Possibly as old as the 1930s.
As used on literally hundreds of Martin guitars of that era.
Grover, gold-plated, removable worm shafts that are threaded at both ends; 7/32” dia. posts.
Three perfectly and smoothly working tuners plus threaded bushing and washer from another.
Components of 1950s-60s American-made Grover Imperial tuning machines.
All original nickel plating.
An almost-complete set, with the cap on one of the treble-side tuners missing.
Full-size six-on-a-side set, clipped.
Complete with all mounting hardware.
American made, 6-on-a-side.
© 2019 Umanov Guitars