Monday 21 March 2016

Binary Key II

Binary Key II

Goh Pit Khiam

Manufacturer & Availability
Produced by Eric Fuller of Limited edition 40 copies made and sold for US$46 in 2003. Currently unavailable.

Type & Classification
Take-apart; sequential movement

15.5cm x 7.5cm x 1.8cm

Materials & Construction
Stainless steel, nylon and acrylic. Laser cut acrylic built to very high tolerances. Excellent quality.


This is my second Key puzzle from Goh, the first was the Tern Key reviewed over 3 years ago in this blog.

Goh's Binary Key II is a re-design of his original "Key Puzzle" (which was also Bill Cutler's IPP24 Exchange Puzzle).

The Binary Key II comes under the group of gray-code or N-ary puzzles as they are called. The well known Chinese Ring puzzles are a good example of this type of puzzle. For a comprehensive explanation of n-ary puzzles, click on Dr Goetz Schwandtner's webpage here.

The object as you can probably tell from the photo is to remove the horizontal rectangular "key" that sticks out a bit on both ends from the "lock" by moving the 10 pieces resting inside the tray. 5 of the pieces move up and down and the other 5 left and right within their confined spaces. Movement is facilitated by the use of short steel pins pressed into the pieces.

While at first it may look like you are moving pieces randomly to try to move the key piece out. However, the fact that there is a "binary sequence" in place means that the movement of the pieces have to be made through a repeated pattern; back and forth, left and right until none of the pieces is restricting the key.

Initially it was a bit of trial and error as I was coming to grips with figuring out the puzzle. But I was slowly able to discern the repetitive moves and discover the sequence. Even then, it took me a good 40 minutes to solve from start to finish.


It is a bit much more than moderately difficult although not frustrating. Early on in play, you are likely to encounter problems eg; one last piece that holds the key back to a complete solve, hence requiring a restart again.

Although the moves are repeated, it takes a hefty 85 moves to free the key, so its definitely no walk in the park. Once solved, returning the puzzle to its original state is slightly easier and more manageable.

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