coupling

[Lloyd Burns]

The Jacobs pattern chuck is the Basic Drill chuck with a Key that turns an outside gear to cause the jaws to extend through an opening which is smaller than the jaws, causing them to get closer as they come forward, gripping the drill.

If you found it in Small Parts, go for it. It wasn't in the kit, and it's not in the additional Hardware List.

Beware the dreaded slippage to which grippers of round things are subject, both in rotation (round and round) and along the axis (in and out).

The trantorque coupling is a workable idea of a similar nature that was part of the kit in years past, and may still be available from SPI.