Potentiometer mounted on motor shaft

[jblack155 0]

Hello, Where can you buy a potentiometer that can be mounted directly on the shaft of the motor? Usually these motors have a 1/4" dia shaft protrusion at the back end, where the optical encoder is mounted. Can you take the encoder off and put a potentiometer in its place? The reason I ask this is that I have figured out how to do forcefeedback and auto centering using the signals from an optical encoder, but I don't know how to simultaneously send a duplicate copy encoder signal to the desktop PC and have it show up as a joystick.