If you're in the market for a rock polisher or tumbler, there are a few things to consider before you buy. The type of rock polisher you'll need depends on the work you're doing and what kind of rocks you'll be polishing.
Sizing Up Rock Tumblers
Most rock polishers are measured by their capacity in pounds. To polish rocks that measure 1.5 diameter inches or more, or to polish several rocks at once, choose a large rock polisher with at least a six-pound capacity.
To polish smaller stones, or to tumble a few rocks at a time, a small rock polisher should work just fine. Three-pound capacity or smaller rock polishers will get the job done easily. Be careful not to overload your rock polisher or the motor will burn out.
Tumblers are rated by weight capacity. A three-pound tumbler will rotate three pounds of weight indefinitely. Many people fail to weigh their load, barrel and rock combined, to make sure it falls within the correct range. This is the number one cause of motor failure.
Barrel of Fun
To polish a large volume of rocks, choose a rock polisher with two or more barrels so you can polish multiple batches at once. Considering that it takes four to five weeks to polish a load of rocks, using this type of device saves you time. A multi-barrel polisher is also handy when polishing several sizes and types of rocks, which can't be mixed into one barrel.
If you're planning on using a rock polisher more than a few times, it's worth the cost to buy the highest-quality rock polisher you can afford to ensure that you're not constantly having to replace parts or invest money in repairs once you get started polishing.
A rotary rock tumbler is also known as a standard rock tumbler and is used by hobbyists and professional rock tumblers alike. A rotary tumbler has a system of barrels that rotate around a metal cylinder to tumble and polish the rocks inside. It's easy to use and creates smooth, polished stones. Small rocks and grit go into the cylinder. Gradually, the surfaces of the rocks are smoothed away, resulting in round, polished stones.
A vibrating rock tumbler works in a slightly different way. It doesn't actually "tumble" the rock. Instead, the cylinder that holds the rocks vibrates - creating friction between the rocks and the grit material. Because the rocks are moving less, they are polished much more quickly than with a rotary tumbler. They also tend to retain their original shape, unlike with a rotary tumbler, where the rocks often come out with a rounded shape regardless of what they looked like when they went in.
More about Rotary Tumblers
Rotary rock tumblers come in a variety of sizes. Choose one with cylinders that are large enough to hold the amount of rocks you plan to tumble at one time. Good quality, heavy duty rotary rock tumblers should be made almost entirely of metal. Most smaller models will have enclosed motors, which are somewhat quieter to run.
Ensure your rotary rock tumbler comes with a warranty and has replaceable parts, since some parts of the tumbler will have a tendency to break before others. Rotary rock tumblers are fairly inexpensive compared to other types of tumblers, such as vibrating ones.
More about Vibrating Tumblers
Vibrating rock tumblers work more quickly than rotary tumblers. Vibrating tumblers use less grit and polish, meaning you'll save money, especially if you're tumbling a lot of rocks. While a rotary tumbler will make rough stones round and polished, a vibrating tumbler polishes but does not change the shape of your stones. Some rock tumbling enthusiasts consider this to be an advantage to vibrating rock tumblers because it's easy to create beautiful, variegated polished stones with natural shapes.
Another advantage with a vibrating tumbler is that the process takes seven to 10 days compared to 30 to 45 days with a rotary tumbler. The trade-off is that vibrating rock tumblers tend to be more expensive. They can also be noisier to operate, and they do require more constant maintenance during the tumbling process, since the grit must be changed approximately every 12 hours.