Getting into the Groove...

Definitely Not Bored with Board Burrs!

Junichi Yananose' Grooved Board burrs
Clockwise from front right - number 1 to 4

At the beginning of November, I woke up to an email from Juno (actually, I am sure that it is Yukari who sends them out) informing me of the release of their 2 latest puzzles and amongst them was the one I had been waiting for, the grooved 6 board burr #4. I am a bit of a completionist and, having the previous 3 in my collection, I would really have to add number 4 to it. But not only for the collection...I had actually really enjoyed the solving of the previous ones in the series and Juno had claimed that this fourth one is a hybrid of the designs used previously. Number 1 was reviewed here - the ideas were so new and the movements are so well hidden that it took me several months to solve it, number 2 here - nowhere near so difficult but still a lot of fun and finally number 3 is reviewed here - this was one incredibly difficult puzzle. I was very much hoping that the fourth and possibly last in the series would be as much fun and a good challenge.

Grooved 6 Board Burr #4

As you can see the puzzle is beautifully made Hickory (the first time Juno has used this wood) with strengthening and ornamental splines made from Rose Alder. This is back to the method used with number 1 rather than the use of Juno's rather lovely home-made plywood used in number 2 and 3. It is a nice handy size for puzzling at 87mm in each direction. The description of the puzzle on the store was that there are round and flat pins that engage with the grooves on each of the X, Y and Z axes, making the interactions and movements quite complex.

I received my copy at the same time as the Sequential discovery board burred box and could not resist playing with that one first. To my shame, this one almost got forgotten after the arrival of some fabulous toys from Brian Menold but when I came to putting those away, I found #4 waiting for me on my desk. Off to play!!

Initial movements are quite constrained and it looked like there was going to be a nice time just finding my way through a little maze without too many choices. Then after the first 3 or 4 moves that I found, the possibilities opened up massively and, despite a very large separation of the pieces, the puzzle remained nicely stable (often a huge problem with board burrs is that as pieces separate out, the possibility of inadvertent rotational moves can make the puzzle very unstable and even prone to collapsing). Realising that there might be quite a complex solution, I returned to my habitual, to and fro method of exploration with me returning back to the beginning many times. As the puzzle opens out it becomes clear that the grooves and pins are very different from the previous puzzles, the pins are on the sides of the plates as well as the interior and also the grooves can be just pin-length as well as form pathways with intersections. very interesting and totally different from the previous puzzles in the series.

I was fascinated to find an extra unexpected early solution to removing the first piece using a rather complex rotation and tilt move. It actually removes the same piece as the correct solution and I would say should be treated as an extra challenge for you to find as well as the correct linear only solution. I was rather pleased to see from his site that Goetz (entry 2019-11-23) had also found the extra solution. The rotational shortcut is pictured below under a spoiler button - don't click the button if you are considering buying it for yourself.

This rotation disengages 2 long flat pins and allows extraction of the first piece.

Having removed the first piece this way, I put it back and continued with the "correct" approach. It took me several days to find a very clever compound movement of several pieces leading to an even more precarious but still interlocked position. It looked like a piece would easily fall out from here but due to the flat pins and grooves, they were all held firm. I got stuck here for a day until I realised that the design was based on a 3 unit voxel and occasionally only a partial move was essential. My Aha moment was wonderful when I found out how to remove the first piece in the designer's intended way.

Even after the first piece was out, the puzzle remained stable and now even more movement was possible. For some reason I found the second piece extraction to be a very logical sequence - there were quite a lot of possible pathways but I homed in on the correct one quite intuitively. With piece number 2 out, I backtracked all the way to the beginning and started again (a little difficulty with my very poor memory cost me an extra evening of success). With 2 boards removed, it remained stable and the continued path to full disassembly was just as much fun.

Some very fine woodwork here. Juno's customary brand now visible.

The amazing detail of the design was now visible with very fancy grooves in unexpected places and of unexpected sizes. Look at these pictures to see it.

A maze pathway groove in one piece and some odd notches on others.

Usually, with complex board burrs (in fact most complex burrs), I am completely unable to do the reassembly myself without help from Burrtools. For me, this is an essential part of the fun of these puzzles - I have quite an extensive collection of BT files and creating more is an enjoyable experience. This time, I had kept a note of the orientation of the pieces and order of removal and surprisingly was able to retrace my steps all the way back to the beginning. With a level of 28-10-5-3, this was a really fun challenge. Just like the previous ones, the BT file required me to use a 18x18x18 voxel grid. In fact, whilst this did create a usable file, it would be more accurate if I had doubled up the grid to 36x36x36 because some of the pins and grooves are more than 1 but not quite 2 voxels deep.

This is one very fine puzzle! To my mind, as a collector, this is essential for anyone with al the others. If you only want one then this is one of the best of them. Number one is fabulous, number 2 a little easy and number 3 impossibly difficult. The perfect difficulty level here and a rather fun path to follow. There is also the extra addition of a hidden rotational solution to find as well.

Juno has 19 of these left in stock - there is still time to get your copy. If you are the significant other of an afflicted puzzler then "why are you reading this blog?" and you should go and buy a copy of this burr for them as a Christmas present...they will love it!