u/TowerWalker

I have been working on an extensive document for Yankee Screwdriver maintenance. This includes the ones by North Brothers, Stanley, and Millers-Falls.

While working on one of my Millers-Falls Spiral Screwdrivers, I disassembled the chuck and have been having trouble getting it back to working order (if it was even working in the first place since)

So I have sought out the patent.

The patent for the screwdriver itself (US Patent: 1,578,866, March 30, 1926) is readily available. But the chuck listed at point 18 is merely listed as "a suitable chuck" (likely due to constantly improving technology). I have looked through every Millers-Falls non-drill chuck patent and not found anything.

The way it works looks to be similar to the Furbish chuck. It consists of

-the chuck body with a gap

-a compression spring

-a bearing

-a semi-circle shaped flat piece of metal (clip)

-a bushing

-a cover

-threaded head

The assembly itself appears very simple. But for the life of me cannot figure out the spring and clip are intended to engage. Sometimes I can get the bit to lock but not unlock, sometimes I can it to unlock but it stays unlocked.

Furbish/North Bros. Patnes

US632560A
US1138465A
US1653762A (unproduced)
US676742A

Trying to identify the maker of this Spiral Screwdriver.

The bit holder looks like a North Bros yankee. But the handle is unfamiliar.

The body itself has a strange welding on it, which could be custom or not. The shaft cover was likely removed at some point which removed the identifiers.