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Ring, by Double Technology

Creating a jewelry wax ring model by CNC machining from three sides

Double Technology Company in Hong Kong is a successful reseller of DeskProto in Hong Kong and China. Their combination of the JewelCAD design software, the DeskProto CAM software and a desktop Roland milling machine proves to make an excellent total system for jewellers.

Double Technology offers more than just a combination of these standard solutions: proprietary hardware and software is added, which enables the machining of complex wax models for rings.
This project was one of the first DeskProto was ring projects using the Two-sided flip + Rotary approach. Many others have followed since.

The original artwork
The sketch of the desired ring, which was created by the client and used as basis for the CAD work.

This project has been realized by Double Technology as benchmark for a customer: Hong Kong based jeweller Gin Jewellery Ltd..
Start of the project was a hand drawn sketch from the client. Based on this sketch Double Technology's service team created the 3D model and next machined and finished the wax model. The actual manufacturing of the ring has been done by the client.

JewelCAD screen
Detail of JewelCAD rendering
Renderings of the final design in JewelCAD.

As said the ring geometry has been modelled in JewelCAD, Version 5.1. This CAD program is meant just for jewelry design, and offers a wide range of tools and options for jewelers. One of the tools is a high quality rendering output: ideal for presenting the design to the client.

After the client's approval an extra "core" was added at the inside of the ring, to be used with Double Technology's special ring machining fixture described below. The resulting combined CAD model then was exported as an STL file.

Toolpaths in DeskProto
Toolpaths, detail
Rotation axis toolpaths in DeskProto.

Based on this STL geometry the toolpaths have been calculated in DeskProto, for a very sharp conical cutter in order to also produce the most intricate small details. Three sets of toolpaths have been created: two using plain three-axis XYZ machining, and one using the Rotation axis (XZA machining).

This machining from several sides makes it possible to create very complex wax models, including many undercuts, on a machine that in theory does not allow any undercuts. As a result the advantages of CNC milling (low cost, high surface quality) are combined with the main advantage of additive manufacturing (model complexity).

Standard XYZ milling
Rotation axis milling
Two sided machining of the wax model, and next rotation axis machining.

Machining of the wax model has been done on a Roland Jewela machine (model JWX-10). The pictures above clearly show the special fixture for ring machining that has been applied. The Jewela makes it possible to do the two sided machining while the rotation axis unit keeps attached: no need to continuously attach and de-attach this unit.

Different solutions for ring machining fixture are available from other suppliers. Advantage of this Double Technology fixture is that it supports full rotation axis machining: 360 degrees around the complete ring.

The part was cut in green carving wax. The two sided milling was done in approximately 2 hours. Next the rotation toolpath took approximately 30 minutes.

The resulting wax model
The resulting wax model.

The wax model as it comes from the milling machine is sufficiently smooth for casting: polishing is not needed. Still some manual finishing is required, as the "core" has to be removed from the ring, and the places where the bridges connected it to the ring have to be smoothened.

The resulting ring
The resulting ring, in platinum-plated silver.

The final product has been cast in Silver. Of course after casting manual cleanup was needed to remove the sprues used in casting. The ring also has been polished to get the gloss as shown above, and has been plated with platinum.
After this the stones will be set, and a final polishing will be applied to achieve the high gloss that is required.