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Rock Tumbling FAQ

Posted November 4, 2013 By Admin

Rock Tumblers are one of our biggest sellers but you may have questions – see the FAQ below and it is very likely you will find an answer.


Time varies but when using a standard rotary (barrel) tumbler, it can take around 4 to 5 weeks of continuous operation. It is usually a 4-step process:- coarse grind, medium sand, fine sand and polish and it often takes around a week per step.


Tumblers are a great way to get started in the lapidary hobby – the process is quite simple and although it takes some time, kids love the end product. An excellent way to learn more about our natural environment.  See this blog article for more info on starter kits.


Apart from a tumbler, you will need silicon carbide grit, some suitable rock polish and a supply of rocks. The silicon carbide comes in a range of grits from coarse to fine. We sell starter kits of grit/polish – Kits A or B are good for about 3 or 4 batches in a 3 pound tumbler.  All components in the kit are available separately so you can restock as needed.  Rocks are readily sourced from the beach, creeks/rivers or keep an eye out for suitable tumbling rock at your local gem show.  Tumblers are listed with optional starter kits or as a complete package deal – just browse here for rotary tumblers of various size.


Some people use coarse river sand instead of silicon carbide grit to grind their rocks. This method can work after a fashion but it takes a lot longer (ie. more electricity) and you have much less control over the process. We do not recommend this method.  Silicon carbide grit is relatively cheap and works much better.


The smaller Lortone tumblers only have a very small motor – they do need to run continuously but they use very little power. The 3A and 33B tumblers have a 0.33 Amp motor – based on 230V power supply and cost of electricity of $0.315 per kW hour, running 24 hours a day will cost around $4 per week.  This is slightly less than leaving an 80 Watt incandescent light bulb on 24 hours a day.  Cost of consumables run at around $2 to $2.50 per week or less if you buy in bulk. If you collect your own rocks, this is a very cheap hobby.


While vibratory tumblers can be quite noisy, the Lortone rotary tumblers use a solid rubber barrel which is extremely quiet. The 3A  has been measured at around 55 decibels which is at the lower end of normal conversation. If you put your tumbler in the garage, you probably wont hear it running at all.


Aussie Sapphire provides full warranty support – the warranty period on tumblers is 12 months and is handled at our NSW office/workshop. In many cases, we can remotely diagnose and provide parts – sometimes it is required to send the machine back for assessment. Warranty issues are rarely experienced – these machines are robust and reliable.  We keep a full range of spares and accessories in stock.


Rotary machines are quite simple and there is not much to go wrong. We recommend oiling the shaft bearings with a light machine oil (Singer Sewing Machine Oil or similar) – just a drop or two every 30 days of operation. At some point you will have to replace a drive belt – these only cost a few dollars and should last up to a year or more depending on usage.


This depends on what size tumbler you buy. A 3 pound tumbler has a barrel of about 10cm diameter and 10cm depth – you fill the barrel up to 3/4 full of rocks so your rocks need to be small enough to move freely within that barrel size. It is a good idea to have a mix of sizes to optimise the tumbling action. If your rocks are larger, then you need to move up to a larger size barrel. Dimensions of the various barrel sizes are provided in the listings. A good rule of thumb is to tumble rocks that are no larger than half the diameter of the barrel along with a generous mix of smaller rocks – probably only one or two of these larger rocks – remember you need sufficient room for the rocks to tumble and grind.


These are very different – if you are just starting out in rock tumbling, we generally recommend a rotary tumbler as these are easier to use for beginners and do not require as much monitoring during use. Vibratory tumblers work faster, use less consumables (grit/polish) but require checking twice daily to monitor correct slurry consistency. Rotary tumblers are slower but can be left to work without fuss between stages and are generally much quieter during operation.


For rotary tumblers, we recommend two starter kits – A or B. Both kits contain the same 3 grades of silicon carbide grit (500 grams each of #80, #220 and #600) – you normally use about 3 to 5 tablespoons of grit per kilogram of rock. You do need to throw out the silicon carbide slurry after about a week of grinding – it is not toxic so you can dry it and throw out in the garbage.

Kit A has 250 grams of Cerium Oxide polish – this one is good for rocks around hardness 6 to 7 which includes the quartz group (petrified wood, jasper, agate, amethyst, etc) or glass (natural or man-made). Kit B has 250 grams of Tin Oxide which is more general purpose and works well on harder rocks such as garnet or topaz as well as the softer rocks – it also contains an additional pre-polish step (500 grams #1500 Alumina) which can help if you are having trouble getting a good polish.  Note that you can recycle polish slurry a few times before discarding.

Both Kit A or B should do around 3 or 4 batches in a 3 pound tumbler. They also contain a small packet of plastic pellets which are used as filler in later stages.


Tumblers are great for metal polishing – we sell many tumblers (both rotary and vibratory) for this job. The most popular tumblers for polishing silver jewellery is the Lortone 3A or the Gyroc Model B. Larger tumblers are generally preferred for polishing brass for reloading. You need different media for working with metal – for polishing only, we recommend stainless steel shot and burnishing compound.  This blog article has more information on using the 3A for polishing jewellery.


We post every day. Note that due to the heavy weight of these items, courier delivery is via Star Track Express – this is a road service and is NOT necessarily faster to some locations. If you need your tumbler in a hurry, please check with us first but it is better to plan your purchase allowing for postage time. You can check postage cost by adding item(s) to the shopping cart and using the shipping estimator on that page – you can do this any time.   We have a range of payment options to suit you – select at the checkout from Visa/Mastercard, PayPal, Bank Deposit or Cheque/Money Order.

Do you have even more questions?  You are bound to find the answer in one of the following websites:


Info about Stainless Steel

Posted January 31, 2013 By Admin

Stainless steel is an important material in the lapidary industry so we thought it might be a good idea to go over some information to help you understand more about it.

Stainless steel is an alloy of steel with a minimum content of Chromium (at least 10.5%) – there are a range of different alloys available which are designed for different jobs and have different properties.  The commonly used alloys have a chromium content of around 18% but content of other metals (notably nickel) varies and does alter physical properties of the steel. When comparing between products or suppliers, it is a good idea to know exactly what you are purchasing.

IMPORTANT: Although Stainless Steel does not readily corrode, rust or stain with water like carbon steel, is CAN rust or discolour under certain types of conditions (namely high humidity, salinity, etc). A more accurate name would be stain-resistant steel – not quite as catchy but it would alert people that you still need to take care of your stainless steel products. Important warning: do not mix stainless steel and carbon steel shot when tumbling – the carbon steel shot may contaminate the stainless and cause rusting.

The 3 most common types of stainless steel we would normally encounter are as follows:

  • Grade 202 – low nickel alloy with less corrosion resistance compared to the 300 series alloys (less common in Australia)
  • Grade 304 – General Purpose; the most common grade with good corrosion resistance for most jobs
  • Grade 316 – Marine Grade; more expensive but recommended where high corrosion resistance is required

The two main products we stock that are made of stainless steel are the Stainless Steel Shot (mixed shapes) and various sized cabbing arbors.

Stainless Steel Shot for tumbling - Aussie SapphireIt is important to note that our Stainless Shot is made from Grade 304 with accompanying certification tests from the manufacturer.  We have noticed some other suppliers selling Grade 202 shot – if made from 202, then it SHOULD be cheaper and will be less rust resistant. When comparing prices, be aware that these products are NOT the same.

We do recommend that whatever grade of steel your shot is made from, it should either be stored completely dry OR completely covered by shot storage solution. If you store your shot in a sealed container when it is still damp, even stainless will rust under these conditions. If you notice some discolouration on your stainless shot, then quick action can retrieve the situation if you wash it thoroughly in a weak acidic solution.

More info in the link below:


Stainless Steel Arbors - Lortone - Aussie Sapphire


For your reference, our Lortone Stainless Steel arbors are made from Grade 304 stainless with grade 416 shafts for maximum strength. This gives the best combination of corrosion resistance and strength – they are more expensive than the power-coated classic options but you know you are buying long-lasting quality.

Even so, we always recommend wiping down your arbor after each use to keep it in top-top condition. Cleanliness when cabbing or faceting is a good habit to get into – it helps protect your equipment and significantly reduces the chance of scratching occuring due to rock dust/diamond contamination.


See these links for further reading:

Hope this information helps clarify some issues around stainless steel – if you have any other queries, feel free to contact us any time.

Cheers from the Aussie Sapphire team