Interlocking Burrs - High Level

The exact history of how the interlocking burr puzzle came about is a bit of a mystery but it is known for sure that this type of brainteaser is one of the oldest mechanical puzzles we know of. The first documentation of the puzzle is not a physical puzzle but a depiction in the 1698 engraving by Sébastien Leclerc’s called L’Académie des sciences et des beaux-arts. But probably there had to have been a physical puzzle made for that artwork to be taken from; possibly from China?

The first burrs would have no doubt been basic designs compared to the our high level burrs on this page. These high level interlocking burr puzzles are described using a series of numbers like 13.3.5.  A level 13.3.5 solution means that it will take 13 moves to remove the first piece. Then only after this first piece has been successfully removed another 3 moves are needed to remove the second piece. Once that is done still 5 more moves will be needed to remove the third piece of the burr. Very difficult by any standards.

A move is considered to be a directional move. ie: moving a piece, and sometimes it is possible that more than one piece is moving at the same time, on a single axis in that direction. Other language we may use to describe burrs “false assemblies”. This is when the pieces would theoretically fit together to make the object shape but there is no physical way of assembling them. This adds another dimension to difficulty ratings for these puzzles when puzzles are being reassembled. The Mega Six puzzle is a particularly good example of this. 

The advent of computers combined with th increased complexity and difficulty of these burrs meant that people started experimenting with computer software that could help them solve these burr puzzles. Bill Cutler created his BURR6 program and Andreas Rover came up with Burr Tools but there were others too.

Bill Cutler is very well known for inventing amazing burr puzzles.  What may not be so well know is that he created his first software program to solve burr puzzles way back in the 1980’s on an IBM PC AT. He then decided to analyse all possible solutions for 6-piece Burr pieces (all 35.5 billion of them) and to do that had to again create his own sofware called GENDA. 

Andreas Rover created a program still available for download today from Sourceforge called Burr Tools. It’s easy to use for the most basic function of solving interlocking burr puzzles but many people now use it to assist in the invention of burrs. Particularly these very complex high level burrs which need a lot of analysis to determine all the possible solutions and moves.

And you would definitely need a computer program to solve a puzzle like the Sequence Cube. Designed and published in 2018 by Aleksandr Leontev it is said to be a 8190.4094.2046.1022.510.135.121.126.62.30.14.6.2 level burr. That’s 8190 moves to remove the first piece. Surely he used a computer to prove that!