As in everything lapidary, the main aspect of jamb peg faceting is the grinding surface. All faceting units I have seen utilize a horizontal, tabletop type of surface. For many lapidary jobs this set up is good, but in faceting, especially when faceting jamb peg style, where working-by-eye is all important, the low horizontal surface restricts vision badly. I have overcome this by easily and efficiently creating a faceting/grinding surface perpendicular to that, ie. a Vertical grinding surface. This allows extremely fine viewing and does away with a lot of the calibration necessary in other systems of faceting. Your vision is optimized and you can begin to utilize it as your prime advantage, which is as it should be. Bill Gallaghers American Jamb Peg Faceting System is much easier to employ and master for making quality and valuable faceted gems.
Besides restricting vision when faceting, the horizontal grinding surface also causes some less natural postures than a vertical surface, as anyone who tries the latter will instantly see; among other things, a vertical grinding surface makes better use of gravity when holding a dop against the peg surface, and the attendant stone against the wheel.
My portable configuration, below, gets firmly C-clamped to a work table. I use a 1x2 spacer between the motor and the table to give clearance for the flat lap wheel and the bench, and I use a cut off clear 2litre bottle as a perfect sized wheel/splash guard. Position a section of the clear plastic bottle to cover the 6” lap wheel but not too much, just enough to keep from getting water everywhere. Do not restrict line of sight with the wheel guard. A 1725 rpm or LESS (Optimum maybe 1100RPM) electric motor sits on said 1x2 wood spacer, tack this plastic wheel guard to that spacer, ant gwon nowheres. If the sizes of your equipment varies from these measurements, adjust accordingly. This set up should be considered very elastic, and customizable to your needs. A permanently mounted configuration will generally help you make better work, but max flexibility runs a close second.
The bench mounted motor utilizes what is called a shaft arbor, or threaded shaft extension, they are made in 5/8” and 1/2” and even smaller. They fit on a larger motors shaft and fasten with set screws. These shaft arbors can be used to direct-drive wheels of many types. This direct drive is usually more integral than even multi-bearing shafts. Be aware of motor directions, and mount accordingly. You want the wheel moving INTO the work. Harbor freight has these fittings and many local hardware stores and rock shops have them too; you want to be able to mount a flat lap sidewise (VERTICALLY), washers either side, tightened down, immovable while operating, but easily removable because there are multiple grinding steps. This vertical grinding surface is a primary innovation. It can be employed for faceting in many ways, and is very well suited for jamb pegging.
The second most important aspect of the jamb peg system is/are the dop stick(s). These must be uniform to a fault, due to the fact that their length and makeup are used continually and interchangeably with a notched board or other like surface type (The peg surface, think of a cribbage board) so that angles of facets are easily repeatable and will tend NOT to overcut. That is the nature and advantage of the jamb peg system, in a nutshell. I use bicycle spokes clipped in various but uniform sizes, 4" 6" 8" and these 3 different sizes come in handy for larger and smaller stones. For some operations (Depending on the make up of your peg surface) sharpening of the end of the dop will aid you well. The aforementioned salvaged bicycle spokes utilize the rim end as the dop end, it is even shaped for it, and the tool notch aids adhesion. These spokes as salvage are free or thereabouts. If they are too thin to hold safely, find larger diameter spokes, or drill a dowel and make a holder for yourself, so the end of the spoke protrudes and can be jammed in the peg surface, but you also have a handle. The cut off bike spokes are especially well sized for small fractional-carat stones, and because of the vertical grinding surface of this system are really a fine tuned aspect of it. Other dop systems can be used, even wax and wood, and a lot of what is conventional for jamb peggers will work as far as dopping goes.
The third and final part of any jamb peg system is the peg surface. This is where the end of your dop is pushed into or against. Some of the jamb peg systems utilizing a horizontal grinding surface use actual peg boards mounted 90 degrees to a table or other platform, and some even use a head affair, cylindrical, curved, and there are even other more esoteric peg surface configs I am sure. To use any of those systems, constant downward pressure must be applied to keep the dop stick jammed into the peg surface as the wheel spins INTO it. The action of the wheel as it spins toward both the work, and the peg surface, has both a pushing back on the dop and pulling down on the stone effect, to a certain degree, but with a vertical grinding surface (lap turned/mounted on edge 90 degrees to horizontal) all that is needed is sidewise motion to cause the wheel to push the dop down into the peg surface, which is mounted to the bench top.
Once again, because of the vertical grinding surface our faceting tools become more useful and simpler at the same time. Because our sight is so much greater in this configuration, and because we have gravity on our side, the peg surface can now be varied and utilized to much greater degree as well. Instead of an actual cribbage board type peg surface which is mounted on the bench in relation to the vertical grinding surface, consider disposable peg surfaces like leather or medium hard plastix. The patterns you make with a pointed dop end as you facet a stone are sure to tell you a story afterwards as well. Be astute.
Steps in faceting: cut the preform from the rough, grind the preform into shape, dop the preform stone with short term epoxy (2-5 minute set - Need acetone soak to remove). The top and the bottom of a faceted crystal are accomplished in two separate steps. Many cut and polish the crown/top/bezel part first. When cutting/grinding before the polish, leave room for loss of material during later steps. That judging of material as you go is the real art of faceting. Practice on hodads before getting antsy with good stuff.
Once the crown/top is finished, transfer the stone from one dop to another, without losing any orientation, by using a transfer block. Below is an illustration of one, it uses set screws and channels to hold the dops while epoxy is being applied or removed. One or both sides slide to make room for the operation with two stix/spoxe. Precision is everything here, and thats another good reason for the bicycle spoke dop stix, they are uniform. You must develop a system of dopping that works well for you, with no variance at all during the transfer. Study well. Net. Library. Rock Clubs.
Cut and polish the bottom (Pavilion, Back, Base) in equal facets according to Eye Appeal and your studies of various cuts and gemstones.
The set up for jamb peg faceting can be as simple as is diagramed here, which is to say portable, or it can be made semi-permanent or permanent, depending on your situation and what you want. This will get you faceting quickly and well, with a distinct knowledge advantage. Experiment with various grits, many times a worn 100 lap will be like a 220 or 360, and so on. In my other lapidary pursuits, abrasives for various stones are almost like recipes, although for crystal one can be assured of a fine finish with diamond, climbing the scale from very heavy to very fine, in as many steps as one can afford.
Safety is important, and I recommend (In this order) wheel guards, safety glasses, patience, and distaste for pain. You will be ok then. No helmet required.
Please do research faceting further, faceting patterns, and other literature. Faceted stones have not been around too long and even some relatively modern stones are just a crystal cleaned up. For the best short history of faceting I must quote Barbara Smigler (Find her free gemology course online, you will be glad you did):
“...Several hundred years ago the jamb peg faceting machine came into use, and faceting, as we recognize it today, began. In order to cut facets on a gem in an organized manner that results in a precise arrangement, three factors must be controlled: 1) the angle of the cut 2) the depth of the cut and 3) the radial placement of the cut. Although modern highly engineered faceting machines have replaced jamb pegs in much of the world, these older systems are still widely used, and a substantial proportion of the gems in commerce today have been cut by them...”
Yes.
There is a plethora of information online and at most libraries. Write luxefaire@gmail.com with questions.
Remember above all that even if you can afford a machine with all the bells and whistles you will be seeking the same end product as a jamb pegger, a bright beautiful stone, and eventually, after enough time and practice has passed, you will be handling your machine like a jamb pegger too, by feel, and with an expert eye.
This system (Vertical grinding surface/bench top peg surface) has the exact same action between grinding surface and stone as the conventional configurations, but is now more amenable to human manipulation and sight.
Finally, I am sure that a lot of this type of thing has been done before, its just that I have only seen horizontally mounted machines and methods, and this change of method works much better for me.
BG
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