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GUIDE: What is Rock Tumbler & How Do Rock Tumblers Work?

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Tumblers can be quite enigmatic creatures. Understanding how a particular tumbler operates often requires experience, and rarely do we get it right on the first attempt. I aim to ensure that beginners are equipped with all the fundamentals: understanding how tumblers work, selecting the right one, knowing what to expect, and understanding what to do with the results. This way, we set the learning curve off on the right foot, paving the way for a smoother journey ahead.

Tumblers work by facilitating collision, abrasion, and friction between rocks, water, and grit. Over time, with the right recipe and steps, these processes turn raw rocks into smooth, rounded, polished stones. Beginners should be aware of electricity costs, noise concerns, and all the possibilities that exist for beautifully tumbled stones.

Read more for a complete beginner’s guide to everything about tumblers.

What is a Rock Tumbler and How do Rock Tumblers Work?
What is a Rock Tumbler, and How do Rock Tumblers Work?

If you are interested in checking out the best rock tumblers, you can find them here (Amazon link).

What is a Rock Tumbler?

A rock tumbler is a machine used to polish rocks and minerals. It works by rotating a barrel filled with rough rocks, abrasive grit, and water. This action smooths and polishes the rocks over time, similar to how waves smooth rocks on a beach.

There are two main types of rock tumblers: rotary and vibratory. Each type consists of two essential parts: the motor and the barrel. The barrel acts as a container for the rocks and minerals to be tumbled, while the motor provides continuous movement to the barrel.

Tumbled stones are highly versatile and are used worldwide for various purposes. They help bring out the inner colours of stones by smoothing out rough edges, cracks, and uneven areas that may not reflect light optimally in their raw form. Additionally, tumbled stones are more comfortable to wear as jewellery compared to raw stones, making them popular for jewellery-making, souvenirs, art displays, and rock collections.

To tumble stones successfully, you’ll need a constant electricity source, a quiet space to operate the tumbler, a supply of rocks and minerals to tumble, and a good understanding of the tumbling process and the interactions between the ingredients involved. It’s a process that requires patience and experimentation to achieve the desired results.

What to know about Rock Tumblers?

If you are debating buying a rock tumbler or trying to figure out how, why, when, or where to use one, here is a brief list of must-know facts about rock tumblers and the process they use:

  1. Rock tumbling is part science, part art.
  2. Tumbling takes a lot of patience to do right.
  3. It is a relatively inexpensive hobby.
  4. Rock tumblers can be loud, so the home you find for it matters.
  5. Though just a motor, it takes a considerable amount of electricity because It runs a lot of hours. (Consider solar panels for the environment!)
  6. Rock tumbling can be incredibly rewarding but is more rewarding if you find the rocks yourself.

Rock Tumbler Types

When it comes to rock tumblers, you’ve got two distinct options to choose from, each with its own unique approach that will impact your tumbling experience.

First up, we have the rotary tumbler. This one operates on a straightforward principle: rotation. Imagine a barrel-shaped container continuously rolling for days on end, much like the waves crashing and receding on a beach. In this setup, rocks inside the barrel collide with each other, aided by water and grit, gradually rounding off their edges.

On the flip side, we have the vibratory tumbler, which relies on friction to get the job done. Stones are placed in a pile of sand-like grit, and the motor vibrates the barrel at a high frequency, causing each grit particle to rub back and forth on the stone’s surface. Vibratory tumblers are also handy for polishing metal objects like coins.

Now, here’s the kicker: rotary tumblers tend to operate at a slower pace but offer a more natural tumbling process. For instance, a batch of stones may take a week to tumble in a rotary tumbler, compared to just 3-4 days in a vibratory one. Plus, rotary tumblers are often more budget-friendly and durable in the long run.

The key difference between these tumblers lies in the final product. Rotary tumblers excel at knocking off larger amounts of material, resulting in very round stones. Meanwhile, vibratory tumblers focus on smoothing the material so the end product retains a similar shape.

When deciding which tumbler is right for you, consider your specific needs and preferences. This summary merely scratches the surface, so take your time and explore all the factors before making your decision.

Carefully consider the application, whether the tumbler is for you or someone else. There are many other things to consider in this decision; this summary just scratches the surface.

TIP: Rotary tumblers spin the rocks around as though they are in a washing machine, while vibratory tumblers shake them up at high speed in one place. Check out the main differences in the article below:
Rotary vs Vibratory Rock Tumbler: Which One To Buy & Use

How Do Rock Tumblers Work?

To approximate the natural process of shaping stone, it is natural to ask – what does a rock tumbler do?

Rock tumblers work on the basic principles of repetitive impact and friction to shorten a thousand-year process into a few weeks, all thanks to the invention of very basic mechanical tools.

The main component of tumblers is the motor. A motor uses an alternating electric current to induce a changing magnetic field. Just as you can manipulate a magnet to spin on a table with its opposite magnet, the alternating current can spin a gear or a belt.

In the case of a rotary tumbler, this rotation only occurs every few seconds and is transferred via a belt to a spinning pin, on top of which the barrel sits.

On the other hand, in vibratory tumblers, gears are used to change the spinning rate. A weight is then unevenly distributed on this spinning object to make the barrel of a vibratory tumbler rock back and forth quickly (or vibrate).

Inside the tumbler, water and fine grit are placed in a solution with the rocks and minerals. The water slowly and iteratively eats away at the rock, while the grit provides the friction of sandpaper to speed up the process.

As the rocks tumble into each other in a rotary tumbler, they collide, trapping grit in between them and causing the smallest of pieces to fall off.

Given enough time, small pieces will fall off on the most exposed parts of each stone, shaping the stone closer to a sphere.

Vibratory tumblers count on the friction of rock and grit to happen without rocks colliding. The frequency of vibration is extremely effective because it results in 100-1000 more “back and forth movements” than would happen in the rotary tumbler.

TIP: To get the best possible results when tumbling rocks, it is good to know what rocks are good for tumbling and what rocks can tumble together. Check out all of them in the articles below:
What Rocks Are Good For Tumbling? 15 Best Rocks & Minerals
What‌ ‌Rocks‌ ‌Can‌ ‌Be‌ ‌Tumbled‌ ‌Together:‌ ‌Complete‌ ‌List‌ ‌With‌ ‌Tips‌

How Much Power Does a Rock Tumbler Use?

A tumbler’s energy cost depends on how big the tumbler is and what type you are using. Because it depends so much, I want to do a calculation example to teach you how to calculate usage based on a tumbler’s wattage rating. 

Before we start out, I want to point out that motors only work for a specific voltage range. Electricity grids on different continents use different voltages, so if you travel or move abroad, you can never expect a motor-powered device to work if the voltage is different (most notably, Europe and the US use different power grids).

Using a US tumbler in Europe or vice versa will break the motor.

Let’s break down the energy consumption of our average rotary tumbler rated at 50 Watts or 0.05 kW, equivalent to the power usage of 5-10 LED light bulbs. Assuming we operate this tumbler continuously, 24/7, which is typical for tumblers, we’re looking at 31 days multiplied by 24 hours/day, totalling 744 hours per month.

Using the formula Power = Energy * Time (a classic from high school physics!), we can calculate that this tumbler consumes 37.2 kWh (kilowatt-hours) of energy in a month. Now, in Switzerland, the electricity rate is around $0.22 per kWh. So, this tumbler will cost approximately $8 per month in energy expenses and will emit around 34 pounds of CO2 into the atmosphere each month.

Unit / CostsRotary TumblerVibratory Tumbler
Monthly Energy37.2 kWh52.1 kWh
Monthly Energy Cost$8.00$11.50
Monthly CO2 Released34 lb47.9 lb
Average Cost of Tumbler Operation

TIP: There are some key supplies and equipment you need to ensure your tumbled rocks come out looking smooth and shiny. Check them out in the article below:
GUIDE: Rock Tumbler Accessories, Equipment & Supplies

How Loud Are Rock Tumblers?

The rocks colliding and vibrating around cause a noise that is generally uncomfortable to have in one’s bedroom. However, if you are like me and grew up with siblings, then you can turn anything into white noise and you will not have much of an issue with a tumbler. 

In seriousness, the main issue people can have with a tumbler is its noise, so you are right to ask.

So, are rock tumblers noisy?

Vibratory and rotary tumblers exhibit a comparable noise level. It is akin in level to a washing machine. While a rotary tumbler can sound more like a beach with waves approaching at three times the speed, a vibratory tumbler is much more mechanical – something like a drill or an electric toothbrush.

At three feet away, the dB level can be anywhere from 61-69. This range is also attributed to the noise level of a normal conversation on a busy street. Therefore, it’s a good idea to put the tumbler in an area where it’s normal to have constant noise, such as a kitchen.

How Fast Does a Rock Tumbler Turn?

Rotary tumblers (vibratory tumblers do not turn) make a full rotation anywhere from 10 to 38 times per minute. Certain tumblers have a customizable rotation rate, usually on the higher end in quality and price.

The average rate for an intro tumbler25 RPM
Optimal rotation for Polishing10 RPM
Initial step rotation rate30-38 RPM
How Fast Should a Rock Tumbler Spin?

It is a good idea to match the rotation rate with the grit coarseness – higher rates with larger grit – to keep the grit always in solution with the water. Larger grits (for earlier tumbling stages) are heavier and tend to sink down to the bottom of the barrel, especially when it is rotating slower.

This is always good to keep in mind when you are thinking of the ideal method of tumbling your stones.

TIP: Talking about speed, it is always good to know how it takes to tumble different rocks. Find out the accurate tumbling times for the most common rocks in the article below:
How Long Does It Take To Tumble Rocks? Values For Various Rocks

How Much Do Rock Tumblers Cost?

You can break the cost of a tumbler down into the tumbler itself, operation, and grit.

The grit cost is minimal compared to the rest – around $25 for a set of grit, which you should get at least 8 months out of. Some rockhounds recommend running a tumbler with more grit, saying that this takes less time.

Electricity cost is the next cost, and this one will largely depend on the cost of electricity where you live (remember, CO2 produced by the electricity you use is independent of cost).

Unit / TypeCosts
Electricity cost (monthly)$4-$8
Grit cost (monthly)$2-$4
Kids Tumbler$40
Hobby Rotary Tumbler$130
Hobby Vibratory Tumbler$110
Large Professional Tumbler$300
Costs of Tumbling

What is a Rock Tumbler Used For?

First and foremost, rock tumblers are used to tumble stones! But what is the purpose of this rock tumbler? Professionals use it to create jewelry quality specimens out of raw stones, hobbyists use it for the same or to brighten up their collection, and kids use it to make normal rocks look shiny and beautiful.

Tumbled rocks are used for many things besides collections, souvenir stones, and jewelry. They make fantastic displays out of just about anything.

Many times, you’ll see them filling up vases in jars around the house, as ground cover in planters, used in artwork for a wall, or crafts for kids.

Otherwise, what are the uses of a rock tumbler? What can you do with a rock tumbler?

Rotary tumblers are not very versatile in that they are meant for rounding out and smoothing out stones. On the other hand, vibratory tumblers are used to get the rust off coins, bullet shells, and other metal pieces by other hobbyists.

Why Use a Rock Tumbler?

There are other options to smooth or round stones, such as a Dremel Drill. So, what does a tumbler do better than these options? Mainly, it takes manual labor out of the equation.

Typical rock tumblers can hold 3 pounds of stone, but there are barrels for professional rock tumblers that go up too much more than that. To manually take a tool to smooth out all the corners of 3 pounds of raw stone would take many hours. With a tumbler, you can fill it up, turn it on, and walk away.

Of course, there are the extra costs of a rock tumbler over a Dremel, but most people acknowledge the work saved as more important.

However, if the shape of the final product is very important to you, using a tumbler will not give you as much control as you need – in these cases, a tumbler is not the best tool for the job.

If you are in the market for a tumbler or just want to check out some of the best quality and highest value choices, here are my top picks (Amazon links).

  1. Lortone 3A Single Barrel Tumbler
  2. Tumble-Bee Rotary Rock Tumbler
  3. NATIONAL GEOGRAPHIC Hobby Rock Tumbler Kit

TIP: Using a rock tumbler can cause it starts to leak sometimes. It’s common for all of us and you can fix most of the leaks easily. Find out more about the most common problems and how to fix them:
6 Reasons Why Your Rock Tumbler Leaks and How to Fix it

How to Use a Rock Tumbler

Rock tumblers are like ovens. They are fantastic for the job they do, but some jobs are better suited for a stove. However, if you are making a cake, the first step is to make sure you have the right mix of ingredients before you put the cake in the oven. Otherwise, it will not be what you imagine.

Similarly, it is very important to use a Tumbler. (They can also sometimes get warm, and that is OK.)

Before we talk about the recipe, it’s important to recognize that taking care of mechanical equipment regularly is key to their long life. Between loads, make sure to do a few things:

  1. Dispose of the grit and water in a safe location. The grit is not environmentally harmful but will clog a drain more easily than a head of hair.
  2. Wash the barrel gently but thoroughly, making sure all the old grit is out.
  3. Put in the new recipe (more in this later) with the rocks you have chosen to tumble.
  4. Replace the barrel, making sure all moving pieces are tight but not squeezed. 
  5. Start up the tumbler and place it in a flat and sound-insulated area.

What to Put in a Rock Tumbler?

What to Put in a Rock Tumbler?
What to Put in a Rock Tumbler?

There are many theories as to what goes inside a rock tumbler, some more simple, some including up to 5 ingredients, changing depending on the step.

The theory of recipe changing throughout the process can be related to sandpaper – you switch a few times, increasing density, to get the softest result.

Some overarching rules for tumbling are generally not argued.

  1. Put rocks of similar hardness together. This makes their collisions more predictable and less damaging (soft rocks getting continuously pummeled by hard rocks is a recipe for dust)
  2. Put rocks of similar size together for the same reason.
  3. Each load should go through 3-5 steps.
  4. The barrel should be anywhere from ½ to ¾ full. Most recommend two-thirds.

Here is the most common process for what to use in a rock tumbler (rotary), consisting of 4 steps.

Step 1: Use 60-80 grit material and fill the barrel with rocks to three-quarters full. Fill with water until just below the level of the rocks. Tumble for a week or two if you want the shapes to be closer to spheres. This step mainly uses rocks hitting each other and grit to shape the rocks.

Step 2: Use 240-400 grit material with the same rocks (which will look less after the first step). Use the same idea with the water. This step takes care of most edges and corners. Tumble for 4-7 days.

Step 3: Use 600-800 grit material with the same rocks and the same water idea. This finishes the rounding process and is the main smoothing process. Tumble for 3-5 days.

Step 4: Use 1200-grit material with the same rocks and slightly more water. Some glass dishwashing liquid is optional. Tumble for up to a week. This step polishes the stones and can be repeated if necessary.

TIP: Proper rock tumbler loading is really important. Especially when it comes to grit and rocks. Check out this complete guide about rock tumbler loading:
Rock Tumbler Loading: How Much Grit & Rocks Do You Put In?

Are Rock Tumblers Safe?

Rock tumblers are not at all dangerous in the hands of a responsible adult. While they are mechanical equipment, the motors are always encased and there is nothing that can be harmful in a normal application.

In the case of a curious or clumsy child, there are some considerations whenever moving parts are concerned. Fingers can get pinched input in the wrong spot.

Make sure any young one knows not to touch moving mechanical pieces, which may be partially exposed on any tumbler not meant for kids.

Kids’ tumblers are usually built to be handled by children but will always require supervision about how it work.

In general, never disassemble anything when it’s in operation. Always turn it off and unplug it to dive into the inner pieces, and keep the cover on during normal operation.

FAQ about Rock Tumblers

I hope you found the answers to all the questions about rock tumblers in this article. But if you still have some other questions, below are some common and interesting questions about rock tumblers.

Can You Use a Cement Mixer as a Rock Tumbler?

The only application for a cement mixer as a tumbler would be for large stones. It is ok to do so, but only to accomplish rock rounding through collision. 

Polishing in a cement mixer will never work because they do not have the cushion required to make the fine grit work its magic. The fine grit will also wear down any steel after a few days, destroying the equipment.

Can You Turn a Rock Tumbler Off at Night?

You can turn a tumbler off at night, but your batch will take 2 times as long because it works based on the number of hours it is running. Therefore, it is always recommended to find a place either outside or in a louder place to let your tumbler run during the night.

What is the Biggest Rock Tumbler?

Thumbler company sells a vibratory tumbler that has a barrel holding 10 pounds of rocks. And a rotary tumbler that can hold 15 pounds of rocks. These are generally considered the largest you can go without sacrificing quality.

What is the Quietest Rock Tumbler?

There are two things you want to look for when looking for a quiet rock tumbler: it must be small and it must be a rotary tumbler with a rubber barrel.

Not only do rubber barrels soften the sound level, but they also make it less piercing and uncomfortable. Quieter tumblers will resemble the sound of a dishwasher.

TIP: Rock tumblers require some maintenance, though, as you will need to oil them regularly to keep them running smoothly. Check out how to properly oil your rock tumbler in the article below:
Step-By-Step Guide: How To Properly Oil Your Rock Tumbler

Does Rock Tumbling Really Work? Conclusion

Achieving smooth, shiny rocks is possible with either type of rock tumbler. However, it’s crucial to choose the right tumbler for your needs, follow the correct recipes and safety precautions, and maintain your equipment properly to ensure it lasts for years of continuous use.

While there are some downsides to tumbling, such as the time it takes, the noise it can produce, and the electricity it consumes, the benefits of obtaining beautiful, round, shiny stones for crafting projects or household displays often outweigh these drawbacks.

If you want to check out some of the best quality and highest value rock tumblers, here are my top picks (Amazon links).

  1. Lortone 3A Single Barrel Tumbler
  2. Tumble-Bee Rotary Rock Tumbler
  3. NATIONAL GEOGRAPHIC Hobby Rock Tumbler Kit

TIP: Check out the complete buyer’s guides about buying hobby rock tumblers and rock tumblers for kids and choose the one that suits you the best:
Best Rock Tumblers in 2022: Beginner and Hobbyist Options
Best Rock Tumblers for Kids in 2022: Options For Diff Ages