Puzzle Collection Extravaganza

I was recently asked how many puzzles I had in my collection and I realized I had no idea. So I figured if I was going to go to the trouble of taking them all out of their boxes and actually count them, I might as well take some pictures too.

Here’s my kitchen table over-run by puzzles:

Puzzle Collection

As you can see, there are some old classics in there, like an original 1980 Ernő Rubik cube and an IMP puzzle (now known as the “Fifteen Puzzle”) from the 1930’s. The most recent addition is Wil Stribos’ “First Box” puzzle – the blue cube in the upper left. That was a fun sequential discovery puzzle, beautifully made from anodized aluminum.

Strictly speaking, not all of those are puzzles. The three black and white toys on the bottom left are just fun to manipulate or make shapes with. And the white rectangular puzzle on the right, sitting next to the black calculator looking thing (a super cool Vulcan Electronics XL 25!), is a Rubik’s Magic puzzle that I modified. Normally, it has paper inserts printed with a pattern of rings; I replaced those with a pattern of semi-circles that I think makes it look more interesting even when it isn’t solved.

OK, coffee break’s over! Back to working on Model #808.

Progress on Model #808

Model #808 continues to make steady (if slow) progress. I had some prototypes machined from aluminum by a fantastic machine shop, Cantabrigian Mechanics. They are gorgeous, if I may say so myself. Take a look:

808 Preview

The prototype at the top of the picture was bead-blasted, then anodized in black. The one at the bottom of the picture was anodized in black and engraved with lettering, which I then infilled with red. Actually, only the top piece in the bottom prototype was anodized black; if you look carefully you can see the un-anodized bottom piece. I wanted to see what the different finishes and combinations looked like.

This is Rev. 12 and it’s been an amazing journey from Rev. 1. Along the way I’ve learned two CAD tools, OpenSCAD and Onshape; prototyped in ABS, PLA, nylon, and aluminum; built an FDM 3D printer; and tried a bizillion different internal mechanism ideas.

I also dove deep into the world of fonts to find what I was looking for: the machine shop typeface that we’re all used to seeing engraved on heavy equipment. It turns out that almost everyone (e.g., NASA, Boeing) used engraving machines from the Gorton and Graham Machine Co. Here’s a picture from one of their brochures. To my immense good fortune, the typeface has been recreated by a fellow named Josh Kraemer and it can be seen on his website here.

So all the pieces have fallen into place. I think this may be the final design and at this point I’m working with Cantabrigian on getting the dimensions exactly right so that the fit and feel are perfect. Getting closer, almost there!

More Prototypes

Though I haven’t blogged in about a year, at least I have been making progress on my puzzles. Pictured here are Model #808 (the rectangular one with two holes), Model #518 (the multi-colored cube), Model #921 (the circular one), and Model #360 (the thicker rectangular one with the red logo).


The internal design of Model #808 (formerly known as Model #873) continues to evolve and I’m hoping to get a prototype today that will confirm the reliability of the new design. I guess it’s no surprise but getting a puzzle mechanism to work in theory is easy, getting it to work once or twice in an actual mechanism is doable, but getting it to work dependably and reproducibly is really hard. I’m on Rev. 9 on this one.

Model #360 turned out to be easier to get working than I expected and it may be the first one to reach production in aluminum. Models #518 and #921 still have a ways to go.

In other news, I now have an FDM type 3D printer (the i3PRO from MakerFront) to shorten the cycle of revise design / make new prototype / test new prototype. I’m still learning how to get good quality prints from it but I look forward to being able to get a physical prototype of a puzzle design within hours instead of days. I’ll post some videos of my experiences with it in case anyone else is contemplating buying one of these things.

On the Asymptote to Perfection!

I just received my latest prototype back from the 3-D print service I use (i.materialise – whom I recommend highly) and I’m very happy with this latest revision (the sixth I think!)

The puzzle has two major pieces, the top and bottom, and the biggest design challenge I’ve had so far has been to keep the two pieces aligned while the puzzle solver is manipulating the puzzle. If the pieces move out of alignment, it can put the puzzle into an unsolvable state or it can keep the puzzle in a partially solved state when it oughtn’t. In a previous puzzle I used Vlier pins to hold everything in place and they worked beautifully. Unfortunately, they’re much too expensive so I’m experimenting with some other approaches. Here’re what the top looks like:


I’ve never used this material before. It’s nylon (polyamide) mixed with aluminum powder and it’s called “alumide”. I like the metallic color but overall the finish isn’t as nice as with the matte white nylon so I’ll probably go back to that. Here’s a picture of the bottom:


If you squint you can see the model number embossed on the right end: “Model #873”. If you really squint, you can make out “www.pyrigan.com” embossed on the left. The low print resolution makes it hard to read the text but this is just a prototype. The final version will likely be made from machined aluminum and engraved with the text on the back and the logo on the front.

The good news is that the puzzle mechanism works very reliably so I will press ahead with plans to manufacture a couple of dozen and see if anyone enjoys these things as much as I do.

Puzzle Prototyping with 3D Printing

The summer was way too busy but I nonetheless was able to design and prototype my first mechanical puzzle. It even works!

Building a working prototype turned out to be much easier than I expected now that 3D printing has become so affordable and so widespread. All I had to do was create .STL files (I used OpenSCAD) and take them to a local outfit called Einstein’s Workshop whose fantastically helpful staff (thank you Katy and Matt!) printed them for me.

I tried prototyping a puzzle about twenty years ago by taking my design to a machine shop and that cost me a couple of hundred dollars. The 3D printed prototype, on the other hand, was about a twentieth the cost and took a quarter the time, thanks to the amazing march of technology. Also, even though I made a mistake in the first version of my design it only cost me the wasted 3D print, not the cost of a machine shop’s time and materials.

So here is a picture (the pen is there for scale):


As you can see, the surface finish is pretty rough since it was made using FDM (Fused Deposition Modeling). I’m currently waiting to get back a higher tolerance version that was made using SLS (Selective Laser Sintering) and hopefully that will compare favorably with the smooth finish of machined aluminum. My plan is to iterate my design with 3D printed prototypes until the puzzle is working perfectly; then I will decide whether it’s worth the extra cost of having them machined from aluminum or delrin or something.

Most important is that the puzzle mechanism is working dependably and as it was designed to. I’ve shown it to a couple of friends and the feedback has been positive: it’s very hard to solve but not unfairly so. (At some point I want to write an opinion piece about puzzle “fairness” but that’s a post for another day.) For some reason I’ve always liked dovetail joints on puzzles – I guess that’s why I have all three (1, 2, and 3) of Wil Strijbos’ beautiful cube puzzles (great review here) – and so I couldn’t resist the temptation of using them for my first puzzle.

So anyhow, I have reached the prototype milestone and hopefully I will be able to finish the puzzle design and put it into production before the end of the year. Feel free to comment or email me at kay en oh see kay at-sign pea why are eye gee aye en dot see oh em.


Storefront debut!

I’ve taken another important (albeit microscopic) step towards complete puzzle industry domination: I have opened an Etsy store. You can find it here. I have some extra square-to-pentagon and square-to-hexagon puzzles so if you want one, they’re a lot easier to obtain now.

One thing that has surprised me is how much people like the way these puzzles look and feel. I keep hearing I should sell them as dining room or living room accessories because they’re the right size to be coasters and because they look very modern and bright. I’m just a puzzle geek so I don’t really know what to make of this feedback. They call them “Puzzle Coasters”.

My friends say I should make more of an effort at selling them so I figure Etsy is a good way to put my toe in the online sales water.

My First Puzzle

Here it is, the puzzle that started my lifelong interest:



Not the Rubik’s Cube – that’s in the picture for scale – it’s the wooden burr puzzle. It’s a simple six-piece burr puzzle, well-made (but hardly an objet d’art), and my grandmother gave it to me when I was in 5the or 6th grade. Over the years, she and others in my family contributed all kinds of different puzzles to my collection. I plan to blog about them periodically as I did yesterday about Rainer Popp’s Tricklock T8.



Popp’s Tricklock T8

I’ve been meaning to post reviews of some of my favorite puzzles for a while now and Rainer Popp‘s Tricklock T8 has the honor of being my first review!

I will be brief:

  1. It is really expensive.
  2. It is beautifully made. I mean it, it’s gorgeous. It is made from stainless steel, brass, and has some details (e.g., a dot of red paint) that make it look fantastic. It is precision made with high tolerances that give it a very pleasing, smooth feel.
  3. The locking mechanism is ingenious and unusual. I know of no other puzzle that uses the same principle.
  4. Like the best puzzles, it is easy and quick to solve if you know the trick.

That’s about it. Here’s a picture of it:

Tricklock T8

(I’ve included the Rubik’s Cube for scale.)

Other folks have reviewed it too:

So as you can see, everyone who plays with this puzzle is pretty impressed with it.

More Square Dissection Puzzles

Well, I sold my first batch of puzzles (the triangle and greek cross puzzles) and have moved on to more difficult ones. Henry Dudeney, brilliant guy that he is, came up with a dissection for turning a square into a pentagon and you can read about his method and the misprint I found in the diagram accompanying his solution here.

I also found a dissection for turning a square into a hexagon by Harry Lindgren. He wrote about it in the November, 1961 issue of Scientific American and I found it through this link which unfortunately misspells Lindgren’s name as “Lindgreen” here and then it gets misspelled again as “Lundgren” here. But anyhow, it’s a really clever dissection and I went and made a bunch.

I also found another square-to-hexagon dissection that’s much older than Lindgren’s. A Belgian mathematician by the name of Paul Busschop came up with one in the late 1800’s and here is a Wolfram demonstration of it. In case you’re interested, there is a wonderful and detailed geometric construction for this dissection here. It attributes this approach to E. Lucas in 1891 but I think that is a mistake because this link to Google Books’ online version of “Dissections: Plane and Fancy” by Greg N. Frederickson gives some background on Busschop and claims, “However Catalan was kind enough to supply Busschop’s full manuscript to Edouard Lucas, who included the dissection in (Lucas 1883).” History is complicated; I’ll stick with math.

So without further ado, here are pictures of the pentagon and hexagon dissection puzzles I made:


(As usual, I put a Rubik’s Cube in the picture for scale.)

More pictures of the puzzles and a little more info (e.g., links to their solution) are on my Items for Sale page.


A Note on Henry Dudeney’s Pentagon-Square Dissection

Henry Dudeney gives a method for dissecting a square so that its pieces can be rearranged to form a pentagon. I found it in a copy of Dudeney’s book “Amusements in Mathematics” on Project Guetnberg here. It is puzzle #155 (“Pentagon and Square”) and I found another copy of it here:

You will notice that two points are labeled ‘F’, one inside the pentagon and one inside the square. I’m embarrassed to say it took me a good fifteen minutes to sort this out but the one inside the square should be labeled ‘E’. I am further embarrassed to say I didn’t know what “mean proportional” meant in his instructions. Uncle Google to the rescue!