I have a vibrating tumbler that I use for cleaning up old rusty bolts. There is a media of ceramic triangles that gets the rust off and leaves the finish somewhat dull, then a media of crushed corncobs is used to polish them up. Then you send them to the plater and they come back looking like new (provided that the pitting was not deep). The vibrating tumbler would not clean grease or sawdust off very well and I always clean and degrease the parts before I put them in the tumbler. The tumbler works very well on cleaning up rusty hardware like dogs, sprockets, bolts, mufflers, etc prior to painting or plating.