Uses a quieter rubber barrel. Easy to clean between tumbling cycles. Also works with jewelry and ammo casings.
Loud operation, remote location suggested. Belts and tumbler sometimes fail within weeks.
A true hobbyist kit, includes everything – stones and all levels of grit and polish. Heavy duty construction and performance.
Some rocks can break into pieces, not polished. Instructions can be vague on grit levels and process. Some reports of missing materials and parts.
Very quiet operation. Rubber barrel is more durable than plastic. Dependable and powerful motor will turn for weeks at a time.
Does not arrive with sufficient grit material. Lid can pop off unexpectedly. Can become unbalanced during operation.
Works well with stones, glass, jewelry, and ammo casings. Relatively quiet operation. Generous 5 pound weight capacity.
Can run hot, so location is critical. Belts not always reliable. Not recommended for heavy duty purposes. Advanced users may want the twin barrel model.
Very versatile, suitable for all levels of polishing and tumbling projects. Highly recommend for silver jewelry. Strong customer support, trusted brand.
Noisy tumbler barrel, can fail unexpectedly. Instructions are minimal, vague. Motor runs hot at times.
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No matter how old you are, rock collecting can be a fun, interesting hobby. It doesn’t require any special knowledge — all you have to do is find a few rocks that catch your eye in your yard, and you’re ready to go — but you can learn quite a bit along the way about different types of rocks and how they’re formed.
If you want to bring out the true beauty of the rocks you find, though, a rock tumbler is an essential tool for your hobby. With a tumbler, you can polish rocks to give them a smooth, almost glass-like finish. Polished stones can be set out for display in your collection, or you can even turn them into creative pieces of jewelry.
But in order for your rocks to look as attractive as possible, you need a good rock tumbler to get the job done. To choose the right model, you need to know what type to look for, as well as what features are most important.
If you’re ready to buy a rock tumbler, take a look at our top recommendations. For general tips on how to choose a rock tumbler, continue reading our shopping guide.
Rock tumblers are small machines, usually small enough to rest on a tabletop. They consist of a motor, a barrel, and a chassis upon which the barrel rests. Many tumblers have only one barrel, but there are models that use two barrels at the same time.
Rocks and water are loaded into the barrel, along with some type of abrasive grit material. The grit is similar to the material used to coat sandpaper, and is rated along the same grades as sandpaper, such as fine, medium, and coarse.
Once the barrel is loaded, the machine rotates, so the rocks inside begin to tumble. As the rocks move, the abrasive grit constantly washes over the surfaces of the rocks. This erosive action simulates the same process that takes place when a rock washes down a stream or river.
To get the proper texture and finish for your rocks, you tumble them in stages. In most cases, rocks are tumbled for one week with coarse grit, a second week with medium grit, and a final week with fine grit, or polish. Depending on the type of rock, you might also opt for a pre-polish stage. The rocks and tumbler must be cleaned carefully between each grit size.
It’s important to mix rocks of different sizes in the tumbler to ensure that there are plenty of points of contact among the stones, where the grit can be trapped for polishing.
Rock tumblers are available in two types: rotary and vibratory.
Rotary tumblers use a motor to rotate the barrel that holds the rocks, water, and abrasive grit. Similar to the way a clothes dryer moves your clothing, the rotary tumbler constantly lifts and drops its contents, causing the grit to wash over the rocks.
Vibratory tumblers use a motor to vibrate the base beneath the barrel or bowl that holds the rocks, water, and abrasive grit. The action of a vibratory tumbler is somewhat reminiscent of a paint shaker at your local hardware store. Just like with a rotary tumbler, as the barrel vibrates, it creates friction between the rocks and grit to help smooth and polish them.
It generally takes four weeks to tumble rocks in a rotary tumbler, while it usually takes only a seven to ten days in a vibratory model.
However, vibratory tumblers are only effective in polishing and smoothing rocks. They don’t wear down angles the way that rotary models can, so they’re not effective for shaping the rocks. If you want your finished rocks to have more rounded edges, you should use a rotary tumbler.
Some avid hobbyists use both. You can use the rotary tumbler for the coarse stages, which will smooth and round the edges of the rocks, then switch to the vibratory tumbler for the polishing stages. This shortens the overall time, and allows you to complete the entire polishing process using less grit.
Not all rocks are suited for tumbling. Choose hard, non-porous rocks that have a non-gritty surface. Agate and jasper, which are types of quartz, are ideal options.
Rock tumblers are available with barrels or bowls in a variety of sizes, so you should consider how large your typical rock batches will be to determine what size is best for your needs.
Bigger may seem better, but if you purchase a tumbler with a very large barrel, you’ll need to add filler material, like plastic pellets, to fill the barrel if you aren’t tumbling a larger batch of rocks in order to meet the recommended two-thirds full level.
For beginners and children, a model with barrel that can accomodate three to six pounds of rocks is usually sufficient.
The tumbling media that you use to fill a tumbler’s barrel if you don’t have enough rocks can be reused many times. Just wash it thoroughly between the various stages.
While many rock tumblers feature a single barrel or bowl, you can find models that are equipped with double barrels or bowls.
With a double-barrel tumbler, you can use just one barrel or run them both at the same time to increase the machine’s capacity.
The double-barrel construction also allows you to tumble rocks of different hardness at the same time, so you don’t have to wait as long for your stones to finish.
Don’t leave your rock tumbler in a location where it’s exposed to direct sunlight or cold temperatures, which can cause the machine to crack and leak.
The barrels or bowls in rock tumblers are typically made of rubber or plastic. Rubber barrels tend to be the most durable, and offer the quietest operation. Plastic barrels are usually less expensive, but they don’t last as long and can make a lot of noise when in use.
Tumblers can be pretty noisy when they’re in operation, so it’s best to keep yours in a garage, basement, or other space where it won’t disturb the rest of the family.
Many rock tumblers come as part of whole kits for rock tumbling, that include all of the items you need to get started. If you’re a beginner, you may want to choose a tumbler that comes with plenty of extra accessories so you’re ready to tumble right away.
Many kits include the different grades of abrasive grit that you need to polish, smooth, and shape the rocks. Some kits even include a selection of rocks that are suitable for tumbling, so you don’t have to search for your own.
You can even find rock tumbler kits that come with jewelry supplies, which allows you to turn your tumbled stones into necklaces, earrings, or keychains.
The grit used in a rock tumbler is similar to the material used to coat sandpaper, and is rated along the same grades as sandpaper: fine, medium, and coarse.
Rock tumblers vary in price based on the size, number of barrels, material, and included accessories, but you can typically expect to pay between $70 and $300.
For a small, single-barrel tumbler, you’ll usually pay between $70 and $120.
For a large, single-barrel tumbler, you’ll usually pay between $120 and $140.
For a small, double-barrel tumbler, you’ll usually pay between $100 and $200.
For a large, double-barrel tumbler, you’ll usually pay between $200 and $300.
Be sure to choose rocks that have the same hardness for tumbling, so they’ll be finished polishing at the same time.
Not all rocks are suitable for tumbling. Choose hard, non-porous rocks that have a non-gritty surface. Agate and jasper, which are types of quartz, are ideal options.
For the most effective polishing, fill your rock tumbler’s barrel approximately two-thirds of the way full with rocks, then cover just over the tops of the rocks with water.
If you don’t have enough rocks to fill the rotary tumbler’s barrel, you’ll need to add plastic or ceramic tumbling media to help take up the extra space.
For the best results, it helps to vary the size of the rocks in the batch that you’re tumbling.
Use approximately two teaspoons of grit per pound of rock that you’re polishing, and add enough water to just reach the top of the rocks for the tumbling process.
Tumblers can be pretty noisy when they’re in operation, so it’s best to keep yours in a garage, basement, or other space where it won’t disturb the household.
Always clean the tumbler’s barrel with soap and water between each stage of tumbling process. It’s important to remove all of the previous grit before adding the next grade, so they don’t mix together.
Q. What features should you look for in a rock tumbler if you’re new to tumbling?
A. If you’re new to rock tumbling, a single-barrel rotary tumbler is usually the best option. It allows you to get used to tumbling smaller amounts of rocks, so you can get familiar with the process. It’s also a good idea to purchase a kit that includes all the items you need to get started, including rough rocks or gemstones and abrasive grit.
For the most effective tumbling, wash the rocks between stages to remove the grit residue. It helps to use a colander for rinsing, but place the colander over a bucket, not a sink. If you wash the residue down your sink, it may clog your pipes.
Q. Can you re-use the grit that you add to the rock tumbler for polishing?
A. As the rocks tumble in the machine, the grit actually starts to break down. It mixes with the water to create a slurry that’s no longer effective in smoothing the edges from the rocks, which means you can’t use it again. Discard the grit after each step in the tumbling process, making sure to clean the tumbler’s barrel well afterward.
Q. Is rock tumbling a suitable activity for children?
A. Rock tumbling is a great hobby for kids. It allows them to learn about rocks, and provides a feeling of accomplishment when they turn ordinary, rough rocks into beautifully smooth, glossy stones. An adult should supervise the activity, though, because it requires an electric appliance.
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