Hollow Polyhedra: Prisms and Antiprisms
by pmoews, published
I recently posted openSCAD polyhedron files for the Johnson solids, thing:16508, based on information in the polyhedra libary at netlib. http://netlib.sandia.gov/polyhedra/
The netlib library contains additional polyhedra. Using the same fortran program I converted the netlib files for the prisms, antiprisms, and Platonic solids to openSCAD polyhedron commands, then to stl files, and printed them. See the images at the left. The models were scaled to a maximum dimension of about 50 mm to make a uniform set. I was pleased at how rapidly they printed and how well the flat surfaces at the tops of some of the models were filled in.
The Platonic solids have been done many times before but they came out so well that I have included them here.
These convex polyhedra were made hollow by scaling a copy to make it smaller and subtracting away the unwanted material in openSCAD. A scale factor of 0.9 was used; leaving enough material for a sturdy model.
All of the hollow polyhedra stl files are included in hollow_stl.zip and the scad files that produced them are in hollow_scad.zip. Prisms included are: triangular, pentagonal, hexagonal, octagonal, and decagonal; antiprisms are: square, pentagonal, hexagonal, octagonal, and decagonal; Platonic solids are: tetrahedron, cube, octahedron, dodecahedron, and icosahedron. A module containing the polyhedon command that produces the polyhedra is at the end of each scad file and can be extracted and used in other openSCAD programs. Separate stl files for the tetrahedron, dodecahedron, square antiprism, pentagonal prism, and pentagonal antiprism are included below.
The excellent site, "Virtual Polyhedra" by George Hart has more information, see http://www.georgehart.com/virtual-polyhedra/vp.html
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The files were printed on a Thing-O-Matic using a heated surface covered with Kapton tape. The surface was cleaned with acetone before each print and the models adhered well to the surface. A raft was used although it may not be necessary if your build platform is well leveled.
As an example the tetrahedron pictured has edges of 59 mm. It took about 50 minutes to print. The finished print weighs 6 grams and has a volume of 24 cubic centimeters. It is light and sturdy.