bodymetal

Body Aluminum

One of the first pieces of aluminum to be put on the car was the scuttle. I don't have much equipment for working sheetmetal, so I had to be creative when forming the bends.

Before cutting the aluminum for the scuttle, I created a paper pattern which included "bend lines." The cut lines and bend lines were then transferred to the aluminum.

I thought bending to the correct radius would be difficult, but fortunately, the phone company provided a handy tool. By inserting the sheet metal between the telephone pole and a PVC down-tube, the PVC pipe became a perfect mandrel around which I could bend the sheet metal.

This is what the scuttle (cowl) will look like once it is finally in place. In this view, it is only clamped in place with a c-clamp on each side. The sheet metal is aluminum with the white protective film still in place. It is bent to conform to the shape of the cowl frame, but won’t be fastened until the frame is disassembled for painting.

When it came time to put the skin on for real (and get rid of the c-clamps) I decided to use a technique used in aircraft construction. Notice the pop rivets are flat top, countersunk. The method used was to clamp everything in place and drill the aluminum and steel tube at the same time. Then unclamp and countersink the steel tubing. Then put the clamps back on, and dimple the aluminum into the countersunk holes in the tubing. The last step was to insert the pop rivets.

It was a little tricky getting the bends around the ends (for riveting) so the aluminum skin fit tightly against the scuttle frame. It took about a bazillion clamps, but the extra time and effort paid off. This is the result. Obviously, the dash has been temporarily installed for this photo.

Here is another view. I included it because of the interesting reflection of the picket fence in the background.

I wish I had taken a photo of the scuttle frame. You'll notice the dull aluminum curving around the front (right). It is an Aluminum angle that was bent to form the hood (bonnet) rest, just below and inside the scuttle skin.

You'll notice the screws around the perimeter of the dash panel. They screw into holes drilled and tapped into the scuttle frame, which was made of steel angle, bent to the desired shape.

I thought it would be cool to have a nice shiny aluminum dash until the sun reflected into my eyes. I had to take the dash panel out and cover it with black vinyl. Thanks to Jim Boone, that looks cool too. He had some upholstery left over from his Lotus Elan restoration. The Elan looks cool too.

Now that the frame has been painted, I'm cutting and bending aluminum sheets. Here is a start at the pedal box. I can't wait to see the master cylinders sticking out from the front panel.

The back of the pedal box, facing away from the camera, will butt up against the firewall of the scuttle.

The white paper is a template of the shape required for the tray in the engine compartment. The template will be transferred to aluminum sheet. Then I'll be cutting up again.

	This is a cool tool for cutting sheet metal. The cutter produces a coil of metal as seen here. It's easy to use, and leaves the edges clean. I figured it was a worthwhile investment since there would be a lot of aluminum cuts.
	The first major piece of aluminum to be fastened to the frame. Seemed worthy of a photo at the time. Attaching this piece showed me where the book left out a lot of little frame details. For example, there needs to be a frame member to fasten the edges of each panel to. Riveting to air just isn't secure. In this case, I had the forethought to bend flanges on this panel where it fits around the driveline tunnel. That gave me something to rivet the tunnel skin to.
	I came up with a quick way to assure the rivets were evenly spaced, and in a reasonably straight line. Drilling holes at each inch mark on a yard stick worked very well. So well that I only used this wooden template once. I immediately made one from a metal three foot rule that you'll see in subsequent photos.
	Here I started putting the floor panels on with the frame up-side-down, on jack stands. Notice the metal drilling template made by drilling holes at each one inch mark of a metal three foot rule. Since the side skin will bend over the bottom and be riveted to the same frame rail, I skipped every other hole. When I fasten the side skin, I will put those rivets in between. The end result will fasten the floor every inch, and the side every two inches.
	I didn't break a single drill bit while drilling 127 holes through the aluminum and the steel tube. All perfectly aligned thanks to 10 Cleco clamps that made sure the aluminum didn't shift during the process. The Cleco pliers are the blue handled babies in the distance. They are inexpensive and work amazingly well.
	After the holes were drilled, the aluminum skin was removed and deburred. Then every hole in the frame was countersunk. In this photo the top three holes have been countersunk, the nearest ones have not. When the skin was ready to be fastened for good, each hole was dimpled into the countersink. That allowed the use of flush rivets. The Cherry Q brand of rivets were used which can be found at aircraft supply stores. They have higher tensile and shear strength than standard pop rivets, and the mandrel remains in the hole. That way they are self sealing (to an extent). The mandrel also contributes to greater shear strength.
	Wearing gloves while drilling makes it easy to brush shavings away -- almost a requirement since the shavings from one hole make it hard to see the center punch for the next. Without gloves it's easy to get nasty metal slivers.
	This is the result from fastening just one side of the floor pan. Lots of drill shavings, and 127 rivet mandrels.
	3 pieces of Aluminum + 281 Rivets = 1 big smile. It really looks like progress. The corners of the piece in the foreground were intentionally cut so there could be drainage if water splashed into the engine compartment. After all, that piece is just behind the nose cone air intake.
	Templates for the sides were made using a roll of butcher paper. I had to have the nose cone in place to make sure and get the correct curve at the front of the body. Spending time at this point really eliminates waste. Getting all the cut-outs and notches in just the right place made fitting the aluminum go much faster. The book calls for the side to be made from two pieces of aluminum. I didn't like the idea of a row of rivets running down the side where the two overlap just in front of the cockpit. My template ran from the front of the frame to the rear wheel.
	The template was taped to a sheet of aluminum. All cut lines were marked with a fine-line marking pen. Long straight cuts were made with an electric shear. That went fast. Notches for frame cross members and suspension components were cut by hand. The aluminum I used was surplus aircraft skin. It was 2024 T3 alloy which may be great for a 737, but a nightmare for a Seven skin. It was very hard to bend the sharp corners needed to wrap around the top and bottom frame members. I got a very good deal, but I really paid for it in hard work.
	After all the hard work, rolling it out into the sunlight for a photo was a real pleasure. There was still a lot to do, but it really was beginning to look like a car.
	A paper template was used to get the shape of the rear panel. It had to wrap around the sides, over the top, and under the bottom.
	I had to hold the skin in place with clamps while I drilled holes for the toneau cover snaps. I had to be careful to avoid leaving clamp marks. No hammering was done at this point, just careful bending. Once I got the holes drilled and tapped. I used the screws to hold everything in place for the finish work..
	Here, I'm just finishing the rear aluminum skin.. The car is on jack stands so I have enough room to get underneath and "roll" the skin around the bottom frame tube. It took a lot of hammering. I worked from the center out, bending just a little with each blow. Then start at the center again, and repeat the process until the ski rolled around the bottom. A similar process was used for the top. I did not use the 2024 alloy here. It would have never made those bends. It work hardens and becomes brittle right a way. Then it cracks. The top is now held in place with the screws that mount the snaps. I've heard of people using clamps to hold the metal in place while they work the bottom. Using the snap screws worked better for me -- no shifting, and no clamping marks. Notice the gloves. They are a must when working with sheet metal. Edges can cut like a razor.

I hope to have photos of the hood posted here soon.