I thought it would be an easy fix... all I wanted to do is shred cardboard so I can feed it to my hungry briquette press! well the shreddeers were more broken than I expected but I fixed one an probably improved it. I think a lower gear ratio would be better, I used the smallest sprocket I could find with taper lock so that I didnt have to weld it to the shaft so it is possible to make a much lower ratio by welding a smaller sprocket.
You could even just run this with a drill and a hex socket but I wanted something more permanent.
In any case I didnt go further since the cardboard doesnt shred small enough to go into the briquette press so I need to revisit this another time, possible with a full custom hydraulically driven unit.