I spent part of the holiday yesterday playing with 3 Hanayama Cast puzzles. Two have been around for some time and the third which came out this month.
Hanayama Cast puzzles are available from most of the usual online puzzle retailers; and for almost all except the latest releases, can also be bought from Ebay.
The U&U is really fresh from the oven; just released in April this month. This one does not even look like it's been made by Hanayama. It has two rods bent U shape with nuts screwed to the ends of each U. The puzzle appears more like it was made from parts sourced from a DIY hardware store. Quality and finish is up to the usual Hanayama standards with a shiny chrome finish.
Physically it looks like an easy puzzle - just unscrew the nuts and the both U-s should disengage. But don't let the looks fool you. The nuts can be screwed/unscrewed throughout the length of the threads they are on, but stop dead at each end and cannot be removed. Here is where the challenge of the puzzle lies.
I took longer than necessary to solve the U&U because I over-complicated things. In actual fact, there is a certain technique to it as I discovered at the end which is simpler than what I was trying to do. The U&U has pretty tight tolerances so you need to be quite precise with your movements in order to solve the puzzle.
Rated 4 out 6 in difficulty, I think that's about right. Its much more tricky and challenging than it appears. Pretty fun and quite repeatable solving once you figure out the correct way to do it.
This version of the Cast Key is a special commemorative edition made for IPP33, which was held in Tokyo, Japan last year. Who better than Hanayama to supply the IPP33 event premium given out to all participants. This version has the two interlocking keys in a two tone Gold & Silver as shown in the photo below. The original Key was just a one colour brass finish. The latest incarnation of the Cast Key is the Key II.
The object is to separate the 2 keys. Not difficult by any means. Its like navigating a maze but with a couple of extra twists and turns. Rated 1 out of 6, I got through mine within a minute or two. This puzzle would do well for new puzzlers.
I chipped and cracked my finger nails puzzling with this one!
Donuts was designed by Vesa Timonen and came to the market in 2011. The puzzle comprises two donut shaped rings interlocked together and each of the rings can be further split into separate halves.
Donuts is one of the most aesthetically pleasing Cast puzzles in the series with a polished two tone silver and dark gray finish giving it a very high quality appearance; relative to some of the other Cast puzzles.
Commensurate with the good looks, it is also a very difficult puzzle. It is rated 4 out of 6 in difficulty but I think it should be a 5 at least. Of the three puzzles, I spent the most time with Donuts and even then, I could not solve it and had to resort to the solution, both for taking it apart and putting it back together. Its one toughie here!
Like the U&U, there is a technique required here, although somewhat more sophisticated. Precise moves are the order of the day and random trial and error will not work. While I can appreciate the elegance of the solution, my only gripe is that I found the parts are fitted too tightly together. I personally feel that the manufacturer could have allowed for slightly more play vis-a-vis the Donut halves and yet this still would not negatively impact the solving experience. In fact, I think it would improve the solving and make it more enjoyable and put to rest any temptation to use unnecessary force.