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Cabochon cutting or cabbing is the most popular form of gem cutting. Although it requires a fair amount of skill, almost anyone can master this technique. Rough material for cabbing can be found or purchased inexpensively. Many people never buy their rough and are content to cut the many stones they trade for or find. Of course, as you gain experience, you can if you wish move on to more valuable materials like turquoise, lapis lazuli, and even phenomenal stones like cat’s eye chrysoberyl and black opal.BY DONALD CLARK, CSM IMG Cabochon cutting is challenging, but with patience and practice, anyone can learn the most popular branch of the lapidary arts. Rhodochrosite and gold ring, photo and jewelry by Mauro Cateb. Licensed under CC By 2.0. Cabochon Cutting Tools Cabbing tools can be as simple and inexpensive or elaborate and pricey as your tastes run. Genie, Diamond Pacific The most popular cabochon cutting machine is the Genie by Diamond Pacific. It has six permanently mounted wheels. The first two are 100 and 260 grit diamond on solid wheels. The other four range from 280 to 14,000 grit. They have a foam backing, which conforms to the curvature of the stones. There are two movable “geysers” that supply water to the wheels for lubrication. You can’t polish everything with one method, so this machine comes with a flat disk you can mount on the end. This disk can hold enough varieties of pads and polishing compounds to polish anything you might encounter. The Genie’s advantages are that you never spend time changing accessories and that the diamond wheels last almost forever. Cost is its primary disadvantage. This machine is a major investment. It’s also large and heavy, which is fine for a permanent setup. However, if you need portability, this isn’t the unit for you. More Options There are a number of cabochon cutting machines available with a variety of features and prices. Some people have made their own machines. The requirements are: an axle of the proper diameter for the wheels you want, a motor, a pulley system to attain the proper speed, and a method to keep the wheels wet. This is usually a drip system. For a simple solution, place a sponge so it sits in water and constantly wipe the wheel clean. You can cab on a faceting machine, but you can’t facet on a cabbing machine. If you’re a beginning lapidary student and budgeting your equipment costs, keep this in mind. You can shape your cabs with the same coarse laps you use for faceting. Clean your coarse lap, then put a piece of firm, 1/4″ thick, foam rubber on top of it. This will hold pieces of 600 grit wet/dry sandpaper (that you must cut to shape) for smoothing. To polish, replace the sandpaper with an Ultra Lap, a piece of leather, or other polishing pad charged with your favorite compound. Cabochon Cutting Techniques The oval cabochon is the most common shape for cabs. Other shapes just require minor technique adjustments. In this section, you’ll learn how to cut an oval. Slabbing Cabochon cutting template Most cutting begins with a slab. Yes, that means you’ll need a saw. Some cabs can be cut without slabbing, but most will need to be cut into 1/4″ to 3/8″ thick slices. Begin by placing a template over the slab. If your material is a solid color, you’re just looking for the largest piece you can cut. If the material has a pattern, then you’re looking for the shape and size with the most eye appeal. This is a bit of a guessing game, since the pattern will change as you round the top. Look at both sides of the slab to get an idea of how it will change. A template isn’t always necessary. Some valuable materials, notably opal, are usually cut freeform for maximum weight retention. However, you’ll want to end up with calibrated sizes and shapes with most gem material, since these will fit into pre-made jewelry settings. Saving a little weight on most cabs but then having to spend time and money to make settings isn’t cost effective. Cabochon outline and saw guide lines When you’ve chosen your area, mark it for cutting. An aluminum pen is ideal for this. The mark won’t wash away like a pencil mark. Furthermore, many gem materials will absorb liquid ink, which leaves an unsightly and costly mess you’ll have to cut away. Once you outline your cab, take it to the saw and cut away as much excess material as possible. Until you get used to this process, drawing guide lines with the aluminum pen and ruler will prove useful. If you’re working with a large gem, you can move on to the grinding stage. Smaller stones should be dopped to save your fingers from unnecessary abuse. Shaping Now it’s time to start cutting. If you’re working with something hard, like a piece of agate, begin with your coarsest wheel. If you’re working with something soft, like opal or turquoise, or something small, begin with one of the smoother wheels. Of course, if the smoother wheel cuts too slowly, you can always go to a coarser wheel. However, it’s best to start gently with it. Getting Started Bring your machine up to speed and get your chosen wheel thoroughly wet before starting to cut. The water serves two important purposes. It acts as a lubricant, keeping the friction and heat down, and carries away the swarf (the cutting debris). This keeps the wheel from clogging. Most manufacturers recommend you use an additive for additional lubrication. Unless your machine is made entirely of stainless steel, you’ll need an additive with rust preventative properties as well. Use the lower quarter of the wheel when grinding. If you try to work above the centerline, the gem will probably be pulled out of your hands. “Pulled” is a tame word for what actually happens. The gem will be yanked violently from your hands and flung to the far reaches of your shop. If you can find the stone, it’ll likely be broken. Start by grinding the excess material down towards the outline you’ve drawn. Use a pair of calipers to measure your progress. Templates are great for shapes but aren’t accurate for dimensions. Leave yourself some room for the remaining steps. Depending on the size of your cab, you may want to leave a half-millimeter or so. This is something you’ll learn from experience. The amount varies with the hardness of the material and the size of the gem. Peeling the Apple Once you have the outline shaped, you’ll start the process called “peeling the apple.” Grind a bevel all the way around the gem at about 45º, bringing it 2/3rd to 3/4th of the way down to the bottom. Then, grind another bevel, all the way around the stone again, at about 60º. Leave some of the previous cut showing. Keep “peeling the apple,” cutting bevels at increasingly steeper angles, until they meet in the center. “Peeling the apple,” side view of 45° and 60° cuts This is the area that causes the most trouble for beginners. It may seem that just three cuts will completely cover the stone, except for maybe a tiny area right in the center. That’s not good enough. If you have even a tiny area that’s flat and not properly domed, the cab won’t take a proper polish. To make matters worse, the flat area will be right on the very top, where it shows the most! Be patient and learn to get the entire stone evenly domed. Look at the stone from both ends and both sides. The curvature should be even in every direction and all the way to the center. You should make this inspection at every step, but especially in the first, coarsest stage. Any irregularities are easier to correct now than later with the finer grits. Preparing for a Bezel Setting This next step may seem like you’re getting ahead of yourself, but it’s presented just so you know where you’re heading. As you’re shaping the gem, leave a small, vertical area on the sides before it begins to taper in. Also, sand a very small bevel on the lower edge of your girdle. This is done in the fine sanding stage. The bevel prevents the edge from chipping and also leaves a small area for solder. Sand a very small bevel on the lower edge of your girdle to prevent chipping and allow a little space for solder. Cabs are usually placed in a bezel setting. The bezel, a thin strip of metal, is soldered to the main piece. Hence, you need a little room for the solder. To hold the gem securely, the bezel needs to be bent inward, over the curvature of the stone. The vertical area on the side offers support without having to bend the bezel too far in. When finished, you want to see mostly the stone. You don’t want the bezel to come so far over the edges that it distracts from the gem. These steps are particularly important with brittle opal stones. If you leave a sharp edge on the girdle, the stone can chip or crack when tightening the bezel. The steeper the sides, the more support the gem receives. Of course, you can also overdo this. The illustration above shows the ideal proportions from the metalsmith’s point of view. Smoothing Once you’re satisfied with the shape of your gem, you’ll start sanding out the coarse scratches. If you’re using diamond, this will take a series of steps. Typically, you’d use a combination like 260, 600, and 1,200 grit. Inspect your gem after each step. Look for proper curvature, as you did before. Also, make sure you’ve removed all the coarse scratches from the previous step. This is very important. If you don’t get them all out before moving to the next step, you’ll either have to do it again or settle for a low-quality finish. The gem needs to be dry for you to see the progress. In a humid environment, this can be challenging. If possible, warm the room before starting. If you can’t warm the room, at least use warm water. Have plenty of towels available. Dry your hands before trying to dry the stone. If you are using silicon carbide, all you need is 600 grit. It wears fast and becomes the finer grit you need for a pre-polish. Unfortunately, these have limited uses. You may need to keep two 600 belts. Use one for shaping and another, well-used one for pre-polishing. I can’t overstate the importance of the quality of your pre-polish, the final fine sanding. This is the single most important element in getting a high polish. The surface should be ultra smooth, with no visible scratches at all. Any time you’re having trouble getting a high polish, go back to the pre-polish step. Soft materials like lapis and opal scratch readily with diamond. 1,200 diamond is a fine pre-polish for agate, but you might need something much finer, like 3,000 or 8,000, for softer gems. Cabochon cut from a piece of pink hydrogrossular garnet. Photo by R.H.C. Langendam. Licensed under CC By 3.0. Polishing Cabochons Polishing can be very confusing for a beginner. There are hundreds of methods. If you buy a new cabochon cutting machine, it’ll probably come with a polishing system. That’s a good place to start. Here are some tricks of the lapidary trade: Use aluminum oxide on suede, soft side out. This is the most versatile polishing method available. It’ll put a high polish on more materials than any other method. Quartz responds best to cerium oxide. This does well for opal, too, but be very careful about heat build up with opal. Stones get hot quickly during polishing, and heat can destroy opals. Jade, on the other hand, needs a lot of heat and friction to polish. Use chromium oxide on leather or felt. Diamond polish can be used on leather or specially made pads. However, it has never gained the popularity with cab cutters that it has with faceters. It’s more expensive than aluminum oxide and doesn’t offer any significant improvements, except on ruby and sapphire. These are the most common and most useful polishing methods. With them, you’ll be able to get a mirror polish on any material. That mirror polish is important. It takes a fair amount of work to procure a cabochon cutting machine, learn how to use it, find the rough, orient it, and finally cut a cab. Getting that mirror-high polish on a beautiful stone makes it all worthwhile. Top-quality Mexican fire opal cabochon in 14k gold ring with rose gold overlay. Photo and jewelry by Jessa and Mark Anderson. Licensed under CC By 2.0. Judging Your Cabochon Cutting When examining a cabochon, start by judging the polish. Look for any scratches or pitting that will reduce the amount of light reflected from the surface. Next, judge the shape. How even is the contour? A cabochon should have an even curvature to its surface. Look at the cab from both ends and both sides. The shape (the curvature) should be a mirror image from side to side. No area should be thicker than its opposite. There should be no bulging. Examine the shape further by holding the cab so light reflects off its surface. Move the gem so the light travels across the top. If the surface is properly cut, you’ll see the band of reflected light glide evenly over its surface. The band of light will begin to snake if there are any irregularities. Poor polishing will also affect how light moves across the gemstone. You’re most likely to see a problem at the top of the cabochon. Often, a small area will be somewhat flattened. From the side, this is hard to see. However, when light passes over the area, it’s obvious. The fact that light doesn’t flow smoothly over this area is why the cabochon cutting would be considered second rate. (If you look closely, that area probably doesn’t have a good polish, either). The oval is the basis for all cab cuts, even shapes like rectangles, teardrops, and hearts. Heart-shaped cabochons, left to right: hematite, rose quartz, tiger’s eye, and two sodalite stones. Photo by Mauro Cateb. Licensed under CC By 2.0.

Emery cloth differs to sandpaper in several ways: Emery cloth has the abrasive glued to a cloth rather than paper, which makes it far sturdier and less inclined to tear in use Emery cloth uses a form of corundum (or corundite) as the abrasive, rather than sand Emery is longer lasting than sand as a glued abrasive Emery particles are of a more consistent size than sand, especially where finer grades are concerned Emery should not be used on wooden surfaces as fine particles of iron and other metals can become embedded and cause staining or other damage to the wood Emery cloth is typically graded into "grit" sizes between 8 and 120, with the grit becoming coarser as the number increases. 80 grit paper is typically used for roughing and chamfering plastic pipe.

Abrasive blasting is the general term applied to finishing processes that entail the high-pressure propulsion of a stream of abrasive material onto the surface of a workpiece. Abrasive blasting can serve many surface finishing purposes, such as removing contaminants or previous coatings, altering the shape and smoothing or roughening the surface. There are many types of abrasive blasting applications, each of which requires the use of different types of blasting materials, referred to as blasting “media.” Finishing Systems has assembled this abrasive blasting media guide to help you select the most appropriate material for your specific finishing processes. One note: the terms “sandblasting” and “abrasive blasting” are often used interchangeably. A conventional “dry” sandblasting process that uses traditional sand is not recommended for most applications. Blasting with sand generally requires twice the amount of material, making it cost-prohibitive for many companies. Glass Beads: Glass is not as aggressive a blasting media as other materials, such as steel shot or silicon carbide. However, it is an excellent choice for applications that require a softer, brighter finish. It is well suited for stainless steel applications. Glass beads can also be recycled multiple times. Aluminum Oxide: Aluminum oxide is characterized by its superior hardness and strength. It can be found in applications ranging from anti-slip surfaces, industrial applications as a blasting media, and as a raw material in refractories. It is designed for abrasive pressure blasting of almost any type of substrate: glass, granite, marble, and steel. Due to its ability to deeply etch it is used in the preparation of surfaces prior to painting or coatings. Plastics: Plastic abrasive is a dry thermoset cleaning media made from crushed urea, polyester or acrylic. Each varying and available in a range of hardness and particle size. Plastic is generally regarded as the best media for mold cleaning, blasting of plastic parts, or in applications where the removal of the substrate material is not permitted. Common industries include automotive, aviation, boating, electronics and industrial applications. Silicon Carbide: Silicon carbide is the hardest abrasive blasting material available, making it the best choice for your most challenging surface finishing applications. It is available in various colors and purities. Its primary use ranges from bonded abrasive tools, lapping, polishing, glass etching and general purpose heavy duty blast cutting applications. Steel Shot & Grit: Steel abrasive is a cost-effective alternative to other abrasives due to its toughness and high recyclability. It can be used on a variety of surfaces to effectively remove contaminants, texture a surface for proper adherence of a final coating, or in peening (hardening) applications. The correct size, hardness and shape play a significant role in the proper media selection. Starblast: Starblast™ is a mined loose blend of coarse and fine staurolite sands with extremely low levels of silica making it an ideal general purpose blasting abrasive. It is perfect for removing scale and corrosion from steel surfaces, while offering a low dust level for improved visibility. Walnut Shells: Walnut shell abrasive is a hard naturally occurring material made from crushed walnut shells. It is the harder of the soft abrasives, available in a variety of sizes for blast cleaning and polishing softer surfaces that could incur damage from harsher abrasives. Typical applications include polishing of soft metals, fiberglass, wood, plastic and stone. It can also be used in tumbling operations for polishing gems and jewelry. Corn Cobs: Corn cob abrasive is a granular abrasive manufactured from crushing the dense woody ring of a corn cob into various grit sizes. It is the softer of the naturally occurring abrasives making it ideal for cleaning, deburring, burnishing and de-flashing applications. Common industries include jewelry, cutlery, engine parts, fiberglass and the removal of graffiti or debris from wood, brick or stone.

Where can I get a copy of the CabKing instruction manual? You can download the Hans Grinder 6″ and 8" Lapidary Grinder and Polisher instruction manuals here. We can also mail you a printed copy.

The Hans Top Quality water pump pushes out 2,400 liters per hour.

No. Our single-pass water system is designed to provide clean, fresh water for your Lapidary Hard and Resin Grinding Wheels to give you the best results. This unique water system prevents contamination that may occur from a re-circulating water system. Important note: Attempting to set-up the CabKing water system as a re-circulating system will void your warranty.

Our video tutorials below explain how to change the wheels on both the left wheel assembly and right wheel assembly on the 6″ hans lapidary grinder.You can buy more one quickly change shaft to change the wheel immiadiatly.

Diamond laps have a 1/2" arbor hole to fit on the left shaft of both 6" and 8 models. Diamond laps are available in both 6" and 8" diameters. Full face diamond laps have a 1/4"-20 thread on the backside to fit on the right shaft of both 6" and 8 models. Full face laps are only available in a 6" diameter but can be used on either hans lapidary grinder machine. There is no difference in how these laps are manufactured. Both of these laps are nickel electroplated with premium diamond grit.Learn more about our diamond laps at https://www.lapidarytool.com/mall/diamond-lapidary-tools/lapidary-flat-lap.html

Both of these wheels are diamond resin wheels however, the resin bond formula is slightly different between the two wheels. Our diamond Resin REZ Grinding wheels are manufactured with an aggressive resin bond, re sulting in a rough texture with sharp points and are more durable than our standard Diamond Resin Sfot Wheels (see image above for close-up of rez and resin wheel texture). Since the rez wheels have a rough texture with sharp points, they require a break-in period while our diamond resin wheels do not. All rez wheels come with instructions for proper use and care.

Yes, as long as the wheels have a 1″ arbor hole. Important note: The wheels that come with your Hans Lapidary machine are specifically formulated to work together, especially the resin wheels. DO NOT MIX OR MATCH OTHER BRANDS OF RESIN WHEELS. Doing so may result in scratching or uneven grinding/polishing. Replace all wheels if you intend on using a different brand.