Part tumbling is a method of deburring and cleaning relatively small objects. This is done by capturing the parts and media inside a rotating container. The agitation continually moves the media around all surfaces and corners of the part, smoothing them out resulting in a uniform finish. The media can be anything from specialty ceramic shapes to ball bearings to even sand. This process can be done in either a wet or dry condition. Think about the beach, the rocks there are smooth. This is due to the waves repetitively rubbing together the sand and stones which result in smooth round shapes.
[imp22b] recently got into ammo reloading and needed a way to clean his used shell casings. The casings are brass and after a little research online, [imp22b] found that a wet tumbling process with stainless steel pins for media was a DIY proven method for this casing material. He then went on to find a commercially available tumbler to model his build after, in this case a Thumler Model B. There is certainly no need to re-invent the wheel here.
As you can see in the photo, aluminum extrusion was used as the frame. Mounted to the frame are 4 pillow block bearings with shafts between each pair. A motor drives one of the bearing-mounted rods which in turn rotates a container resting on the rods. [imp22b] started with a 1/15 hp motor that he had kicking around but that wasn’t powerful enough so he did have to step up to a 1/3 hp unit. The container is made from off the shelf PVC pipe pieces and holds the media and casings along with some water. A bit of Lemon Shine and Dawn detergents are also added and help clean the parts. After a few hours of tumbling, the casings look pretty darn good.