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CAD models for Freeform cabs


Are any jewelers using cad software to design settings using
freeform cabs? If so, what process are you using to create the models
for the freeform cabs? Are you creating wire frame models by hand or
using scanners? Or is everybody designing with calibrated stones? I
have been working on some custom designer sets that incorporate
cabochons and faceted stones. I am interested in producing some
jewelry using cad technology from sets that we have. I have been
interested in the cad aspect of jewelry design for a while, but I
haven’t pursued it because I don’t know what all is involved to
produce the wire frame models, and the difficulty in doing so. So,
many things I want to do :slight_smile: You can see an example of what I am
talking about at:


  • james carpenter -


James, I have been using Rhino, Art Cam, Corel and others for some
time now. I have even cut some stones with CAD designs. David


Dear James, I hate answering a question like this because some
know-it-all will tell me I don’t know what I’m talking about. But we
do it here in my shop all the time. Here’s how. I take the cab in
whatever shape given and put it on my probe digitizer. We use Dr.
Pixa. Just a little two sided tape and it is secure. I usually scan
in a fine resolution of about .002". This can take a day or so. But
it is not any operator time so we do other things. Now I save the
shape in DXF or STL format. I take my surfacing program, import the
shape and design around it. The shape is exactly the shape of the
stone so there is no guesswork. I cut the part out with a CNC Mill in
either purple file-a-wax or plastic. I like the plastic better
because you can steam it out when you are done. You can’t steam the
wax. This gives me a very detailed part to mold and put into
production. The stone will drop right in for fit and if it doesn’t I
just take my foredom and fine tune it. You can basically build a
library of stone shapes and bezels.

I don’t use wire frame. The surface resolution of AFFORDABLE parts
is too rough. Even with resolution of .0005" which is what we grow
all our wire frame parts in I don’t like the surface resolution.
After you cast the stuff you still need to polish this model and can
loose between 5 and 10% of the detail. The part is now molded and has
further reductions factors. If the wire frame part was to be cast in
gold, silver or platinum and go directly on the customers hand it may
have different cost considerations. But for production a surfacing
CAD program like ArtCam, Cimigraphy or Type 3 will deliver a finely
detailed part. Those parts are then cataloged for future use.

Best Regards,
Todd Hawkinson
TR the Teacher


James, Todd offered you one way of accomplishing the task, so let me
offer some others. In Type3, you can scan in the stone with a regular
scanner directly into Type Edit and using the drawing tools convert
the edge into a vector which you can then modify. Once you have the
outline, you can then do an offset for wall thickness, and determine
the height either in Type Art as a relief, (which in this case is not
necessary) or just assign the height of the setting as a Z depth
instead from the CAM application. This is assuming that the bezels
are simple and do not require rapid prototyping but just cutting on a
mill. Todd’s method is an excellent way to go if you truly want or
need the 3D surface data that represents the stone, or in my case,
you don’t care or need the surface and that you are only
interested in the outline. By going the 2 1/2D route, this will allow
for many many stones per day to have settings cut for them. Time is
money after all is said.Therefore the determination on how much
is necessary, or required, to handle the task in hand
needs to be established. My customers only care about the finished
product and really don’t care on how it gets done, and 95% of the
time they trust in my ability to interpret their needs and give them
what it is they want without the need to supply renderings. If you
want a library of 3D surfaces that represent stones to create
renderings of a finished product then as Todd suggested, the
digitizing route is well worth the processing time. However, just for
cutting out bezels this could be over kill for many situations. It
all depends on your intended function for that stone, whether it is
merely a template to create settings in 2 1/2D ,or whether it needs
to be part of a 3D library or a combination of both. Either way
works as intended, just determine the bottom line of what it is you
are really after.

If I can assist you further, give me a call and I will be more than
happy to accommodate.

Best Regards.
Neil George