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Cabochons and Freeforms

How to Make Cabochons and Free forms and be a Creative Genious

Steps involved in making a Cabochon or Free form

Cutting a Slab: Slab saws are designed to auto feed stones into the cutting blade to produce slabs of material of various thickness. Cabochons slabs are generally 3/16 to 1/4 inch in thickness; although larger pieces require a thicker slab to complete the dome shape typical of a cab. The slab saw requires a cooling fluid to preserve the blade and keep the material cool. Cutting oils must be rated for use machine tools. Water can be used as a cooling fluid if an anti rust agent is added. A saw will produce a fine mist even with the saw lid closed. The mist if not approved as a safe cutting fluid can be a heath risk to the user. The saw's vice holds the stone secure as it is feed into the blade. Wooden wedges are helpful in blocking the gemstone to insure a tight fit. It is extremely important that the stone is held secure or the blade can be wrapped, effectively ruining the blade. Diamond saw blades are not cheap. Most slab saws have a calibrated feed that moves the stone horizontally to set the thickness of the slab. After the first slab is cut the artist can continue to move the piece horizontally, producing several slabs at one cutting session. The lid must be kept closed during operation to keep oils from being slung from the blade into the shop area.	Twenty four inch Highland Park Slab Saw - it just doesn't get any better. Notice the rock vice and automatic feed.
Choosing the Shape: Cabs can be any shape desired although circles and ovals are the most common. Findings for the finished pieces are available in calibrated sizes. If a purchased finding is to be used the cab must be cut to fit the setting. Templates are available that are designed to match the typical setting sizes. The key to beautiful cabs is to be artistic in choosing good cutting material and identifying the area on the face of a slab that will produce the best cabs. Several cabs can typically be cut from a good sized slab. Do not waste your time with cutting material with little color and few or no patterns. Mark the piece with an thin aluminum rod beveled with a cone shaped point. The aluminum will not easily rub off while working the piece and the rod can easily be sharpen with a grinding stone. Templates can be purchased that have crosses, hearts, squares, and many other shapes. A free form is a piece that is cut to any shaped desired. Free forms require the artist to create the setting since the piece is not calibrated to fit a purchased finding.	The template is designed to give a calibrated cab that will fit purchased findings. Picture: http://www.cabbingmachines.com/accessories.shtml
Trimming the Piece: A trim saw has typically a 4 to 10 inch blade (6 inch being the most common). A 10 inch saw can double as a slab saw for the beginner just getting started. The slab is placed on the saw table and the excess material is removed. Do not force the slab into the blade or the life of the blade will be greatly reduced and do not cut to close to the shape. A trim saw cuts straight cuts so that several cuts will be needed to roughly lshape the piece. Quite often water is used as the coolant .	http://www.rockhounds.com/rockshop/oplc_cab.shtm
Grinding the Edges: The trim saw leaves many rough corners that must be removed to complete the shape. Lapidary grinding wheels come mounted on an arbor and are available in various grits. A typical set up could be an 80 grit , 220 grit, 400, and 600 grit wheels. Common wheel sizes are 6 inch and 8 inch diameters made with ether silicon carbide or diamond grit. Hold the rough piece and slowly remove the corners beginning with the coarsest wheel but do not cut to the aluminium line but stop about 1/16 of an inch away. Further grinding on finer wheels will finish the piece. Grind the pieces as shown in the photo to avoid chipping the piece.	Picture: http://www.rockhounds.com/rockshop/oplc_cab.shtml
Dopping the Stone: Lapidary equipment is relatively safe but as with any moving equipment safety is important. The stone can be attached to a dop stick to avoid grinding fingers. The stick is attached using dop wax that is melted in a dop pot. The tip of the stick is rotated in the wax and attached to the back of the piece. A handle is created that allows the artist to easily finish the grinding and polishing steps. (see picture) After the piece is finished the wax can easily be removed by placing the assemble in a freezer for a few minutes.	http://www.inlandlapidary.com/user_area/howtocab.asp
Shaping the Dome the First Cut: Cut a shallow (1/16 inch) bevel on the back of the piece to avoid chipping the stone. Cut a bevel on the edge of the stone at about a 45 degree angle; cutting to within 1/16 of an inch from the bottom of the piece. (see illustration) An edge is typically required for proper mounting of the cab especially if the piece in wire wrapped. I use the 220 grit diamond wheel at this stage to avoid rough cuts and chipping the piece. Do not try to remove too much material at one time but slowly twirl the piece with the dop stick. Remember there are more stages to follow so do not think it has to be perfect at this stage. Lapidary work is quite forgiving if you do not over cut a piece in the beginning steps.
Shaping the Dome the Second Cut: A broader bevel is made as shown in the diagram at a 60 degree angle. Do not make the cut in one step but continually rotate the piece to get the desired shape. Now smoothly shape the dome. I use the 220 diamond to get the shape. Do not grind the top or a flat will be created. The object is to create a rounded dome. A finished cab will be terminated at the top of the dome.
Fine Grinding: The object of the fine grinding is to remove any scratches left by the coarse wheels and to prepare the cab for polishing. The stone is moved from one wheel to the next finer wheel . The process continues until the stone looks almost polished. My lapidary set up uses 80 and 220 grit for the coarse grind. I progress to 325 then to 400, 600 and 1200 grit diamond wheels. The process can also be accomplished with sanding drum with increasing finer belts used. A flat lap is another piece of equipment that is often used. Remember that for calibrated pieces the stone will need to be ground to the aluminum line that defines the template. The process is often stopped at 600 grit but I am looking for a mirror polish and I find the 1200 grit wheel serves my purposes.	Eight inch diamond wheels on a Highland Park machine. Notice the grit on the wheel gets finer from right to left. The wheels are kept cool with dripping water.
Polishing: There are several methods used to polish a piece and several kinds of polishing compounds. Each has its advantages depending upon the type of material being polished. I have a 50,000 grit diamond polishing wheel that I use for very hard materials like ruby to effect a polish. However on most pieces I use a leather or felt wheel. Mix a small amount of polishing compound with water so as to not waste it. Wet the leather or felt thoroughly and apply a small amount of polishing compound to the wheel with a small brush. Rapid polishing requires firm pressure with most material to effect the required finish. The leather will begin to dry and the best polishing will occur just before it drys. An inexperienced artist will allow the wheel to dry and pull the stone off the dop or worse crack the stone. A little experience and the craftsman will get the feel of the wheel.The polishing process requires the shortest amount of time in making the cabochon. After a brief period check the piece and it should have a bright shine. Now stop. More polishing will cause the stone to pit. Remember a mirror polish is possible only on relatively hard stones. Soft materials generally will have a satin finish.
Types of Polishing Compounds: Tin Oxide Cerium Oxide Aluminum Oxide Tripoli Diamond dust
Slabs to Cabs Quick Link	This is an instructional guide provided by Inland Craft Products, Co. I did ask permission to post this article by the company. However their request was put a direct link to their business and with our efforts to keep advertising off of these pages I choose to make a page under my profile, pvjjh, and post the link and article there. This is an excellent article in my opinion and thought it may help others that are getting started in the wonder world of cabbing. Paul

gamaliel114	Latest page update: made by gamaliel114 , Aug 21 2009, 8:37 AM EDT (about this update About This Update Moved from: Educational Guides - gamaliel114 No content added or deleted. - complete history)
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aubreyreynolds9@gmai

Cabochons and Freeforms

Oct 26 2008, 12:10 PM EDT by pvjjh

Thread started: Oct 20 2008, 11:21 PM EDT Watch

I have added a great deal of my knowledge on making Cabs and freeforms. I will be adding more. Feel free to add your knowledge. The page contains links to other sites on cabochon making. I hope you enjoy. It is about 75% complete but the subject has just been scratched,
Bill

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