Remelting Bad Welds and MIG vertical.

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As some of you may know I have been getting into MIG and I got to where I can do some decent flat beads so I decided to try some other welds going vertical. So I tried them using an adaptation of my torch technique and the welds were very bad. I dont know what I did wrong but I have big clumps and high pourosity. Clearly I need more practice. I can do that with a torch in my sleep but this is clearly different. I was doing a basic lap weld. This got me to thinking. Although I was only working on scrap, if this had been a real project how could I fix it? Would it be possible to remelt a bad weld with a torch and fix it or would that be problematic. If it is a problem, why? Finally what is the key to vertical mig. Clearly a push up technique didn't work. I had a very fluid puddle that sagged fast. Thanks in advance.Victor Journeyman OA TorchVictor Edge RegulatorsLincoln 180HD (240v) MIG/FCAWShark LT v7 CADMiller Digital Elite Helmet35 Milligrams of Insanity
Reply:Originally Posted by RellsThis got me to thinking. Although I was only working on scrap, if this had been a real project how could I fix it? Would it be possible to remelt a bad weld with a torch and fix it or would that be problematic. If it is a problem, why?
Reply:Bad welds = Grind out...... or scarf then grind if you have the equipment. Vertical up can be done, but a lot depends on what you are welding. The technique in the video will work just fine if the material is thick enough to handle the heat. If the material is too thin, you may end up with a big hole. Will
Reply:Very good vid.
Reply:Grind out the junk or goin over top of it will get messy. You want sound weld material blended in with eachother, not welded over top of some porosity and weld defects like cold lap that dont burn out. the best way to learn is from fixing your mistakes and practicing doing it right the first time. A common occurance that causes porosity while mig welding up hill is that when you are welding you may tend to pull the nozzle back from the steel and lose the shielding gas. The saggy weld was caused from lack of manipulation, you might have to turn the settings down to help gain control. As it was said already, make a shelf, then step it up from there, the next pass can weave from plate to plate riding up onyour shelf each time, kinda like stacking horozontal welds on top of eachother.  Remember that wire will go where ever you point it.Nothing Ever Got Done By Quitting, Never Give Up.
Reply:And try not to over weld the previous bead too much or that will also sag.
Reply:If it can be done the easiest MIG operation is down hil, pushing back up  /into the corners of the puddle
Reply:I my garage: A bad weld.Everyone says grind it out. Where I have good luck is...  4 1/2" cutoff wheel and cut it out. much faster. Then what's left, I fuse it back into the base. I'm just doing my own stuff. Must agree, it's still not as good as doing it right the first time.my 2 centsLast edited by Vern2; 02-27-2010 at 09:08 AM.
Reply:Even if you scarf out some bad weld it still needs to be polished up with a grinder before you weld another pass.  It just makes it easier on the welder. You may not have time to do it right, but you'll have to have time to do it twice2011 Dodge 3500 diesel duallyLincoln SA-200Lincoln SAE-300LN-25'sLincoln Idealarc R3RMiller Trailblazer 302