Rock Tumblers » Vibratory Rock Tumblers
Vibratory Rock Tumblers
Vibrating tumblers polish rapidly without rounding the rock
What is a Vibratory Tumbler?
Vibratory tumblers are small machines designed to polish rocks, small metal objects and other items with a rapid vibrating action. They consist a small vibrating machine and a bowl that mounts on top of it. They are commonly used to polish tumbled stones, preform cabochons, beads and sawn slab pieces.
How Do Vibratory Tumblers Work?
Rough rocks, abrasive grit and water are placed in the bowl on top of the vibrating machine (see photo at right). The bowl is filled close to capacity with rock. Grit and water are added (see the instruction manual of your tumbler to determine the proper amount of grit and water). A lid is then placed on the bowl, the lid is secured and the vibrating machine is turned on.
The bowl vibrates rapidly and that action produces a lot of friction between the vibrating rock particles - this is why a vibrating tumbler works quickly.
The rocks do not "tumble" in the bowl but a circulating action develops that moves rocks from the bottom of the bowl up to the surface along the outside edges of the bowl and then back down to the bottom along the center post (see photo at lower right). The tumbling action of a rotary tumbler that rounds the rocks is not produced.
The rough grind step is run for about a week. The fine grind, pre-polish and polishing steps are run for just one or two days. The total time required to process a batch of rock is about two weeks - about 50% less time than a rotary tumbler.
Some vibratory tumblers are sold with two bowls - one for the grinding steps and one for the polishing steps. If you only receive one bowl it might be a good idea to buy a second bowl. Silicon carbide grit from the grinding steps can become embedded in the walls of the plastic bowl and scratch the rock during the polishing steps.
Advantages of Vibratory Tumblers
The main advantage of a vibratory tumbler is that it has the ability to polish rocks and other objects very quickly. A rotary tumbler will require several days to do the pre-polish and polishing steps for a batch of rocks but a vibratory tumbler can do each of these steps in just one or two days. This speeds production. A final advantage is that the vibratory tumbler subjects the rocks to less impact than a rotary tumbler. This gentle action is important when you are tumbling stones that break or bruise easily.
Disadvantage of Vibratory Tumblers
The disadvantage of a vibratory tumbler is that it does very little to change the shape of the rocks. It simply smooths their surface. If your goal is to start with crushed rock that is angular in shape and produce nicely-rounded gemstones then a rotary tumbler is the better machine to buy.
Producing Rounded Tumbles Quickly
Many people who process a lot of tumble-polished rocks run the grinding steps in a rotary tumbler and the polishing steps in a vibratory tumbler. The rotary tumbler shapes the rough into nicely rounded shapes and the vibratory tumbler speeds them through the polishing steps. Production time can be cut by 40 to 50 percent.
Polishing Preforms and Saw-Cut Shapes
Many people also use a vibratory tumbler to put the final polish on hand-cut cabochons or to smooth and polish saw-cut beads and other shapes. These need very little shaping - just a smoothing and final polish.
Go back to the article Selecting a Rock Tumbler.
|This is a Thumler's Ultra-Vibe 10 vibratory tumbler. Up to ten pounds of rock can be processed in the bowl. A motor in the base causes the bowl to vibrate rapidly. That vibration produces friction between the rocks in the bowl to produce the grinding and polishing action.
| A Lot-O-Tumbler vibratory tumbler. Up to four pounds of rock can be processed in the black rubber barrel. The motor causes the barrel to vibrate at a rate of thousands of vibrations per minute. The Lot-O-Tumbler can process a load of rock from rough grind to polish in under one week..