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This time, I present you the 'X Marks the Spot' puzzle. Although the original idea is around since the beginning of the 20th century, the modern version was created by Japanese puzzle designer and inventor NOB (Nobuyuki Yoshigahara), back in 1981. NOB is also responsible for the design of several Cast Puzzles for Hanayama.
You can think of the 'X Marks the Spot' as a wooden version of the Cast News puzzle. If you solved it, then you know the mechanism is exactly the same. What differentiates the two puzzles however, besides the material used, is their presentation . The Cast News is more pleasant to the eye, looking like an ancient piece of art, but the 'X Marks the Spot' looks much more intriguing and harder to come up with a solution. How can one take the X apart with that frame in the middle? - At first glance, this task seems impossible, but it's not what it looks like. The goal is simple: Take the two interlocking pieces apart and remove the square frame.
NOTE: If you don't want to know anything about the solution, don't read the italic paragraph below.
A close inspection to the puzzle will reveal that it makes a rattling sound when it's shaken. This proves that the mechanism inside has loose pieces that somehow lock the two pieces of the X together. So how do you separate it? - The answer lies in a physics principle called, the centrifugal force. After you figure how to move the loose mechanism, you just have to slide the two pieces out and remove the square frame. Solution here.
I love puzzles like this one, that have a hidden mechanism and makes you wonder for quite some time, looking as almost impossible to solve. Such a simple and easy to explain mechanism, and yet so complex that puts experienced puzzlers scratching their heads. Great for when you have friends over and see their frustration as they try to figure it out.
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