Anyone can do this. I am just dwelling on thin metal techniques I do. Thick metal is easy. I have a Miller stick and Miller Mig. I don't take pictures of my screw ups.
So to add some more: Don't use air or electric discs to deburr the edges. You can take off .010 on each side in the blink of an eye. Then the edge is down to .030 or less. Right where you are going to weld. Inviting a blow out. Use a hand file with light pressure or a hand edge deburr tool or leave it alone altogether. Hammering on edges will do the same thinning. If you are hammering on dolly, just light taps, just short of smashing .010 material but straightening whatever you are doing.
Thin metal, with no rear access, can not be planished either. So you try to cool each dot with air or wait a long time. Water cooling has it's alleged draw backs. Bottom line is: You will have some warpage. You can't stop it all. It will be way less on small areas, with bends and curves near by, than it is on big flat surfaces.
These guys you see on videos that "bounce around" when welding dots, one area and then another. It's BS. They are better than me but I do ONE at a time. You heat a LARGE area with a weld. If you keep going, albeit "far away", you are still adding heat to the panel before the other heat cools. We only have one truck and one panel to fix. We are not in a hurry and can not afford to warp it. If you warp, you are done, you are sad, you are in deep trouble with the whole project. You have a disaster. You don't want that. Don't pay any attention to someone showing to "move around as you go". Especially on small patches. It's BS!!!! Maybe it will be OK. Who knows? The risk is disaster that can't be fixed by us mortals.
