The Six-Piece Burr Puzzle

1928, Bruce Publishing Company

The root of the burr puzzle is the six-piece burr puzzle.  An interlocking puzzle of 6 rods, with 2 on each axis at 90 degrees to each other.  The puzzle is known to date back to the 18th century and was produced in both Asia and Europe.  Six-piece burrs are also documented in the Bestelmeier Toy catalog from 1803.  According to the IBM research the first US patent was issued in 1917 for a burr puzzle.  Edwin Wyatt published Puzzles in Wood in 1928 documenting the construction of multiple burrs, and this book is still in reprint today.  Although burrs now can be found with odd solutions, ropes, magnets and pegs to complicate them, the purist puzzler knows the best are the simplest, in high precision notched wood.  Bill Cutler is the modern father of the burr puzzle having written his paper in 1978 that showed that there were 25 possible notchable pieces that can be put together in 314 ways.  A notchable piece  can be cut on a table saw with no inside corners.  Once you expand the concept to non notchable pieces, which require a chisel to notch and inside corner, there are 369 pieces in total and the possible solutions escalates to 119,979 ways to make a solid burr.  in all these cases a solid burr is one where there are no empty internal spaces in the assembled puzzle.  Once you begin to analyze non-solid burrs, as Bill Cutler did in the 80s through the mid 90s, the combinations become astronomical numbering about 35 billion and requiring multiple moves to even separate the first piece.  The masters of today's Burr puzzles, still include Bill Cutler, joined by Stewart Coffin, Philippe Dubois, and Peter Marineau.  Many other have now come up with wonderful designs expanding from the simple six-piece burr  to ones that are 6 by 6 by 6 and some that are not even rectilinear.

IBM's Site at http://www.research.ibm.com

A few sites tell the story of the 6 piece Burr, but in my opinion, none is better than IBM site: http://www.research.ibm.com/BurrPuzzles.  I first discovered this site as a fantastic way to understand the history, the mathematical terminology and the huge variety of Burr puzzles, all made up from six rods.  I believe the site was an early experiment in cloud computing, which I find very purposeful and successful.  This predates the wilder experiments such as "Watson" which many of you might be familiar with from Jeopardy.  This site has not only the history, some of which I referenced above, but all the definitions and detailed descriptions of the mathematical nomenclature.  The site also has a burr calculator to help you design your own puzzles, or even solve the ones you have that you simply cannot figure out how to put back together.  It is the first stop for any novice burr puzzler, and the reference that everyone still uses, although many of the links are outdated because IBM does not maintain the site.a quick Google search will fill in the gaps.  and i will cover some of my other favorite sites in a future blog.