About this 3D model

Wooden Knot Cross Puzzle, OCC, Three Pieces, Kong Ming Lock This is a simple yet fascinating cross knot puzzle of three interlocking pieces. It may have a Chinese origin, dating back to the days of Zhuge Liang (aka. Kongming, AD 181-234). Easy as it looks, it takes a bit of planning in 3D design. One has to make sense of the physical constraints. While the length of each piece is largely arbitrary; its width has to be three times as much as its thickness. Further, one has to consider the tolerance. This makes a great entry-point 3D design project for STEM teachers and their students. Yes, a bit of struggle is healthy! In the current design, I have added a 0.5mm tolerance to the OCC slots and a 0.25mm tolerance to the opening so that children can slide them back and forth smoothly. There are two styles with various widths and lengths. Have fun! References: https://en.wikipedia.org/wiki/Burr_puzzle http://chinesepuzzles.org/interlocking-burr-puzzles/ http://www.mathematische-basteleien.de/devilsknot.htm