1940 Ford truck rear fenders ( really bad shape)
These fenders are for my own project, if I live long enough to do it. I bought the truck many years ago, and my friends all laughed at me when they saw it. I bought it cheap. Figured I could do the metal work and that's what is going to happen. I am fixing one fender and leaving the other one bad, so as to display it at the swap meet in a couple weeks here in Lethbridge.
So, I made up a hammer form for the fender opening. I had to go and find a good fender to take the pattern from , as mine were so bad that i couldn't get them sized quite right. They had been welded so many times that the wheel opening had shrunk down from its original size a couple inches.
Traced the pattern onto a piece of 1/2 inch thick compressed sawdust board, and cut the opening out on the bandsaw. Took a router with a 1/4 inch radius roundover bit, and did both sides of the board, so I could flip it over and do the other side with the same pattern. The opening is rounded on the inside and outside so even if I was only building one fender, I would still have had to round over both the inside and outside.
After that was done, I had to cut a piece of plywood about a quarter inch larger wheel opening to use for clamping the sheet metal down so it wouldn't "lift" when hammering over the fender lip. I also used a few screws through the sheet metal to the mdf board so it would not move when hammering on it either.
It actually turned out pretty good. I should also mention that before I hammered the lip over, I ran the metal through the english wheel, so as to give it some slight shape, as the circumference of the wheel opening is not flat. The fender has shape, starting right at the wheel opening.
The new wheel opening piece turned out pretty nice, and fit the fender with zero gaps for welding and/or very minimal gaps. Its hard to get an absolute zero gap on a four foot long curved weld. Lots of clamps, then tacking with the mig, then grind the tops off the mig welds. AFter that, a pass with the tig, right over the mig spots a little at a time to control the warpage.
Grinding the weld is always the ugly part. Takes a little time to do it right but the results are worth it. Then the planishing begins. This was actually not too bad, very little warpage to deal with.
I got the fender fairly straight before welding this patch in, will do the same with the back end.
Made up the little dogleg section that goes on the inner bolt flange at the rear of the fender. Was a bit of a pain, but had to be done. Spot welded in, in case it has to be changed later when the rest of the patches are put in place back there.
I backed up a step or two. The piece I made for the bottom back end of the fender didn't have the proper profile to it. It was too narrow, and didn't have the proper curve along the outside edge, so it went in the scrap bin.
Decided to try to make the whole back end piece in one piece so as to eliminate one weld. It turned out okay. Got it all done, except for a final planishing of the whole fender.
Stretched out the middle on the stump, as well as the shot bag ( no pic of that), and shrunk the tucks on the stump on the top and bottom so as to facilitate the curvature from top to bottom to create the shape needed. It took a couple rounds of going from the stump to the e wheel, then stump again. It didn't all happen in the first pass. Good news is that each time, the e wheel polishes the metal up and smooths it out again.
Takes a few hours to get it all the way you want it. It is also easier when you have a good "buck" or good fender to take the profile from. All I have is the old buggered up fender, so there is a bit of guessing involved. As the masters will tell you, this first fender will be "art". Doing the other one to the exact same shape, when the time comes to do it, is actually metal shaping. That's the hard part. Making something the exact opposite of the first piece. Actually not really that hard, just tedious and takes time and patience.
That big mallet is a little hard to swing. It was designed by a man much bigger than I am, so I have to choke up on the handle quite a bit. But it does move the metal.
FWIW, the 18 gauge I am using here, was measured at .047 thick, and the piece I threw away was 19 gauge, which measured .038, which is a little on the thin side for 19 gauge. The 19 I have in stock is closer to what its supposed to be, about .0418 and it doesn't seem like much, but makes a hell of a difference when you are pounding out a shape on it. The thin 19 I used was part of the 57 Ford roof skin. My crossover sheet for sheet metal thickness says 19 gauge starts at .0378 and goes as thick as .0458. 18 gauge on the other hand, starts at .0438 and goes as thick as .0518.
It welded up nicely, but I still have a lot of planishing to do, and have to work on the bottom rolled edge of the new piece to get it to the properly shape.