The Rotary Tumbler – Everything You Ever Wanted To Know

Why A Rotary Tumbler?
Polished rocks are some of the most attractive things that catch your eye in jewelry and hobby stores. The idea that a rough hunk of rock can be made into a smooth polished gemstone over the course of time using only powdered grit is fascinating to most. Looking at the polished stones, you might imagine someone laboring for days with a piece of sandpaper or perhaps a wheel grinder. But in order to get to that finished product, no hand grinding is needed. It is actually accomplished by using a rock tumbler, either a vibratory or a rotary tumbler to be precise.

Of the two, most people start out with a rotary rock tumbler. This is probably due to the fact that it can perform a wide variety of grinds and it is a little easier on the wallet compared to a vibratory tumbler. In this article, we will go over the different types of rotary rock tumblers and point out the things to look for in your next (or maybe your first) tumbler purchase.

If you are purchasing a tumbler for the first time, it is a good idea to get a medium sized unit. Some hobbyists have special sized tumblers for different specific projects, but for the beginner, it is a good idea to go with a medium sized tumbler that will cover a wide range of applications. Size when referring to rock tumblers, is usually focused on the actual tumbler part of the machine. The tumbler is the cylindrical part of the unit where you place the rocks.

The Debate: Small Entry Level Unit Or Larger Rock Tumbler?
One question many new hobbyists have is what size rock tumbler to buy. There are different schools of thought on this. On the one hand, you can go with an entry level rock tumbling kit which will include a small tumbler, an instruction book, abrasives, and maybe even rocks for your first batch. This is not a bad choice but in the long run it could cost more if you just upgrade to a bigger tumbler anyway.

Another Question: One Tumbler Drum Or Two?
Some rotary rock tumblers come with multiple cylindrical tumblers that can run different abrasive levels at the same time. So for example, you might have two tumblers running at once and one might hold a rough grind and one an intermediate grind. In this way, you can polish more stones at once. Since rotary tumblers usually have to run for a week or so at each grind level, this is an attractive option for many hobbyists.

However, this type of setup does cost a little more. There is added expense for the tumblers themselves, and on top of that, a unit with a motor that is designed for the extra load of multiple tumblers will obviously be heavier duty and cost more.

This comes down to budget and experience. If you know you already want to polish rocks for the long term and you have the budget, this is a great idea. However, if you’re just starting out, it’s probably wise to go with a single tumbler unit and upgrade if and when budget allows.

If You Go With A Small Tumbler –
Without a doubt, even if you go with a small entry level kit in the beginning, you should always go with a good brand like Thumler. You may pay a little more initially, but you will get something that will actually work and will last a long time. Rock tumbling with a rotary tumbler is a long process. Your tumbler will have to run for weeks at a time, 24 hours a day, while turning heavy rocks and abrasives. This can be hard on motors and other moving parts. A cheap, no name tumbler that was bought in a toy shop, is not cut out for this type of work. The motors will burn out, the tumbler surfaces that are constantly rubbing against surfaces will fail, and the lids of the tumbler’s sometimes leak and cause a mess. Even worse, the leaking slurry can ruin the unit if it gets on the moving parts. (While slurry may sound like a delicious frozen drink, it is actually the term given to the muddy mixture of water and abrasives). At the very least, a leaking tumbler will ruin your rock tumbling project and you’ll need to start over.

A quality brand like Thumler will not have these issues. They are designed to run for the long haul and not leak. So again, even if you go with an entry level kit, be sure to get a quality brand. The small amount you pay upfront will be worth it in the long run.

Maintaining Your Tumbler For A Long Life
One of the secrets to making a cheaper rotary Rock Tumbler last a long time is simple maintenance. Make sure and oil all moving parts on a regular basis. In addition, the cleaning steps you’ll take in-between grind stages are essential. Skimping on the cleaning can cause abrasive to work its way into small areas where it can do damage. Even the best made lids can’t withstand a poor cleaning job that allows grit to build up in the seals. This is another area where a little bit of work pays dividends in your future success.

Heat Buildup – Don’t Do This To Fix a Noisy Rotary Rock Tumbler
Rotary rock tumblers are less expensive than vibratory rock tumblers, but they have to run longer. Each phase of the grinding process might be a continuous week at a time. For this reason, noise can be an issue. You’ll need to place the unit somewhere where the noise won’t be an issue. However, one thing you should not do is close the unit up in a box to try and reduce the noise. Closing the tumbler up like that can cause heat buildup that is bad on the motor. Remember, these motors are turning rocks for weeks at a time. They need all the cooling they can get. It might be possible to build a box that has attached fans, but for the most part, stay away from placing your rock tumbler in a box.

Rotary rock tumblers are a great investment and a joy for adults and kids alike. Make sure and go with a quality name, maintain it just a little, and you will have fun for many years to come. I have quite often talked to people that have had the same rotary tumbler in operation for DECADES by just following that simple advice!

2 thoughts on “The Rotary Tumbler – Everything You Ever Wanted To Know”

  1. Hi Ronnie,
    We have been tumbling stones. We completely wash stones and tumbler after each session of tumbling. On the last (4) polishing tumble. The stones all come out dull. But when you rub them for 15 sec. On a cloth they will shine up. We experimented with ways to shine them up, but still no shine. This has happened over and over again on this stage of polishing. Do we need to leave them in longer then a week? Would like to achieve that wet look. We even did a ivory soap tumble and still no shine. What are we doing wrong?
    We need help.

    • Great question. It sounds like you’ve already done some good work to try and find the problem. The fact that you can rub them on cloth and get a shine sounds to me kike it’s not an issue with the type of rough stone you are using. I would have suggested doing a burnishing step like you did with the Ivory soap, but you did that with no luck. So I would suggest you try and adjust your burnishing step to shorter or longer and see how that helps. One other issue might be the water you are using. If you are getting other stones to polish up nicely then the water should be ok, but if all your rough won’t take a good polish then you might try using distilled water instead of your municipal water. Some city water is a little too “hard” to get a good polish on the stones. Distilled water is pretty cheap by the gallon at your local store. I’d give that a shot too. Good luck!


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