I want to build a Ball Mill. I want to be able to process an average of 1#. I will be using 1" lead balls for the mill. I am interested in a 12V system. Perhaps an old drill gun as a drive system. I have a transformer and an extremely safe "pit" for manufacturing. What size tumbler? Length? Diameter? Are 1" lead tumbler balls better than smaller? How long would you tumble for? How would you design the roller mechanism? Would you isolate the drive from the roller system? [thinking that there may be sparking from the brushes in the drill gun] Seen any designs somewhere? "A single effort is worth a thousand dreams!" PS, Pics coming of what a 3# lead ball does to 1/2 plate steel at 350 yrds.