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DESIGNING PARAMETERS
DESIGNING PARAMETERS
Things get quite interesting when you define
parameters that turn a single design into multi-
ple, and possibly infinite, versions of itself. Well-
designed definitions are the best way to adapt
one design into a range of successful furniture
outcomes that offer desirable, perceptible dif-
ferences and which suit a variety of contexts.
Finding parameters of a design starts by identi-
fying fixed relationships between elements as
well as external constraints. Does the design
have basic ergonomic rules that need to be fol-
lowed? Will specific material and machine lim-
its govern the size of the largest part? Does the
design have particular connections or struc-
tural assemblies that need to be maintained? Is
maximizing material yield or minimizing cutting
time during production an essential require-
ment?
Sometimes relationships and constraints can
be obvious. The need to preserve a comfortable
ergonomic angle between the 90-Minute
Lounge Chair’s seat and back is an example of
a fixed relationship. No matter how long the
Lounge Chair gets, it can’t function without that
angle. The four legs that hold up the Cat in Bag
ii tabletop is another example of a fixed rela-
tionship. Even if the spacing between these four
legs varies, their interlock and relationship to
the table’s four corners is a constant.
Another illustration of constraints is how the
maximum length of a tabletop is limited by how
much it can span before deflecting. Similarly,
its minimum length is determined by the point
at which it becomes functionally useless as a
table. The range between that maximum and
minimum length is a variable, offering multiple
structurally viable and useful versions of a
table.
Less obvious parametric opportunities demand
a deeper analysis to find the complex interde-
pendencies between elements of a design.
Should particular proportions be preserved in
the design? Do connections require a particular
amount of spacing between them? Does a part
require additional support if its span grows
beyond a set limit?
Developing sets of parametric definitions for
each AtFAB piece involved answering such
questions. For instance, the One to Several
Table can span a longer distance, simply by
adding an extra member or deepening its
structure. The Five to Thirty Minute Chair
doesn’t need to transform in every direction,
but it’s quite useful when it’s incrementally wid-
ened into a bench that comfortably seats two
or three people. Simple adjustments to depth
and shelf spacing radically tranform the Open
Storage from media center to display cabinet
to tool storage.
PARAMETRIC CASE STUDY: THE
CAT IN BAG II TABLE
The Cat in Bag ii is a coffee table that began as
a study to produce an elemental, parametri-
cally transformable shape. Named for a meta-
phorical cat in a metaphorical bag, its four
tabletop corners mimic the movement of four
kitty paws independently pushing an envelope
in four different directions.
A parametric operation can push each of the
table’s four corners (paws) toward or away
from the center, stretching the tabletop perim-
eter (bag) in different directions. Depending on
which corners you stretch, and how far you
stretch them, you might extend, elongate,
shrink, and shape the tabletop to complement
any furniture arrangement around it.
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DESIGN FOR CNC
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