TUMBLING MACHINES

- AND TUMBLING

Tumbling semi-precious stones makes an enjoyable and rewarding hobby. Whether you collect pebbles on the beach or purchase rough samples of more exotic gemstones you will be constantly amazed at the wonders a tumbling machine works! The stones go in as dull and perhaps angular pieces and come out highly polished.

So how does the process work? The first thing you need is a tumbling machine. These act like small cement mixers, continually churning their contents.

Stage 1. You put enough stones in to fill the drum 2/3 or 3/4 full, add 80 grit silicon carbide abrasive powder (about 1oz per 1 lb or 30 gms per 500 gms of stone. The mixture is covered with water, the lid of the drum replaced and the machine set in motion. Ideally the tumbler should run continuously (the amount of power consumed is very small, less than that used by a small light bulb).

At the end of a week open the barrel, wash the stones and check that they are all smooth. If so go on to stage 2. If the stones need further grinding replace in the drum with a fresh charge of grit and water and run for another week. This is where a tumbler with two barrels is an advantage : half of the load can carry on tumbling with 80 grit whilst the other half goes on to stage 2.

Stage 2. With both stones and drum thoroughly rinsed the drum is charged with a fine 400 grit silicon carbide and, again, the contents are covered with water. This tumbler runs for a further week, after which time the drum and stones are once more rinsed clean. Then on to the final stage!

Stage 3. This time a similar charge (1 oz per 1 lb of stone) of the polishing compound Cerium Oxide is added, again with water, and the tumbling process continued for 3 days. By this time your stones should be perfectly polished! The polishing compound, unlike the abrasive grits, can be used over and over again. Rinse it off the stones into a basin, let it settle out and save it for the next load, perhaps adding a little fresh compoiund to make up for any losses.

Beach Lapidary Tumblers  

We stock the two Beach machines shown above. Both come with a comprehensive instruction sheet and a 5 year guarantee.

Beach Spares

Evans Tumblers

We stock the Evans Junior tumbler and the very sturdy Evans CR1 tumbler. Both are available with either two plastic 1½lb barrels, one plastic 3lb barrel or a 3lb rubber barrel (although more expensive rubber barrels tend to be quieter in operation).

Evans Spares

Grits and Polish People use a variety of "recipes" for tumbling, but to start off we would recommend two grits (80 and 400 grades) and cerium oxide polish.

At the polishing stage many people prefer to add an inert "carrier" to cushion the stones as they are tumbled to that final high sheen. The polishing slurry tends to be thinner than the grinding slurry and some stones may frost as they contact other stones. We have bags of white plastic pellets which offer just the right amount of cushioning. The bags contain 250 gms of pellets, and the pellets can be used over and over again. Bags of pellets                          £1.25

Rough Stone for Tumbling
We have bags of rough stone crushed ready for tumbling in three mixes : A is an agate mix (agate, jasper, chalcedony), B is a quartz (rock crystal, amethyst, rose quartz, aventurine) and C a soft mix containing materials like malachite, sodalite, Connemara marble etc. etc.

Bags contain approximately 700gm and cost £6.00 each. (Please note : contents may vary.)

For more information about the tumbling process we can recommend 

"How to TUMBLE POLISH GEMSTONES and make tumbled gem jewelry" by Jerome Wexler.
This has 32 large format pages of information, diagrams and photographs, many in colour.   £3.50

All prices are + postage and packing (This costs £9.00 within the United Kingdom for a tumbler and set of grits and polish, and £9.50 for a tumbler, grits and up to 2 bags of rough stone. We will be happy to quote for mailing costs overseas).

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