3D-printed burr puzzle

Burr puzzle, assembled

I read Scientific American religiously as a child. Sometime around 1980, in Martin Gardner’s “Mathematical Games” column, he reprinted a woodcut from an 1893 book called Puzzles Old And New by one Professor Hoffman. The illustration showed the pieces and assembled form of what Hoffman called the “Nut” puzzle, and Gardner explained that there were many variations of this puzzle.

I was fascinated, and wanted to see how it worked. So I made one out of balsa wood, and solved it. Then, with my father’s encouragement, I built a jig to speed the process and made a bunch of them, and gave them as gifts. My aunt says she still has hers, but my copies have long since been broken or lost.

A couple of weeks ago, my friend Melba Kurman and her husband Hod Lipson kindly lent me a 3D printer, the 3D Systems Cube. If you’re not familiar with 3D printing, their new book, Fabricated: The New World of 3D Printing is a must-read.

I’ve been enjoying making things with the printer. This is the first model I designed from scratch for printing. The Blender and STL files are available on Thingiverse, and below is a short animation showing disassembly of the puzzle.