Rock Tumblers are a great way to start into the Lapidary game - they are easy to use and one of the cheapest ways to polish gems. But the choice can be confusing - below is some information to help you choose the most appropriate tumbler.
Tumblers are not just used for polishing rocks - they have many other uses in polishing and burnishing jewellery (Gold and Silver), brass items such as gun cartridges and other metal parts (from cutting to final polish). Mass finishing of many manufactured products actually uses a tumbling process.
WHAT TYPE ?
Tumblers come in two basic types : Rotary and Vibratory. Each have their place and we suggest you consider the table below carefully to decide which might be best for you.
|ROTARY advantages||VIBRATORY advantages|
|ROTARY disadvantages||VIBRATORY disadvantages|
In Rotary Tumblers, we stock and recommend the Lortone range - these are made in the USA from a simple, robust design and are designed for years of continuous operation. The Lortone tumblers use a small 240 Volt motor to drive a shaft via a belt & pulleys to continuously rotate the barrel. Lortone barrels are made from long wearing rubber with a well designed screw-down lid (no clumsy O-rings) that works well and is designed to prevent leakage. They are simple to operate.
Currently we offer Thumler Ultravibe and Diamond Pacific Mini-Sonic Tumblers (by special order) - mechanical and the newer type utilising a magnetic vibration system. The cheaper Tumblevibes are suitable for light-weight hobbyist use only while the Thumler are extremely popular and long-lasting. Gyroc (Gy-Roc) tumblers are another popular brand but are no longer available in 230 Volt motors for Australia. Both types have an electric motor which drives an eccentric weight to cause the tumbler bowl to vibrate. The Thumler range is very reliable and versatile with a range of sizes to suit all jobs. The newer Mini-Sonic tumblers from Diamond Pacific use a type of ultra-sonic vibration to process the material which has the advantage of no moving parts to wear out.
When choosing a rock tumbler, you need to consider a few main questions:
- Amount and Type of material to be tumbled?
- Are you in a hurry? - rock tumbling is a slow process but some tumblers are faster than others.
- What is your budget?
- Do you have time to monitor the vibratory type of tumbler?
TUMBLER CAPACITYTumblers come in a range of capacity which represents how much material can be tumbled in a batch. It is important to consider this carefully as tumbler barrels or hoppers need to be loaded correctly (usually between ½ and ¾ full) for best results. Choosing a tumbler with too small a capacity tends to lead to overloading and frustration. A larger Barrel can always be used for smaller lots by adding some cheap Plastic Beads as a Filler. Barrel capacity is usually quoted in pounds but usually better to think in terms of volume. Please click here for document for information on size dimensions and volumetic capacity.
Some tumblers offer the use of two barrels at once so you can tumble more than one batch at a time,this speeds the process up greatly. Can use just one Barrel on these if desired but you have the option of doubling your output. Generally, two barrels are better value but many are quite happy with just one.>
TYPE OF MATERIAL TO BE TUMBLED
A whole range of items can be tumble polished and generally any type of tumbler will do a similar job on polishing. The difference is that rotary tumblers will smooth and round your stones while a vibratory tumbler will polish them in their existing shape. If it is important to retain the original shape of the item or if the items are very delicate, you probably need a very gentle polishing action rather than the grinding action of traditional rotary tumbling.
In these cases, we would recommend the Thumler Ultravibe tumblers or similar machine.
SPEED OF ACTIONTraditional Rotary tumblers are generally quite a bit slower than the newer Vibratory tumblers. Keep in mind that even with the slightly faster vibratory tumbling, it can be still quite a slow process. Total time required will depend on a number of factors such as hardness/smoothness of material, type of abrasives used, etc. However, all other things being equal, you should get a significantly faster result with a Vibratory tumbler.
Generally, rotary type tumblers are cheaper but use more Media ( Grit ) than vibratory tumblers so if speed of operation is of lower priority, a rotary tumbler may be a good choice. The Vibratory tumblers will work faster and use less Media.
We get a lot of enquiries from people wondering about buying a tumbler for their children. This is a great way of getting young people interested in the hobby of rock collecting and gems although they do need to understand that it will take some time to achieve the final result. However, we do not recommend the very cheap rock tumblers aimed at this market - these are usually not strong enough (both in construction and in the motor) and often do not last very well at all. In these cases, we would suggest a cheaper rotary tumbler that will last and work well - if it proves not be a lasting interest, these types will be easily sold to someone else.
OTHER ISSUESWhen purchasing a tumbler, you will need to get the basic kit of abrasive grit so remember to add this to the total price - these start from around $35. We offer a complete range of "Starter Kits" and larger lots of Polishing Media for almost any use. You will also need material to tumble - perhaps you have a pile of stones gathered from fossicking trips that are just waiting for some attention. If you can find a gem club or some local experts, this is a great resource that will help you work out the finer points of the process.
Hopefully these notes have been helpful in making the right choice. Also, we suggest you check out these links for other opinions on tumbler types:
Selecting a Rock Tumbler - Geology.com
Before you buy a Rock Tumbler - About.com:Chemistry
Tumblers FAQ from Dads Rock Shop
Ready to Buy?? Check our range in the Tumbling Category.