Neil's Puzzle Building Blog
12Sep/1110

Coffin Involute

My first home built Puzzle

After the successes with creating both Square Sticks and Cubes, I had to go do something with them; and see if I could create a puzzle. I decided to make some of Stewart Coffin's designs, and having been in touch with him, he very graciously gave me permission to try to recreate any of his designs, and encouraged me to do so. With that endorsement, I was off and running. Well, almost!

I had to work out which puzzle I was going to create. There's so many to choose from that it's not an easy decision. In the end, I decided to create something that I didn't already own, so I'd be adding to my collection if it turned out to be any good. So I settled on a copy of STC #214, the Involute puzzle. The Involute is the third in a series of puzzles from Stewart Coffin, each an improvement over the predecessor.

My first attempt - Involute by Stewart Coffin

My first attempt - Involute by Stewart Coffin

The first was Convolution, a 4x4 interlocking cube which requires a rotation in the solution. Due to the rotation, some material needs to be removed from one of the cubes in the solution (if you have a tight fit) to allow the rotation to happen. You can read my review here. Stewart Coffin notes that given the rotation, and the nature of cubes (which don't like to be rotated when hard against one another), that this design could be improved. In his book "The Puzzling World of Polyhedral Dissections", he leaves it to the reader to see if they can find a solution to this problem.

At the same time, Stewart Coffin had already solved the problem, and created STC #198, Involution. Again a 4x4 cube with a rotation required in the solution, but this time because of the design of the dissection, no material needs to be removed from the pieces to allow the rotation. I'll not give away how this is done, as it would spoil the puzzle, but I will say it's a simple and clever solution! I was able to play with one of Scott Peterson's copies that he had made on my recent visit to see Scott, so I can say I've solved both the Convolution and Involution puzzles at this point.

The third in the series is STC #214, Involute. This is the final puzzle in the series, and is again an improvement over the Involution and Convolution. Again there is a rotation required in the puzzle, and again, no material needs to be removed for the rotation to take place. There's an extra trick in this puzzle, that I'll get to in a bit which makes it just that bit more devious.

All three puzzles in the series look identical from the outside, each having the same cross pattern on all six faces, so without knowing which puzzle you have in your hand, it could easily be any one of the three. Have I mentioned that this Coffin is a devious bloke?

Thanks to Allard and Kevin who both reviewed their copies of the Involute puzzle, I was able to model the pieces in burr tools, and from that create myself a parts list and a gluing diagram to be able to build the puzzle.

My piece and gluing diagrams for the Involute.

My piece and gluing diagrams for the Involute.

Given that it took several hours to create the diagrams, including the time to create the model in burr tools and so on, I'm not going to give you the whole thing. Not to mention it would spoil how to solve the puzzle (or would it - I'll come back to that thought). But the image above gives you an idea of what I created.

All the pieces needed to build the Involute

All the pieces needed to build the Involute

With the design in hand, I went off to the saw, and using the crosscut sled and my stops, I cut all the necessary cubes to make the puzzle. There's quite an array of pieces there when you see them all sitting together. Also in the picture is one jig I hadn't talked about previously. This is my cube gluing jig. It's not overly complicated, just three pieces of MDF cut and glued together to hold a 4x4 cube cut to my 3/4" stick size which has all edges at 90 degrees, and has been waxed to prevent any glue from sticking to it. I also have three 'end panels' which will distribute the clamping pressure evenly across all the blocks so as not to twist the blocks while the glue dries.

At this point I made something of a realisation. Sitting looking at this array of blocks, and my gluing diagram, gluing up one of these puzzles is hugely complicated. You're working in three dimensions gluing any number of pieces together, all of which needs to be accurate, and with no glue squeeze-out. If you thought Ikea furniture plans were Convoluted, then this is much more challenging!

Dry fit in the gluing jig  - bottom layer.

Dry fit in the gluing jig - bottom layer.

Dry fit in the gluing jig - three layers.

Dry fit in the gluing jig - three layers.

Dry fit in the gluing jig - full puzzle.

Dry fit in the gluing jig - full puzzle.

Dry fit in the gluing jig with clamp blocks.

Dry fit in the gluing jig with clamp blocks.

Next up I placed all the pieces into the gluing jig, to match my plans. This serves a couple of purposes. Initially, it shows me how good the fit is, and also verified that my plans were correct (at least in as much that I had the correct number of pieces). The other benefit to the dry fit is that it allows me to select which pieces I want to put where in the puzzle. Looking at the grain in the wood, I can select the 'nicest' grain to be on the outside of the puzzle, or look at creating grain patterns by selecting pieces carefully from the pile. Given that this was a first ever attempt, I wasn't too concerned with the grain pattern, but I didn't entirely ignore it either.

Since this was the first glueup I'd be doing, I decided to go with gluing up two layers at a time. This meant that I didn't have to work quite as quickly to get the clamps on the jig to ensure that tight fit I was going for. Fortunately, the way the pieces go together, there is a flat surface after every second layer, which was ideal as a stopping point. I also have a smaller glue bottle, where I've decanted some of the glue from my big bottle. This small bottle has a fine nose, and is much easier to work with that the full sized bottle. Given the small amount of glue I'd need for each piece, this is the only way to work.

Involute in layers ready for the glueup

Involute in layers ready for the glueup

With all the pieces separated into layers, I was as ready as I was ever going to be to start putting this together into a puzzle. Fingers crossed!

First layer glued in place.

First layer glued in place.

Two layers glued up and clamped.

Two layers glued up and clamped.

Working reasonably quickly, I glued up the first two layers, and thanks to tips from Scott Peterson, I managed to do so with little to no glue squeeze-out. That's pretty important since any glue squeeze-out will glue blocks together that shouldn't be, making the puzzle unsolvable. You'll notice the fairly large block of wood on the top of the gluing jig in the photo on the right. That's because I only have two layers build at this point, so the puzzle is half way inside the side plates. I needed to add some height to be able to clamp the puzzle effectively.

Glueup completed, clamped and waiting nervously.

Glueup completed, clamped and waiting nervously.

After the glue had set, I came back and added the remaining two layers, building on the two I already had. This time, you can see that the puzzle fills all the space, and there are no extra spacers required. I then had to wait a few hours for the glue to dry properly before I could take the clamps off, and see whether I had created a puzzle or a paperweight.

They may have a been a few of the longest hours I have experienced in a long time. My fiancée was about ready to kill me, as I wanted to go take the clamps off and see what I had, she kept telling me to leave it alone. I was like a kid on Christmas morning waiting to see what presents I had. I could barely sit still! When things had been left for long enough, I was finally allowed to go take the clamps off and see what I had.

I should note at this point, that I have never solved an Involute puzzle prior to making this one. Given that rotations are required in the solution, Burr Tools can show that there is a solution, but it can't animate the assembly for you (or in my case the dissassembly), so I have no idea how to take the puzzle apart. I'm now in new territory, and given that I don't know how to take things apart, or whether the pieces are glued together correctly, and not glued to one another I know this is going to be interesting!

Since I know where the key piece is, I can remove that fairly easily, but then spend the next ten minutes pushing and pulling on various pieces hoping that something else will move in the puzzle. I can see that there is movement in the pieces, so at least it's not all glued together, but I am having real problems in finding the second move. The pictures that follow were taken by my fiancée, so are unedited as I make progress. That grin on my face is real!

The moment where I figure out move 2.

The moment where I figure out move 2.

Now what?

Now what?

Seeing the individual pieces of the Involute for the first time.

Seeing the individual pieces of the Involute for the first time.

As I mentioned, I've never solved the Involute before, so I had no idea how the puzzle was supposed to come apart. The key piece in the puzzle is really well hidden, and without knowing where it was I would have struggled to start, especially not knowing if the puzzle was entirely glued together at this stage. The second move is also very clever. One thing that Stewart Coffin regularly has in his designs is pieces which are created so that the average person will hold the puzzle in such a way that you will be holding the piece you need to move, effectively pushing the puzzle closed and preventing it from being opened. The Involute is no different, and has this very same trick to allow move two. The look on my face when what looked like half of the puzzle slid to the side perfectly must have been quite the picture. I think for me not only was I solving a puzzle for the first time, which always brings a smile to my face, but also it was a puzzle I had built, and seeing it work the way it is supposed to is an ever bigger achievement.

I took the puzzle fully apart, and was left with the eight individual pieces sitting on my sofa, with a huge grin on my face. I then realised that I had absolutely no idea how to put the whole thing back together! In my excitement of taking the puzzle apart, I wasn't paying any attention to how the pieces were coming apart! I then spent the next 15 minutes with my gluing diagram trying to put the puzzle back together. Remember I mentioned that having the full diagram may not help that much! I did get there, and the smile on my face seeing the puzzle back together was truly from ear to ear.

Closeup of the fit between pieces

Closeup of the fit between pieces

The rotation in the puzzle works perfectly, and I haven't removed any material from the rotational piece to make that move easier. The fit of the pieces is superb. It's difficult to tell individual pieces apart as you can see from the closeup above. This makes finding how the pieces come apart even more difficult that if the pieces fitted loosely together as there is no movement between the pieces. In case you're wondering, that tiny gap that looks like there's a chunk taken out of one of the pieces isn't tear-out as a result of a poor cut, but was some natural holes in the walnut. It's also worth noting here that there is no sanding done on any of the pieces, these are all straight off the saw. Many people in the puzzle community have noted that sanding reduces the accuracy of the pieces, and that a good clean cut can have every bit as good a finish as a sanded piece, perhaps better, since sanding is effectively scratching the surface.

Yes, I made a second to prove it wasn't a fluke!

Yes, I made a second to prove it wasn't a fluke!

To prove that it wasn't just a fluke and this was a one-off, I went off and created a second copy of the Involute. So what you're seeing here isn't some clever photography, but the two copies side by side.

Taking one of the cubes apart

Taking one of the cubes apart

And just to show that it works, there's a partially assembled version next to the fully solved cube.

I was really happy with the results. Over the weekend I produced two copies of the involute puzzle, and both have a very snug fit, and I'd be happy to add these to my collection. In case you're wondering, they're made from walnut with redwood corners. And not to sound like an American advert trying to get you to place an order for something you didn't want ...

But that's not all!

There's another of Stewart Coffin's designs that I've wanted to play with for a while. That's his "Half Hour Puzzle", STC #29. So I drew up the diagram for that, and made one of those too! The brilliant thing about the half hour puzzle is that even though Stewart coffin designed it to only have the cube solution, there are hundreds of possible solution shapes that can be made with the pieces. I've created a burr tools file with many of the solution shapes, so if you're interested in a copy of the file, just let me know.

STC #29 - Half Hour Puzzle

STC #29 - Half Hour Puzzle

Three Coffin's

Three Coffin's

So there you have it. Three puzzles in one weekend, all which I am very proud of, and is the start of hopefully great things. As Allard has put it, "One day there'll be a couple of us around who can say that we had one of the very puzzles created by someone the whole puzzling community now knows as the Juggler-guy! :-)" Maybe ... one day.



9Sep/111

From Square Sticks to Cubes

I recently wrote about the first of my puzzle making jigs to create square sticks as the first stage in creating the building blocks of many puzzles. With that jig successfully completed, and working pretty well, I had to move to the next stage and create some cubes. I said in the Square stick post that I'd tell you about it soon. Well, soon is now, and it's time to make a crosscut sled!

The starting point for a crosscut sled

The starting point for a crosscut sled

For this jig, I needed a larger platform than the square stick jig, and as such I was going to be using both miter slots on the table saw. I cut myself a slab of MDF and marked it up for adding runners. I don't have enough of the fancy metal miter bar that I used for the last jig, so I made my own. Starting with a strip of wood rough cut to the correct size for my miter slot, I sneaked up on the correct width by taking thousands of an inch off at a time until I had a snug fit. It didn't take as long as I thought it might, and I think I now have an even better runner than the metal versions I used on the first jig.

My intention was to drill and counter sink holes in the top of the sled and screw straight into the runners below. Sadly that didn't quite work out as planned as I didn't have screws which would fit. What I had was either too short or too long so I had to go to Plan B. I decided to screw through from the runner side into the base. As it turns out, it wasn't too much of a change and in the end achieved the same end result.

Runners mounted and a slot cut

Runners mounted and a slot cut

With the runners mounted, I flipped the jig over and tested the fit in the miter slots with the blade below the table. I had a couple of spots which were binding slightly, so I lightly sanded the offending areas until I had a tight but smooth fit with no wobble in the jig. For anyone wondering, the way I found out where the runners were binding was to run a sharpie along the length of the runner sides, then move the jig in the slots. When you take the jig back out, where the sharpie has been rubbed away is where you need to remove a small amount of material. Simple yet effective!

With the sled moving smoothly, I raised the blade up, and cut myself a slot part way through the sled. That slot will help aligning the crosscut fence as I need it to be perfectly square to the blade. Without having the blade through the sled that would be almost impossible.

Some reinforcement across the back of the sled.

Some reinforcement across the back of the sled.

Given the slot I've just created, I now have a potential weak point in the sled where it could flex, and degrade the cut. Despite how it may look in the photograph, I wasn't trying to create a wing to add down-force to the sled.

Each of the three spacers on either side is screwed to the piece below with three screws, and gives enough clearance that with the blade raised to the point that the blade stiffeners are just below the base of the jig, it doesn't cut into the cross bar. The cross bar keeps either side of the sled stable and prevents any twisting or warping of the sled. Yet again simple but effective. (I'm liking the fact that I can keep things simple. Less chance of things going wrong!)

A beautiful Dragonfly that stopped to see what I was doing

A beautiful Dragonfly that stopped to see what I was doing

Given that it was getting on for around 5 hours that I'd been working on the saw and building the jigs by this point, I took a break, stretched out my legs and back and relaxed for ten minutes. While I was doing that, I spotted a dragonfly floating around the garden. Standing watching him for a few minutes, he landed on the radio antenna for our car. Given that I still had the camera in my pocket from taking pictures of what I was doing, I grabbed it, as he posed for me! Looking at the pictures later, there really came out well, so I thought I'd share...

Anyway, back to the jig ...

Adding the fence and a stop

Adding the fence and a stop

With the back reinforced, I had to add the fence to the sled. The important thing here is that it is at exactly 90 degrees to the saw blade. If it's off, then the cut will not be square, which isn't going to make for a good cube. Using the best square I have, I sat one edge against the blade, and the other against the fence board I'd cut. Keeping both edges in firm contact, I drilled one screw hole, counter sank and then screwed the fence to the sled at one corner. With one corner in place, I double and triple checked the fence was square, on both sides of the blade (using two squares). That may be a little overkill, since the blade shouldn't be different on either side, but I figured it couldn't hurt!

Everything checked, I pre-drilled and screwed the other side of the fence to the sled, and checked again for squareness. With everything looking good, it was time to add the stop. Now this was something that I'd been puzzling over for a good few days at this point, and hadn't really figured out how I was going to perfectly measure the offset so that I ended up with good low tolerance cubes. As is ever the case, the answer came to me when I least expected it, in the shower in the morning before heading to work.

The answer. Make sure that the stop is far enough from the blade to make the biggest cut you'll need, plus a bit. The reason ... Well if you properly size a piece you want to cut (and I'll get to that) then you can use that piece against the stop, then cut a 'spacer' by placing it against the fence, and the piece you want to cut, then cut that piece. You get a perfect spacer, and no complicated measuring required. (Other than the piece you want to end up with). Yes, I know that's all very confusing, but I'll annotate the pics below and it will make more sense!

Clamp removed now that the stop is screwed in place

Clamp removed now that the stop is screwed in place

Having screwed the stop in place I could remove the clamp. The stop is placed 6" from the blade. I'm unlikely to ever cut a stick that needs to be 6", unless perhaps I'm making 18 piece burrs, so this is lots of space to create whatever sized stick I need.


Creating the spacer for a single cube

Creating the spacer for a single cube

If you click on the image on the left, you'll see I've annotated it to make my previous explanation simpler to understand. The single cube in walnut was created by shaving a few thousands at a time from the edge of the block and measuring after each pass until it matched the dimension of the square stick. In some regards, that is probably the most time consuming part of the process, as if you take off too much, then it's a case of starting again.

With the first cube created by hand, it can be placed against the stop, then a long stick placed against it to create the spacer. In the diagram, you'll see I created mine from some of the redwood sticks I'd cut when I was testing the square stick jig.

Batching out some cubes

Batching out some cubes

Now it's a simple task of swapping the order of the pieces so that the spacer is against the stop, and batching out some cubes. I've used a clamp to keep the spacer in place, both against the fence, and hard up against the stop to make sure that it doesn't move between cuts. It's also important after each cut to clear out any dust that gets between the block and the fence as this will affect the accuracy of the cut. It is possible to adjust the spacer by adding feeler gauges between the stop and the spacer and before each run of cubes, I'll need to check the sizes to make sure everything is within an acceptable tolerance.

Running through a few cubes, each cube came out almost perfectly. The worst cube had a tolerance of 0.001" from the size of the square sticks. I can't really complain when the cuts are that close. It's going to be pretty good for any initial puzzles I make.

Making double size cubes

Making double size cubes

Now with a few cubes cut, I measured them, and selecting two that were exactly cubic, I placed them together and verified that the length was exactly double that of a single cube. Repeating the process I had used for the first cube, I cut a 'two cube spacer'. This spacer will let me make double sized cubes, perfect for making any of Stewart Coffin's Convolution/Involution/Involute puzzles.

Let the fun commence!



7Sep/111

A Humbling Experience

Many of you know me on a few of the forums around and about the puzzling community, and a fairly well known Puzzle Box maker, let's go with Allard's name for him and call him 'Stick guy' posted asking what I was up to. It's no secret I've bought a bunch of tools, and even started to use them to create the building blocks of puzzles, but I've never really mentioned what I was planning.

Well I answered Stick Guy's "challenge", and put up a brief summary of what I had been doing and what I was doing. You'll know if you're a regular reader that I designed a puzzle which I call Lock Cube some time back. I even prototyped it in Lego, then had it printed at Shapeways. Well at some point I'll be making it out of wood too. (At least that's the plan)

So here's where things get interesting, and when I get to the point of the title of the post. Seems like a few people out there are interested in owning a copy of my Lock Cube, when I make it.

Now at this point, many things go through my head, including a few that I can't print...

"Are you serious?"
"You really want one?"
"People want to own a puzzle I designed?"
"Is my puzzle good enough?"
"What will people think of it?"

The bottom line is that I was truly humbled by the response from quite a few people asking if I'd make a copy for them. I never expected to make more than just the one for myself, so this was a shock for me, and really left me not quite sure what to say. Quite impressive really since I've written an entire post about it!

So to everyone that has already shouted 'Me please' for a copy of a puzzle that I've not yet made from wood - Thank you.

If you want a copy, let me know. I'm not promising anything at this point, but I'll keep it in mind as I make those early copies.

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7Sep/110

Zauberflote – Magic Flute

Eric Fuller recently offered a few new puzzles through Cubic Dissection and I picked up "Zauberflote" designed by Gregory Bendetti as well as "Stand Py Me" which I reviewed recently. Both puzzles sold out very quickly.

Zauberflote translates as "Magic Flute" and is an opera in two acts composed in 1791 by Wolfgang Amadeus Mozart. Gregory wanted to make a series of puzzles which had a link to the opera which he enjoys.

Zauberflote - Königin der Nacht pieces

Zauberflote - Königin der Nacht pieces

In a change from my usual style, I'm not showing the completed puzzle at the top of the post, but rather the pieces. I'll get to the reason why soon enough. Eric has created this 4 piece version of Zauberflote from acrylic and yellowheart, and describes it as a pocket puzzle, given that its full length is just 2.25". Gregory gave the four piece version the full name "Zauberflote - Königin der Nacht", and each of the puzzle in the series with a different number of pieces in the flute has a different sub-name. I really like the use of the acrylic here, as even when the puzzle is solved (as you'll see below) you can still see the internal burr of the wooden pieces, which is a nice touch. Eric made 45 copies of this puzzle, and they are all signed with Eric's usual squiggle.

I spent about 30 minutes working on this puzzle, and after a few false starts I found a way to get all the pieces in place and the flute shape (or possibly more of a set of pan pipes) is easy to see. When I was solving it, I started by putting the smallest piece in first, and I required a couple of rotations to get the pieces into their final location.

My solution requiring rotations

My solution requiring rotations

Feeling quite happy with myself I put the puzzle aside for a few days. When I came back to it, I opened the trusty Burr Tools and created a model of the puzzle there. Now I fully expected burr tools to be able to put the pieces in place, but I didn't expect it to be able to give me an assembly given that rotations were needed (when I solved it). To my surprise, Burr tools came back with 72 solutions and one assembly!

Solution found by Burr Tools

Solution found by Burr Tools

Burr tools notes a 14.4.2 assembly and shows that it is possible to solve the puzzle without using rotations as I had. If you look very closely at the two images, you'll see that the internal burrs are in different locations showing that clearly it's a different solution. Also Burr Tools puts the largest piece in first, although I believe it is possible to insert the pieces in any order.


So having used burr tools, I think there are more solutions than it shows, even without the rotations. I did talk with Gregory as to whether rotations were intended, and he admitted that he hadn't checked for rotations, but it wasn't cheating, since I still solved the puzzle without forcing the pieces, and had found a solution that he hadn't. The solution with rotations is much shorter at 7.1.1.2 (if my counting is correct).

Overall, this is a fun puzzle, which isn't too hard and is very nicely made by Eric.



6Sep/114

Cutting Square Sticks

The start to many a good puzzle is a square stick. But not just any square stick. One which is accurately sized along its length and each side square to its neighbor. Not an easy task.

A while back, Scott Peterson sent me a tutorial for building a table saw jig to create square sticks. Over the Labor Day weekend which is a holiday for us in the US, I set about making the jig (mostly) following Scott's tutorial so that I'm firmly on the road to making my own puzzles. Scott kindly game me permission to make the tutorial available to anyone that wants it, so feel free to download a copy.

The following is my attempt at creating square sticks ...

Starting off with a sheet of 3/4" MDF I cut myself a strip that was wide enough to go between the miter slot and just past the blade of the saw. I left a good sized area on the other side of the miter slot so I had room to attach a handle to help push the jig through the cut, and back after the cut. I marked the position for the miter bar and after pre-drilling the holes, screwed it in place.

Preparing to attach the miter bar.

Preparing to attach the miter bar.

Miter bar attached to the base of the jig

Miter bar attached to the base of the jig

The miter bar that I bought has plastic screws that protrude from one side to ensure that the bar is a perfect for for the slot. Taking some time I adjusted each of the screws to make sure that there was no wobble in the slot, as this would compromise the cut.

Taking Scott's advice, I also added a UHMW plastic base to the cut side of the jig to back up the cut and help prevent tearout. Using blue tape I secured the plastic to the base, and marked out the positions for the screws, predrilled, countersunk then screwed the plate down. The Blue tape came in really handy as it's almost impossible to mark the UHMW plastic with a pencil.

UHMW plastic set in place ready for drilling and screwing

UHMW plastic set in place ready for drilling and screwing

The UHMW screwed down.  Note the screws are all below the surface of the plastic

The UHMW screwed down. Note the screws are all below the surface of the plastic

With that done, It was time to make the first cut, and trim the extra material that I had left off the edge of the jig, ensuring that the blade ran along the edge of the jig which is needed for an accurate cut. Making sure that the blade was at 90 degrees to the table top, I made the first cut. And immediately noticed that there was a gap at the front of the jig which wasn't there at the back. It was pretty small, but enough that I could see light between the blade and the jig, so I knew the jig wasn't good enough. It seems that I didn't do a good enough job of adjusting the miter bar, so I readjusted, and remade the cut. Fortunately, I'd left enough space between the edge of the jig and the screws holding the UHMW plastic down to be able to do this. This time things were much better and I got the accurate cut I was looking for.

Ready to screw the fence to the jig

Ready to screw the fence to the jig

The magnets to hold the steel bar in place

The magnets to hold the steel bar in place

Fence screwed gown and ready to go.

Fence screwed gown and ready to go.

Next up I need to install the fence on the sled which the stick will be clamped against when making the square sticks. As Scott notes in the tutorial, I have a steel bar as a spacer, and use some brass feeler gauges to get an accurate cut. I also embedded some Neodymium magnets in the fence to hold the steel spacer firmly against the fence. The fence is clamped securely against the saw's rip fence, then predrilled and screwed down.

Those eagle eyed readers out there may notice a couple of extra drilled holes in the fence. Well yet again, I managed to get things a bit wrong, and screwed the fence in a little squint. Now that's not a lot of use when you're trying to get accurate cuts, so I re-drilled and re-attached the fence. So there's a couple of extra holes there now. It won't affect the jig, but a squint fence would have!


Adding some toggle clamps to the fence and I have something where my fingers are well out of the way, and the sticks will be firmly held against the fence.

Cutting a stick square

Cutting a stick square

Ten minutes later; five identical sticks

Ten minutes later; five identical sticks

With everything set, It was time to put some sticks in there and see if I could make some square sticks and whether they would be accurate or not. At this point I was looking to test the jig, so I used some redwood I had to spare, and ripped it into roughly sized sticks. Now you'll notice the knots in the wood so even I knew things weren't going to be perfect. Still it was good enough for a test.

Measuring the sticks using my digital calipers, I am getting sticks with a 0.005" tolerance between either end of the 12" sticks. That's not too shabby. Given the knots in the wood, which will most likely make it twist as the knot is cut, I'm fairly happy with the results. At this stage in my puzzle making career, it should be more than accurate enough for making cube based puzzles, and burrs.

But that's not the end of the story ....

I came back to the jig in the morning, used some walnut that I had bought a few weeks back for making puzzles, and used that to get some square sticks. The walnut is much nicer wood, no knots, and a beautiful grain to it .... The results. I cut four 9" long sticks with a tolerence of 0.002" across all four sticks. Now that's a result I'm proud of!

Next up, I need to create a crosscut sled so that I can cut these sticks into accurate cubes for use in making puzzles. That post is coming soon, so stay tuned.

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2Sep/111

Stand Py Me

Stand Py Me is a new puzzle from Gregory Benedetti. It's familiar shape is similar to Stewart Coffin's Three Piece Puzzle, however it comes as four pieces (plus the stand) not three, and every bit as challenging to solve.

Stand Py Me by Gregory Benedetti

Stand Py Me by Gregory Benedetti

This version was made by Eric Fuller, and stands at 2.75" with a Wenge frame and Zebrawood and Maple blocks to make the pyramid shape. Gregory comments that the name is a play on words; the Py, not coming from Pi (3.14159265...) but Pyramid. It's as though a Pyramid is saying "Put me on a stand". Well regardless of how it was named, it's a fun name, and really fun puzzle.

The blocks which make up the puzzle are all joined on a half face or quarter face making for some interestingly shaped pieces. The puzzle is made significantly harder by the addition of the frame. It's fairly easy to create a pyramid of the blocks outside the frame, but doing it so that the pieces are captured inside the frame is a lot tougher.

Four pieces, plus the frame.  Signed by Eric

Four pieces, plus the frame. Signed by Eric

To get all the pieces in place, you need to move them around much like a standard Burr puzzle, which leads to a 5.1.2 solution. In case you're not familiar that means 5 moves to insert the first piece, one for the second and 2 for the third. So it's a tricky puzzle, and took me around 40 minutes to solve it the first time. Now knowing how the pieces fit it takes just a few seconds, although I keep putting the pieces in 'upside down' so I don't end up with the Zebrawood pieces in the corners the way it was made to be.

Having solved it, I modeled the puzzle in Burr Tools, and it confirms the 5.1.2 difficulty, and also points out that there are 2 solutions (not including rotations) but only one assembly.

Eric made 30 copies of Gregory's design and has signed and dated them. I picked mine up at a recent Puzzle Paradise auction, although they all went very quickly. This is a really well made puzzle, and the choice of woods really shows it off well.

Interestingly, the puzzle doesn't hold itself inside the stand overly well, and wants to fall out of the gaps, meaning that you really need to turn it upside down and hang it to get it to keep its shape. Not a problem, but it is something that even Gregory admits himself.