Saturday 30 April 2011

Coffin’s Grand Pin-Hole Cross

OK, so we seem to have a bit of a theme going here, let’s not disappoint ... on to Coffin’s Grand Pin-Hole Cross ... 

This was the ultimate incarnation of Coffin’s Design #20 – The Pin-Hole Puzzle. Essentially the Pin-Hole Puzzle is a set of building blocks (think big boys' Tinkertoys!)  in a specific number of shapes: the Elbow (the left hand piece), the Pin and the Bar (in the centre) and the Cross (on the right hand side of the base). There are also a number of joints (picture an elbow with a bar attached to the unpinned end) for joining bits together. 

This one is made of Queensland Blackbean and came from Mr Puzzle. It formed part of his Limited Edition run from 2007 – and as at the time of writing, he had one left ... 

Seeing the dimensions of the puzzle on the web-site is one thing – seeing the pile of wood on your dining room table is another thing entirely! This puzzle is big, and heavy, and I now understand why Sue suggested that she ship my order in two parts – if nothing else, it saved me having to contribute to my postman’s disability benefits! The web-site says it comes assembled, but again Sue suggested that shipping it flat-packed might be a better idea – this results in receiving a pretty large lump o’ lumber – but that lump is infinitely easier to handle, secure and ship... good call Sue!

Right, so the lump o' lumber duly arrived on the morning of the MPP2 and it lay in the dining room table all day, and no-one made a serious attempt at constructing anything all day – not a good sign, as these as some of the best puzzlers I know ... what have I let myself in for? Brian’s web-site passes on the following helpful advice: ‘If you're worried about taking the Grand Cross apart Stewart offers the advice that "by persisting with the simpler figures you can gradually become familiar with the more difficult tasks".’  Hoo-boy!

During the course of the week I started fiddling around with some of the bits, and discovered that, given free reign with the bits, it’s not too challenging to make up a single cube ... however it’s pretty clear that you’ve been given just enough bits to complete the Grand Cross (picture a central cube with a cube coming off each face) ... literally, just enough... so this will require a little thought ...

OK, brain is engaged and we establish reasonably quickly that there are only really two ways to build a cube with the limitations imposed by the pieces we have – handily confirmed by Burr Tools. (For a laugh I also asked Burr Tools to solve the Grand Cross, giving it all the bits in the right quantities ... however, when it went away and thought for a little while and duly announced that it should have the solution within the next 18 years! I had flashes of Deep Thought spinning away for eons to proudly come up with “42”. So having eliminated that as an avenue of last resort – I really don’t have that sort of patience! – I had to rely on the mk. 1 noggin – Uh oh!)

Right, so notice that there are just enough joints to build the entire central cube of them, handily providing something to build all the outlying cubes onto ... spend a little time analysing the pieces you have and working out what you need inside the inner cube and what you want on the arms (so you don’t find yourself building 6 cubes then realising you have the wrong bits left for the last one) and then get to it ... I started by building the central cube as a framework for the rest of the pieces, and then worked my way around the outlying cubes – one of them needed a bit of thought as there’s a sticky-outy-bit that sort-of stops you from building the cube the way you might like to ... but the old mk. 1 manages to see a way around that and has it all together in just a little while...

The resulting construction is impressive, it really has presence!

[But if you don’t like the shape, Brian provides a card with a bunch of other constructions to try your hand at ... I like the Grand Cross, just the way it is...]

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