Encoder Question / Recomendation

[RacerX]

Quick question on encoders and sensor from a mentor new to the encoder and sensor world.

We have an actuator arm that moves plus or minus 90 degrees. Our current set up from last season's game has a small encoder, I am guessing a US Digital MA3, mounted in the end of the hex shaft that rotates the actuator arm. The end of the hex shaft was drilled to accept the shaft from the encoder. During most of the year we seemed to battle the actuator arm not holding values, likely due to the encoder not being secured in its bracket, or slipping in relation to the hex shaft. As a last resort, everything was epoxied in place to try and maintain position. Unfortunately, things are still moving, so now is a good time to try something different.

If you had a hex shaft that was rotating an arm approximately 90 degrees, what would you recommend for an encoder or sensor, and how would you recommend attaching the encoder or sensor to the end of the hex shaft?

Any suggestions or recommendations are appreciated. Again, just trying to get up to speed as kids have graduated, and some mentors have moved along.

Thank you for your help,