Improving Buildability of Overhangs of 3D Printed Objects Through Non-Planar Slicing Informed by Force-Flow-Analysis (2023-09)¶

The traditional method of data preparation for 3D printing, known as planar slicing, involves slicing the 3D model into horizontal layers and printing them gradually. This is the simplest option with the main parameter being layer height. However, this method has several limitations, including poor surface finish with stair-stepping contours of layers at steep angles and a necessity to print additional support structure for overhangs. Nonplanar slicing is a newer method that involves slicing the 3D model into non-horizontal layers with varying layer heights. This technique is mostly explored in plastics, with observed improvements in buildability, surface finish and reduction of cracking alongside the layers. In construction scale, non-planar printing is used primarily for achieving unique surface finish, or for printing on an uneven base. Its potential for improving buildability is still yet to be properly tested. This paper examines how non-planar layers can be derived with a help of force flow lines and how it affects the buildability. While printing overhangs, shear force can ultimately break the interlayer bond and layers can start deforming and sliding on top of each other, resulting in buckling, or even collapse. By guiding these forces into the bulk of layers instead of interlayer bonds, printing capabilities can be improved. Goal of this paper is to present how buildability of overhangs can be improved using non-planar slicing. Non-planar layers are derived from force flow line simulations done in Karamba3D. For printing we use clay, as a fast and simple prototyping method with the aim to later utilise our findings into concrete printing.