The B1A1 is a rock tumbler that I built. I wanted to grind some big loads, as in a bunch of pounds, and I wanted to try my hand at grinding and polishing larger rocks - softball to football size - so a machine larger 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.
B1A1 Rock Tumbler - Design
The B1A1 Rocks
Update: March 23, 2010
This picture shows one of the many reasons that I really enjoy running the B1A1 rock tumbler. The pile of rocks on the left is from a Thumler Model B - a 15 pound machine. The Model B barrel is sitting behind the rocks. On the right is a load of rocks from one tire of the B1A1 - about 65 pounds of rocks. If you have enough rocks to feed it, the B1A1 can grind 200 pounds of rocks and does it with the same ease as a Model B.
B1A1 Milestone
June 25, 2009
Today the B1A1 Rock Tumbler is running a 175 pound load. This is total rocks, grit and water in the tires but does not include the weight of the tires in the total. The loads vary in size and composition but two of the tires are carrying mostly fist sized pieces. I just loaded up, so you can hear some fierce grinding going on. Once the rocks round off a little, the load runs much quieter. I will note though, if you hear too much banging you are running a rock crusher and not a rock tumbler - and this machine can make lots of gravel in a hurry - use full loads to avoid bouncing.
I really like the load stability that came after installing the new central support. I used roller blade wheels as guides to protect the central supports from being rubbed by the tires - with a 3/4 horsepower motor (pulling through a 23:1 gear reduction) contact would grind away both wood and tire, but not slow down the motor.
Note too, I use masking tape to post notes on the load, how much of what went in when. This augments the notes I keep in my journal and helps me interpret the sound coming out of the load. Yes, you manage the process more by sound than by sight or touch. You judge the final product by touch and sight but while the machine is running it is by ear - and the symphony is quite enlightening.
The rest of this page presents earlier milestones reached by the B1A1 Rock Tumbler. As you look through the videos and read the comments, you can see that this has been a genuine learning process. Play hard. Learn more.
April 23, 2009
Assembly of the B1A1 is complete. Here is a short video of the first load. The tire is loaded with 25 pounds of rock, 2 pounds of 46-70 grit and 1/2 gallon of water. You can hear the rocks grinding. This is a "1 Up" configuration - running 1 tire. I will add more tires as soon as I can get the lids built.
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 real rocking!
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. The rushing sound it the 70 pounds of 3/4" - 2" stone I am running. The thunks are from the 40 pounds of baseball to softball size rocks. You can tell by the sound that this batch is early in process - it will get quieter as the stones get more round. Come back for additional videos.
