Mill and fold: Shape simplification for fabrication

• Published in: Computers & graphics Vol. 80; pp. 17 - 28
• Main Authors: Muntoni, Alessandro, Nuvoli, Stefano, Scalas, Andreas, Tola, Alessandro, Malomo, Luigi, Scateni, Riccardo
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-05-2019; Elsevier Science Ltd
• Subjects: 3D meshes; Algorithms; Assembly; Dihedral angle; Fabrication; Finite element method; Furrows; Geometry processing; Marching cubes algorithms; Mesh simplification; Milling; Milling (machining); Milling machines; Numerical controls; Polygons; Shape; Simplification; Triangles; Fabrication; Geometry processing; Mesh simplification; 3D meshes; Milling
• ISSN: 0097-8493; 1873-7684
• DOI: 10.1016/j.cag.2019.03.003

•Simplification of Shapes for Fabrication with sheets of rigid materials.•Milling flat sheets of material to produce foldable models.•Smart unfolding for taking into account the manufacturing properties.
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We introduce a pipeline for simplifying digital 3D shapes and fabricate them using 2D polygonal flat parts. Our method generates shapes that, once unfolded, can be fabricated with CNC milling machines using special tools called V-Grooves. These tools create V-shaped furrows at given angles depending on the shape of the used tool. Milling the edges of each flat facet simplifies the manual assembly, which consists only in folding adjacent facets at a constrained angle. Our method generates simplified shapes where every dihedral angle between adjacent facets belongs to a restricted set, thus making the assembly process quicker and more straightforward. Firstly, our method automatically computes a simplified version of the input model, using the marching cubes algorithm on the original mesh and iteratively performing local changes on the resulting triangle mesh. The user can then perform an additional manual simplification to remove unwanted facets. Finally, an unfolding algorithm, which takes into account the thickness of the material, flattens the polygonal facets onto the 2D plane, so that a CNC milling machine can fabricate it from a sheet of rigid material.