Constructing a ballmill
From PyroGuide
Tutorial coming soon from Pianomistro!!!
When your going to make a ballmill one of the most important parts is a motor. You can find these in washing machines and vacuum cleaners, although it would be best to obtain one from an old washing machine. These are often quite old, but because of this are made from solid materials, and shouldn't burn out for years. Vacuum cleaner motors may lack the needed torque/power, as they spin fans instead of drums weighing several kilos.
Remember, you need a reliable motor that wont burn out, and since washing machines stay on for a long time they should be most reliable motors that you can find cheaply(or free, just rip apart an old washer or drier). You should be able to find a washing machine or vacuum cleaner that someone doesn't want.Here is a video that shows how to covert a washing machine motor so it works on mains electricity. Washing machine/drier motors aren't the only source though; any motor that doesn't spin too fast(around 1400rpm), has a few kilos of load on it and operates for a long time will also be usable.
http://uk.youtube.com/watch?v=xspjAg66vUk&feature=related
When constructing the ball mill, it is best to find light axles and easily rotatable bearings. Unless you are going to be powering both axles, if one axle is harder to rotate than the other, it will increase wear on the rollers and drum and ultimately slow the rotation speed. If you want to rotate the 2nd axle,attach a second pulley to the first axle and a pulley to the second. Make sure the two pullers are of same diameter or one axle will spin faster than the other.
Unless you can find a roller easily spun(this would mean spinning it once by hand and having it rotate several times before stopping) it is best to find suitable wheels. Rollers off old baggage converyor belts would work well as they spin easily. However, if rollers are un obtainable, skateboard wheels or other small wheel will work. Again, they have to be easily spun and of the same size directly parallel to the first axle. If not, the container will slowly roll off. However, if you find you drum progressing up or down the axles, attaching a wheel for it to push against will minimise any friction and keep the drum stationery. A great source for these small wheels are old suitcases. They spin easily, are usually made out of rubber, and dont have any bearings on them.
Here's a good explanation about ball mills. http://www.youtube.com/watch?v=9pFsjQgBFYk