I’ve been preparing for and making the passenger side door skin. Like everything else in making these doors, there’s a lot more work to it than I ever thought before starting.
First step was to mark and cut the inner door frame for an even gap. I used a vernier caliper with sharp points to mark cut line.
After snipping close to desired gap, a short piece of 3/16” round rod was then used to check gap. Check, file, check, file, etc.
Once the gapping was done on the frame, I then made a cardboard template for door skin. There’s a sharp turned flange at the window opening that needed to be precise to prevent wind and water entry inside the door.
Using the template, Al 5052 .063 sheet was cut for door skin. I left about ¾” extra around the edge for later fine tuning once I have worked out the tipping and hemming procedure on some test pieces.
Next step was adding the shape. This door skin curves in one way but I also gave it a very low crown for strength. The shaping/curve was done on ewheel with go-cart slick and low crown added with flat anvils. This is my first door skin so I took my time. It took the better part of a day to get the shape right. The 5052-alloy work hardens fast so the initial shaping went fast and once hardening set it, it went much slower.
Next was putting in the flange for the window opening. First the sheet was annealed at the bend line. I used a Magna-bend break for the first 120 degrees of bend. The next 15 degrees was done by hand. I should have annealed again after initial bend but didn’t. It went slow, lesson learned. I used the long bar from Magnabend held with bench vice and bricks on workbench as a fixture, holding the door skin with C clamped long metal pieces to continue the bend. After a few hours of hammer, then check measure, hammer, check, the flange was finished
After experiencing how much force it takes to bend this alloy (even when annealed), I concluded that a solid dolly backup would be needed for hemming when attaching the skin. There was a section on upper rear of inner frame where the flange angled upwards and would not adequately support the skin and dolly during clamping. I decided to weld on supporting metal in that area to build up inner frame edge.
The skin was placed on door frame for marking the edge cut line. I decided to go for ¼” of wrap on the straight edge parts and 1/8” wrap on curves. The inner frame is 1/16” (.063) so I marked the skin for trimming to 5/16” on straights and 3/16” on curves.
I had done 4 test pieces using various tools/techniques to get some experience with tipping and closing the hem with the 5052-alloy. These steps seemed to work best. I used bead roller with soft plastic lower and tipping wheel upper to initiate the flange. This left a small crease on the backside and started the bend. With the flange line now marked with crease, I then anneal door skin edge in preparation for further tipping.
I used an adjustable wrench (sometime referred to as Crescent wrench) for next stage to turn flange. In areas where required, I would tip, then use mechanical shrinker, tip, then shrink. This is the area where the inner frame was reinforced, thus thicker, so there was more metal to tip. I had to anneal this area twice more during tipping and shrinking to get it to 90 degrees.
I then placed shrinks on various parts of the edge till the skin sat flat on the inner frame. Going slow, I had the skin on and off the frame at least 20 times to complete this step.
More to come as I progress.