This is a method that we came up with to fit a VEX VersaPlanetary Integrated Encoder on a ½” hex shaft. We cut the small gear off on the lathe and then drilled a ½” through hole. We then used a ½” hex broach to cut the hex into the remaining steel gear. If this is something that would work for you and you need to ask any questions, please feel free to contact me. My email is [email protected]. I would also be glad to make the modification to your encoder at no charge if you send me the part.