Octadecahedron by Another Name – Pinwheel Crystal

What was the last octadecahedron puzzle you played with?  I thought so.  You’ve never heard of one.  That’s because of the lack of publicity that octadecahedron receives.  Now if I asked you about a truncated rhombic dodecahedron puzzle, you’d all be jumping up and down shouting that you have one in your collection.  Maybe even the Pinwheel Crystal made by Dave Rossetti.  It’s all in the naming.

I’ve always wanted a puzzle made by Dave Rossetti and I finally got my wish at this year’s International Puzzle Party (IPP).  Dave’s entry in the IPP Puzzle Exchange was Pinwheel Crystal designed by Stewart Coffin.  This is a geometric shaped puzzle in the form of a rhombic dodecahedron with truncated tips.  And the interior is hollow in the shape of a rhombic dodecahedron.

The puzzle is made from Granadillo and Maple and gets its name from the nice pattern made by the contrasting colors of the woods.  The puzzle consists of 6 pieces that are used to construct the truncated rhombic dodecahedron (just roles off the tongue, not like octadecahedron at all).

I’m always amazed at the complexity of these types of geometric pieces.  My woodworking skills top out at cubic dissection constructions.  The jigs and setup up required to make the angled cuts for geometric puzzles like Pinwheel Crystal is a whole other game.

So Dave used his amazing geometrical angly cutting skills to make 24 identical pieces (12 each of Granadillo and Maple) which he separated into 6 piles of 4, sprinkled them with glue, and shook them in a bag until he had the 6 puzzly pieces with a nice finish.  A little more shaking and he had the assembled Pinwheel Crystal.  Repeat 99 times and you’re ready for the puzzle exchange.  Sounds like magic, but everything seems like magic until you know how to do it.

Pinwheel isn’t a difficult puzzle to solve but it is a very attractive puzzle and beautifully made by Dave.

 

Half A Dozen Rhombic Dodecahedrons - Cluster Buster

For puzzlers used to working with cubic dissections, it may be a bit daunting to be presented with a puzzle based on rhombic dodecahedrons.  Rhombic what?  To keep it simple, a rhombus is a diamond (all 4 sides of equal length), dodeca means 12, and hedron means a shape bounded by some number of planes.  So, a rhombic dodecahedron is basically a 12-sided object with diamond shaped sides.  The rhombic dodecahedron also has the nice property that if you have a lot of them (at least a cluster), they will pack together with no empty space between them.

Cluster Buster and Truncated Cluster Buster were designed by Stewart Coffin in 1973 and described in his book, Puzzle Craft, 1985.  Both consist of a cluster of 6 rhombic dodecahedrons that has been dissected into 6 identical pieces.  The truncated version has the 6 outer tips cut off to provide a square face on the outward facing side of each rhombic dodecahedron.  The difference between the two is cosmetic and both operate the same way.  The two objectives are to take it apart and to put it back together.  You might be thinking, Duh!, but these challenges are quite a bit different.

Cluster Buster has 1 sliding axis and you need to position your fingers in very precise positions to pull it apart.  This is more difficult than you would imagine with a well-made version of this puzzle.  There is an alternate method of disassembly, but I wouldn’t recommend it for a nice version of this puzzle.

Getting it back together is an entirely different matter.  It isn’t difficult to determine how the pieces should be oriented for reassembly but trying to hold 6 pieces with two hands makes this an interesting dexterity challenge.  In addition, the pieces have to be perfectly aligned to get them reassembled.  A lot of Coffin designs seem to have this theme.

My version of Truncated Cluster Buster is a 3D printed version from Pacific Puzzleworks that was a gift from John Rausch of Puzzle World.  For a 3D printed puzzle, this one is well made.  However, it is quite a bit easier in both the disassembly and assembly compared to a well-made version in wood.  The rounded edges of the pieces provide the ability to get a hold of the edges instead of having to only used the faces when puzzling it apart.  That combined with the frictionless surfaces of the PLA plastic allow the puzzle to be quickly disassembled.  Similarly, the rounded edges make assembly a bit easier since you don’t have to be as exact in aligning the pieces before putting them together. 

The 3D printed version is a very nice puzzle, but if you want the full experience, I recommend finding one of high quality made in wood to play with.  However, if you’re planning on buying one, a nice one made in wood is going to cost you a lot more than a 3D printed one.  The one from Pacific Puzzleworks is available on Etsy here.