Rotary and Vibratory Rock Tumblers
We polished the six rocks on the left side of this image in a vibratory tumbler and the six on the right in a rotary tumbler. Note the difference in their shape. The rocks on the right are nice and round and the rocks on the left are nice and angular. :) Rotary tumblers "round" the rocks while vibratory tumblers simply smooth and polish them without a major change in their shape.
Rotary & Vibratory Tumblers Explained
[Transcript of the video]
A lot of people ask us: "Should I buy a rotary tumbler or should I buy a vibratory tumbler?" I would like to explain a few things about these two machines, how they work and the differences in the types of rocks that they produce. That should help you make a better decision in which type of tumbler to buy.
The rotary tumbler - you put the rough rocks in a barrel and that barrel slowly rotates on the machine, while it's rotating the rocks in that barrel are rolling and while they are rolling the edges are being knocked off, they are becoming rounded and they are being worn smooth. So the rocks that are produced in a rotary tumbler are going to be rounded.
In a vibratory tumbler instead of slowly rotating it's very rapidly shaking. And, the rocks inside instead of rolling they are rubbing against one another. So the rocks in the vibratory tumbler do not change shape very much. They stay close to the same shape as when you put them in.
Differences in the Polished Stones
Let's zoom in and take a closer look at the rocks.
These are polished rocks produced by the rotary tumbler. Notice how the have been rounded they have a nice rounded shape.
These rocks over here have been produced by the vibratory tumbler. And instead of being rolled they have just been rubbed against one another. And they have retained their angular shape.
So in a vibratory whatever shape the rocks are when you put them in, they are not going to change very much. But in a rotary tumbler the rocks are going to move towards a more rounded shape.
An example of a rotary rock tumbler with 2 3-pound rubber barrels by Thumler's. Rotary tumblers take about four weeks to process a load of rock - one week for each of the following steps: coarse grind, fine grind, pre-polish and polish. Some people run their rocks for two or more weeks in the coarse grind to obtain superbly-shaped gems. Check out our rotary tumblers.
Using Both Types of Tumblers
You can have the best of both worlds. What you can do is tumble step one - the coarse grind step - in a rotary tumbler. That will produce nicely rounded rocks in about one week, then you can do steps 2, 3, and 4 in a vibratory tumbler. Those will only take about two days each, so instead of going one month in a rotary tumbler you can have it done in less than two weeks.
That will save time, it will also save electricity because you will be running your tumbler only a couple of weeks instead of four and it will also save you on grit and polish because the vibratory tumbler uses a lot less grit and polish, maybe half or less as much as the rotary tumbler. And that way you can have the nicely rounded stones that a rotary tumbler produces in a fraction of the amount of time and also at a cost savings.
|Hobart M. King has decades of rock tumbling experience and writes most of the articles on RockTumbler.com. He has a PhD in geology and is a GIA graduate gemologist. He also writes the articles about rocks, minerals and gems on Geology.com.|