. Just don't make it too far or you will lose your gas shielding. Small sections of bead at a time, nowhere on auto panels will you need to run full beads.If you don't have the time to do it right, then you definitely don't have the time to do it over.
Reply:I guess I should have mentioned that I was using .035 flux core wire.  I plan on getting gas for this unit, just haven't done it yet.  And I do the majority of my welding outside.I was trying to do short welds...  Maybe 1/4 inch long.  I'll do even shorter spot welds and see if that helps.  And play with turning the speed up.
Reply:But I cannot for the life of my weld sheetmetal together (auto body panels).
Reply:lol @ zap..035 + flux (does not equal) good sheetmetal work.fluxcore penetrates deeper than regular wire which makes fluxcore great for getting through rust and welding thicker materials... but not for sheetmetal.  Sorry for the bad news but it's the wrong tool for the job.***************************************Lincoln AC225 stick welderLincoln HD100 WeldPak flux core wire feed welderThree of the cheapest grinders money can buy
Reply:Nuff said.If you don't have the time to do it right, then you definitely don't have the time to do it over.
Reply:That just tells me that I need to go on the bottle sooner than I was planning...Could that also be why they don't really touch on flux core in the classes either?KRS, it's not bad news...  I am continuously learning here.  I would rather do it right and not keep screwing up good body panels.
Reply:Hi KeithI just finished some auto-body panel work on the weekend with my Lincoln SP-175T (MIG PAK 15).  It's like the boys have told you; I used 0.023 solid wire and CO2.  I wouldn't use flux-core wire - too much penetration.I was welding metal thicknesses from a low of about 22 gage though a maximum thickness of 18 gage.My settings on the Lincoln were:1st : the spot welds - amps at position A, wire feed = 1 to 2        (it is impossible to burn through - unless you try to lay down a bead)        Go from one end of the panel to the other - don't heat up the same region for a while, just keep moving top to bottom, one side, then the other.2nd: grind-off the high points of those now overlapping spot welds3rd: fill-in with continuous bead over the ground-down spot welds - amps at B, feed = 34th: grind again5th: final fill-in/flow over - amps at C, wire feed = 4Note: by now everything was ~18 gage thick.  I had one burn through, my fault for lingering too long in one area.  I fixed that fast: spot it - cool, spot it - cool, fill-in!6th:final blending with grinder7th: buff up with 40 grit then 80 grit flap disk.I found that the Lincoln Guide, inside the cover, was just about right on.e.g. for 18 gage thickness with 0.023 inch wire and CO2, it said C-4.I hope that helps,Rick V
Reply:I picked up the bottle today.  Still have plenty to do on the jeep body I am working on.I guess i am so used to welding larger stuff outdoors that the flux core doesn't even bother me anymore.  I just haven't welded sheetmetal in over 10 years.