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Department of Engineering, ICT and Technologies for Energy and Transport Patent Title ZĞƉƌŽĚƵĐƟŽn method. Ref. CNR 10278 Assignee(s): CNR CNR InsƟƚute: ISTI Main Inventor: Paolo Cignoni Countries: IT Priority date: 25/07/2013 Abstract Method to fabricate a cross-joined physical structures ƐƚĂƌƟng from a given digital 3D model (represented by a triangle mesh). These cross-joined structures are composed of several (hundred) unique interlocking planar pieces whose 2D profiles are auƚŽŵĂƟĐĂůly generated by the proposed method. These planar pieces are cut by a laser cut machine and manually assembled into a rigid self- suppoƌƟng object whose shape approximates the input 3D model. These structures are composed by interlocking ribbon-like planar pieces that are approximately perpendicular to the surface and that, when available, follow a cross ĮĞůĚ ĚĞĮŶĞd over the surface of the 3D model. The proposed approach is based on three main conƚƌŝďƵƟŽŶƐ: Interlocking mechanism, Joinery absƚƌĂĐƟŽŶƐ through graphs and GeneƌĂƟŽn and placement of the slices. Background Wooden Puzzles build by crossing slides are well known. Commercial examples are available and they consƟƚƵƚe a sŝŐŶŝĮĐĂŶƚ market. However, all these models are laboriously designed by hand by skilled ĂƌƟƐƚƐ͘ Tailored CAD tool, like 123DMake, can help the design of simple interlocking structures based on the classic wĂŋe slit scheme, but are unable to produce complex arrangements. Technology The proposed approach is based on three main ĐŽŶƚƌŝďƵƟŽŶƐ: “Interlocking mechanism”, “Joinery abstƌĂĐƟons through graphs” and ͞'ĞŶĞƌĂƟŽŶ and placement of slices”. The Interlocking mechanism has been extended by relaxing the geometric constraints that seriously limit the quality of the ƌĞƉƌŽĚƵĐƟŽn. We have introduced a graph based ŵĂƚŚĞŵĂƟĐĂů represenƚĂƟŽŶ of the arrangements and devised a slice placement strategy that follows a cross ĮĞůĚ for an higher ĮĚĞůŝƚy in the represĞŶƚĂƟŽn. Advantages and ApplicaƟons The present inveŶƟŽn allows the fabrŝĐĂƟŽn of low cost illuƐƚƌĂƟǀĞ represĞŶƚĂƟŽn of 3D objects. The shape of the pieces of structure are generated autoŵĂƟcally and can be assembled to compose a self-suppoƌƟng robust structure. With respect to the classical interlocking mechanism, this method is capable of more Ňexible joinery’s and allows a beƩer adapƚĂƟŽn to the characterisƟĐ shape of the ŝŶŝƟĂů 3D object. Development stage A prototype ŝŵƉůĞŵĞŶƟŶg the ĞŶƟƌĞ pipeline is already available; it is capable of ŐĞŶĞƌĂƟŶŐ a model that can be printed with laser cuƫŶŐ techniques. Together with the slices, it’s also provided a user guide useful for the assembly procedure. The technique has been experimented with several complex input shapes. 61