Tuesday, 18 November 2014

Bob's 5x5 & Jerry's 4x4

When I first saw Bob's 5x5 during Nick Baxter's recent puzzle auction, I knew I had to get it. This was because I was a little surprise (and also a little disappointed) to find out that someone else had already earlier (in fact some 16 years earlier) come up with a design concept similar to my "Interlace 4x4" puzzle. More about the latter later.

The Bob's 5x5 I won at the auction is a reproduction of Robert Darling's IPP18 (1998) Exchange Puzzle. This is a huge puzzle, measuring a good 15.5cm (6.1in) square with a thickness of 3.5cm. Can you imagine the size of the box or crate needed to hold 99 exchange copies! 

It is very well made of wood (either teak or walnut I am not sure) and really solid and heavy. The bottom is even felt lined (so it won't scratch the surface it sits on). Displays nicely on the coffee table and one might even mistake it for a cigar box. Definitely well worth my $48 winning bid!.

Its a packing puzzle and the object is to pack 10 notched burr pieces (or sticks) flush into the box frame. 

Now to my Interlace. Its not a packing puzzle, although at one point in time I did consider making it so, but decided a free form interlocking solid with curved edges looked far more sexy. But as mentioned, the design concept is similar to Bob's 5x5. Until the Baxterweb auction in November, I had never even seen Bob's 5x5 or anything similar. The Interlace was something I came up with around September this year. 

My design consists of 8 board burr pieces that "interlock" to form the shape in the photo. I had it cut from 10mm thick plexiglass. While Bob's 5x5 pieces are two units thick, the Interlace is four. And both puzzles each have a unique solution.

The Interlace also became the starting point for my CrossRoads interlocking board burr with a level 12 solution. There are probably other puzzles out there with a similar design to Bob's 5x5 or my Interlace. If anyone knows, please drop me a note, thanks!


  1. Hi Jerry,

    Nice find! And I like your puzzle design, too.
    There are actually quite a few puzzles based on similar concepts. Have a look at my section on "Weave" puzzles:


    1. Hi Rob, thanks. And thanks for your link to the weave puzzles. Yes, I can see quite a number of variations based around this design theme. Your Lego version looks very nice!