unidenified brace

[Paul Catterson]

Greetings all. I have uncovered a early style brace with no maker's marks (they've rusted over or worn away). The thumbscrew-secured chuck doesn't quite match anything I've seen (also someone has replaced the screw) Any ideas?

(AMENDMENT Sept 2 2013:
I neglected to note that there is a 7/8" long horizontal alignment post sticking out from the stationary side of the chuck. Shown at top right of photo 3, it's hard to see given the head-on angle of the picture)

[Paul Catterson]

I'm guessing that I've stumped the forum with this brace. One thing I did find out is that some braces of this era (1880s -1890s) had the maker's mark on the thumbscrew itself. Given that the thumbscrew is not original, determining the brace's identity is a hit-or-miss proposition.

[Rick McQuay]

Have you removed the knob and checked there? A very long shot but easy to do.