I have decided to undertake a project too long overdue. I bought my YJ from the bank a number of years ago. The jeep came out of Michigan and has rusty floor pans as well as the driver side rocker panel. I have taken the seats out and the carpet. Like I said I need to replace the rocker panel, front floor pan, under drivers seat and rear drivers side floor pan. My jeep is going to be parked for awhile in my garage. HERE comes my question. I have never welded before. I pick things up quickly so since most of the welds will never show how much trouble do you think I will get in if I do it myself with a MIG welder? Any tips or suggestions?
Think about what else you may want to weld later, I got an old Hobart 135 Handler and a 225 Lincon and can do any thing I need to do, I would think no less than about 125 on the wire feed and you can do a lot of other stuff after you learn to weld.
A basic welding class is a great investment for beginners. There is a lot to know. The important thing about sheetmetal is that if you try to weld a solid bead the metal will warp from the heat. You should weld it in short bursts (tack) and bounce around the edges to keep from getting any area too hot. Continue tack welding until it is a solid weld all the way around, then grind it smooth and apply seam-sealer (if it's someplace out of sight like a floor pan) to seal any pin holes. If the finish is more critical, like a patch in a body panel, skip the seam-sealer but the first application of filler should be fiberglass before finishing with Bondo or equivalent because the 'glass won't absorb water if there is a pin hole in the weld.
Sandy has the right idea, but keep in mind that if you use the right wire, sheilding application and technique, you shouldnt have any pinholes at all. Just remember that when you weld (spot weld or tack in this case) cleanliness is key! your base metal needs to be completely free of any paint and oil. Make sure after its nice and clean, when you make your tacks, make sure that your tacks overlap, so that you get good penetration and a nice solid bead all the way around. work your tacks 180 degrees of each other, and let cool a bit after every 4 to 6 tacks. try it on some scrap 18 guage sheet metal, you should pick it up quickly. Nubby has the right idea on welders also. you dont have to have anything fancy for body work, and I like to use a solid core/gas mix, so the weld is clean and leaves no slag.
Good points from Prime. I can't stress enough how beneficial a basic welding class would be Dave. At our local community college, the night class is less than $400 with materials and new PPE. Less than $300 if you have the equipment or can borrow it. Some of them focus on 1/8" and thicker steel, but it will still give you a lot of good info that you can apply to sheet as well. It will also give you more info on welders to help you make a purchasing choice. And yes, the idea is to avoid any pinholes, but especially for a beginner, it is possible to have some that you don't see, so I recommend waterproofing precautions to extend the life of your repair.
Good luck and let us know what you do and how it goes. And remember we all love pics.