Machine a wax model using a rotary axis
Design and production of a Trapezoid Ring in platinumThis project is a good example of how a great result can be achieved using lowcost tools:
Rhino for CAD, DeskProto for CAM and MiniTech for a 4-axis CNC machine. Lowcost as these tools may be, they bring state of the art technology within reach, both because of the low price and the ease of use.
Goldsmith Mark Morrell of MWM Jewelers Services has been a bench jeweler for over 32 years, and recently started working with CAD/CAM technology. These new tools fit in well with his way of designing: he says "I am finding that my interest in milling is becoming a strong force in my business. I believe that this solution has brought me 'home'".
The ring design in Rhino, as a wireframe and next as Flamingo rendering.
MWM Jewelers creates both custom designs and small series for the MWM showroom. About this project Mark Morrell says: "The 'Trap' ring was created for a special client. I built the piece according to their basic definition. We worked via email sending photos and Rhino shots back and forth to each-other until the ring was properly defined for manufacture." See the illustrations above.
Rhino shading of the ring, both complete and exploded to obtain the wax part.
Quotation continued: "After the client approved the project, I removed from the Rhino file the stones and bits of the model that were not necessary for milling the body of the piece. The basic ring was then made into an .stl file and processed through DeskProto and set up to run on my MiniTech #3 mill via FlashCut milling software."
The illustration shows the very sharp conical cutter that was used, to provide the needed level of detail. For machining rings obviously a rotary axis is needed: DeskProto offers full support for such device.
Rotary toolpath in DeskProto, and machining the wax model on MiniTech.
"After the part was milled, I cut out the openings below the side stones by hand. We then cast the piece in platinum and hand polished the casting. The side stones were then set and the side wires were put into place. After inspection, the center stone was set and the entire piece was hand polished again for delivery.
Milling of my basic parts still leaves me with some hand work to perform on my waxes but the control that the mill affords me is a tremendous help in making very precise pieces."
Immediately after casting in platinum, and the final result.
Jewelry design and manufacturing is a very good application for DeskProto, as CNC machining can very well be combined with the 'traditional' manufacturing processes.
Since many centuries gold and silver ornaments are manufactured using investment casting (the "lost-wax method"): first a model is created in wax, which is converted into a plaster mold by casting the plaster around and then melting the wax out of the cavity. The gold or silver is cast in the plaster mold, and afterwards finished by (hand) polishing.
The complete ring, after setting the stones and hand polishing.
This method can very well be applied in a small jeweler's workshop. Traditionally speaking the original wax models are carved by hand from a sketched design, the current alternative is using CAD/CAM technology.