Tuesday, April 10, 2018

BSA Hornet tank...

A while back ago, a customer asked me to build him a gas tank for his 60'S BSA Hornet.  I actually did one several years ago and wished I would have documented it a little better.  So, here's my chance.

First things first, the material needs to be cut roughly the correct size.  There is quit a bit of shrinking to be done and any extra material will only hinder the process.  I used some thin paper to make a rough template.  Everywhere there is a fold, the metal will be required to be shrunk.

Transferring it to some aluminum sheet, I marked the area that I did not want to manipulate.  This area will be the relatively flat sides of the tank.

I use a set of thumbnail shrinking dies in my Pullmax.  There are some disadvantages of using a Pullmax to shrink with compared to using a power hammer.  Mainly, the Pullmax doesn't compensate for the change in material thickness.  A power hammer has a spring loaded anvil and tends to be much less abrupt.  As I have not gotten very far on my power hammer build, so this is really my only option.

Here it is after about 20 minutes on the Pullmax.  About every 5 minutes, I stopped and checked my progress on the buck just to make sure I was obtaining the correct shape.

After a slight adjustment on the die spacing, I have the basic shaped roughed out.  You can see my markings where the front needs to be brought out or raised "up".  It appears that I actually shrunk it a bit too much, however, the English wheel will have no problem stretching it back out. 

I am always amazed at how well the English Wheel smooths out the lumpy mess left from the shrinking dies.  This is only after a couple minutes of wheeling.

There is still a way to go, but at least the hard part is done.

Here is the other tank that I built: