Sunday, 15 May 2011

Boxed LUV

I got a copy of Boxed LUV, a.k.a  Four Blocks in a Box or simply Coffin #189 from Tom Lensch after I dropped him a random email asking him if he, by any chance, had any stock of a few things listed as out of stock on his web-site – I know it’s a bit rude, but sometimes web-sites can be out of date, or folks might just have a couple of spare puzzles lying around for sale, you never know! 

He came back and let me know that he had a couple of Coffin puzzles available – one of which was Boxed LUV – I’d vaguely remembered having seen a packing puzzle by that name somewhere in the dim and distant past, so I took one (and a Four Fit and a 4-piece serially interlocking cube, but that’s another blog post altogether!). 

I received this package o’ puzzles a couple of weeks before MPP2  and set about trying to solve them – but this one, evaded all attempts at solution. It seems so simple – it’s what I call an ‘honest’ puzzle: there’s nothing sneakily hidden or disguised, it’s all out there in plain view all the time. It’s a simple walnut box with a slide-on lid which helpfully has a hole cut out of it the same size as the standard cross-section of the pieces – that should be handy... inside the box are four maple pieces that make up the letters LUV (actually there’s a 3*1 cube stick, a pair of “L”-shaped 3*1*2 pieces and a “V”-shape made up of 3 joined cubes). I said this was an honest puzzle and you can quickly confirm (I sense you’re the sceptical sort, since you’re reading this!) that the cubes making up the pieces are identical and square – no funny business here!

OK, so it’s easy – put the pieces in the box, so that you can (easily!) close the lid – they’ve even left a window in the lid so you can have stuff peaking out if you like – this should be simple...

...and yet, in two weeks, I got nowhere! Actually that’s not quite true. In two weeks I did manage to find an awful lot of ways to not solve this puzzle ... in my defence, several came close, some would even ‘allow’ you to force the lid closed (while scoring lines in the inside of the lid!), some would have things sticking out of the window at strange angles, but none of them could really be called a solution. The size of the box is positively fiendish - effectively stopping all sensible ideas from working!

So when I had a puzzler-of-note staying over for the weekend, Gill and I hatched a plan – we would threaten not to feed Louis until he solved the Boxed LUV and put me out of my misery. In the end we forgot to issue the threat, but he did take up the challenge and managed to solve it in way less time than I’d wasted on it ... to be fair, it did take the puzzle-meister-of-note a good couple of hours, but he had succeeded where I had failed, somewhat dismally! 

The solution is very elegant and makes a mockery of all the rules your brain tries to impose in order to pack these oddly shaped pieces efficiently into the box – and don’t get me started on the biggest red-herring of all!

This puzzle quite quickly became one of my favourite “Give it to the non-puzzlers”-puzzles, not only because it’s pretty hardy and can withstand even an angry teenager, but also because once folks have played with it for a while, they are usually absolutely convinced that it's physically impossible to get those four simple blocks inside that box ... until you show them ...


  1. Headache fodder!

  2. I got this puzzle from Tom Lensch as well and has been great fun. I kept thinking that the hole in the lid must be craftily shaped so that you can get the lid on with a piece barely sticking out. This red herring had me going for quite some time, but eventually I found the solution.

  3. Thank you for the honorable mention, Allard (and for the fish-and-chips, I don't remember if that was before or after solving it).
    I luv'ed playing with this puzzle, because of its apparent simplicity, and because it has several almost-solutions that make you smile when you discover them and then build them, only to prove you wrong when the lid does not fit!
    To anyone who likes this puzzle (including you Allard), I recommend "pack+1" which is almost as devious as this one, but commercially available (at Sloyd).
    I hope to add "packed luv" to my collection one day.

  4. ...a fish supper was the least I could do after you put me out of my misery, Louis! (and I'll definitely be looking at a Pack +1 after your recommendations...)

  5. My daughter loaned me the puzzle. She had been given it by a friend who bought it from a Paris street vendor. I enjoyed the puzzle enough that I thought it would be fun to make a video out of it.

    It would be great to hear about any errors I made in the video or some information that I should have included. In particular, I wondered whether Stewart Coffin or somebody associated with him had made the version of the puzzle I have. It is very nicely constructed, but it is somewhat different than the version of the puzzle shown above.

    1. Hi Dave - thanks for posting...most of Stewart's works have pencil inscriptions with the puzzle number and his initials on them somewhere... BTW I suspect that your solution in the animation doesn't quite work - is the lid a little stiff when you slide it on? It shouldn't be... and if you adjust things a little you can get it to slide on freely... :-)

    2. Thank you very much for your reply.
      Did Stewart Coffin make the version of the puzzle I have?
      I looked over every surface carefully after your reply and there doesn't seem to be any identification marks. The puzzle is beautifully constructed and that surprises me that somebody would do such nice work on a copy, but it is certainly possible. I wonder if Stewart Coffin knows of the people that made it.

      Solution not quite right:
      This idea was a complete surprise. I went back and matched the physical puzzle step by step with the animated solution and I can't see a difference. The lid slides on and off very easily with this solution. The blocks in my puzzle are 20 mms thick and the clearance below the lid is about 3 mms.

      Is it possible that my puzzle is not quite identical and there is another solution for the Coffin version?

      I notice also that my puzzle seems to have metric based dimensions. Perhaps that is another clue that it is not a genuine Coffin puzzle?

    3. Sorry, can't tell for certain whether Stewart made that copy, but can tell tell you that lots of people make the puzzle - Stewart encourages people to make his puzzles and sell them! :-) Some very talented woodworkers make copies of his puzzles that are serious works of art (Peterson, Devost, Buie, Krasnow).
      Solution - if the tolerance is 3mm below the lid with your animated solution, then I suspect that your box is not quite as snug as it could be on this puzzle and allows a few false solutions... although it still clearly makes for a fun puzzle! :-)

    4. Thanks for the response. It was interesting to learn that a lot of people make the puzzle. I am thinking of making a copy myself. Coffin's book is on-line with some clues as to the woodworking skills necessary. He recommends a planer that I don't have but I think I might be able to make the pieces well enough with my table saw and a little sanding.

      As to your additional solution. That was very cool. I had a very strong feeling that I had found all the solutions and I enjoyed seeing how wrong I was.
      I made a short video of demonstrating what I think is the solution that you were describing:

      The alternate solution seems to not fit any better than the solution in the first video in the version of the puzzle I have. It will be really interesting if there is yet another solution.

    5. Hi Dave - yip that solution will need exactly the same external dimensions as your first solution - I think you can do slightly better than that... :-) Tell me when you've had enough...

    6. Hi Allard,
      I haven't given up yet. There is a slightly different solution where I can get almost 4mm of clearance instead of 3mm. Is that possibly the one you are thinking of? I rejected it because it didn't seem to reduce the clearance of all the peaks. But in some magic way if I use one particular permutation of the solutions in the video and rotate one of the pieces it actually reduces the clearance by a mm for all the peaks. I don't understand why. I am off to do productive work (or at least try to) but I'm going to take a look at what is going on this evening.