Selecting the best saw blade for your needs requires the consideration of several factors:
- The type of material to be cut, its value and purpose. The more expensive the material, the thinner the blade you should use to reduce material loss.
- The capacity of the saw, its condition, blade RPM, and other equipment characteristics. For slabbing, thin blades should only be used on machines that are in good condition and are capable of high RPM’s. Thicker blades usually give better service for general slabbing purposes.
- Production volume to be cut.
- Operator experience. Generally, thinner blades should only be used by experienced operators as they can be more easily damaged. For school room type conditions, thicker blades will generally last longer.
- The type of coolant required by both the blade and saw. Some saws and blades should only be used with oil, while others can be used with just water or water with a proper additive.
- Type of blade rim. The diamond edge of the segmented and notched rim blades have an interrupted surface which improves cutting ability and coolant flow.
Sintered continuous rim blades mean just that—the edge of the blade has a continuous rim of sintered diamond matrix. Most smaller and thin rimmed blades are either of the sintered continuous or plated rim type.
NOTE: Blades need sharpening as they are worn from use. See page 48 of our catalog to order blade dressing sticks.
- For longer life with your saw blade, your saw and equipment must be in proper condition. Whenever you install a new blade, check your arbor shaft for radial and axial play. Try moving the shaft back and forth, and in and out. Any movement indicates the arbor shaft needs adjustment, new bearings, or replacement.
Lapidary blades are manufactured with the arbor hole .005″ oversize to provide a snug fit on the shaft. If the shaft is worn, the blade will not spin concentrically with the arbor.
The machine should be located on a level floor or platform so that it will not vibrate during operation. All belts should be properly tensioned.
- Flanges support the blade over a large surface area and help prevent deflection at the beginning and ending of a cut where there is little or no workpiece support. They must measure at least one quarter of the blade diameter. Make certain the flanges are smooth, flat and parallel, without gouges or burns on the surfaces. Flanges must be recessed about three quarters of their diameter from their center. This provides support to the blade around its outer area while avoiding distortion of its center core.
- A lapidary diamond saw blade requires a lubricant which also works as a coolant. An ample supply must be directed into the saw cut to lubricate the blade rim and workpiece, and to flush out all debris. A light cutting oil is best, and is required for most slabbing operations. A water soluble oil or plain water can sometimes be used in trimming operations. Rust inhibitors should be used and extra care taken to prevent rusting of the blade and/or saw.
- With a new blade it is best to make your first cut using a soft, abrasive material. This will assure that the blade is properly broken in by bringing the rim into concentricity with the arbor and will open up the rim, increasing diamond protrusion.
- Start cuts by feeding in the workpiece when the blade is running at operating speed. Make sure the surface of the workpiece will not cause the blade to deflect at point of contact. If the blade starts cutting to either side of its plane of rotation, you will get a nonparallel cut and even damage to the blade. When a cut is almost complete, a break will often occur, leaving a jagged spur. This spur can damage the blade. To prevent this, infeed pressure should be reduced or stopped near the end of the cut. Saws with automatic power cut-off, when properly set, will do this for you. With screw feeds, the workpiece and vise can be hand fed.
- A diamond blade should be reversed occasionally to insure even wear and long life. A diamond blade can become glazed over at its cutting edge especially when cutting hard, dense material. To sharpen the blade, make a few cuts in a soft, abrasive material. This will generally abrade away some of the metal bond and rim and expose more diamond.
The tumbling of stones has been going on in Nature for eons of time, as anyone who has picked up a smooth and rounded stone from a beach can testify. This process in Nature is the same that man uses today to tumble polish gemstones: rubbing one stone against another in an abrasive substance, and generally in water. Man carries the process a step further—uses machines (tumblers) to achieve a high polish on his gemstones.
Tumblers can come in several kinds and dozens of shapes and sizes, as described on the following page. All use the basic process of grinding, sanding, and polishing stones through movement in a series of abrasives from coarse to fine.
The steps in tumbling vary from the use of an extremely fine polishing material for only a few hours to put a final polish on a valuable gemstone, to the general sequence of coarse grit (60/90) silicon carbide through three, four or more polishing abrasives in subsequently finer grit, to the final polishing step. This can take from a few days to four to six weeks.
Most stones with a hardness of 5 to 7 1/2 on the Moh scale will tumble polish well. Softer and harder stones may still polish, but may require more or special steps and abrasives to achieve a satisfactory polish. Some stones will never polish no matter what you do to them.
Tumble polishing stones is an easy and great way to start kids (and adults) on a lifelong interest in the natural world around them. Finding your own rocks, and turning them into shining marvels of Nature is a rewarding experience.
There are two main types of tumblers—the rotary and the vibratory. The first tumblers were of the rotary type, where a barrel revolves as it rides on two parallel revolving shafts. The vibratory type sits and shakes, causing the load to move within the barrel but without the harsher action of the rotary. Both types require a series of abrasives starting with coarse and working up to a fine polish.
Rotary tumblers are the most familiar type, and range in barrel capacities from around 4 lbs. to commercial sizes that will process hundreds of pounds of material. The smaller units (2 – 4 lbs. capacity) are popular for youngsters and beginners, but the less expensive kinds have more maintenance problems. A well built rotary tumbler can last for years, however, even decades, if given care.
Rotary (barrel) tumblers are generally easy to load, require a minimum of attention, and produce satisfactory results on most stones and metals. Their main tumbling action abrades away any sharp edges and points, leaving finished stones with rounded surfaces and contours. Rotary tumblers are not suitable for material that is pre-formed and desired to retain it’s shape.
Rotary tumblers generally take more time to finish a load of stones, from four to six weeks or more, depending on material and abrasives used. They also use more grit per load, but generally need fewer steps in the tumbling process, and less attention the rest of the time.
Vibratory tumblers have either mechanical or electronic drives. Mechanical units use motors for power, while the Mini Sonic and Vibra Sonic tumblers use magnetic energy. They have no moving parts such as shafts, belts or pulleys, and are exceptionally long lived.
The action in vibratory tumblers is more gentle than that found in rotary tumblers. The barrel in a vibratory tumbler remains stationary even as it vibrates, producing a continuous movement of material and grit within the barrel.
Because of their unique, gentle polishing action. vibratory tumblers do not wear away the shapes of stones, so that they retain their original form. Hearts and squares will come out as hearts and squares. This makes vibratory tumblers ideal for polishing preforms, carvings, metal jewelry, castings, etc.
Vibratory tumblers are generally faster in polishing a given load of material than a rotary tumbler, but actual time can vary from one day for a final polish on a preform to several weeks on hard-to-polish stones when starting from scratch.
The main principle in polishing stone is to start with a coarse abrasive for grinding, and work through a series of increasingly finer abrasives to the final polish. The whole process is basically this simple, but there are variations in gemstone properties, types of abrasives, many recommended grit (abrasive) sequences, and results produced by the different types of tumblers. All these variations and choices can be confusing, especially to a beginner, so it should be remembered that tumbling is basically simple, not an “exact science”, and can be great fun once the basics are mastered.
The first choice to be made is the type of tumbler to be used, Rotary or Vibratory. A brief description of the two types is given on our types of tumblers page. Further descriptions can be found on the pages of the catalog listing the tumblers themselves.
Both rotary and vibratory tumblers use the standard silicon carbide grits with water in the mix as well as a filler of some type. However, Vibra-Dry mixes can be used in vibratory tumblers for the polishing steps, and produce higher polishes on almost all stones and metals. Vibra-Dry mixes do not use water, and can be re-used multiple times.
The beginner should be aware that some stones will not polish in either type or tumbler nor with any grit sequence. In order not to waste your time and money, be selective. See page on “Selecting Stones”.
Over the years, individuals have developed procedures and grit sequences that give them good results, but what works for one person doesn’t always work for someone else. As a result, you will find that advice, books and manufacturer’s instructions vary in their recommendations. All follow the basic principle of tumbling, but reading “Use 80 grit to start” in one source and “Use 60/90 to start” in another is confusing. Both work, and there is actually little difference between those grit sizes. In fact, most grit sizes that are used actually cover a range in particle size. The 60/90 range includes 80 grit, a sample of 220 grit might range from 100 to 300 in particle size. Finer grits and polishes are more closely graded so that particle size is more uniform and so are the results. As a consequence, finer grits and polishes are move expensive
Fillers are recommended for use in both types of tumblers and in each step in almost all grit sequences. Fillers soften the action, fill space between stones, and carry the grit to the stone’s surface more efficiently. Fillers generally can be reused if thoroughly cleaned between grit sequences. We recommend the ceramic bits for both stones and metals as they seem to do the best job and will last longer.
Dry polishing stones and metals with Vibra-Dry mixes has been around for forty years, but we have improved the mixes to where you can achieve a brilliant finish seldom achieved by any other method.
Vibra-Dry+ mixes allow you to polish stones and metal pieces without the addition of water, additives, thickeners, or fillers of any kind. Everything you need is in the mix. No more worry about keeping the right amount of liquid or slurry levels, and no mess at the end of each polishing step. Vibra-Dry+ is a dry process, so that your stones, coins or jewelry pieces can be easily removed from the mix, cleaned with only a polishing cloth or rinsed in water. The mix is then ready to process another batch of material. You save time, labor and compound, and achieve a superb polish as well.
Vibra-Dry+ mixes are formulated for the pre-polish and final polishing steps in processing stones and metals. They were designed for use in vibratory tumblers, and are not recommended for use in rotary or barrel type tumblers.
There are three main ways to use Vibra-Dry+ to polish stones and metals. For someone, especially a professional jeweler, who wants to put a final, outstanding shine to finished pieces of jewelry, loose faceted stones, pre-formed or poorly finished cabochons, then using the 25,000 and 50,000 Vibra-Dry+ mixes fills the need. This applies to most metal pieces as well, such as finished jewelry, castings, coins, etc. In some cases of severe tarnish or fire scale, the metal pieces may need to be run through one or more coarser grits of Vibra-Dry+ first.
For those wanting to process valuable or delicate materials such as amber, pearls, opals, etc., most of the finishing process may be done just using a series of Vibra-Dry+ mixes, avoiding the use of most or all silicon carbide steps. It just depends on your material.
Then for those just wanting to tumble, polish rough stones such as agate, jaspers and similar gemstone materials, you should prepare your stones by processing them through the standard silicon carbide grits: 60/90, 220, and 600 grits, followed by 800 grit aluminum oxide pre-polish. This sequence prepares most stones even for standard final polishes, but a far better shine is achieved by then using the 25,000 or 50,000 Vibra-Dry+ mixes.
The Guidelines given here are just that. For most stones from 6 to 8 in hardness, going through the silicon carbide grits will prepare your stones properly. Softer stones are harder to polish, and you might find that using some of the coarser Vibra-Dry+ mixes will help.