vintagemotif,
Thanks for the video. I watched most of it last night. She answered my questions about the belt in the first minute or so of the video. At over 9 minutes it took well over an hour to download maybe 3/4th of it. I watched about that much then clicked off.
I don't think I'd go for a metal belt unless I could get one for cheep. I can see it would come in handy for a "one size fits all" treadle base. One base with a belt that would stretch and contract for use on a variety of machines.
Leather doesn't work too good for that.
But I'd still be concerned about excessive wear on the drive wheel and hand wheel.
Joe