Pelican Parts Forums - need opinion and help on rust

You have to turn up the power with your welder you have zero HAZ and too high of a bead. Problem with MIG welding is guys insist on grinding or using 36 grit on the metal surrounding the patch. This of course makes the metal thinner then it actually is. Try blasting or at least do not use a grinding wheel.

The gap between your patch and the surrounding metal should be approx the thickness of metal being welded. Take a piece of metal and pull the trigger while adjusting the wire and power. When you hear a nice sizzle stop and check the back of the metal for penetration. If done correctly you will be right on the edge of blowing out and your bead with be 80% in the gap rather then sitting on top. Adjust the welder while it is running a bead not hit and miss style.

The welds shown are all on the top. What happens then is you grind away 75% of the actual weld and add the now grinder thin metal and it is a very weak repair. Hit a couple times with a hammer you will small cracks appear.

Adjust your welder as I said an you will see a huge difference. Only grind on the weld once you get to sheetmetal use a flap sanding disc.