What Happens in a Rock Tumbler?
In this video we replace the lid of a Thumler’s MP-1 rotary tumbler with a piece of
glass to show what happens in the barrel with various amounts of rock.
The amount of rock placed into a rock tumbler barrel is very important. Too much rock
does not allow enough space for tumbling to occur. Too little rock results in ineffective tumbling.
The ideal barrel level is 2/3 to 3/4 full.
Barrel 2/3 to 3/4 Full - Great Tumbling Action
This is the right amount of rock. Notice how the rocks are lifted up the right side of
the barrel and then tumble downslope to the left. There is plenty of space above the
rocks to allow a tumbling action.
Barrel Too Full - No Tumbling Action
If you fill the barrel more than ¾ full there is not enough space in the barrel to allow
a tumbling action. In the video you can see there is very little tumbling. The rocks
stay in the same place as the barrel turns.
If you fill the barrel too full and tumble for seven days you will open the barrel and
find that your rock have not changed very much and your grit has not broken down.
Filling the barrel too full will also put stress on the tumbler motor, tumbler belt and
tumbler bearings, reducing their useful life.
Barrel Not Full Enough - Damaged Rocks
If you run the rock tumbler with less than about ½ barrel of rock the rocks will be
violently tossed around. This can result in bruised and chipped stones. Also the
jerky motion will be hard on your tumbler’s bearings, belt and motor. And, notice how
much noise the tumbler is making. If you hear rocks crashing in the barrel you know
that you don’t have enough rocks in there.
Tip: If you don’t have enough rocks to fill the barrel to the proper level we recommend
filling that extra space with large ceramic pellets. Ceramic pellets are a great cure
for a rock tumbler’s impatience!
Happy Tumbling!  |
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Rough rock crushed to size and ready for the rock tumbler. |
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The tumbler used in the video above is the Model MP-1 by Thumler's Tumblers. It is sold as a kit with everything that you need to tumble one batch of rocks and make two jewelry projects with your tumble-polished gemstones. |
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