Math Monday: Giant Burr Puzzle
JANUARY 11, 2010

by George Hart



Building the Giant Burr Puzzle
For the Math Midway exhibition, the Math Museum created a set of large geometric puzzles. This one is a traditional six-piece burr in which the six notched pieces of wood interlock in a clever way.  When assembled, there are two pieces each in the X, Y, and Z directions. Even if you are familiar with this type of puzzle, it is an entirely different experience to solve it on a giant scale.
burr-parts
Plans for the six pieces of this particular puzzle are shown above. Any woodworker can make these from 4-by-4 stock, which you can buy at any lumber yard. All cuts are 90 degrees and all dimensions are an integer multiple of half the width.
burr-puzzle-parts
If you prefer, instead of cutting you can simply glue together unit cubes. Here are the six parts assembled from 104 one-inch hardwood cubes.  In this version, the ends are shorter, but the central interlocking portion is the same.  (Add four more cubes to each end if you want the proportions of the colorful version above.)
burr-puzzle
They assemble into this rather sculptural puzzle. Many other burr designs are possible — some easier and some harder than this. If you build this puzzle and then find you can’t solve it, try the applet by Jürg von Känel at http://www.research.ibm.com/BurrPuzzles/, which will solve any burr puzzle in this family.


This article first appeared on Make: Online, January 11, 2010.

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