Found this at a flea mkt today, paid $2 for it. Well machined, smooth operation, obviously used.
The ‘arm’ slides along the right wall of the main ‘tray,’ then is clamped into place.
I don’t know what operation would need a three sided clamp that’s 1/2” deep.
Maybe it’s a part someone needs for a machine, or maybe it’s forever an “I dunno.” Can you help with a guess?
-- Don't anthropomorphize your handplanes. They hate it when you do that. -- OldTools Archive