Printing structures with openings in a side surface

Abstract

A method for producing a 3D item () by means of fused deposition modelling, the method comprising a 3D printing stage comprising layer-wise depositing an extrudate () comprising 3D printable material (), to provide the 3D item () comprising 3D printed material (), wherein the 3D item () comprises a plurality of layers () of 3D printed material (), and an opening () in the 3D printed material (), the opening () having an opening edge () that is at least partly defined by one or more interruptions () in a subset () of one or more layers () of the plurality of layers (), wherein the method comprises providing each interruption () by 3D printing a layer () of the subset () with oppositely arranged turns (), wherein each turn () connects a first layer part () and a second layer part (), the first layer part () and the second layer part () forming legs of a U-turn (), wherein, for each turn (), the first layer part () has a first length (LI) and the second layer part () has a second length (L), the second length (L) being shorter than the first length (LI) such that over only part of the layer () the first layer part () and the second layer part () are configured adjacent, and wherein each turn () has a path length (Lr) with a radius of curvature (r), and wherein each path length (Lr) is selected from the range of 0.9*7c*r<Lr≤7r*r