Thin-Wall Calculation for Layered Manufacturing

We describe a new algorithm for making partially hollow layered parts with thin, dense walls of approximately uniform thickness, for faster build times and reduced material usage. We have implemented our algorithm and tested its output on a fused deposition modeling (FDM) machine, using separate build volumes for a loosely filled interior and a thin, solid, exterior wall. The build volumes are derived as Boolean combinations of slice contours and their offsets. The Booleans are efficiently calculated via OpenGL winding number rules and the offset contours are generated from robustly generated Voronoi diagrams of the slices. Our algorithm guarantees that the exterior surface of the final part will be of high quality with no gaps while still allowing an efficient build.