Rich Gain has been designing interesting interlocking cubes for a while now… and for almost as long, he’s been tinkering with 3D printing, and at the obvious intersection of those two pastimes, he sells printed copies of his designs.
At the last MPP he had a few things for sale and I piled in and bought a couple I didn’t already have.
Coronation Cube was Rich’s entry in the 2014 Nob Yoshigahara Design Competition. Seven pieces will form a 5*5*5 cube if you manage to coax them together properly…
It’s a long way from being a trivial assembly, and if you are tempted to invoke the gods of BurrTools, you will be sorely disappointed, for the gods will tell you it cannot be solved – which is all just really code for “some rotations may be required”.
Starting with a pile of pieces, it’s not too difficult to establish where each of the pieces needs to be as the result is going to be a cube… getting them there, is another story, however.
There are a couple of pieces, coincidentally the same colour, that would appear to be a logical end-game, so we concentrate on the rest of them for now…
Experimenting with the rest of them shows that there’s a lot of interlocking-ness going on in there… and a little rotating-ness along the way… and it’s weird, almost planned (!) how the colours seem to be getting used up together in the process… the puzzle rewards a bit of thinking along the way.
This one has only 6 pieces to assemble a 5*5*5 cube, but IMHO offers an even better challenge.
There are a couple of pieces that offer some pretty clear clues to their relative positions – it was pretty obvious to me how the blue and yellow pieces should go together and I spent a while working on that as a starting position… until I realised that there was in fact another way to combine them which turned out to be a better idea… so I spent a while working from there.
Actually, I ended up spending quite a while working from there!
Once you’ve got a few pieces correctly positioned, you can generally work out if the remaining pieces can complete the cube or not, moving onto another combination if that doesn’t really work… toward the end of that process you’ll end up with a pair of pieces to slot in, without a definitive answer as to which way around they should go… now comes the fun bit: trying to derive the order of assembly that permits the complete assembly – there are a lot of possible avenues to explore – most of which require some other starting combination of pieces.
It’s a serious challenge for a simple-looking six-piece puzzle… very rewarding once you finally get it all together, not least because of all the movements required toward the end to place the final couple of pieces in the right place… very rewarding!
Postscript: I took these two little puzzles along to Wil’s King’s Day Puzzle Party and watched a huge number of people play with them – most managed the Coronation Cube, but only a couple managed PIC#4 – clearly, it’s a decent challenge!