Casted 8-axis cube core by grafalex

Last crawled date: 3 years ago

Although printing a Twisty puzzle core is relatively easy, 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 2-part mold (there are plenty of videos on youtube describing this process)
In this thing I am printing a mold for a mold to simplify creation of a 2-part silicone mold. General idea is to cast silicone into printed mold, and then cast polyurethane into 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 pcs of each wall type
Core is a hidden part, so no extensive post processing required. It is up to you whether to sand printed parts
Use 8 pcs of M3 6mm screws to assemble the mold
For one of the parts you should prepare channels to get polyurethane in and let air bubbles out of the mold. For this purposes I used short wooden sticks glued with a hot glue. Second half does not require this.
Put 15mm wooden sticks in 2 holes in 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 a polyurethane:
At this point you should get 2 halves of the second generation mold. They should be almost identical except for keys orientation and air/polyurethane channels in one of the halves.
It will be pretty hard to drill casted part and make thread there. Instead, it is much easier to make thread 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 was 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.
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 adjustmentshttps://cad.onshape.com/documents/46fffb7b3854b23195036a9e/v/71facd1f5f256f872f48ed01/e/8b5e9c6d5f92229d873db161