Auto body repair & detailing: Welding in floor panels, seam weld, heart ache

Question
I want to weld in some new metal in the floor and later the bottom of the doors of my 87 F250. I have never done this before, but I have gone out and bought a mig welder along with a tank of Argoshield gas and so I want to learn. My question is do I butt weld or do I flange the metal and do an overlap type of weld? Thank you

Answer
Hello anthony, and well done on the mig welder and gas set up! Flux core will work, but man, it sucks. Now, I prefer flange welding. It's stronger, and the welds are less prone to blow thru the sheet metal. Don't seam weld, only do half inch stitch welds. Bounce around, don't follow one after another across the panel. It will help minimize warping. You can use play dough as a heat sink. Sounds crazy, but it really helps minimize warpage. Simply place wads of it about an inch on either side of the weld seam. For additional instruction, Year One has an excellent body repair book "How to repair and restore bodywork" Part No. MB9030. I really don't suggest going into this project blind, you will hate the results. A little professional instruction can save a lot of head, and heart, ache. Bill