Diamond Saw Blade Types

Posted February 26, 2017 By Admin

Have had a few questions recently about the different types of saw blades so thought it worth a post.

Essentially, there are three main types of diamond saw blades used in the lapidary field – all have their pros and cons.

A) Sintered Blades

Sometimes referred to as Continuous Rim Blades, these blades are more expensive but tend to be longer lasting and offer better performance. Sintered blades are made embedding diamond particles in a metal bond around the rim of the blade – the diamond extends through the full depth of the rim and so as the metal bond rim wears away, new diamond particles are exposed and keep the blade cutting.

These blades are available in premium or economy versions – the manufacturing process is essentially the same but a premium blade will be better quality.  Please note that even though the sintering process will give a more durable blade, they can easily be damaged by incorrect usage (insufficient cooling, rock jams, etc).

For smaller blades, the sintered metal bond rim will be continuous around the whole rim while for larger blades (say above 16″ diameter), there may be sections cut out along the rim to improve coolant flow and debris removal – these are called Segmented Blades.

The 301 Gemking Blade made by Barranca/MK Diamond is often called a Notched Rim Blade but this is a bit misleading.  This one is still a sintered blade but the deep notches along the sintered metal bond rim allow for better coolant flow. This blade is designed for cutting of harder material but MUST be used with oil – water should not be used with these blades. This blade is just a slightly different type of sintered blade.

As the diamond particles are embedded in a metal rim, over time the surface of the metal bond can glaze over the diamond particles and affect cutting performance.  If you feel that the blade is not cutting as it should, we recommend “dressing” the blade by cutting into it a few times with an abrasive material (ie. dressing stick, old silicon carbide wheel, house brick, etc).  This process re-exposes the diamond particles allowing the blade to cut properly again.

B) Notched Rim

A classic notched rim diamond blade is made by pressing diamond grit into the edge of a solid steel core – the process leaves small notches along the rim where the diamond works to cut the material.  This is a much cheaper process compared to sintering and so these blades are generally much cheaper.  They will not last as long but are very low cost for those on a budget.

They can be made very thin which can be useful for those cutting material where you want minimal wastage.  The notches can be very thin or slightly thicker as shown in the photo at left but there will be less diamond to work with compared to a sintered blade so factor this in when considering a blade of this type.

Like the sintered blades, these ones can be dressed if they appear to be slowing down but do this only as needed as these blades are nowhere near as durable as a sintered blade.

C) Electroplated 

Electroplated blades are made by electroplating a thin layer of diamond usually in a nickel metal bond on to the surface of the steel blade. As the diamond is only adhered in a very thin layer onto the surface of the blade rim, these blades are not as durable as a sintered blade.  They are generally quite a bit cheaper than a sintered blade but will not last as long – we do feel that they are better quality than the very cheap pressed Notched Rim blades though.

One advantage is that they can be made very thin so may suit applications where you want minimal wastage of valuable material.  They have also proved popular with our glass customers as a blade that cuts clean with less chipping. Generally not available in very large diameter blades and not suitable for slab saw applications.

These blades should NOT be dressed – this will just wear them out with no benefit. Make sure you are using plenty of coolant – the diamond will rip off in seconds if these blades are used dry or with insufficient coolant.

These are the three most commonly available lapidary saw blades – there are a few other less common types suitable for specialised applications (eg. CBN blades for cutting meteorites or iron-rich material).  Please consider your usage and available budget when selecting a diamond blade.  The three most important specifications are blade diameter, blade thickness and bore size (ie. centre hole) – please note that these measurements are usually quoted in imperial measurements (inches).

If we can assist with any advice, please email us any time.

     

Gyroc Model B – what’s the problem??

Posted September 17, 2015 By Admin

The Gyroc Model B has been the workhorse machine in many jewellery studios for many years – the smallest 3 pound model is an ideal size for the small scale polishing requirements of jewellery makers.  While the 3A Lortone Rotary tumbler is a similar size and also a fantastic machine for the job, we do find that there are a lot of people out there who learned to use a vibe tumbler and prefer to continue with the method they are familiar with.

Unfortunately, the manufacturer of the Gyroc Model B can no longer supply a working 230V version of this tumbler and therefore we (and other Australian dealers) can no longer supply this machine.  The story is a bit more complicated (you can read more below if you are interested) but here is the current situation.

  • 230V/50Hz Gyroc Model B tumblers are no longer available. The 60 Hertz motor will NOT work correctly in Australia.

Current Options for people needing a tumbler:

  • You can still purchase a 110V version from the USA and run through a power transformer – warranty support will be limited or non-existent but this is an option you may consider.
  • You can refurbish an older or 110V machine by fitting a compatible 230V motor – available here. This is a simple job that does not require any electrical wiring.
  • You can buy a rotary tumbler such as the Lortone 3A instead for cheaper option with similar capacity.
  • You can buy the slightly bigger Thumler Mini Bowl  (available now) – these have a better build quality compared to the Gyroc but offers only one speed as opposed to the two speed pulley of the Gyroc.

gyrocIf we can answer any other questions about tumblers for jewellery polishing, please email us.  For more on the whole sorry saga, read more below: Read the remainder of this entry »

     

Tumbler Size Options

Posted March 9, 2015 By Admin

We are often asked about sizes of the various tumblers in our range. While information about barrel/bowl dimensions is included in the listings, it can be a bit confusing to compare between them. So we have put together a chart which outlines the dimensions and volumetric capacity of the most popular sizes.

CLICK HERE TO VIEW the PDF document on Tumbler Barrel/Bowl Sizes

Note that we do list volumetric capacity in the chart as well as physical dimensions.  While almost all tumblers are described in terms of weight capacity (usually in pounds), this rating usually includes the weight of the bowl or barrel and can be influenced by a range of factors.  We find that it is more sensible to think in terms of volume (described in Litres) or available space with consideration taken not to overload the motor.

Bowl_Barrel

Whether you are tumbling rocks, rifle brass, or another material, just work out the batch size as it relates to the effective capacity of the barrel.  You can use a kitchen jug to help visualise the space taken up by a volume in litres.

     

Slab Saw Coolants

Posted November 23, 2014 By Admin

We are often asked what is the best coolant to use in a rock saw and given that there are lot of different “recipes” out there, we thought a more thorough look at this topic would be useful.

The job of the coolant is three-fold:

  • to cool both the blade and the material being cut
  • to flush out abrasive particles formed while cutting
  • and provide lubrication to keep the cutting edge clean.

It is vitally important that you use an appropriate coolant in your saw – this will extend blade life and improve cutting performance. Excess heat on any diamond tool (including saw blades) is the fastest way to damage the tool – using an inappropriate coolant will kill your blade quickly so choose carefully.

TRIM SAWS: for these smaller saws (up to 6″/6″ size), water is generally fine to use as the coolant. Some users choose to add a coolant additive to the water which has a rust inhibitor and surfactants to improve cutting performance. Please note that these additives will not completely prevent rust (you will still see rust forming at the water line if you leave the blade in water) – so we always recommend emptying out the saw reservoir after use. Examples of suitable coolant additives are Covington Koolerant #1 or Tool Cool – there are many others out there.

MEDIUM SIZE SAWS: for saws in the 8″ to 10″ range, we start to need a more efficient coolant such as oil. In a reservoir type saw, water usually does not pick up on the blade well enough to use as the coolant. For saws that use an overhead water supply via a pump, then water can be used as long as it is supplied freely at the point of the cut to provide maximum effect. Excess heat can cause blade glazing in sintered blades or remove diamond entirely for electroplated or cheap notched rim blades.

SLAB SAWS: Water should not be used in large power feed slab saws – water (alone or with an additive) is just not able to cool efficiently and can damage the power feed mechanism. We recommend a good quality cutting oil (light mineral oil) for best results in slab saws – for very heavy duty cutting, you may choose to use a cutting oil additive for better results on very hard stone. We recommend Covington Rockhound Oil but there are other similar products available.

What about the old diesel or kero/oil mix??  This is a traditional coolant and many still use it but there are a few good reasons NOT to use in your saw:

  • These mixes are very flammable with low flash point temperature – it is just not worth the risk of fire or explosion.
  • The unpleasant smell makes it annoying during the cutting and it is very difficult to wash off the slabs after cutting.
  • Dangerous to your health – even when used in an enclosed slab saw, the mist generated during cutting can be harmful. Can also cause skin irritations.

 

A light mineral oil has a much higher flash point (110°C or more) so are much safer to use – if you are cutting very hard rock. adding a bit of Covington Koolerant #2 will increase the flash point even more.  These oils have almost no smell at all, are easy to clean off the slabs after cutting and are much kinder to your body (hands, lungs, etc).  Play it safe – just use the right stuff.

If you are concerned about cost – note that these light oils can be filtered and cleaned for re-use. Low tech filtering can be done using layers of paper bag filters but Aussie Sapphire is now importing the EasyClean oil cleaning units to fit to your slab saw. These will conveniently clean your cutting oil and separate out the sludge for disposal – one initial investment means your oil will last longer, your blade will cut better and your saw will stay in good condition.

See this document from Barranca Diamond for more information on Slab Saw Coolants.

Also review this helpful document on Care and Feeding of Rock Saws (Richard Gindhart).

 

     

Classifier Mesh Sizes

Posted November 16, 2014 By Admin

Classifiers are used to size material accurately for classification – often used by gold prospectors who need to size concentrate for use in spiral wheels or the like.

  • 1/2 inch (the largest screen) is about 4 holes per square inch (use to remove worthless larger rocks)
  • 1/4 inch is about 16 holes per square inch (use to reduce size of gravel material for easier sluicing or panning)
  •  1/8 inch is about 64 holes per square inch (use for final clean up of gold concentrates from black sand or for recovery of small gem stones)
  •  1/12 inch mesh – good all around size.
  •  1/20 inch – FINE MESH is about equal to window screen (use for final clean up of FINER gold from your black sand or for recovery of very small garnets and gemstones, etc…)
  •  1/30 inch  – SUPER FINE MESH – a very tight weave
  •  1/50 inch – VERY FINE MESH – 2500 holes per square inch- OFTEN USED WITH #30 and #70 screen for BLUE BOWL CLEANUP
  •  1/70 inch – VERY FINE MESH – 4900 holes per square inch – use with the #6 (1/30″) and #7 (1/50″) screens for best blue bowl recovery.
  •  1/100 inch – the smallest screen – use for microscopic gold recovery and ultra fine gold dust and flakes.

Note that the standard pair of gemstone sieves will almost always be 1/4″ and 1/8″ – you can quickly go through the larger material on the top sieve and then anything that goes through the bottom sieve will usually be too small to worry about.

See the photo gallery below to get a feel for what these mesh sizes look like in reference to a metric/inch ruler.