How important is it to make round bends in tanks if you're scratch-building them?  Certainly the "bought" ones I see all seem to have rounded bends -- is this necessary to prevent fatigue cracks, or just something to make them look good?

I use a bending brake. It's as sharp as it is. No problems.

A bending brake is OK for heavier metals.  K&S tinplate bends easily over a hardwood form, by hand.  My tanks start out as a pine form and it's normal to slightly round the edges of the form.  The end caps are also made on the same form, by lightly tapping the metal piece around the end of the form with a small hammer.  By going slowly you can avoid kinks: the metal actually stretches and the overlap ends up smooth.

Floyd

HI Tim,

I have a set of sheet metal vise grips.  The "jaws" are about 4 1/2" wide.  I use these for doing most of my tin bending.

Nothing wrong with using "cans" for the sheet metal, they are just usually a touch heavier.  I like the lacquer thinner cans when I am out of the K&S.  There seems to always be one or two laying around!

Big Bear