Started with a 3.5″ disk. Started the bend with a bending tool (think metal bar with a slot), then cold forged it over a wood form to 2 7/8″ inside diameter.
In theory the edges are thicker than the base metal, but I don’t have a way to accurately measure it.
- a 3″ hole saw doesn’t give you a 3″ wood form. 3″ is the diameter of the hole, not the slug.
- don’t go crazy with the pre-bending or you’ll introduce a lot of wrinkles that take forever to fix
- hit it like you are planishing, not forging. Lots of rapid taps move the metal, heavy blows just bend it