DEFINE A PROJECT PROGRAM
ing you through an approach for solving a
design problem, the process, concepts, and
modeling techniques practiced here can be
applied to projects throughout the book. We
encourage you to find ways to hack each 3D
file, whether by modifying overall dimensions to
widen a chair or by pushing/pulling connec-
tions in a cabinet to add another shelf. Once
you understand the principles of modification,
we believe that you will soon want to design
your own pieces from scratch!
DEFINE A PROJECT PROGRAM
As you embark on a design project, whether
furniture or anything else, it’s essential to first
research your design program (introduced in
“Programs” on page 58). A program starts with
having a defined need that a design must
address. In this exercise, the need that you’ll
fulfill is a bench that seats two people. While
you already understand the basic program for a
bench is seating, you’ll also want to identify
more detailed features like ergonomic dimen-
sions and key proportions. The more knowl-
edge you have about the function and context
of the thing that you are designing, the better
the design will ultimately be.
ERGONOMICS
If you’re designing a custom piece of furniture
for your personal use, you could simply take
your own measurements and use them as the
basis for your design. However, because this
bench seats two people, and might be used by
others besides yourself, it helps to think in
more universal terms. Because you can’t antici-
pate the comfort of every individual who may
use your bench, you can rely on ergonomics
and design standards (see Appendix A) to
ensure that it will accommodate the greatest
range.
Consider the following:
• How long does a bench need to be to seat
two people?
• What height and depth are comfortable?
Dimensional requirements:
• General ergonomic standards suggest that a
two-seater bench needs to be about 48″
long, and for comfort should be about 18″
deep and 18″ high (1220 mm × 450 mm × 45
mm).
FABRICATION CONSTRAINTS
Other variables that will impact your design are
the structural capabilities of your material, as
well as the CNC machine size, end mill diame-
ter, and stock material size and thickness. Like
other AtFAB projects, the stock material and
machine dimensions are already determined.
We’ll use 4′ × 8′ sheets, with a nominal material
thickness that is ¾″. Our end mill diameter will
be ¼″. We can safely assume that our optimal
bench dimensions will easily work within these
constraints.
Consider the following:
• How big is my material?
• How big is my machine?
Dimensional limits:
• Machine and material size are both 4′ × 8′.
However, there are numerous other program
requirements that you might want to research
prior to jumping into the design process of a
project. “Develop a Program” on page 224 will
elaborate on these additional considerations
that your design program might also include.
FILE SETUP FOR DESIGN
Chapter 3 introduced techniques for using lay-
ers, components, and groups to keep your work
organized. Setting up your CAD workspace,
using layers that facilitate the design process
88
DESIGN FOR CNC
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