Thursday 8 September 2011

4 Steps Visible Lock

The 4 Steps Visible Lock ("4SVL") designed and made by Robrecht Louage won the Jury Grand Prize in the 2011 IPP Competition held in Berlin during the month of August. After seeing his puzzle on the IPP 2011 entries list with the different combination of materials used in its construction, I knew I just had to get one. Fortunately Robrecht's email was listed and I promptly emailed him to buy a copy of his prize winning entry. A week later, the puzzle arrived at my doorstep.
The 4SVL is about 5in x 2 1/2in x 7/8in. The puzzle is made up of a rectangular block of Trespa (a very strong and durable composite laminate made of resin reinforced by cellulose fibres generally used for interior table tops). Within the block, a number of channels have been cut which resemble a maze. Screwed onto and covering the top of the block is a sheet of acyrlic (perspex) and sandwiched in between the trespa block and acrylic cover, there is a thicker center slab also made of acrylic which slides. Within the internals of the puzzle, one can see two large ball bearings, two smaller ball bearings and a 1 Euro coin (hence the name "visible lock"). Construction and quality of the 4SVL is very good indeed and the puzzle feels really solid and heavy in the hand. Some have remarked that the 4SVL bears some resemblance to one or two of the Roger puzzles and while I have never seen an actual Roger puzzle before except those in photos, I would tend to agree.

The object of the puzzle is of course to remove the 1 Euro coin out of the block, by moving the center acrylic slab towards the left so that the coin and be extracted from a hole in the top cover. Here is where the "lock" part comes in; the center acrylic slab is "locked in" by the ball bearings and can only move sideways within certain limits. The way to solve the puzzle is to use (some) dexterity to manipulate the ball bearings around the maze to "unlock" the center acrylic slab and allow it to slide towards the left, so that the coin matches up with the hole on top. But wait! It's not just the ball bearings that have to be dealt with; there are a couple of other necessary challenges as well.

I am not sure if I just happened to be lucky that day, but I managed to solve the 4SVL pretty quickly (I guess its faster when you can see exactly what is going on). As I repeated the solution, I realised that indeed 4 steps are needed to remove the coin. Step 1 may pose a challenge for some (but I think experienced puzzlers would know how to overcome this step quite easily) but Steps 2 and 3 are quite manageable. It is Step 4 that is a surprise and probably the one that would stump people. However, once you have solved it once, the 4SVL is pretty easy to solve repeatedly.

I think Robrecht Louage has designed a very nice and well made puzzle and while not very difficult in terms of  puzzling, it nevertheless poses a fair challenge. I would dare say that the 4SVL epitomises the term "mechanical puzzle" and justifiably deserves it's IPP award. Definitely worth acquiring for keeps.


  1. "Definitely worth acquiring for keeps."

    Gasps in horror!

    Surely Jerry, ALL puzzles should be hoarded until all available space at home is filled - then you have to move some of "her" stuff out! To make room for more, more, more...

    Nice review, thank you. Now I want yet another puzzle!!!


  2. Kevin,

    Thanks. Yes, I couldn't agree with you more! Thankfully haven't reached the point of moving "her" stuff out yet....Hmm... might as well do some pre-emptive space planning now....

  3. If she threatens to throw you out then you can send your entire collection to me at…


  4. Sure! And vice-versa...Ok? recipient pays shipping charges and applicable taxes!!

  5. Hello Jerry do you think that Robrecht have still some previous puzzle to sell ?