Originally Posted by sailah
I think I understand what you are talking about with bending the two pieces outwards and then burning the seam, makes sense. I'm making this tank from aluminum seems like that would put more heat in the metal due to the amps required to melt back the seam. Do you have any pics of what you are talking about because I'm a little fuzzy on it right now and I want to make sure we are talking the same thing.
In my case, the sheet metal frame was steel (bend out), and the gas tank (inward) was aluminum.
I think the frame was gas welded, and I know the gas tank was gas welded in about 1959, so I had not built my first TIG.
In both cases, the bend makes the metal stiff at the edge. That is what keeps the distortion small.
Sorry, no pictures.