Greg Wade Belt Bowden Extruder for Delt Bad Boy. Delta Bad Boy: Bearing Belt Wheels for better precision and free run. It can run on 1.75 and 3mm filament A geared Timing belt Extruder, 80 tooth on the extruder and 16-20 on the motor. 20-80 4:1 16-80 5:1 Upgrade with 4mm Lock nut, Belt Wheel Bearing and smoother and stronger print. I used this : If you use the Delta Bad Boy Mount you have to clean it....