This works very well, providing a few things are considered....the shaft, when wet, will cause the tire to lose its grip, and stop spinning, so the slurry/water amount is critical, keep it on the dry side. One shaft can run more than one tire. Use shaftstops and washers to keep separate, and also plastic separators can be made to ride between tires as splash guards and to reduce contamination of grits. The speed of the shaft should not exceed 100 rpm, and you have to get that right by adjusting motor speed and/or pulley size. One of my better innovations is attaching motors to cinder blocks so they can be hefty enough to pull and they can also be clamped easily, but can be moved around as well. This tumbler was a lot easier because of that kind of set up.