OpenForge mould

thingiverse

Human: An attempt is being made to build a mold for casting OpenForge streets out of plaster. I am finding it necessary to make use of Meshmixer 'make solid' in order to resample the shape completely and obtain a manifold. From there, Meshlab 'laplacian smooth' and 'quadric edge collapse decimation' produces a workably simple mesh. These meshes can be subtracted from the mold lower texture by editing the OpenSCAD, or can be subtracted from the 'no texture' STL and then flipped upside-down for printing. The "no texture" STL is positioned such that if an OpenForge piece is placed with a corner at 0,0,0, it should subtract correctly. The OpenForge pieces are positioned at various places, but those places seem to be multiples of 25mm, making it relatively easy to line them up. Alternatively, you can use a bit of software to align the piece at the origin: I think I wrote a Java app to do it, which is laying about somewhere on my hard drive. 21-Nov-2017: Separating the mold is proving to be a pain, so I have added tabs onto the side pieces to grab onto. The hemispheres in the base were too high and interfering with the texture. I have removed them. I have increased the sliding clearance to .5mm. I should rename the variable - this is a fitting clearance, not a sliding clearance. I have decreased the texture relief. The 'gutter tee' texture was clipping with the old setting. The 'make solid, laplace smooth, decimate points' procedure seems to work. I set the laplace smooth to 1 pass only, and decimate down to .1 of the points created by the 'make solid' operation. 23-Nov-2017: Having an open top and troweling it smooth definitely works better. I am using cooking spray as mold release. I think I'll mark this project as no longer a work in progress at this point. There are a couple of mold examples, but I'm not going to process all the OpenForge textures and turn them into molds, so I'll just leave the two that I have done here.