Last update (this page): January 8, 2020
As mentioned elsewhere, I don't worry about mixing rock types during coarse grinding. Everything goes in my big tumbler with the 31-inch tire for a barrel. You can read the (original) technical documentation here.
One photo nearby shows the revised door design (as of November 2003), including a screw-eye I added to the edge of the door after drawing up the revised design (grin) to make it easier to pull it off the "slurry glue" when opening it. This picture shows what it looks like when the door seal or the rim seal leaks a little! Also note the supports I had to add after all to keep the tire upright. You can't see the rollerskate and rollerblade wheels between the supports and the tire.
|Another photo nearby is a side view. A third photo nearby, taken without a flash, shows the tumbler in motion.|
Here's a 20-second MP4 video (89 Mb) of the tire tumbler in action, taken in 2017, after replacing the painted wooden doors earlier with white nylon cutouts. (Might not play smoothly on Windows 10 though, sigh, at least not via Firefox...)
Coarse-ground stones then move to smaller tumblers for fine grit (220), pre-polish, and polish; one week per cycle, yielding 1 gallon (12-15 pounds) of polished stones every ~3 weeks.