Having good equipment really is an essential element in generating good results. I get good results with the Thumler rotary tumblers. Processing one batch of stones takes 4 to 6 or maybe even 10 weeks. I started with the 15 pound rated Model B and have added other machines as my interest and needs grew. To tumble really large rocks - 3 to 8 pounds - or large batches - 150 to 200 pounds - I use the B1A1, a home-built, large capacity tumbler. I recently added a Thumler UV - 18i vibrating tumbler. It rocks. These machines run almost 24/7. The only down time is while I change grit in the barrel and clean and lube the bearings.
Thumler Model B
My favorite is the Thumler Model B tumbler. This is a 15 pound rated machine, so it does a lot of work. When it was my only machine, it did everyting and worked great. If you can hose it with a lot of water you can clean it up enough to avoid grit contamination as you move to polish. When I added more machines, I used the Model B mostly for coarse grinding and with 46 - 70 grit, it really grinds. Now that the B1A1 is on-line, I will use the Model B for pre-polish and polishing. If I could only have one machine this would be it.
The Thumler Model A-R12 tumbler. This is a 12 pound rated machine, with a rubber barrel. You might expect it to be quieter than the Model B, but it is not. This is one of my multi purpose machines. I generally use it to finish larger stones (ones that are too big for a 3# drum and most of my stones are too big for a 3 pound barrel) and it is handy for testing new techniques. I made several movies while running with a plexiglass lid.
The Thumler Model A-R2 tumbler is a 6 pound rated machine - with two 3 pound barrels. It is very nice for small batches - where small is under 3 pounds and the stones are an inch or less in size. Rough grinding is slow in this machine and I wouldn't go more coarse than 60 - 90 grit.
The Thumler UltraVibe - 18i (i = industrial) is an 18 pound rated, industrial tumbler. This machine works great for tumbling rocks. I use it mostely for polishing rocks as the vibrating action tends to polish whatever shape is there and is far less smoothing than a rotatary tumbler. This is no surprise. The UV 18i is very aggessive - completing a grinding operation or a polish cycle in 1/3 to 1/2 the time of rotary machines. Caution for rock hounds - there is a UV - 18 out there that looks just like this one but it is lighter duty and while it polishes cartridges great it won't survive on a diet of rocks. It goes for a lower price, but for us rockers it is no bargain.
The B1A1 is a rock tumbler that I built. I wanted to grind some big loads and try my hand at grinding and polishing larger rocks - softball to football size - so a larger machine than my Thumlers was needed. The design was done using Google Sketch Up - it is a great drawing package - all parts correctly dimensioned and 3D. The machine has a capacity of between 100 pounds and 200 pounds of rocks - mostly dependent upon the size of tires used. This has been fun to plan and a hoot to build. Follow the assembly process here.
The B1A1 Rock Tumbler
May 19, 2009
The B1A1 is running with 110 pounds of rock today. This is a "3 Up" configuration with 3 truck tires. I am fiddling with different sizes and profiles of tires to see which work best. I need one more to get to design capacity. Come back for more videos.
Here is what the action looks like inside one of the B1A1 tires while the machine is operating. This is a 17 inch truck tire loaded with 30 pounds of hammer broken stone, 3 pounds of 46 - 70 silicone carbide grit and 1/2 gallon of water. I can hardly wait to get 4 of these running - that is hard rocking!