So rather than burn precious time waiting on replacements from Graves, I elected to drill out the nubbin myself.Īfter drilling one out using a drill press, a close inspection revealed the dop was not machined from a single billet of brass. I was under the gun to finish Spinning Wheel 40 and of course all my other large cone dops were currently occupied. Upon their arrival it was immediately apparent the cone recesses were not cut clean to the apex, leaving culet-crushing nubbins of brass where the apex should have extended through. It was one of a pair of defectively manufactured 1" Graves brass cone dops ordered late in the game to work on my Spinning Wheel 40 entry for the 2008 Faceter's Hobnob. This was the first and only dop I've managed to break while cutting a stone. I had nearly finished the second round of pre-polishing when the lap grabbed the stone and exerted so much torque on it as to cause the shank of the dop on the pavilion side to fracture nearly clear through and bend approximately 15 degrees! I was lucky that the stone was not yanked completely from my hand and flung and smashed against the side of the cast metal splash pan on my faceting machine. D'oh!) By the time I got C1 properly flattened it had become overly wide, so it was back to recut the entire crown. (After all, the "rough" was a molded gemstone. After cutting and prepolishing the rest of the crown side facets, I discovered the surface of the pre-existing table was nowhere near flat enough to polish. The first complication was caused by being lazy and using the pre-existing table of the glass gemstone as a "prepolished" surface for the C1 facet. My target size for the prototype Soda Bar 19 was 60mm in length, but several complications during its cutting resulted in a 55mm x 34mm finished stone weighing 250 carats. More is better here for some insurance in the event you encounter problems requiring recutting like I did.īigger Stones = Bigger Fun but can also involve bigger problems. 770 to ensure you will have adequate material remaining to complete the stone after transfer. Verify that your blocked out stone has sufficient height (H), which should be at least a fat tad over W x. I suggest blocking out the stone width (W) first and then the length (L), which should be made equal to W x 1.613. After some initial trimming down and preforming of the glass gemstone on my 6" trim saw, I decided to dop the existing pavilion in a 1" cone dop and cut the crown side first. These inexpensive molded glass gemstones are manufactured in China and are available in 40mm through 120mm sizes in various colors through the Cutting Rocks web site. The prototype Soda Bar 19 was re-cut from an 80mm SRB pattern gemstone molded from ordinary soda-lime glass. The C6 "girdle" facets may be considered optional on exhibition sized stones, but I incorporated them in the design to facilitate channel or tension mounting of jewelry sized versions. Because I designed and cut Soda Bar as an exhibition stone I was unconcerned with mounting it in a jewelry setting. This geometry is achieved by foregoing a conventional girdle all around the perimeter of the stone. The barrel shape of Soda Bar is generated by the intersection of the arched crown facets with the angled plane of the P1 facets. While this design utilizes only 19 facets, the overall effect belies the relative simplicity of the cut and provides a paradigm example of a sum exceeding its parts. This opposed bar arrangement produces a highly dynamic checkerboard pattern that shifts and dances with slight changes in perspective as the stone is viewed. Soda Bar 19 is a step cut, "opposed bar" type design, employing bands of parallel bars arched across the crown oriented at right angles relative to parallel bars on the pavilion. I designed and cut Soda Bar 19 as a large exhibition stone and my 2009 entry for synthetic division of the "Most Beautiful Stone" competition held during the annual Tucson Show Faceters Hobnob, hosted by Tucson's Old Pueblo Lapidary Club. 234Wĭownload PDF format printer friendly cutting instructions: ĭownload the GemCad format design file: Winner 2009 OPLC Hobnob "Most Beautiful Stone" Competition - Synthetic Division Winner 2009 OPLC Faceters Hobnob Most Beautiful Stone CompetitionĪn exhibition stone designed by Bob Keller October 2008
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