I just ordered my mig welder last week and looking forward to start cutting and welding. 1st order of business is weld in patch panels in a few extra fender i have. I have 2 drivers sides that just has rust coming through. brace is okay. I did a couple of 72 fenders like this. I just cut a piece of sheetmetal larger than the hole I needed and scribed cut it with a cut off wheel for a nice fit, did a butt weld came out nice. I did bend it to match the contour of the fender.
Now the pass fender is rotted real bad. I have a spare 72 fender thats going to donate the lower portion of the back part of the fender including the brace. Question I have is how do you accurately measure where to cut the bad fender to match the donated lower portion? Im hoping to butt weld this part together also. any ameture or professional advise is greatly appreciated! thanks Jim

The best way I have found is to cut the patch panel to the correct size to replace the rusted section. Then roughly measure where you are going to want the weld. Then I cut about a 1/2 inch underneath the line where you will weld them together. You will also have to cut away the panel where it begins to bend around for the wheel well and the inside of the door jamb, so the all that is left is the flat outer edge of the fender. Then take a panel crimper(dirt cheap air tool, very useful too) and crimp the section that is left. This will countersink the bottom half inch of metal. Now take and put the fender on the car and take the time to line it up where you want it. Then take the patch panel and hold it up to where it will be at the correct installed height(ie the lower bolt holes line up) and you can eithe find a way to clamp it into place or use tape to hold it in place while you tack it in place. You can then either weld it right on the car or remove it and then weld it on a bench. You may wind up with some section of the repair where the countersunk area is still visible just fill the entire thing with kitty hair and mud over the top of it.