Gearbox for turbo oven style coffee roaster

This is the gearbox I put together using a slightly modified herringbone gear system from a wades extruder, for use as the agitator in a turbo oven coffee roaster.

All you need is
-a pair of 608zz bearings
-an M8 bolt (I used a 90mm bolt in my design), with a pair of nuts to lock the drive gear
-M8 washer between the 608zz bearing and the large gear
-NEMA 17 stepper motor.

I used an arduino nano to run a A4988 stepper driver that drove the stepper motor.

hope this is helpful for so