K-MODDL & Tutorials & Reuleaux Triangle - StumbleUpon If an enormously heavy object has to be moved from one spot to another, it may not be practical to move it on wheels. Instead the object is placed on a flat platform that in turn rests on cylindrical rollers (Figure 1). As the platform is pushed forward, the rollers left behind are picked up and put down in front. An object moved this way over a flat horizontal surface does not bob up and down as it rolls along. The reason is that cylindrical rollers have a circular cross section, and a circle is closed curve "with constant width." Is a circle the only curve with constant width? How to construct a Reuleaux triangle To construct a Reuleaux triangle begin with an equilateral triangle of side s, and then replace each side by a circular arc with the other two original sides as radii (Figure 4). The corners of a Reuleaux triangle are the sharpest possible on a curve with constant width. Here is another really surprising method of constructing curves with constant width:

BlenderArt Magazine Preparing Blender Files for 3D Printing - Shapeways This tutorial was written by Shapeways community member Jeff LaMarche. Introduction Okay, I've been fighting the good fight with Blender for a few weeks trying to convert some models I originally created for rendering into a printable file. Finding non-manifold edges If you have a model created from several objects or meshes, first make sure that each individual mesh is manifold (water-tight). Any vertices that get selected when you press that key combination are non-manifold vertices that have to be fixed. If there are three or four attached polygons that it says are non-manifold, but says there is already a face, try deleting the face and, if necessary, recreating it. Tip: hide geometry to focus on the non-manifold areas One trick that makes things easier is to select non-manifold, then press ctrl+ several times to increase the selection. Cleaning up: join meshes using Booleans Once you've got all your meshes manifold, make sure that every mesh is its own object. Finally, export to STL.