Well over 25 years ago, my first job was at a rubber molding company that used modified wheelabrator machines to remove flash from o-rings. These were HUGE belt machines vs the turntable style machines. The blast chamber was somewhat sealed and we'd pump in liquid nitrogen to freeze the flash and then knock it off with very small shot. Larger o-rings went directly on the belt, smaller o-rings went into cylindrical "baskets" with a wire mesh or perforated steel. We'd shut those machines down twice a year for a complete rebuilt. Those machines tore themselves up! They are pretty cool to operate and even cooler to see the insides of them during a tear down. You would get filthy when operating or repairing them. You'd end up looking like you just walked out of a coal mine.
