Acrylic Spikey

thingiverse

A stellated truncated dodecahedron. It is also the logo for Mathematica. My first two attempts were cut from 3/32" clear acrylic. The third is 1/8" tinted acrylic. I calculated the angles for the triangles and connectors using Mathematica. The angles for the connectors were 65.0126630 degrees, 152.13568896 degrees, and 164.70420180 degrees. The triangles are isosceles triangles with a base of 1 inch, and a base to side angle of 111.4999145471926 degrees and a side length of 1.36425707926833 for the tall one. The short triangle had a base to side angle of 123.53604428357949 degrees and a side length of 0.90504049664228. (Due to an ordering error, the tinted acrylic was .110" instead of 1/8", fortunately I noticed this before I cut the connectors, and so I was able to adjust the slot with in the connectors to compensate for this.) Instructions You need 60 of each triangle, and 60 of each connector. Use the fat triangles, and the second most obtuse connectors to make 12 pentagons. Then use the most accucte connector and the tall triangles to make 20 tetrahedrons. The you can use the most obtuse connector to join these together. I made two halfs, and then joined them together. Common mistakes I made were to put the fat triangles in the wrong way. Make sure the longest side faces the outside of the pentagon. Also, make sure you don't confuse the two obtuse connectors, as they look very similar. My first attempt used cyanoacrylate glue, which makes a big mess. For the second attempt I used plastruct bondene, which worked a lot better. The sheets of parts have been offset .004" to account for the kerf of the laser cutter. The tinted spikey was assembled using weld-on acrylic cement. This is by far the best way I have found to glue acrylic. Just put a drop on the joint, and capillary action will draw the glue into the joint. It sets enough to let go in about 30 to 45 seconds.