Carl,
You can certainly use aluminum, if the tank is well designed, but Vincent did not use aluminum. If you look at the underside of a Vincent tank it is extremely complicated when compared to other tanks. When Vincent had the large tank made for Gunga Din they supplied a badly damaged tank from which the tank builder could cut the bottom. The new tank would be built from the stock bottom.
I will have to check the thickness.
The metal is here:
Aluminum killed drawing quality steel from Alro Steel is a high strength, low alloy steel that has excellent formability, surface texture, and flatness. It is also noted for its uniformity and consistent performance. It is used for appliances, exterior automotive components, shelving, and more...
www.alro.com
I could not spend the time making a fancy buck, so I made a foam buck out of urethane foam, which I glued together with a very thin layer of polyester resin. Polyester does not melt urethane. I used an electric carving knife to shape the buck. When the buck was done I coated it with polyester. I would shape the metal piece to fit the buck.
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I lined the sections on the buck and cut steel parts to fit. It meant a lot of pieces and more welding, but the parts were quick to make and did not involve deep drafts.
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All the parts.
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The bottom is one piece.
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The bottom welded in.
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Tank mounted for Daytona practice. I gave myself a week to build it and I had 80 hours invested from start to finish.
David