Neil's Puzzle Building Blog
25May/114

Building a Matrioshka (Part 2)

This entry is part 2 of 3 in the series Building a MaTRIOshka

At the end of the first post on my Matrioshka build, I'd finished gluing up the 'ends' as I think of them for each of the puzzle pieces. I still hadn't cut out the centre sections (or as I'm referring to them, the bridges) that join the two ends of each puzzle piece together, and I still had a lot of sanding to do so that the pieces were all the same size. In this second part, I go through that process, and get closer to the finished puzzle.

On a side note, I originally referred to this project as a MaTRIOshka, however what I'm actually building is a single layer of Vin&Co's puzzle. Stewart Coffin originally referred to this assembly in "The Puzzling World of Polyhedral Dissections", which I have been reading recently as the Expanding Box puzzle. There Mr. Coffin refers to this as a curiosity more than a puzzle, but I'm going to continue on none the less with this build. It is helping me learn about puzzle creation and improve my skills, although I dare say that as with most puzzle creators early works, this will be less than impressive. The bottom line is that it is still a nice co-ordinate motion puzzle.

With 12 'ends' all glued together, I had quite a task to remove all the excess glue from the pieces, and sand them all down to a nice smooth finish. I had deliberately left the pieces slightly larger than they would be for the final glue-up, so that I had some room for cutting errors and the like. This is fairly standard, as it's easier to correct for problems with your saw being slightly off, or gluing issues when you have a little extra material to work with.

Puzzle Pieces before sanding

Puzzle Pieces before sanding - not pretty!

As you can see from one of the pieces, things weren't exactly pretty at this stage. Yes I could probably have allowed the glue to set for about 30 minutes, and then scraped off the excess, but I let things sit overnight without touching them, so I may have created more work for myself here that I needed to. You'll also note that there are apparent gaps between the individual pieces. As I mentioned, this is a learning experience, and I expected that I would have a problem like this! (Oh, and the large lump of tearout on one of the pieces is pretty obvious too.)

If you're wondering about the interesting pattern in the dry glue, this is because I'm using plastic wrap to prevent glue getting onto my clamps. It's effective at keeping the glue where it needs to be, but until I build some gluing jigs, I'm left with this sort of mess.

After a lot of sanding, and some time measuring each piece against a 'perfect' reference piece, I was left with 12 identical pieces. The puzzle has six sides, which are all identical, so this would be the basis of the finished pieces. (ok, so I only photographed 10 pieces. The other two were on my workbench.)

Sanded End Pieces

Sanded End Pieces

As yet I still hadn't cut any wood for the join between each end of the piece. I'll be honest here, I still hadn't entirely figured out how these should be cut, the angles required on the cut etc.

Some stock laminated together to give the thickness I needed

Some stock laminated together to give the thickness I needed

All I could tell from the pictures I was working from was the length of the piece, and that the base touched one side of the end and the top of the triangle touched the other side. Note: I had not started reading Stewart Coffin's book at this point which told you exactly how to make this! (Thanks Stewart) With that information on hand, I decided the best thing to do was to just go for it. I cut six rectangular blocks which were a match for the dimensions of the end of my end piece, marked the mid point on the end, and took to the band saw. (These rough cut pieces are what you see in the image above. Note that they were only true on one side, as I was cutting to a point on the other so I didn't care!)

The rectangular stock marked up for cutting to make the bridge

The rectangular stock marked up for cutting to make the bridge

As I have learned, I cut close to my lines, but didn't go over, to allow me to sand the pieces to the perfect size. You may notice from the image, that my lines are not in pencil Given the accuracy of the cuts I wanted, I used a hobby knife to make the lines. This gives a much more accurate line than pencil, since the edge is much thinner, and also helps to prevent tearout by severing the ends of the fibres if you're working across the grain. Yes, these marks are in end grain so it's not helping me here, but I though it worth mentioning.

Note: If you've not figured it out already, all the images I upload are at least twice the size you see here. Click the image to see the full size version, and to browse all images for this blog entry.

The result was six identical pieces which would form the bridge between each end of each puzzle piece. So far, so good. Now the interesting thing I found out taking this approach, and working purely from pictures, is that the piece required for the bridge is a standard triangular cross-section, the same as the rest of the pieces in the puzzle. The only difference is that the bridge is slightly taller than the end pieces. Going back to Coffin's book, this is exactly what he shows, so this was confirmation that I had this right.

The Bridge pieces ready for assembly

The Bridge pieces ready for assembly

In the next part, I'll look at tackling the problem of gluing up the final pieces and seeing if this thing actually works. On a side note, I have my copy of Vinco's Matrioshka now, and the puzzle I'm building is large enough that the Matrioshka will fit inside it. So does this mean I'm actually building a Quadrioshka?



25Apr/112

Building a Matrioshka (Part 1)

This entry is part 1 of 3 in the series Building a MaTRIOshka

I've had a bit of a break from working on my own puzzles, as work and life in general have been rather hectic meaning I've just not had the time. However over the Easter weekend, I had three whole days that I could do something puzzle related. I've still not been able to pick up some wood to get back to working on my burr cube, however I did have a lump of oak left over from the box project my oldest son wanted to make as a birthday present.

After reading Kevin's review of the Matrioshka here. I noticed that the puzzle is entirely made of triangles. Now I just happened to have a number of leftover 'scrap' that would fit the bill perfectly from the box. So I sat down with a pencil and paper to figure out how Vinco created his box, and see if I could replicate it.

Note: This project is purely for my own learning, and experience in working with wood to build puzzles, at the scale I need to be working at to create my own puzzles. This is not for sale. If you like Vinco's puzzles, please buy them, they really are great puzzles, and the craftsmanship is superb. I own several of Vinco's puzzles, and highly recommend them.

With all that said, on to the build ...

To break down how the puzzle is built, we need some good photos. Kevin happened to upload some excellent pictures, and I'll not repost them here. Go read his review and have a look if you're interested. The bottom line is that the outer shell is made of 54 idential pieces. They are equilateral triangles on the edge, with a piece length that is twice the length of the side. So, I set about creating 54 identical pieces.

The first thing was to cut the wedge shaped strips of wood which I would eventually cut to the correct length. I took out my mitre saw, and set about making the cuts. One small issue I had was that the amount of the blade in contact with the wood generated a lot of heat, which warped the strips I was cutting. As a result, I had to tape two together as they cooled to make sure the wood was going to end up straight again when I was ready to cut it to length.


With all the strips cut, I had to cut them down to the correct size for each piece. I measured one piece, cut it and checked that it was exactly right. With that done, all I had to do was clamp down a stop, put a sacrificial fence in place and start cutting. As you'll see from the photo, I used a scrap piece of wood as a zero tolerance fence to avoid chipout on the pieces I was cutting. It just saves some time later.


After about half an hour, I had a reasonable pile of pieces next to me, and it was time to do a little rough sanding before gluing up the pieces.


With the rough edges sanded down so that things were a bit neater, and all the pieces labelled to make the glue-up easier, it was time to get the clamps out. The shape of the pieces I was gluing up made things a little more challenging, but with a few of the scraps from cutting the pieces out, life was made simpler again.


It's worth noting at this point, that all these pieces are oversized. This gives me a little bit of material to work with so that I can sand and fine tune all the pieces. For this to look good, it has to have a tight(ish) fit, and the only way to do that is to make sure the pieces are all the same. Despite using the fence, and stops on the saw, not all my pieces came out to be the same size. After all, I'm still learning, and you could say that this is an ambitious project. That said, how do we learn if we don't push ourselves?

In the next post, I'll continue with building the Matrioshka and think about putting each of the six pieces together that will form the final puzzle.



7Mar/111

So you want to build a burr

I've had a request sent to me about making puzzles from Lego, so I thought rather than reply to the person individually, I'd throw something up here, so that everyone can benefit.

I already commented in a previous post that LiveCube was a possibly way to create Burr puzzles, however as I already mentioned, they are not as easily available, and from what I have been told, when you add shipping from the US it's a rather expensive way to go.

Given this, I was asked what Bricks and plates you'd need to be able to create Burr puzzles from Lego. This post is my attempt to answer that.

I should say, that there are many ways to go about creating a burr piece. There are a lot of Lego designers out there who are far better than I am, however at it's simplest, the process is fairly easy.

The first problem we have to overcome is that a brick is not a cube, as you can see here.

So to make it square, we need to add a couple of plates. Now the type of plate we add depends on whether the piece is going to form part of the Burr body, or the top of the Burr. For an 'internal' piece, we use a standard plate. For the top we use a 'tile with groove'. The images below show the two pieces we will use.

Now that we have the basic pieces, how do we make a cube? Well the dimensions of a lego brick 'cube' are 5x5x3. Each stud on a Lego brick represents 2.5 units. Each plate is 1 unit high. So to get a cube, we need one brick and two plates.

So as you can see, the height now matches the width, and we have a cube. Building up Burr pieces is fairly simple from this point. Take the piece you want to build, and using those dimensions, create the part in Lego. Having longer bricks and plates does help to make the whole thing more stable, as long as you remember that each brick requires 2 plates to make it square then you'll be fine. Of course, if you think about the height of 2 bricks, that's 10 units. You can make that from 3 bricks and 1 plate or 2 bricks and 4 plates, or 10 plates.

The skill comes in working out how to get the tiles in the right place so that you have smooth surfaces on the top of each Burr piece. Equally, the piece made from 3 bricks and one tile has far less pieces, and by definition less joins, so should be more stable. That's not always true however , as the thin plates have a greater surface area per thickness, so don't 'bend' as easily!

The example below shows a basic Burr piece made from Lego.

Each 'layer' is in a separate colour so that it is easier to see the height of the piece. Creating this piece is left as an exercise for the reader, however the parts used are:

4 - 2x2 brick (part #3003)
2 - 2x4 brick (part #3001)
2 - 2x6 brick (part #2456)
4 - 2x2 plate (part #3022)
6 - 2x4 plate (part #3020)
1 - 2x8 plate (part #3034)
6 - 1x4 tile (part #2431)
2 - 2x2 tile (part #3068b)

So that covers the basic burr parts. What happens when we need a half sized wall? Well it's fairly simple, we just use a 1x2 brick and plates. The part above is modified to give a more complex piece just to show the difference.

So from that you should have the basics. I highly recommend getting LDraw, there's a link under Puzzle Creation tools, and also a GUI designer such as MLCad for Windows or Bricksmith for Mac. There a good tutorials on using these on the LDraw website. The tools will help you to build the pieces ahead of time, and work out how best to build each piece. It can make things quicker, depending on how familiar you are with building in Lego. If I'm honest, most of the time, I build it in Lego first, and come back to LDraw later!

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