[Ty Tremblay]

I'm a big fan of a 10-32 tapped hole in the end of the shaft, a 10-32 screw with loc-tite (or a lock nut) in it, and surgical tubing stretched over the screw on one end and the encoder on the other. If the encoder is mounted properly and not damaged, it should spin very freely and the surgical tubing grip is more than enough to ensure 1:1 rotation on the arm. The tubing also allows for some axial misalignment which is common on FRC robots.