Two Color Archimedean Solids - 1

thingiverse

A "Dualstrusion" Replicator arrived Monday. I set it up on the kitchen table, leveled it - nice built in leveling algorithm - and printed a two color test cube - it was identical to the one that came with the printer - all in under three hours. Very nice! Models of the Archimedean solids are usually multicolored and make good test objects. While waiting for the Replicator I prepared a number of Archimedean solid models for two color printing. Here are four of them: 1) truncated tetrahedron, 2) cuboctohedron, 3) truncated cube, and 4) truncated octahedron Two stl files are included for each solid; trunc_tetrahedron_less_faces.stl and trunc_tetrahedron_faces.stl cuboctahedron_less_faces.stl and cuboctahedron_faces.stl trunc_cube_less_faces.stl and trunc_cube_faces.stl trunc_octahedron_less_faces.stl and trunc_octahedron_faces.stl The files can be merged and printed in two colors. For those interested in the details a few words follow: The stl files were created with openSCAD. A zip file containing the open scad files is included - 2color_archi_scad_01.zip OpenSCAD's polyhedron command does most of the work. A hollow Archimedean solid from thing:17571 has two copies of the polyhedra, an outer copy and a smaller, but otherwise identical, inner copy. Suppose we wish to extract a single face, for example a pentagonal one. The coordinates of the vertices for the outer and inner pentagons are available from the hollow polyhedra scad file. These 10 coordinates define a polyhedron that corresponds to a face. It needs to be closed with 16 triangles, see the openSCAD manual for details Often a single openSCAD polyhedron command can be used to create a complete set of faces. However openSCAD does not work with shared vertices and where they occur shifts have to be made to avoid them. A program is needed to write the openSCAD commands as there is too much bookkeeping to keep track of without help. OpenSCAD's "thrown together" command can be used to catch errors. Instructions There seem to be few parameters to set for dual color printing - at least I have yet to locate them. The build surface needs to be carefully leveled as rafts evidently do not work. The surface at right angles to the z axis is the one placed on the build surface. The truncated cube printed perfectly but there were some smudges on one or two faces of the other solids although most of the wrong color can be scraped off. It looks to be possible to minimize smudging by rotating the model around the z axis. The fluorescent red and black models are striking - see image.