After looking at different ways to remove the dent in the right rear fender of my 40 Ford pickup, I decided that today was the day to do the deed. I had pondered using a rosebud torch and a body hammer to back out the dent that Henry put in it to mount the spare tire, but that would stretch and distort the metal. Cutting out the dent outline and reversing the panel was a good option.
My chosen route was to reverse the dent the same way it was put in there at the factory. I didn't have that big of a stamping machine like Henry's plant had, but I could still work it out slowly a blow at a time. After purchasing a C-frame to mount pneumatic muffler chisel in, I added some air valves to control the air to it. Cutting off the bits and welding on new blunt mushroom shaped ends, provided me with a shaping tool to work the metal of the fender. A contoured disc on the bottom side allowed me to have some backing for the inner fender to rest on while I worked the metal. The whole setup cost less than $150, I call it my Poor Man's Planishing Hammer.
At first I clamped it down to the work bench to try it out and see how it worked. I ended up vibrating almost everything off the bench on to the floor. The noise of the hammer beating the metal reminded me of being in a tin garage during a hailstorm in my youth. I built a solid four leg stand adjusted to my 6'4" height, added rubber feet to the legs and a couple of sandbags to absorb the shock on the framework that helped to deaden the noise. Adjusting the BPM (beats per minute)again brought down the noise factor and aided in more productive work by allowing me to pre-plan my next move on my project. After practicing for a few nights, I was able to get the feel for the metal that I was working. I could shape a flat piece of metal in to a crescent shape, as well as remove ball-peen hammer dents that I applied to a sheet of metal. My confidence level was growing steadily.
On the Day of Decision, I hauled out my old Ford fender to the planishing hammer and mounted the fender over the lower backing plate. My course of action was to start hammering around the perimeter of the inward dent with an overlapping motion on the previous hammer mark, working towards the center in a sea snail's body path. After one pass around the perimeter, I had to back off the pressure of the backing plate a couple of turns because the surface was showing signs of 'peening' marks. Peening marks are sharp high spots and look like a dent that was made with a ball peen hammer or hail. They really stretch the metal in a small area. As I worked the metal of the fender in my chosen path, it was gradually conforming to a new convex shape which blended into the overall fender's shape. It took me about 40 minutes to get the spare tire dent to an eye pleasing surface that resembled the left fender except for a few high spots that I had to pick-hammer down. A light coat of body filler would fill in any blemishes that were showing.