Automated Topography Slicing for Support-Free 3-Axis FDM

Support-free fabrication of geometries with extended overhangs remains a fundamental challenge in non-planar fused deposition modeling (FDM), as conventional 3-axis printers cannot reorient the nozzle to maintain favorable deposition angles. To overcome this limitation, this work proposes a novel method called automated topography slicing. The proposed pipeline performs automatic overhang detection, heightmap-driven deformation-field generation, geometry warping, slicing, and inverse G-code reconstruction in a fully automated manner without requiring additional hardware or multi-axis kinematics. Experimental validation on a benchmark Tube Bracket and two additional geometries (Stanford Bunny and Elbow Junction Tube) demonstrates generality across free-form and slender features and confirms print feasibility and extrusion stability using an off-the-shelf 3-axis FDM printer. Across three geometries, the method consistently reduces support material with predictable dimensional trade-offs. High-resolution optical measurements, including full-field geometric deviation mapping, Geometric Dimensioning and Tolerancing (GD&T) evaluation, and surface roughness analysis, reveal that the reverse-mapped G-code accurately preserves the intended geometry, while observed deviations on large unsupported regions are primarily attributable to thermo-mechanical warping during material deposition. These findings delineate the boundary between algorithmic accuracy and process-induced deformation and motivate future extensions that incorporate feedback-driven or compensation-based strategies to further improve dimensional fidelity. Overall, this work establishes a practical, measurement-informed foundation for support-free, deformation-based additive manufacturing on standard 3-axis FDM systems.