A ball mill grinds materials into a fine powder for use in ceramics, some pyrotechnics, paints and the mineral dressing process. Cylindrical in shape, a ball mill rotates around a horizontal axis.
The container used to grind the material must withstand the tumbling of the grinding media. High-density plastic -- lightweight yet strong -- makes a suitable container. A one-gallon container works for most personal applications.
The ball mill attaches to an axle and sits on a frame. The container cannot touch any part of the frame, and turns on the axle for milling action. The frame may consist of any material -- such as wood, plastic or metal -- that can support the weight of the container plus its contents.
A small motor, such as a three-quarter horsepower with a half-inch diameter axle, powers the container's rotation. A belt serving as the interface between the motor and the axle works on the same principle as a car's fan belt.
The Grinding Media
The grinding media chosen must weigh more than the material being crushed. Steel balls of varying sizes -- depending on the final product -- do the trick. Other grinding media used include ceramic balls and rocks, small nails and drill bits or marbles.