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Gyroc Tumblers – How Much Shot?

Posted August 20, 2011 By Admin

The Model B Gyroc Tumbler is a really popular tumbler for jewellery makers – this fast and reliable tumbler is an ideal size for polishing small batches of gold or silver jewellery.  However, it can be difficult to know exactly how much media to use – we get quite a few enquiries on this so thought we’d take a few photographs to help you out on this issue. Please click the link below to see these photographs and rest of the article.

Vibratory tumblers tend to work best when they are filled quite full – for best results you can fill the bowl up to about 15mm from the top.  However, if you use a very heavy media such as stainless steel shot, you run the risk of overloading the tumbler if you add too much.  So if you want to use shot as your polishing media, you need to compromise between adding enough to polish well but not so much that it overloads your tumbler motor.

The Gyroc Model B is rated as a 3 pound tumbler – this means you should try and keep the maximum weight under 3 pounds if possible – ie. when the bowl is loaded with parts, media and water, the total weight should not exceed 1.4kg.

If you buy your stainless steel shot from the USA, you will often find that it is sold in 1 pound lots – this is about 450 grams and in my opinion, is not enough to do the job properly.  Please note that there should be no need to buy your shot overseas – our prices are really competitive so please check before you pay expensive freight costs.  I feel that 1kg is a much more appropriate amount – perhaps even a little bit more.  View the photos further down in this article to see what I mean…

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Coin Tumblers

Posted August 16, 2011 By Admin

One really popular hobby is metal detecting or treasure hunting.  It can be really fun to see what you can find with a metal detector and in some cases, can be financially rewarding as well.  While the big noise is usually about gold, many detectorists do well by searching for coins at beaches and other places where people tend to lose small change.  Got to be a win-win situation – a hobby that makes you money instead of costing 😉

One issue when finding coins is that they get very dirty after a long period in the ground.  These usually need to be cleaned up before you can spend or bank them – a rock tumbler is ideal for the job, particularly when you want to do a large batch.  If the coins are particularly discoloured, some banks may refuse to cash them in and want to send them to the Mint first for evaluation.  If you clean them up first, you can cash them in without any fuss.

CAUTION:  do NOT tumble any coin which may be valuable!

I cannot emphasise this enough!  Coins which may be rare or valuable should be left as they were found until you get expert advice.  You will destroy value if you clean a rare coin inappropriately.  The following advice is recommended for current legal tender which is worth face value only and intended to be spent or banked. Note that there are some rare and collectible decimal currency coins – check your dates so you dont make a costly mistake.

What type of tumbler?

Most rotary tumblers are very suitable for this job – just need to pick which size works best for you.  The 3A or 33B Lortone tumblers are ideal, well priced and very reliable.  The 3 pound barrel of these tumblers can take around 850 to 900 grams of coins, water and tumbling media – ie. the loaded weight of the barrel should be no more than 1.4kg total (including the barrel which weighs around 475 grams).

Cleaning Coins

There are a number of recipes for this job and most will work.  Try a few out and see what works best for you.

A few things to note:

a)  Separate your coins into different types – do not tumble a mix of copper coins, clad coins (“silver” coloured coins) and “gold” coloured coins like our $1 and $2.  Separate them first.

b) Dont tumble for too long – this can wear detail and make them look unnaturally clean or a strange colour – you are just cleaning them up well enough to spend so dont go overboard.

c)  You can try a few different types of media – often a bit of coarse river sand in with the coins will work well to remove crusted-on dirt.  Some use gravel or pebbles for a similar effect.  Add enough water and a small amount of detergent to allow the coins and media to tumble well.

Some add a little vinegar and/or salt but essentially, the tumbling action with a gentle abrasive will normally work well enough without getting too fancy with the recipe.  Check the links below for other suggestions.

Alternatively you can just use the standard metal polishing method of tumbling with stainless steel shot and burnishing compound – if the coins are extremely tarnished or dirty, you may need a more abrasive media but for just routine cleaning, this method will work well without fuss.

LINKS OF INTEREST:

See here for links to further information.

Hope this article was of interest.   Good luck while treasure hunting and cheers from Aussie Sapphire.