The short answer: Using a rock tumbler to convert rough rock into
polished stones can take as little as one week or about one month. The amount of time mainly depends upon the type of
tumbler that you use and how picky you are about producing nicely-rounded stones.
There are two types of tumblers in common use by people who do
rock tumbling: Rotary tumblers (see image at right) and vibratory
tumblers (see image at right below).
Rotary Tumblers - About Four Weeks
Most people who do rock tumbling use a rotary tumbler. With the
typical rotary tumbler you seal your rocks in a soft rubber barrel
with a grinding compound known as "tumbling grit" and a little water. The barrel then rolls
on the tumbling machine for about a week and the rocks tumble
inside of the barrel.
Most rotary tumbling is done using a four-step process with two
grinding steps, one pre-polish step and one polish step. Each of
these steps takes about one week. So, rotary tumbling generally
takes about four weeks.
Some people who want superbly-shaped tumbles run the rocks in coarse grit for two or more weeks. (We want really pretty stones so we inspect every rock after the first step and rerun any that have imperfections that could be tumbled out.)
Vibratory Tumblers - About One Week
Most vibratory tumblers have a bowl that is rapidly shaken by a
motor. This shaking produces a lot of friction between the rocks
in the bowl and results in a rapid removal of material.
Most vibratory tumblers are run for 12 to 24 hours with a fine
grit and then the spent grit and mud are washed from the rocks.
This step is repeated until the rocks are nicely smoothed. This will
take a few days depending upon the type of rock and their starting condition.
The rocks are then processed one day with pre-polish, and one or two
days with polish. So, vibratory tumbling generally takes about one week.
Why then doesn't everyone use a vibratory tumbler? The first reason
is that a vibratory tumbler costs about 50% to 100% more than a rotary
tumbler. The second reason is that the grinding step of a vibratory
tumbler "smooths" the rocks but does not "round" them like a rotary tumbler does
(see rock photo at right). People who like rounded rocks use a rotary tumbler. Those who like angular rocks use a vibratory.
Rotary Tumbling Followed by Vibratory
Many people use both rotary and vibratory tumblers to tumble-polish rocks.
They begin by running the rocks one week with coarse grit in a rotary tumbler.
This first rotary step rounds the rocks.. They then finish the rocks with three
steps in a vibratory tumbler.
This rotary followed by vibratory process produces nicely-rounded rocks in less than two weeks.
If you run a rotary machine and a vibratory machine at the same time you can produce a new batch of finished stones every seven days. A Lortone QT12 rotary tumbler, if run continuously will produce enough rounded rock to feed a single Lot-o-Tumbler vibratory machine.
Happy Tumbling!  |
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 | An example of a rotary rock tumbler with a 12-pound rubber barrel by Lortone. 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. |
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An example of a vibratory rock tumbler with a 4-pound rubber barrel by Lot-O-Tumbler.
Vibratory tumblers process a load of rock in one week or less.
Check out the Lot-O-Tumbler. |
| We polished the six rocks on the left side of this image in a vibratory tumbler (we used a single Lot-o-Tumbler) and the six on the right in a rotary tumbler (we used our favorite - a Lortone Model QT6). 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 "smoothe" them. We sell tumbled gemstones! |
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