Thumbscrews, in conjunction with the L-bracket and wall lug, hold the resonator on the banjo. These screws were made of brass and then plated. There were two lengths of thumbscrews used on prewar Gibson banjos. Short-bodied thumbscrews were used on two-piece flange banjos. Around 1929, Gibson began using longer-bodied thumbscrews on single-piece flange banjos, due to the extra thickness of the flange. However, many early single-piece flange banjos came with short-bodied screws as Gibson was most likely using up old stock. Thumbscrews all feature a knurled head that varied in thickness throughout the years. Around 1940, the knurl became noticeably coarser.

Short thumbscrew, two screws with various head thickness, ‘coarse’ knurled thumbscrew

Thumbscrew in action

Hex Head Screws

Early ball-bearing banjos used hex head screws. These are not technically thumbscrews because a wrench was needed to tighten them, however, they served the same purpose.

Ball-bearing Hex Head Screws