Packable Springs

Abstract

Laser cutting is an appealing fabrication process due to the low cost of materials and extremely fast fabrication. However, the design space afforded by laser cutting is limited, since only flat panels can be cut. Previous methods for manufacturing from flat sheets usually roughly approximate 3D objects by polyhedrons or cross sections. Computational design methods for connecting, interlocking, or folding several laser cut panels have been introduced; to obtain a good approximation, these methods require numerous parts and long assembly times. In this paper, we propose a radically different approach: Our approximation is based on cutting thin, planar spirals out of flat panels. When such spirals are pulled apart, they take on the shape of a 3D spring whose contours are similar to the input object. We devise an optimization problem that aims to minimize the number of required parts, thus reducing costs and fabrication time, while at the same time ensuring that the resulting spring mimics the shape of the original object. In addition to rapid fabrication and assembly, our method enables compact packaging and storage as flat parts. We also demonstrate its use for creating armatures for sculptures and moulds for filling, with potential applications in architecture or construction.

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“…Exploring time and support saving digital fabrication processes of 3D objects has been of great interest to researchers. To achieve this goal, researchers have worked on laser cutting [3,19,35,42,36,40,15,43], block stacking [20,29], and vacuum forming [41]. Although these methods can be acceptable substitutes for 3D printing, their final artifacts tend to have sharp edges or gaps, and thus cannot make a smooth and gapless surface required of many designs.…”

“…Also, Schüller et al [25] proposed a method to disassemble 3D structure into flat ribbons with zippers, which can be joined by zipping and deconstructed by unzipping. As another strategy, researchers proposed several methods to push and sustain 2D sheets with mechanical constraints (e.g., plastic holders [40], pneumatic inflation [13,21], pre-stretched elastic sheets [10], and springs [15]) to build programmable curved surfaces. These surfaces can go back to the original flat sheet by removing the mechanical stress constraints.…”

“…), this 3D shape is tapered between z = t min and z = t max . In order to detect the tapered regions, we referred to the algorithm used in Packable Springs [40]. First, we classify all the facets by the positive-negative signs of the z-coordinate of their face normals.…”

“…In addition to the constraints discussed in the previous section, general 3D shapes, such as the Stanford Bunny, tend to have fewer tapered regions. To enhance the capability of our process, we implemented a remeshing process by modifying the remeshing algorithm introduced in [40]. In contrast to their optimization-based algorithm, we implemented a new recursive function that can remesh the points on each cross-section with relatively simple steps.…”

“…Other than 4D printing, several fabrication methods have achieved reversibility [44,25,40,13,21,15]. However, they suffer from complicated processes required to transform between the compact and the expanded states and/or extreme limitations regarding the range of final shapes.…”