I needed to grind up some cat little to test if it would be suitable as a source of bentonite clay, I needed a ball mill but I didn't want to spend a lot of time making a decent ball mill if the cat litter wouldn't suit my needs.
Step 1: What you will need
a plastic tub ideally with a screw top
a cordless drill
1 nut or wing nut
and some lead balls, you can make these using the following instructable
Step 2: Prepare the tub
put a washer on the bolt and push it through the lid so the shaft of the bolt is on the outside.
then put a washer on the bolt and put the nut on the bolt and tighten it up.
that's it, for the tub, just pour in the medium you wish to grind and put in the lead balls, screw the top on and move to the next step of this instructable.
Step 3: Prepare the drill
clamp the drill to a solid desk
put the bolt on the tub in to the chuck of the drill and lock it in place.
Step 4: Start the milling
using another clamp, a pump clamp would be ideal, tighten it around the grip of the drill depressing the button, do this slowly you don't want the drill to get out of control.
its best with this method of milling to go slowly, other ball mills run faster than this one, but this is not intended to be used a lot, it's a light mill.
have a look at it working.
after about an hour and a half it has turned the cat litter in to a fair powder, if it left it much longer it could be much finer.