Beginners Question MIG Welding

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I am new to welding and teaching myself. Right now I am trying to figure out why my welds are all pitted. The solution I find on the web is lack of shielding gas. I am using a LIncoln sp-100 with .035 flux core wire right now. The welder has a hook up for gas, and I have the tank but it isn't connected b/c of the flux core wire. THis is the way I bought this used machine. Should I use the gas? Change polarity, which is reversed right now for the flux core? Other Ideas? Thanks
Reply:I have not used the flux core wire much because it doesn't make as nice of a weld. That is appearance but I was losing faith in the flux core stuff when compared to what I could do with the gas and plain wire. I have a Lincoln Pro MIG 180 and many of my early flux core welds also looked porous but I think I had the arc length too long.For what it's worth I am much happier with my learning to weld progress with the gas and solid wire. It just seems to work better and that lets me be better, as long as I keep practicing!Tom Hintz, publisherwww.newmetalworker.comLincoln Pro Mig 180Lincoln AC 255Determination
Reply:Some questions.  How do you know the polarity is reversed?  How clean is the material you're welding?  What's the thickness of the steel and what are your settings?  Are you certain it's flux core wire?Jack OlsenMy garage website
Reply:I know the polarity is switched b/c I reversed the two cables according to my owners manual.  The steel is new and clean.  The thickness is 3/8.  I know it is flux core b/c the wire breaks instead of bends, and it says so on the roll, and they guy I bought it from told me so.  I adjusted the wire speed and voltage all over the place trying to eliminate the problem but it is there no matter the settings.  This is not a structural weld and I know it is a little thick for my welder.  Is that the problem?
Reply:Maybe you should step down to .030 wire and 3/8" is to thick for your machine.
Reply:Yah 3/8s steel is thick, I always weld with .30 wire but I am a rookie. I always weld in true mig using shielding gas much nicer looking welds IMO.Millermatic 130XPTilesetter by Trade
Reply:are you welding outside or in windy conditions ?  do you have a good ground ? are you laying a consistent bead and its coming out porous ?350P 30A spool gun cut master 51  syncro 250 other stuff " take a dog off the street and make him prosper and he will not bite you sad the same cannot be said for man" i didnt use punctuation just to piss you off
Reply:Originally Posted by natz803I am new to welding and teaching myself. Right now I am trying to figure out why my welds are all pitted. The solution I find on the web is lack of shielding gas. I am using a LIncoln sp-100 with .035 flux core wire right now.Fluxcore wire = no gas. The welder has a hook up for gas, and I have the tank but it isn't connected b/c of the flux core wire. THis is the way I bought this used machine. Should I use the gas? No.Change polarity, which is reversed right now for the flux core? With fluxcore wire, connect your electrode (the gun) to the negative pole. The work clamp should be positive.Other Ideas? Thanks
Reply:Originally Posted by Jay OMaybe you should step down to .030 wire and 3/8" is to thick for your machine.
Reply:To practice on thin plate with MIG, I hang on to old edger and lawn mower blades. You can grind the edge of the edger blades flat, to practice butt welds, use the long sides for creating angle iron, and/or tees for fillet practice. Ask your neighbors to donate that stuff to you. You also get to practice cleaning and prepping rusty, dirty metal for proper welds.