The Diagonal Burr is one of the truly "classic" interlocking puzzles, the origins of which are a mystery. The earliest US Patent is No. 393816 to Chandler in 1888, but shows an unnecessarily complicated version with a sliding key piece. The earliest record of this symmetrical version appears to be US Patent No. 779121 to Ford in 1905. Curiously though, in his patent description Ford shows a very awkward method of assembly rather than the mating of two mirror image halves.

In its simplest form, each of the six identical pieces to this puzzle is made by cutting a side-by-side pair of Vee shaped notches diagonally (i.e. into the edge) of a section of square stick. Although a rough model of the Diagonal Burr is easily whittled from soft wood or sawn by hand, to be entirely satisfactory it should be made very accurately, for which power tools and special jigs are required. Here at Pacific Puzzleworks, I make these puzzles in a slightly different manner than most puzzlemakers -- rather than cutting each piece from a solid square stick, I build each piece by attaching square stick segments onto an octahedral center block. My reasoning here is twofold: primarily I do it this way because I can achieve a higher degree of accuracy, but also because it allows me to make matched sets of Diagonal Burr and Pseudo Notched Sticks puzzles.

Whereas the Diagonal Burr is a very old idea, the Pseudo Notched Sticks puzzle is a relatively recent invention. Stewart Coffin realized that people familiar with the Diagonal Burr would always disassemble it by grabbing two parallel square sticks by their opposite ends and then pulling the sticks apart from each other. In one of his more diabolical design efforts, Coffin came up with the Pseudo Notched Sticks puzzle which looks identical to the Diagonal Burr, yet is designed such that any attempt to disassemble it in the "standard manner" (i.e. grabbing sticks by their opposite ends) will only result in holding the puzzle tightly together -- it will feel as if the puzzle is glued solid.

As such, this puzzle is probably more difficult for a serious collector to solve than it is for a novice because the serious collector has a preconceived notion of what it is, and thus how to go about solving it. The collector would likely take his failed attempt to disassemble it as a sign that the wood has swollen (due to humidity) such that the puzzle has locked up and cannot be disassembled until the weather changes. A novice will think no such thing and is thus more likely to keep playing around with the puzzle, eventually finding a way to get it to come apart.

Although the Diagonal Burr is one of the easier assembly puzzles that I manufacture, it is worth noting that reassembly of the pieces can be tricky if one is not familiar with the concept of mating two mirror image halves. The Pseudo Notched Sticks puzzle is significantly more difficult to reassemble than the Diagonal Burr -- not only does the awkward shape of the pieces make it more difficult to hold them firmly together in halves, but also the shape of these puzzle halves themselves are such that six sharp tips must all be simultaneously lined up with each other in order to get the halves started sliding together. In this sense, reassembly of the Pseudo Notched Sticks puzzle is somewhat of a dexterity problem.

Beyond the physical difficulty of getting the Pseudo Notched Sticks pieces back together, care must also be taken to ensure that the various species of woods are oriented properly so that the assembled puzzle retains the illusion of each square stick being a solid piece. My matched sets are carefully manufactured so that the two assembled puzzles will look essentially indistinguishable from each other as they sit side by side. Furthermore, I made certain that the wood grains themselves line up properly when the puzzle is assembled, thus maintaining the illusion that each square stick is a solid piece. Lastly it is worth noting that it is possible to interchange pieces between the two puzzles, resulting in a variety of different hybrid combinations, some of which have interesting external symmetries whereas others have no apparent symmetry at all.

Here at Pacific Puzzleworks, I manufacture my puzzles with every glue joint internally reinforced by three small steel dowel pins for the utmost in precision alignment, durability, and ease of do-it-yourself repair should the need ever arise. Crafted with attention to detail which is second to none, you will never find higher quality puzzles like these for sale anywhere else in the world. Each puzzle is laser-signed and dated. Each species of wood used is laser-engraved with both common and scientific names. Ships disassembled.