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By
Michael Plesh
Director, Technical Skill Center
Art Center College of Design
Pasadena, California
Art
Center College of Design is recognized as one of the world's
foremost institutions for art and design education. Obtaining a
degree from this institution has often been compared to attending
medical school, just without all the blood. You might expect that we
would be investing heavily in the latest computer visualization
tools that allow our students to produce highly realistic 3D
renderings of their design creations and you would be right. But
many people are surprised to discover that we also insist that our
students learn the skills needed to produce an accurate physical
prototype of their work, both with conventional and computer-driven
tools.
This article will explain why we
believe that it’s so important for designers to learn prototyping
skills and some of
the methods that we use.
While
the latest computer modeling tools provide a very realistic view of
a proposed design, there are often very important aspects of the
design that go beyond visual appearance. One example would be that
of "fit". Let’s say you are designing a project and that project
utilizes a handgrip in its design. No matter how many times or what
direction you rotate it in the computer, you will never be
absolutely sure that it is right until you can actually put it in
your hand and try it. To carry that further, a garden trowel needs
to fit the hand differently than a gearshift lever or a fly swatter.
The only way to determine whether the handgrip, or any other part of
a design that interfaces with the human body feels correct and works
for that application, is to build one and modify it until, it
provides the feel that works for that application.
Hard to get it right on the computer
In
fact, there are lots of objects whose visual appearance is very
difficult to get exactly right on the computer. One reason is that
rendering software alone is unable to perfectly represent the way
that an object appears under certain lighting conditions, certain
angles or any combination of those two. The computer comes close,
but close isn’t good enough when you are about to make a decision to
invest millions of dollars, bringing a new product to market. An
automobile is a great example of this.
Most automobile companies make
heavy use of computer modeling but still depend on clay models as
their final design criteria. (In fact, full size clay models are now
being machined using CNC programs and large five axis machines.)
Why
not just use the computer? Surely it is faster and easier to
manipulate. The simple fact is, that nothing beats the reality of a
three-dimensional model sitting in front of you. With a 3-D model
you can see, touch and feel the subtle changes in a curve or line,
or the way a door handle transitions into the door panel. You can
walk around and look from any angle at the way the light reflects
off a given surface. This holds true for any product whose
appearance is very critical, not just automobiles. In the television
commercial market, art directors and producers recognize the value
of having a physical model to work with, and most of them insist on
it even though it would be possible, and certainly quicker, to
create these models on the computer. Directors and producers have
discovered that they are able to obtain a level of control over
their products appearance through camera placement and lighting,
they cannot achieve with just a computer model.
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Building a prototype also forces the designer to resolve issues that
would be too easy to gloss over in a computer model. There are
hundreds of issues that usually don’t begin to get addressed until
the first prototype is built. Just exactly how do pieces fit
together? Does it work the way it is intended to? How does the user
hold the product? Exactly how will it be used? How does it fit in
with other products that it is to be used with? Does it have the
right feel? How does it look in the environment in which it will
actually be used? How do the products potential purchasers react to
it? You aren’t likely to get an answer to any of these questions or
many others until the first prototype is built.
Addressing Manufacturability Issues
Prototyping also addresses another major concern – how easy or
difficult will it be to manufacture the product. Manufacturing
problems, which are not so obvious in a "computer generated" model,
come into sharp focus in the actual fabrication of that model or
prototype. With the latest computer modeling packages you can create
virtually any shape, but is it really possible, or cost effective to
make it that way in the real world? Building the design will force
you to think through the different manufacturing steps and may cause
you to make design changes, even very subtle ones, that will make
the design much easier and less expensive to build. There are times
when a model can also be used as a pattern to go directly into
production with. For example, I once built a model primarily as a
visual aid for a company’s marketing people to look at, prior to the
manufacturing stages. As it turned out marketing loved the model and
with a minor little technical change, they ended up using the model
as a master, and production molds were created directly from it.
Where possible, smart companies try to make a prototype that can
also be used as a pattern.
Here at the Art Center College of Design, we offer three classes
that deal with basic model construction. The first two focus on use
of manual tools and the development of hand skills, and the third is
an offering into the use of the CNC routers.
These are required classes for our industrial design
students. After those there are more advanced RP classes that
students can take, such as machine surfacing, etc. Once learned,
students then make use of these skills in all areas of study. For
example, our environmental design students will build topographical
scale models of landscapes and buildings, and full sized pieces of
furniture on our CNC Techno routers instead of cutting out pieces on
a band saw.
The beauty of the CNC routers is
that you can define every detail of the piece in the software, send
it to the router and then go do something else while the machine
produces the part.
While CNC machining isn’t perfect, its accuracy and
appearance is far beyond what can be achieved by hand. For example;
in the case of the topographic models, instead of a bunch of layers
of cardboard that has been cut out on a band saw, stacked and glued
together, a model would be accurately machined from a solid block of
foam with every contour line layer machined to accurate tolerances,
and all surfaces and edges would be clean and smooth with very
little sanding necessary. While programming is somewhat of a
labor-intensive process akin to cutting out the first piece by hand,
once it is completed other pieces can be produced without the
attention of a person except for loading raw materials and unloading
finished pieces on the machine and with occasional checking to be
sure the tool hasn’t worn out or broken.
With today’s new "user
friendly" software, even
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Selecting a CNC router
We selected the Techno machine because it is constructed on steel
stress-relieved bases with hardened steel linear ways. Its
shaft-and-bearing system produces very smooth, play-free motion and
is an extremely rigid system that produces high-quality cuts. The
machine also uses anti-backlash ballscrews. These screws have
excellent power transmission due to the rolling ball contact between
the nut and screws. This type of contact ensures low friction, low
wear, and long life. The ballscrews also make it possible to produce
wooden parts to the machine resolution of 0.0005 inch.
Instead of being ballscrew-driven, the less expensive
machines use rack and pinion gearing, which has too much play to
make accurate cuts in small areas. Also this type of gearing wears
out quickly in the dusty environment of a carpentry shop.
The other main difference
we found between the Techno machine and the others was that the
Techno uses a servo motor to control cutting motion while other
machines use stepper motors, which can give a stair-step cutting
effect. With a smoother cut, sanding and finishing time is kept to
an absolute minimum. Believe me when I say that this is a real plus
to any Art Center student.
Our
students begin by defining their concept design in a computer aided
industrial design software package such as Alias, FormZ and
SolidWorks. (Almost any software package that produces 3-D geometry
can be used, with the only limiting factor being, having the proper
translators) Next their model is imported in the IGES format into a
CNC programming package to produce a file that the router
understands. Once the CNC program
is generated it is sent to the Techno machine to cut patterns from
3-inch thick sheets of 7-pound or 15-pound density polyurethane
foam, Ren shape material, or plywood from which their model or
pattern is made. They also have the option to machine the top and
bottom halves of a model separately, drill alignment holes in each
half and then marry the two halves by inserting steel rods into the
holes and gluing them together.
This allows students to make models twice the depth of the
machine’s cutter depth. This model can then be used as a pattern to
produce a mold, or it can be used as the model itself. Our Techno
Routers are not limited to just Environmental students. Product
students also make use of it to machine out their models (last term
it was computer speaker housings, this term it was toothbrushes) and
transportation design students use it for automotive details such as
rims, tires, seats and other components. This term we are teaching
Fine Art students how to machine objects on them.
Besides the above mentioned benefits of a designer learning basic
modeling skills, there exist the fact that in the real world, when
the economy is tough, and industrial design jobs are hard to find,
especially for students coming straight out of school, graduates can
use their model building skills to pay their bills until design
opportunities come around.
(Model building skills will also improve their employability
and make it possible for them to earn a good living in secondary
fields of employment that are closely enough related to their
specialty that they can keep their skills sharp while waiting for
the right opportunity to arrive) A great example of that is the
opportunities that exist in the model building field that was my
business. A business that produced high-quality, innovative props,
patterns, "hero" products and prototypes for major studios, prop
specialty shops, ad agencies, photographers, manufactures, museums.
etc. My 30+ year success of my business, plus the success of
thousands of other similar business, provides proof of the important
role that prototypes have played and will continue to play in the
product development process.
Michael Plesh is currently the Director of the Technical Skill
Center, at the Art Center, College of Design in Pasadena,
California. For the past 30 plus years he has owned his own business
making props, patterns, models and prototypes for film,
architectural, industrial and ceramic work. Some samples of his work
can be viewed at
www.propmakers.com
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