On the bold assumption that you might find an independend
opinion of the Saunders process of use, here are some
observations. I’m sure Rolf can give you more detailed info on
just what his system can and can’t do, but your questions
suggests to me that you may have some slight misconceptions of
the computer aided design and manufacturing process.
Kim, the process is two fold. The CAD (computer aided design)
process is the design one, and takes place in your computer only,
where you must draw the design. But unlike paint programs, you
must completely design the 3D form, using either wire frame
constructions, or better, NURBS curve surfaces, or solids
modelling software. The computer must know exactly where all
surfaces and solid portions of the design are, and it knows that
because you input it. It’s not automatic. The software will
provide drafting/designing tools, but you must construct the
design in digital space before a machine like the Saunders
modelmaker can create the model for you in real life. Once
you’ve designed a piece, you then can decide which of several
options you wish to use to actually produce the piece. This
includes the Saunders machine, or tradtional CAM machine tools,
or other methods.
The Saunders process is a variant of traditional CAM machining
(usually using various machine tools, like milling machines etc.)
that falls into what’s called RP, or rapid prototyping methods.
These generally avoid a whole slew of setup process, involving
selection of cutters, considerations involving tool paths for the
cutters, or holding mechanisms for holding the block of raw
material for machining. They do have their own limitations, in
some cases, but it’s a lot quicker to go from CAD design to a 3D
model with RP methods. The accuracy of these processes, and
there are several of them, can be phenominal, and the types of
curves and complex shapes attainable is more limited by your
ability to design them on the computer than the RP processes
ability to translate them to real life models.
The computer driven milling machines used in traditional CAM
machineing can be made to give you almost glass smooth surfaces
if you’re willing to take that much machining time, and have a
machine tool of sufficient accuracy (expensive). Most RP
processes, including the Saunders one, use buildup methods Build
a model in succesive layers with a descrete thickness to each
layer (The Saunders page says their range from .03 to .07 mm
thick, which is a damn thin layer. Their resolution is about
.025 mm, which again is pretty precise) that leave at least a
slight “stair step” sort of surface, like a topographic map, or
the pixels on a digital image, or dot matrix image, on surfaces.
The scale of these stair steps in some processes, like larger
scale stereolithography, can be coarse enough to be very
objectionable in jewelry scale models. The Saunders process,
though, is quite good in the fineness of it’s resolution. Some
models may need a little touch up finishing, either to the model
or the resultant casting, before final molding, but others may
not. And in some cases, the characteristic surface left by RP
processes may itself found to be an attractive feature to be used
by the designer, instead of being shunned.
Back to CAD… (the designing phase). I’ve seen some software
that can take a graphic, 2D image, and translate it into relief
images of varying depth. The one I was most intrigued with, last
time I looked, used a TIFF file as input, and the output was a
CAM toolpath for a milling machine, with multiple paralell
straight lines, much like the scan lines on a T.V., where the
variable depth of cut was proportional to to the light/dark value
of the image. Darker meant deeper. so a digitized or scanned
photo could be milled, and the deepest cuts would be where the
image was darkest. The resulting carving, in metal, or wood, or
wax, once fed to a milling machine, was an uncanny translation
of a 2D photographic image to a shaded relief, but the relief was
not actually a relief carving of the image. That’s what I liked
about it. Kinda abstract in the end… There are also, more
polished and now marketed, software packages out there, usually
sold along with the mills they drive, that take a 2 D drawing or
scanned image, and translate it into a true, “what you’d
expect”, relief carving. These things probably cannot take a
scan of a photo of a face, and produce a really good looking
milled image of that face (unless you take the time to actually
design, in a CAD program, the complex surfaces and curves
required) , but they certainly can take a scanned image of a
celtic interlaced knot, and turn it into a highly precise and
detailed relief carving in wax, suitable for casting into a nice
piece of celtic interlace design jewelry… Sort of the same way
you can take a normal image in Photoshop and using an “emboss”
filter, create the look of that image translated into a relief
embossed image…
For some ideas on what can be done in the design process, go
look at the Rhino web site http://www.rhino3d.com/ and see what
those images look like. They are true 3D designs, complete with
all the needed 3D to let a machine like the Saunders
one produce the shapes with accuracy in 3D. My old alma mater
for grad school, Tyler School of art, now concentrates in it’s
graduate metals program, on CAD/CAM/RP methods, and their web
page shows the efforts of current and past students as they
explore what they can create with these rapidly emerging
technologies. Worth a look.
http://blue.temple.edu/~crafts/mjcc/mjcc.html will take you to
the main page of that department. Look for the links to the
galleries at the bottom of the page, to find some past work, and
current works in progress of the students.
Hope this helps.
Peter Rowe