N12.bikini

Continuum Fashion
N12.bikini
C7712DA
Support Document
Design
One of our main principles behind Continuum is
pushing the possibilities of digital fabrication tools
by creating designs that specifically reflect the
technology behind the manufacturing process.
Our dream technology would be something that
could completely produce a garment, all in one
piece, with the closures included, so no sewing is
needed. It would be akin to knitwear, where the
textile and the clothing pattern are designed in
unity and made at the same time.
Last year, we experimented with 3D printing to
make the first completely 3D-printed, ready-towear, item of clothing.
The result is the N12 Bikini, named for the
material it is printed in, Nylon 12. Nylon 12 is
a solid plastic, but it’s strength allows it to be
printed as thin as .7 mm, and it can be made into
springs that bend and stretch. Thus our design
is actually a 3D printed fabric, where thread-like
connections form a material that also cohesively
create the aesthetic design. It is flexible, and
comfortably wearable. The nylon makes an ideal
swimsuit material, being waterproof and chlorine
safe.
Designing the bikini was an endeavor of pushing
the capabilities of the machine as well as working
with constraints. A bikini was the natural choice
to start with for 3D printed fashion, due to the low
amount of material needed. The printer also has
a set bounding box, and our original bikini design
exactly fit within the print area in a single piece.
Our first print models came out of the printer in
one piece, with no additional assembly required.
While conceptually exciting, this was really not
efficient for production, due to the large amount
of empty volume that the model took up. We
felt it was important to design something that
could be produced affordably enough for retail.
Making this a ready-to-wear design was our main
goal, as other 3D printed fashion experiments
have remained experiments, or conceptual oneoffs. We wanted to prove that this design and
production process can go beyond just a concept.
So, in our finished bikini design, the top is
composed of 4 pieces that hook together. This
is beautiful in its own way, as it packs flat, and
provides a modular system for sizing. And, of
course, it makes it easy to put on and take off.
N12 is inclusive of more than just the bikini. The
patterning we created in order to make wearable
3D printed fabric is visually appealing for a
number of things. We also have a variety of 3D
printed jewelry and accessories available. It is
easy to see how the design method extends to a
purse, or a necklace.
3D printing technology is really only in its infancy,
and it is extraordinarily exciting to imagine what
we can do as its capabilities improve. Right
now, the challenges in the process also become
points of inspiration. We have plans to do a dress,
perhaps in modular pieces, and shoes…
As we like to say, the future is an awesome place.
Technical
With the N12 system, we are trying to reinterpret
textile design through a computational lens. This
is especially appropriate considering that textile
design contributed greatly to the beginnings of
computation.
General Motivation for the Pattern
We knew we needed to subdivide our surface
into small patches that could connect to each
other by thin elements in order to achieve both
the coverage and flexibility we were after. While
we’d seen a somewhat similar system tried on a
flat surface using triangles, we decided this was
not going to work well in 3D, especially when
trying to conform to the curves of a body. While
triangles and other polygons are great for tiling
flat surfaces, and even for approximating curved
ones, they tend to result in a fairly wide range of
aspect ratios, and thus the occasional very pointy
piece. This problem is generally exacerbated if the
pattern is trying to transition from one size range
to another. Circles, however, don’t suffer from this
issue. They are, of course, always perfectly round.
2D Pattern on Surface
Clem Rutter, Rochester, Kent
Jacquard looms were the first machines to use
punch cards. They used these cards to create
the complex woven patterns and texture of the
final cloth. A Jacquard loom in motion is a very
impressive, and computational, sight! Charles
Babbage used the idea of punch cards as the
input mechanism of the un-built analytical engine,
and punch cards were, indeed, used as an input
method for computers in the mid 20th century.
Now, of course, modern computers are used to
control many types of textile production, such as
commercial knitting machines. However, these
methods are still mostly used to create traditional
fabrics with weaves that could be achieved by
hand. With the N12 system we are attempting
to use the variability, continuity and precision of
complex 3D modeling in combination with 3D
printing to produce a textile with new and unique
properties.
Circle packing, at least on two dimensional flat
areas, is pretty well understood. There are plenty
of technical math papers on the subject, and
implementations of various algorithms can be
found for most programming languages and
environments. Our requirements, however, were
rather specific and complex. For one, the pattern
is not flat, even though its initial calculation
can be seen as “two dimensional” since each
individual circle is flat to its own plane. Instead it
lies on an arbitrarily doubly curved surface. We
also needed the size of the circles to respond to
curvature and edge conditions of the surface in
order to create smooth edges and a responsive
pattern. Minimum tolerance values also needed
to be maintained between circles. So, instead of
a traditionally optimized algorithm that tries for
maximum coverage, minimum size variation or
similar metrics, we were looking for something
quite different.
We found inspiration in the way a necklace of
beads can coil against itself and form a fairly well
packed but also well organized configuration.
The patterning starts with a curved surface, some
geometry to indicate edges and value ranges for
the circle sizes and tolerance parameters. The
pattern begins placing circles at a point near the
edge. Each subsequent circle tries to stay as near
to the nearest edge geometry at possible. The
circle’s size is determined using this nearness
and the local curvature of the surface. Curvier
areas get small circles and flatter areas larger,
both to help with accurately approximating the
surface and to ensure flexibility where it is needed
and efficiency of pattern where it is not.
Every time a bend or elbow is encountered in
the surface edge a small gap will be left in the
pattern. Gaps will also occur near the middle
distances between edges where the placement of
the next circle is less certain. After the first level
of pattern has been created these open areas are
infilled with smaller circles to ensure complete
coverage, and to create a more interesting
aesthetic pattern.
Now that we have all the circles, connecting them
is relatively simple. Circles within a reasonable
distance of a given circle are gathered and
connection paths between them are determined.
If a path passes within the radius of any other
circle that connection is considered bad and
discarded. This process leads to a connection
diagram between all nearest neighbors.
Connection intersections themselves are allowed.
These occur more often in the small regular
packing near the edges, leading to stronger and
denser fabric there.
3D Geometry
Of course, the placement, size and
interconnectedness of the circle pattern does not
actually create a fabric. To do that, volumetric
3D geometry needs to be created. There are two
phases to this.
The first is relatively simple. The circles are
extruded at the minimum allowable thickness,
copied and offset out. The two resulting plates
are connected through their centers by a central
cylindrical stalk.
Although the earlier patterning steps ensure a
minimum tolerance between neighboring circles,
due to the concavity or convexity of the surface
some plates may intersect each other. These
intersections are checked for and, if found, the
radius of the offending plate is reduced.
Now we have good and non-intersection circle
geometry. All that remains it to connect them
together. Using the connections calculated in the
patterning steps, 3D spiral curves and volumes
are created which connect the circle assemblies
from central stalk to central stalk.
The calculated connection curve is offset through
the vertical center points of the starting and
ending circle assemblies. A simple helix curve
is draw around the result, leaving just enough
space so that the piped volume will not touch
the circular plates, and instead will only connect
to the central stalks, giving the structure more
flexibility.
Seams
One of the goals of the circle patterning system
is to be able to adapt it to any surface, at any size.
While the code and concept work well enough
at this we are, unfortunately, constrained by the
physical limitations of the printer itself. Anything
that is to be printed must fit within the bed size of
the printer.
For a bikini for a rather small person, an entire
model can just fit. However, to print efficiently, or
to make a larger size, or to make garment larger
than a swimsuit, the model will have to be bigger
than the size of the printer’s bed. How can this
be achieved without destroying the continuity and
flexibility of our fabric system?
As it turns out, the original pattern already holds
the key. The circle pattern that you see on the
outside can actually be thought of as three parts.
The outer and inner surfaces (what you see) are
thin circular disks. They are joined in the center
by a stalk. The springs which connect these disks
together all dead end into the stalk. So, to create
a smooth seam in the fabric, I modified how these
stalks are created.
Along each seam’s edge the disks are split from
each other and alternately separated out to one
side or the other. The stalks are divided in two,
with one side receiving a hole and the other a pin.
The springs for each piece are directed either only
at the top half, or bottom half of these divided
stalks as appropriate. The end result is a sort of
alternating snap configuration that joins together
nearly invisibly and keeps the integrity of the
surface in tact.
Our custom sized bikinis use seaming to create a
form that exactly conforms to the wearer’s body,
with minimal need for closures.