If you are considering buying a rock tumbler, use this article as a reference for purchasing and what to expect when processing your first batch. Whether you are buying a rock tumbler for yourself or your family, tumbling is a great and relatively inexpensive hobby for the young and old alike. Rock tumbling is an ideal gateway to spending quality time with your family while incorporating an educational element at the same time. Tumbling offers the opportunity for you and your children to bond through science! Families have the opportunity to learn about geology through hands-on application. It is a great experience to watch the tumbler accomplish in four weeks what would take millions of years in nature!
The article is broken down into the following topics.
- How to Get Started Rock Tumbling
- What to Buy to Get Started Rock Tumbling
- About the National Geographic Hobby Tumbler
- Types of Rocks for Tumbling
- Rock Tumbler Grit & Polish
- The Rock Tumbling Process Step by Step
- Tips for Tumbling Rocks
How to Get Started Rock Tumbling
Getting started with the rock tumbling hobby is easy. All you need is a tumbler, grit to smooth the rocks down, water, and rocks to tumble.
If you are not sure what type of rock tumbler you should buy, I recommend the National Geographic Hobby Rock Tumbler Kit. The National Geographic Hobby rock tumbler is a great entry-level option. With its simplistic design, it is a reliable tumbler that will produce batch after batch of smooth and shiny rocks.
What to Buy to Get Started Rock Tumbling
These are the items you will need to get started tumbling rocks.
|National Geographic Rock Tumbler||Check Price on Amazon||Yes||This is the best rock tumbler to buy when starting out.|
|Material||Check Price on Amazon||Yes||Material = rocks (i.e. gemstones)|
|Grit||Check Price on Amazon||Yes||There are four different types of grit - one for each of the four weekly stages.|
|Filler||Check Price on Amazon||No||Filler helps protect your rocks as they tumble.|
|Extra Belt||Check Price on Amazon||No||The tumbler comes with a belt, but it will not last forever. Consider purchasing an extra belt to have on hand.|
About the National Geographic Hobby Tumbler
The National Geographic Hobby rock tumbler is the best rock tumbler for beginners.
The tumbler comes with everything you need to get started with your first batch. In addition to the rock tumbler itself, the kit includes gemstones, four polishing grits, a sifter, and a necklace and earrings to attach your gems to once polished.
The National Geographic tumbler is a one-pound tumbler. It will hold about 12 – 15 rocks that are about 1.5″ in diameter.
The tumbler is a two-piece system – the base and barrel. Rocks, grit, and water are added to the barrel. The barrel sits on the base. The motorized base turns (tumbles) the barrel via a rubber belt. After 1 week your rocks are smooth and after 4 weeks your rocks are shiny and beautifully polished!
From a sound standpoint, the National Geographic Hobby Tumbler is not nearly as loud as plastic tumblers. National Geographic has reduced the noise by designing it with a rubber barrel. The rubber absorbs most of the sound. In fact, it produces about 75% less noise than a plastic tumbler. You will not hear the tumbler at all if you run it in your garage. If you run it your mudroom or utility room, you can shut the door and barely hear it. Another good option is running it in your basement. The loudness is comparable to an older model washing machine, but a bit louder.
Rock Tumbler Barrel
The barrel has a rubber coating and is sealed with two separate lids. It features a “tire-like” interior which is what muffles the sound more than rock tumblers with a plastic barrel.
The first lid is a thin piece of metal (possibly aluminum) with rubber edges. This piece acts as a seal that can be pushed down to fit tightly inside the barrel. It sinks down a few millimeters to make a very snug fit. This lid has a screw post on the top.
The second lid is made of stainless steel and wraps over the top of the barrel. It has a small round hole cut out in the middle. The screw post on the first lid sticks up through the second lid. There is a nut used to tighten the two lids together. See the picture at the top of the post for a graphical representation of what the barrel looks like when the lids are screwed together. Screwing the two lids together makes an air and watertight seal around the barrel.
Rock Tumbler Base
The tumbler is electric and driven with a rubber belt. The only real concern I have about the rock tumbler is how long the belt will last. I know it will break at some point and I will need to purchase a replacement.
You can schedule the rock tumbler for the amount of time you want it to run. Scheduling options are by days measured in 24-hour increments. The options are one to seven days.
There are two buttons on the front.
- The “Set” button which allows you to pick the number of days to run the tumbler. The schedule, or amount of time to run the tumbler, is measured in days. The number of days is listed across the base. Keep pushing the “Set” button and a red LED light indicates how many days the tumbler is set to run.
- The power button. Once you have the number of days set, push the power button and the tumbler starts rolling the barrel.
Types of Rocks for Tumbling
There are all types of rocks available. You can dig them up in your backyard, but don’t expect the results to be very spectacular. Regular rocks will grind down, but aren’t nearly as appealing as gemstones.
Gemstones produce the best results for rock tumbling. You can find gemstones locally at a “gem mine.” These are often found at vacation destinations. At gem mines, you buy buckets of dirt with gemstones mixed in. There are a predetermined number and quality of stones placed into each bucket. Buckets range in price based on the size of the bucket. The size of the bucket correlates with the number of stones included. At gem mines, there is a trough of swift, running water and you use a sifter to wash away the dirt and find the stones. Gem mines are a lot of fun, especially with the family!
Another option is to purchase the rocks online. Amazon offers a wide selection of gemstones from a variety of countries. Buying rocks for tumbling online is the easiest way for most folks to get quality rocks quickly. Below are examples gemstones by country and region you can buy online.
|Country / Region||Price||Types of Gemstones|
|Asia||Check Price on Amazon||Ruby, Lapis Lazuli, Amethyst, Sodalite, Crystal Quartz, Rhodolite Garnet, Yellow Aventurine, Red Jasper, Dalmatian Jasper|
|Madagascar||Check Price on Amazon||Labradorite, Desert Jasper, Red Jasper, Yellow Jasper, Petrified Wood, Rose Quartz, Blue Apatite|
|Brazil||Check Price on Amazon||Green Aragonite, Green Onyx, White Aragonite, Clear Quartz, Orange Calcite, Red Jasper, Red Onyx, Citrine, Blue Calcite, Blue Quartz, Amethyst, Rose Quartz, Blue Onyx, White Quartz, Orchid Calcite, Fuchsite, Green Quartz|
|India||Check Price on Amazon||Black Volcano, Lapis Lazuli, Clear Crystal Quartz, Grey Agate, Rose Quartz, Green Amazonite, Sunstone, White King Quartz, Tree Agate, Garnet, Leopard Jasper, Landscape Jasper, Volcano Coffee, Fancy Jasper, Unakite, Picasso Jasper, Dalmatian Jasper|
|South America||Check Price on Amazon||Fuschite, Orange Calcite, Clear Quartz, Amethyst, Sodalite, Green Aventurine, Snow Quartz, Citrine, Rose Quartz, Blue Quartz, Red Jasper|
Rock Tumbler Grit & Polish
There are four different types of grit & polish – one for each of the four stages. The grit for the first three stages is silicon carbide. The grit goes from coarse, medium, and then fine for stage one, two and three, respectively. The polish for the fourth stage is aluminum oxide.
When you buy the grit, most vendors include instructions for how much grit to use and the length of time to tumble for each stage. Both measures are dependent upon the size of grit. Each of the four stages run approximately one week.
With all things equal, when buying grit, choose a vendor that sells it in sealable bags. Otherwise, plan on putting the grit for each stage in its own bag after purchasing. If you are depending on storing it in a non-sealable plastic bag and a rubber band, expect spills when you open and close it.
The Rock Tumbling Process Step by Step
Tumbling rocks from start to finish can take up to four weeks. The process is broken down into roughly one-week increments. Each week the water and grit must be changed.
If you don’t have four weeks to spare, no worries. For most folks, the first week is all you need. The most noticeable change happens during that period. The first week is when the coarsest grit is used. In addition to it taking less time, tumbling them for only one week prevents the rocks from being worn down as much. If you let them run the entire four-week process, the final product can result in the rocks being ½ to ¾ of their original size, depending on the type of rock and its hardness. To the untrained eye, the first week can look about as good as the fourth.
The image above shows the basic four-step process. I expanded upon the process by breaking it down into eight steps and provided context around each one.
Step 1 – Source Rocks
The first step is to pick out your rocks. The National Geographic Hobby Tumbler Kit comes with rocks to get you started, but for your second batch, you will need to dig up or buy your own. Please see the “types of rocks for tumbling” section for recommendations.
While the rocks you buy will be more visually appealing when polished, the ones you find (or dig up) can be much more meaningful. Finding them with your family can be a fun adventure and is time well spent together.
Step 2 – Load the Rocks into the Tumbler
Step 3 – Add Grit
Once the rocks are in the barrel, add the grit. There are four different sizes of grit intended for each of the four stages. The coarser grit is used during the first stage. The finer grit (polish) is used during the fourth stage for polishing. The goal is for the rocks to “tumble,” allowing the grit to constantly move across and wear the rocks down making them shiny and smooth. The vendor you purchase the grit from will most likely include instructions for how much grit to use for the particular specs of the grit. Generally speaking, use about one tablespoon for each stage of a one pound tumbler.
Step 4 – Add Water
Step 5 – Fit the Lid
Put on the lid. The National Geographic tumbler has two separate lids. The first lid, which is flat and has rubber edging, seals and waterproofs the barrel. The second lid fits over the top of the first lid by screwing down and making the barrel airtight.
Step 6 – Set the Time
Set the length of time you want the tumbler to run. Each of the four stages takes about one week. The time is set per stage. To set the time, press the “Set” button repeatedly until the red LED indicator lands on the number of days you choose. The days are in 24-hour increments. Once you have the number of days set, press the power button. The tumbler will stop automatically once the number of days you set has been reached.
Step 7 – Remove the Lid
To remove the lid, you will first need to unscrew the nut that tightens the top lid. The top lid will still be very tight around the barrel. I use a small flat head screwdriver to pry up the edges. Once the top lid is off, the second lid is easy to remove by screwing the nut back on the screw post and simply lifting it up.
Step 8 – Straining the Rocks
Be sure to strain the rocks OUTSIDE or over a bucket if straining inside. When you open the lid, you will find the liquid has turned into a grey sludge. This sludge consists of water, grit and broken-down rocks. Whatever you do, don’t pour the sludge down your sink or toilet! The sludge basically turns into concrete and will do major damage to your plumbing. I recommend taking the rocks outside and rinsing them off with a garden hose. The same can be done with rinsing out the barrel. Make sure you get all the old grit out of the barrel in preparation for the next stage.
That’s a summary of what you need to do to process any given stage of tumbling your rocks. There are four stages in a typical project, but you can choose to only run one or any combination of the four.
Tips for Tumbling Rocks
Make Your Rocks Keep a Lasting Shine
If you want your rocks to keep a lasting shine, put mineral oil on them. Folks commonly use baby oil. When you first take the rocks out of the tumbler they have a great shine because they are wet. Once they dry off, the shiny color “pop” from the water dies down. Mineral oil allows the rocks to keep that wet look for an extended amount of time. I put the rocks in a plastic bag, add mineral oil, and work the oil across the rocks for a few seconds. Mineral oil makes them look great!
Loosen the Grit After They Have Been Sitting
If the rocks sit stagnant in the tumbler for a period of time, start the tumbler back up and let it run for about 30 minutes. After the rocks sit for about a day, it gets hard to clean the grit off the rocks and sludge out of the barrel. If you start it up and let it run for about 30 minutes, the sludge will break up and makes the rocks much easier to clean. Running the tumbler for a few minutes mixes everything back up and loosens the grit that is stuck to the rocks.
Rock Tumbler Belt
Keep an extra belt on hand. The National Geographic Hobby tumbler and other rotary tumblers are operated using a rubber belt that connects the motor wheel to the rollers that turn the barrel. Even though I have run mine for months without having to replace a belt, I expect the belt to be the first thing that breaks. If for some reason the belt rubs against another object while running, that will break it for sure. It’s a good idea to keep a spare belt on hand.
Rock Tumbler as a Noise Machine
When running, rock tumblers make a very consistent noise. If you are the type of person that needs noise to sleep, a rock tumbler is a great alternative to a sound machine. You may not want it right beside your bed, but at a distance, it is a very effective sound machine alternative. Consider putting it in another room where you can shut the door during the day and then crack the door at night.
If you are looking for a new and exciting hobby for your family, rock tumbling is a wonderful option. The National Geographic Hobby Tumbler has everything you will need to get started with your first batch. If you found this article helpful, consider sharing it with others on facebook!