что такое рок тумблер
Rock Tumbler Categories
Rock tumblers are made in toy, beginner’s, hobbyist, and commercial grades.
Categories of Rock Tumblers
Rock tumblers are made in many sizes and qualities. Some will tumble just a few ounces of rock, while others can process thousands of pounds of rocks in a single load.
Rock tumblers are made in a wide quality range. Some are designed with the objective of being sold for a very low price. These tumblers might last through a few batches of rocks, but are not designed for long-term use. Some are high-quality machines that can last through decades of regular use, if carefully cared for and gently operated (just as you should treat your automobile), needing only regular cleaning, regular lubrication, and an occasional replacement part.
We believe that most tumblers belong in one of the four groups listed below: toy tumblers, beginner’s tumblers, hobbyist tumblers and commercial tumblers.
The information below is personal opinion, developed after being a rock tumbling hobbyist for over 40 years, owning and using dozens of tumblers, selling thousands of tumblers, and communicating with thousands of consumers.
Each of these tumbler categories has a legitimate place in the market. They target consumers at different spending levels and consumers with different performance expectations.
Toy Rock Tumblers
Toy tumblers are easy to identify. They have a plastic base and a small plastic barrel that will tumble between 1/4 and 1 pound of rocks. When a toy tumbler is running, the rocks impacting the inside of the plastic barrel will produce a large amount of noise.
We believe that toy tumblers have done more to build the reputation that «rock tumblers are noisy» than any other type of tumbler. Much larger beginner’s and hobbyist tumblers operate with a small fraction of the noise.
Manufacturers design toy tumblers with the goal of producing a child’s toy that will sell at a low price. The best way to cut costs when building a tumbler is to use a low-cost motor. A low-cost motor and a low-cost plastic barrel are what you get in many toy tumblers. The motor, the barrel, or a drive train component often fails before a few batches of rocks have been polished.
Should you buy a toy tumbler? I purchased and operated several toy tumblers, so I can give an opinion based upon experience. I believe that most toy tumblers make a lot of noise for an entire month to produce a half-cup of stones that do not have a nice polish. Combine that with their failure rate, and these tumblers are giving rock tumbling a bad reputation. If a person spends a little more money, they can get a much better rock tumbler.
Beginner’s Rock Tumblers
The identifying features of most beginner’s rock tumblers are a plastic base and a small rubber barrel. The barrel is usually large enough to tumble one or two pounds of rocks. They operate with less noise, produce a larger amount of rocks, and produce rocks with a better polish than most of the toy rock tumblers that we have seen.
Their plastic base is not necessarily a bad feature. We purchased several beginner’s tumblers and tumbled several batches of rocks with each of them. Some of these tumblers are well-made, quiet, operate smoothly, produce a nice polish, and last through many batches of rocks.
Replacement parts for beginner’s tumblers are often hard to find or not available. So we can’t say that all beginner’s tumblers will last through many years of use or be used by multiple generations of a buyer’s family.
Marketers often call these tumblers «powerful», «high-capacity», or «heavy-duty». We do not think these adjectives apply to beginner’s tumblers. They belong to machines in the «hobbyist» or «commercial» category.
Hobbyist Rock Tumblers
Hobbyist tumblers are designed and built to last through years of regular or occasional use. They have high-quality metal bases, quality rubber barrels (of at least 3-pound capacity), and quality motors. A hobbyist tumbler will cost more than a beginner’s tumbler, but you get what you pay for.
It is not unusual for hobbyist tumblers to be used by a person in their youth, and then that same person will use the same tumbler with their children or grandchildren. That is the life expectancy of many hobbyist tumblers if they are maintained properly and used gently.
If you need a replacement part for a hobbyist tumbler, they are usually easy to obtain from the manufacturer or by doing an internet search. The cost of a set of bearings can save you the cost of buying a new tumbler.
In our opinion, most vibratory tumblers are built to hobbyist quality levels. They are more expensive to purchase than rotary tumblers. The people who buy them are generally more experienced and are willing to pay the cost of a higher quality machine.
With regular lubrication and common-sense use, many hobbyist tumblers last for decades and across generations of a family. Small hobbyist tumblers usually have three-pound barrels, which is a more worthy amount than what you get with a beginner’s tumbler. Larger hobbyist tumblers have six-, twelve-, or fifteen-pound capacity barrels.
Commercial Rock Tumblers
Commercial tumblers are large tumblers that a company or an individual can use to produce tumbled stones, polish pre-formed cabochons, clean rough stones before sorting, polish ammunition casings, or perform other tasks as part of a very serious hobby or business. The words «high-capacity», «heavy-duty», etc. belong here.
Commercial tumblers are expensive. A small (ten to twenty pound) commercial tumbler will cost a minimum of a few hundred dollars, and a larger commercial tumbler can cost over one thousand dollars. However, the electricity and labor cost for the amount of stones processed is much lower than using small tumblers. People who do tumbling in this quantity are usually collecting their own rough, purchasing rough by the barrel, and obtaining their supplies in large quantities.
The weight of the stones in the large barrel produces a more aggressive tumbling action, resulting in a faster stone processing rate. A strong person is needed to handle the barrels, and a good system for handling the used slurry is needed if you are running these machines.
Rock Tumbler Instructions
Directions for Turning Rough Rocks into Beautiful Tumbled Stones
Rock Tumbling Is Easy
Using a rock tumbler to convert rough rock into sparkling tumbled stones is easy if you follow a simple procedure and observe a few rules. We are writing this to share the procedure that we have used for many years with a number of rotary tumblers.
Chalcedony
agate, bloodstone, carnelian, chrysoprase, jasper, chert, flint, and petrified (silicified) wood.
Quartz
amethyst, aventurine, citrine, milky quartz, rock crystal, rose quartz, smoky quartz, tiger’s eye.
Rock Types
andesite, basalt, diorite, gabbro, granite, mookaite, novaculite, quartzite, unakite.
The «Golden Rules» of Rock Tumbling
«Garbage in Means Garbage Out»
If you start with garbage (low-quality rough), you should expect low-quality tumbled stones. So, don’t hesitate to discard a rock that is porous, fractured, misshapen, or that is not expected to produce an attractive tumbled stone.
You will spend a lot of time and valuable supplies tumbling a batch of rocks. Using quality rough saves time, gives you better value for your money, and produces tumbled stones that are of much higher quality.
We buy lots of tumbling rough from online vendors as part of our hobby and to educate ourselves. We have the best experience buying rough from vendors who: 1) provide clear written descriptions and large clear photos of the rough they are selling, 2) show photos of tumbled stones that they produced themselves from the rock they are selling, and, 3) provide a detailed description of the steps that they followed to tumbled the stones. We have the best experience buying rough from people who are actively involved in rock tumbling.
«Avoid Contamination»
You will use a different size tumbler grit for each step of the tumbling process. If coarse grit gets into your medium grit step, it will scratch up the rocks and you might need to do the medium grit step over again.
Avoiding this type of contamination is easy: just thoroughly clean the rocks, the tumbler barrel, and your tools when you change from one grit size to another.
Another way that contamination occurs is when you include rocks that are brittle, or have a granular texture. These rocks might break or shed grains in the tumbler. These grains and broken pieces can scratch up every rock in the barrel.
Here is a test that we use to detect rocks that will shed grains in the tumbler. We pick up a piece of rough in each hand. We then rub them together while applying a bit of pressure. If we are easily dislodging grains from the rock, we believe that the rock will likely shed grains during tumbling.
This type of contamination is also easy to avoid. Simply examine your rocks before tumbling, and don’t tumble suspect rocks in the same barrel with quality rough. Tumble new types of rough or suspicious materials separately.
«Great Results Take Time»
Don’t be in a hurry. Spend time doing a great job. If you tumble a batch of rocks through the coarse grit step and they still have a few rough edges or are not nicely rounded, don’t hesitate to run them through the coarse grit step again. Also, spend the time needed to thoroughly clean your work area, tumbler barrel, rocks, and tools between steps to avoid contamination.
Inspecting Your Rough
Remember the rule «garbage in means garbage out.» Practice that by starting with quality rough, and you will have a chance to produce high-quality tumbled stones. We prepare to tumble by examining our rough rock. If we find porous pieces that will not make nice tumbled stones and will carry grit from one step to the next, we discard them.
Rocks that are fractured will break while tumbling and scratch other rocks in the batch. When we see a fractured rock in our rough we discard it or break it along that fracture before it is placed in the barrel.
For best results, your tumbler barrel should be loaded with rocks of mixed sizes (from about 1/4 inch up to about 1 1/2 inches in diameter for a 2-pound or 3-pound capacity barrel). If we need more rocks to fill the barrel to the proper level, we often add rocks that were previously polished but have a rough spot or a blemish that, if ground away, will improve the rock’s appearance.
Two final tips before we load the barrel:
The Four Step Tumbling Process
Now you are ready to begin what most people call the «Four-Step Tumbling Process.» This is described below for a rotary tumbler with a three-pound capacity barrel such as the Thumler’s Model A-R1, Thumler’s Model A-R2, Lortone Model 3A, or the Lortone Model 33B.
If you are tumbling with the Thumler’s Model MP-1 tumbler (which has a two-pound capacity barrel), you can follow the instructions below, but use about two level tablespoons of grit or polish in each of the tumbling steps (Step 1 through Step 4).
Loading the Tumbler Barrel
Before you load the tumbler barrel, be sure that it is perfectly clean. There should be no grit or rock fragments left in the barrel from a previous tumble. To prevent leaks, the rim of the barrel and the lid should be totally free from grit or rock particles.
Once you have a clean barrel, add enough rock to fill the barrel about 2/3 to 3/4 full. With small tumblers it is best to tumble rocks that are between about 1/4″ and 1 1/2 inches in size. If you don’t have enough rough to fill the barrel at least 2/3 full, the rocks might be tossed around in the tumbler and bruised. (Varieties of quartz bruise very easily.)
The first step of the four-step tumbling process is to run the rocks in the tumbler with coarse grit. We begin with a barrel that is about 2/3 to 3/4 full of tumbling rough, then add two level tablespoons of coarse grit (we use 60/90 grit silicon carbide) for each pound of rock. Then, add water until the water line is just below the top of the rocks. Seal the barrel and run for about seven days.
At the end of seven days, open the barrel. You will find a barrel of rocks in very muddy water! Dump the contents into a screen or a colander over a plastic bucket and rinse off every speck of grit and mud. Wear safety glasses to protect your eyes from a splash of mud.
Inspecting the Rocks:
Now that you have washed the rocks, it is time to inspect them. Your goal is to determine if they are ready to move on to STEP 2, or if another week in STEP 1 would improve their appearance. We almost always tumble the rocks for a second week in coarse grit. We believe that improves their shape and removes more blemishes from their surface. Then, we usually move all of the rocks to the medium grit step.
Perfectionist Tumbling:
Here are some rocks right out of STEP 1. Note how they are covered with a gray «mud.» This mud is spent grit and tiny rock particles that were worn off of the rocks during tumbling. Wash the rocks thoroughly so none of this grit goes into STEP 2. We wash our rocks in a colander over a plastic bucket so none of the mud goes down the drain.
IT IS VERY IMPORTANT TO WASH THE MUD FROM THE ROCKS IMMEDIATELY. If the rock mud is allowed to dry on the rocks it is almost impossible to wash off.
The second step of the four-step tumbling process is to run the rocks in the tumbler with medium grit. Before you begin it is extremely important to clean all of the coarse grit and rock mud from the rocks, from the tumbler barrel and from the barrel lid. It is very important to avoid having even a few grains of coarse grit in the medium grind step.
During the STEP 1, your rocks were reduced in size. When you return them to the barrel for STEP 2, they will probably not fill the barrel to the recommended 2/3 to 3/4 full level. If the barrel is only 1/2 full or less the rocks can be tossed violently around in the tumbler. See the accompanying video. This can break or damage fragile materials such as quartz. So, when tumbling quartz or another fragile material we always add enough ceramic media (or some rocks that need a little more tumbling) to bring the barrel up to the 2/3 to 3/4 full level.
(This is less important with varieties of chalcedony because it is more durable material. However, if your tumbler barrel travels at more than about 60 revolutions per minute, we recommend adding enough ceramic media to bring it up to the 3/4 full level reguardless of what type of rock is being tumbled.)
After your barrel is at the proper level, add two level tablespoons of medium grit (we use 110/220 grit or 150/220 grit silicon carbide) for each pound of rock (and ceramic media). Then add water until the water line is just below the top of the rocks. Now tumble for seven days.
At the end of seven days, open the barrel and clean all of the grit from the rocks, barrel, and lid (don’t let any grit go down the drain). At this point in the tumbling process, a dry rock should have a smooth frosted surface. Inspect the rocks, looking for any that are cracked or broken. If found, they are discarded or saved for the next time we run Step 1.
The third step of the four-step tumbling process is a week in a fine grit such as 600 grit or 500 grit silicon carbide. Begin with a barrel that is perfectly clean. Place your rough and any ceramics that are with them into the barrel, and add two level tablespoons of fine grit per pound of material. Then add water until it fills the barrel up to just below the top of the rocks. Run this for about seven days, and then do a thorough cleaning of the rocks, the barrel, and the lid.
Remove any rocks that have broken or show signs of fracturing. At this point in the process, the rocks should be extremely smooth, and some of them might display a slight luster.
Place the rocks in the barrel and add two level tablespoons of rock polish (we use TXP aluminum oxide powder for almost all of our rotary tumbling) per pound of material in the barrel. Add water to just below the top of the rocks. Then, close the barrel and run for about seven days.
When you finish this step, your rocks should be bright and shiny. If they are, congratulations! Admire them for a while and share them with your friends.
If the stones have an extremely smooth surface but do not shine, they might need cleaned up using the burnishing step described below. If they have scratches on them, then you will need to go back to STEP 2 and repeat the medium grind, fine grind, and polishing steps.
Burnishing
Sometimes our stones are a little «hazy» when they come out of the polish, or small particles of polish are in micro-size crevices. We shine and clean them up by tumbling for an hour or so in soapy water. This is called «burnishing.»
Keeping Records
To help you with your record keeping, we have prepared a printable tumbling log.
We usually have multiple tumblers running here and we record every barrel of rock that we tumble on these logs. Even if your memory is better than ours, record-keeping is a good idea. When you learn something that works or something that doesn’t, you will have it recorded. This information can help you repeat great results and avoid repeating bad ones. Also, we have trouble remembering which day a barrel of rocks was started. Using the log takes away the chance of forgetting.