Casted 8-axis cube core

thingiverse

Although creating a Twisty puzzle core is relatively simple, regular home FDM printers do not produce parts strong enough. Printed pieces either crack on layers or screws break their thread and pop out. This time I decided to make the core by casting polyurethane in a silicone mold. Usually this technique is used to copy existing objects, but generally it is quite complicated - it requires a complex sequence of actions to get a 2-part mold (there are plenty of videos on YouTube describing this process). In this case, I am printing a mold for a mold to simplify the creation of a 2-part silicone mold. The general idea is to cast silicone into printed molds and then cast polyurethane into the silicone. Core size is 44mm. Printing and Assembly Algorithm Part 1 - Making a Silicone Mold: Print Part 1 and Part 2 of the mold. Print 2 pieces of each wall type. The core is a hidden part, so no extensive post-processing is required. It's up to you whether to sand printed parts. Use 8 pieces of M3 6mm screws to assemble the mold. For one of the parts, prepare channels to get polyurethane in and let air bubbles out of the mold. For this purpose, I used short wooden sticks glued with hot glue. The second half does not require this. Put 15mm wooden sticks in 2 holes at the top - this is required to make a thread later (see picture). Mix silicone and cast it into the mold. After silicone solidifies, you can disassemble the mold and remove glued wooden sticks. Repeat for a second half. Part 2 - Casting Polyurethane: At this point, you should get 2 halves of the second-generation mold. They should be almost identical except for key orientation and air/polyurethane channels in one of the halves. It will be pretty hard to drill casted parts and make threads there. Instead, it's much easier to make threads on this stage. Use 8 pieces of an M3 thread rod, each 15-20mm length, insert them into dedicated holes of the mold. For 4 of them, I designed special chambers so you can use regular screws. Fix 2 parts of the mold with rubber bands. Mix polyurethane and cast it into the mold via channels made in one of the mold halves. After polyurethane solidifies, you may get part out of the mold, unscrew thread rods and screws, and cut off material in channels. The core is ready to use. Bottom Line Attaching also a regular 3D model for the core. There is one for whole core. Other is a half - print 2 and then glue together. Here is a model source. Feel free to learn, review, clone, and make your adjustments: https://cad.onshape.com/documents/46fffb7b3854b23195036a9e/v/71facd1f5f256f872f48ed01/e/8b5e9c6d5f92229d873db161