Giant burr puzzles

By George Hart for the Museum of Mathematics

For the Math Midway exhibition, The Math Museum created a set of large geometric puzzles. The one seen here is a traditional six-piece burr puzzle 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’re familiar with this type of puzzle, it is an entirely different experience to solve it on a giant scale.


Plans for the six pieces of this particular puzzle are shown below. 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.


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 shown in the opening image.)


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 here, which will solve any burr puzzle in this family.


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Introducing “Math Monday”