12mm hex hub adaptor for DFRobot motor with metal shaft

thingiverse

I upgraded my robot motors from the ones with the 20 tick optical encoder to these with the high res quadrature encoders fitted on the motor shaft (http://www.robotshop.com/en/micro-6v-160rpm-1201-dc-geared-motor-encoder.html). Unfortunately, the metal shaft has a slightly smaller diameter than the plastic shaft in the originals so the wheels didn't fit. So I made these adapters which fit a standard 12mm hex hub.