Clay Non-Planar Printing of Overhangs

prof. Dr. Henri Hubertus Achten, Ing. arch. Jiří Vele

While the CAD model is being prepared for 3D printing, it is sliced into layers. Contrary to planar slicing, where an object is cut by horizontal planes and then a curve for the toolpath is generated from these intersections, non-planar slicing uses twisted planes for object cutting. It brings freedom to toolpath creation and each object can be printed in adjusted layers that reflect its geometry. Benefits of such printing are being explored in plastics and involve enhanced surface finish, cracking reduction and ability to print cantilevers. This paper examines printability of overhangs using clay non-planar printing. Basic potter's clay, from an art supplies shop was mixed with additional water and let in room temperature for one day. Desktop FDM delta printer was retrofitted with a clay printhead, its extruder motor was geared into a 19:1 ratio and connected to the ram. This ram pushes clay from a tank and nylon tube through a 4mm thick nozzle. Set of vase-like objects was designed, each with a different overhang. Starting at 10 degrees and ending at 70 degrees, in increments of 5 degrees. Objects were modelled in Rhinoceros software and G-code for both planar and non-planar print was generated in Grasshopper. Each of those objects were printed twice, once planarly and once non-planarly. During the printing buckling and collapsing of printed objects was monitored. Non-planar printing improves buildability and reduces deformation of overhangs. Right after the print and after they got dry, objects were measured for their deformation. Shrinkage during the drying was measured to be 12,5%. Ideal toolpath for non-planar printing seems to be the one having layers perpendicular to the overhang. Model evaluation and non-planar printing data preparation is being discussed in the paper. If used on a large scale, non-planar printing may allow printing walls with holes for plumbing, or even printing vaults or bridges.

Za obsah této stránky zodpovídá: prof. Ing. arch. Petr Vorlík, Ph.D.