{"id":576,"date":"2018-10-28T18:14:37","date_gmt":"2018-10-29T01:14:37","guid":{"rendered":"http:\/\/www.kylescholz.com\/wp\/?p=576"},"modified":"2019-03-17T21:48:51","modified_gmt":"2019-03-18T04:48:51","slug":"brain-puzzle","status":"publish","type":"post","link":"https:\/\/www.kylescholz.com\/wp\/brain-puzzle\/","title":{"rendered":"Brain Puzzle"},"content":{"rendered":"

A few weeks back, I saw a great video from Maker’s Muse on YouTube, describing how to make custom 3×3 puzzles<\/a> (eg. a Rubik’s cube) out of any 3 dimensional model. I’ve always been curious about how these puzzles work, so what better way to learn than to make my own?<\/p>\n

\"\"<\/a>
Final puzzle. 3D printed and painted.<\/figcaption><\/figure>\n

Yup. It’s a brain.<\/p>\n

From brain scan to brain surgery<\/b><\/p>\n

I started with this brain model from Thingiverse<\/a>. These puzzles work best when there is good symmetry across X\/Y\/Z axes, so I scaled the model asymmetrically to improve its overall symmetry.<\/p>\n

\"\"<\/a>
Scaled brain with deep folds and crevices.<\/figcaption><\/figure>\n

I had to create a solid “core” for the model, because there is a large gap between lobes and several deep folds that would have made it impossible to divide the model into contiguous puzzle pieces. To create this core, I used MeshLab to create a “bubble shell<\/a>“.<\/p>\n

\"\"<\/a>
The bubble shell core.<\/figcaption><\/figure>\n
\"\"<\/a>
Original model with bubble shell core.<\/figcaption><\/figure>\n

Next, I took the union of the scaled model and core, then took the boolean difference with the 3×3 puzzle template from Maker’s Muse.<\/p>\n

\"\"
Model after boolean difference with Maker’s Muse 3v3 template applied. Each puzzle piece has chamfered edges to improve movement.<\/figcaption><\/figure>\n

Models generated from 3d scans are often really messy and if they aren’t repaired, mesh operations fail. When I have problems with bad meshes, I often turn to Netfabb to repair the meshes and move on. It turned out that Netfabb’s “standard” repair operations weren’t good enough for this model. I had to use the full version for “extended” repair. I also used Netfabb for all of the boolean operations.<\/p>\n

\"\"<\/a>
Final model with painted folds. This model would be very hard to solve if it monochrome.<\/figcaption><\/figure>\n

When the modelling was finished, I printed all of the parts on a Prusa i3 Mk3 (about 24 hours of print time for one puzzle). I then sanded and primed the unassembled parts. I assembled the puzzle with springs and M3 screws. Finally, I painted the interior of the folds on each “side” with acrylic paint.<\/p>\n

\"\"<\/a>
Final puzzle. Printed and painted.<\/figcaption><\/figure>\n
\"\"
Interior view of model. Pieces are centers, edges, or corners. Centers connect to a 6-side core (not pictured) with screws and springs.<\/figcaption><\/figure>\n

Learnings<\/strong><\/p>\n