With special grinding wheels in place this machine will grind the perimeter and dome the top of the

cabochon in one easy operation. When you have cut the first cabochon, you can use the same setting to cut the next in order to produce more of the same size and shape. [1] 


The set of 40 cams shown in the picture allow you to cut a cabochon of almost any size oval, round or other shapes. (See the sample in the picture. These are cabochons actually cut on the machine.) About the only thing it cannot do is put the notch in the top of a heart shape, or produce straight sides when using the cams shown that have flat sides. [2]  Special grinding wheels will allow you to obtain interesting and special shapes including bullets and teardrops.    


A variable speed motor allows you to control the rotation of the preform [3] against the grinding wheel in order to minimize the problem otherwise encountered of bumping the stone and having to re-dop it, before continuing. 


Grinding wheels are made in a manner that will shape the dome at the same time the perimeter of the cabochon.  The dome can be high or low, and can even be pointed or bullet shaped with use of different grinding wheels.  [4]


Concave profile-type [5] diamond plated grinding wheels are powered by a one-third horsepower (3450 rpm) fixed speed motor. The motors can be converted to use either 110 voltage or 220 volts. The smaller variable speed gear motor is, however, not convertible to 220 and will require use of a transformer.  We recommend that if 220 is standard in your country you have an electrician install a transformer and we ship the machines for use only with 110 – 115 volt systems.  Make sure too that the polarity is correct and for your own protection, that your machine is plugged into an outlet that has ground fault circuit interrupter (GFI) protection.     


The cutting process removes material from the perimeter and dome part of the stone as it rotates against the diamond plated profile type grinding wheel. The result is a pleasing shaped cabochon. Lapidary books show cabochons being cut where the dome is three dimensional with no portion of the dome not an arc in both directions. [6] Depending on the type of material being cut, it is frequently possible to use a tumbler or vibrating polisher to finish the smoothing and polishing.  


We have attempted to build in the maximum amount of flexibility.  For example, replacing the profile type grinding wheel with a flat one the machine is ready to cut performs for the lapidary prior to faceting.  A special wheel or wheels could be made to provide the initial shapes achieved when roughing in before cutting he first facet of a brilliant or other cuts. Without having special wheels made the carriage could be detached from the base of the machine and positioned to cut a taper without first having to order special wheels. A hole in the center of the carriage is provided just for this purpose. [7] 




Shipping list – what is included and what is not included when you buy the Cabochon making machine:


Item #1. The Addexton Company’s semi automatic cabochon machine. (Size 16 x 27 x 13 inches, Weight about 65 pounds.)

Item #2.  Plastic bag containing 40 assorted cams made of a tough plastic material. These have a center hole and offset small hole to cam from ever slipping while cutting a cabochon. 

Item #3. Blue and orange colored adjustable plastic tubing, and a brass value to connect the machine to a coolant system. You will have to buy a small pump, copper, rubber or plastic tubing and other fittings necessary to construct a circulating cooling system, if one is not already in place. You should also acquire a supply a suitable coolant – (i.e. one to which water is added and which contains a rust inhibitor and detergent.)

Item #4. Coolant tray to be connected to a

Sump. You will need a tank to use as the sump where the small pump will circulate water to flow over the cabochon while grinding is in process. (see #3 ) 

Item #5. One (or more – depending on your order) profile type diamond plated grinding wheels. Occasionally these are shipped separately.   

Item #5. A 3 foot long black electrical cord that plugs into the outlet at the back of the machine to provide the variable power to the small motor. When not in use this small motor can be switched off from a switch at the side of the cover of this motor.

Item #6. Several flat-head bolts (as a sample of what you may want to use for dopping the rough.)



Setup and Installation:


Select a place where an electric outlet is away from but near enough so that the Addexton Cabochon machine can plugged in. Again, for your protection the outlet should be one protected by a Ground Fault Circuit Interrupter (“GFI outlet”) and should be tested first to make sure polarity is not reversed. Always make certain that the power supply is disconnected before attempting to replace any electrical switch,   speed controller, or making any alterations to the machine.    


Using the machine:


A comfortable height bench would be at waste high (36-38 inch) and operator will usually sit on a stool when not standing.  One operator can operate two machines but can also smooth and polish the cabochons as they come off the cabochon machine.


Avoid the mess coolant causes:


Most coolant will be directed into the pan under the grinding wheel, but it is impossible to prevent or avoid having the bench or tabletop get wet. Clean-up includes flushing grim off the base of the machine and the bench or tabletop. Plan for this.  One way if to installing an 1/16th  to 1/8th sheet of aluminum under the machine that will also  protect wood surfaces. A machine shop might be engaged to make bends in the aluminum sheet to direct the water away when cleaning up.


You need a sump and sump pump:


You will need to obtain plastic pipe and fittings so that coolant will be drained into a sump from which it will be re-circulated. [8]. The sump should be of a sufficient size to allow the sludge to settle at the bottom. You will occasionally add more coolant and water and if the sump is large enough you will not have to deal with the sludge but just once or twice a year.


The electrical outlet on back of machine:


The electrical outlet on the back of the cabochon machine provides the power for the small variable speed motor.  There is an on/off switch on the side of the cover for this gear motor which rotate the preform as it is being cut into a cabochon.  When not in use switch the small motor off  [9]. 


Selecting the cam:


When cutting round cabochons any size of round cam will do.  When cutting ovals select the cam that approximates the size of finished cabochon. A cam that is (for example) 10 mm by 14 mm can be used to cut ovals that are approximately that size. That is, you can cut a 11 mm by 15 mm, a 12 mm by 16 mm, or a smaller 8 mm by 12 mm.  But as the size of the cabochon desired becomes larger that the cam the machine will tend to sharpen the ends (or if smaller may fatten the middle) distorting the shape of the finished cabochon.  [10]


What a cam will not let you do:


When you select a cam that has straight sides i.e. square, triangles, etc. you will find that the finished cabochons will have sides that bow out. (see picture of sample cabs produced on the machine) The cabochon is perhaps as attractive, but if trying to fit a stone into a ready-made mounting, this will require that it be done manually. [11]


To dop the stone:


You can dop your stones using the way you have done in the past. If you are using epoxy, you will want to use a type that will release the stone when soaked in acetone or when exposed to heat. [12]


Replacing the chuck:


For maximum flexibility the machine comes with chuck, into which the dops are placed and secured. This chuck in time will have to be replaced with another - or you may want to replace it with one that can be tightened by hand or a quick release collet available from many machine supply companies. To remove the chuck now on the machine you will need to heat it with a torch in order to allow the Lock-tight or Bolt- locker (epoxies) to release the chuck from the shaft. 


Dop sticks:


A solution to what dop sticks to use are 2 ¼ or 2 ½ flat head bolts with flat heads that are about 3 mm across. [13]  


Installing the grinding wheels:


When installing the grinding wheels be careful to not abuse the shaft of the motor. If at first the wheel does not go onto the shaft do not try to enlarge the hole. Check to make sure there is no the edge of the whole is smooth but attempt to enlarge the hole except as a last resort. The wheel should fit snugly onto the shaft but be so tight that it will be difficult to remove it.  A little oil or grease should be used and some fine steal wool used on the motor’s shaft should allow to be mounted. If a problem does arise in removing the wheel - and pulling from the outside edges by hand does not work, you will need a pulling device that can be purchased at most auto parts stores. [14] 


Concave grinding wheels: 


We will provide you with the concave grinding wheels you need.  But we can not guarantee that we will be still doing this ten or fifteen years from now - or that someone else will have taken over here who will be able to provide you with what you need. There are a number of companies that provide the diamond plating. In order to obtain what you want in order to produce different domes [15] or to make larger or smaller cabs, bullets and teardrops you should look for someone near you that will be able to machine cut the concave grinding wheels that when plated will produce the shapes and sizes you want. Anyone with a computer controlled lathe will have no problem producing the arc that produces the shape of the dome desired. [16] 


Motors and parts:


The cabochon making machine has been designed so that should a motor or the controller need to be replaced you will be able to find it obtain it at a place near you.

It is unlikely that the large motor will wear out but if it does it can be replaced. The smaller gear motor may need to have brushes replace occasionally depending on use. Should you need to replace motors or controller these you will available at the  Grainger Industrial Supply store near you. [17]


Targeted production:


With one machine, depending on the hardness of the material being cut and the condition of the grinding wheel 50 to 75 finished cabs.  This is assuming that you would be starting with stones that have already been attached to dops. An operator sanding and polishing while others are in process (not including the back) is likely that you would have 50 completed.    



In assembling the cabochon making machine the next to the last thing we do is to align the carriage. This is aligned to center of the shaft of the motor to which the grinding wheels are to be  installed. At the same time make sure that the carriage will move from left to right and right to left. The last thing we do is assemble and install the support for the strike plate (i.e. the hard rubber wheel).


So as not to have to disassemble the unit first install a wheel on the motor shaft. Next put a  pointer [18] in the chuck and then you should loosen the bolts at the top and the bottom of the slides. [19]  You will not be able to align the pointer to the center of the motor’s shaft but you can align it so that as follows he edge of the wheel as the wheel is rotated. Holding it in this position the front guide is held against slide making sure that it is parallel to the front edge of the base [20] before tightening the ¼ inch bolts slightly. Make sure the slide moves freely and tighten these bolts until they are secure. Move the back guide so that it is in contact with the slide and tighten the three ¼ in bolts making sure the slide will continue to move easily as these are made secure. [21]


Once we had a jump ring come off and had to replace it in order move the carriage by turning the big knob. We doubt that you will have to align the carriage and the only time that has happened was when someone took one of the first machines we sold apart.  We have since made a change to prevent it from happening.   




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Copyright © 2005 The Addexton Company



[1] To obtain repeatability the will need preforms of the same thickness. Be sure that when inserting the same size dop that both are inserted to the bottom of the chuck each time.  After cutting the first stone fix the position by tightening two screws so that the position will remain the same.  You can also, by using the pointer provided and a marker) come back to the proximate size, then use a template to obtain the exact size desired. 

[2] The machine is best used to cut up to 30 mm round and oval cabochons. Larger ones can be cut as buff-tops, finished by hand or will require special grinding wheels.  

[3] It is best to, by hand, preform the rough in order to save time and prolong the life of the grinding wheel. If starting with slabs, consider using diamond cord drills to obtain round performs.  See the our section on core drills and drilling machines.  

[4] We will provide standard size grinding wheels.  However, we recommend that you have special wheels made by working with a machine shop in your own area and having them plated at one of many companies that perform that service. We will be happy to provide you with a drawings to which you might made modifications to obtain the shapes you want.  (At my age I can not guarantee that I will be available ten or fifteen years from now to provide the wheels you may need.) 

[5] Wheels are not exact concave but are profiles of the dome to be cut (i.e. the arc is one or two degrees at the outer perimeter and progress to +/- a thirty degree arc and finally to ninety degrees.) 

[6] In the last ten years of showing the cabochons to hundreds of people, only one person has commended that, when (i.e. cutting imperial jade), he would want to finish the shaping of the cabochon by hand.

[7] Another example is the length of the carriage itself.  It is much longer than necessary for making cabochons but that extra length is there to accommodate dop sticks of different lengths and the extra length that might be required for cutting tear drops. 

[8] A small submergible pump such as might be used to circulate water for a garden fountain is generally sufficient.

[9]   This gear motor has considerable torque. Loose hair, clothing, neckties or scarfs require caution.

[10] No way has yet been discovered that will compensate for this distortion. Make sure that the first cabochon is the right shape to fit.  If it does not then try a larger (or smaller) cam.  These cams were cut by a company that also manufactures computer boards using computer controls.  Companies that have water-jet machinery would also be able to provide special cams when desired.

[11] Also, you will have to manually cut the “v” shape in the top of a hart shaped cabochon. 

[12]  Use acetone with caution. Acetone also requires soaking and sometimes does not work. Also use caution when using heat as some stones, like opal, are sensitive to heat and even doping with wax pose a problem.    

[13] Care must be taken not to allow this metal to come in contact with the diamond plated grinding wheels (the metal will drag diamonds off the surface of the wheel and make them useless).

[14] These devices have three prongs that are hooked over the edge of the grinding wheel and a screw center piece that will fit into the notch at the center of the motor’s shaft.

[15]  The wheels we usually stock provide the high domes that we find most of our customers want – because the commercial cabochons produced by factories overseas are generally low domed and lack the appeal of well cut high dome cabochons.    

[16]  At the perimeter of the wheel the computer should cut an at about 2 degrees for 1 to 2 mm. From that point the degree of the arc increases until it is ninety degrees at the end of the arc.  Avoid having the person making the wheel for you, ordering or making “a tool”.  With a computer controlled lathe a tool is not necessary.  Remember the wheels will then be plated so allow for the extra thickness once that is done.  

[17]  If no Grainger Industrial Supply store is near you most shops that sell motors will be able to repair or replace these motors. 

[18]  The pointer can be any sharp pointed tool that will fit into the chuck. 

[19]  These bolts are those holding the top stainless-steel piece and ½ inch thick aluminum guide below it.

[20]  It may already be parallel to the front of the base and then so all that you need to do is retighten the three bolts making sure that when you do so the slide moves freely.

[21] The guides are ground to provide some resistance from the slide but not enough to prevent it from moving. Before we starting providing this extra care we frequently had to shim the guides to allow the slide to move easily. If you encounter a problem shimming should not be necessary except as a last resort.