Double Feature

Saul Bobroff's IPP37 Exchange Puzzle, the Double Feature designed by Stewart Coffin reviewed.

http://mechanical-puzzles.com/double-feature-stewart-coffin/

Hexsticks

Stewart Coffin puzzles, especially those hand-crafted, exotic wood and multi-piece interlocking ones are not typically readily available for sale most of the time. And when they do become available, and even tho' they're pretty pricey, they get snapped up in a jiffy. 

So when I chanced upon the Hexsticks in a hotel souvenir store in Hokkaido, Japan last year, I bought a copy, even though I am not a die-hard fan of such puzzles...but what the heck...it was at a rather reasonable price of 2,900 Yen, or about US$25/-.

The Hexsticks is Coffin design #25A, which was based upon his earlier #25, the Hectix. My version came from a Japanese company called Woody Craft and there doesn't appear to be any website link for this brand. My copy, being made in Japan is a quality product and very well constructed. Not sure what sort of wood, probably local but the fit and finish is very good with no sloppiness or movement of the pieces in the assembled state.

The Hexsticks consist of 12 pieces, 9 of which are identical, cut in a certain way with notches and the remaining 3 also identical, but their notches cut differently. All the pieces have a hexagon cross section and the notches are all cut diagonally at a specific angle. Apparently there are three solution shapes that can be formed from the 12 pieces. This puzzle (and its variants) has been crafted and produced by a number of well-known puzzle makers.

The puzzle came un-assembled and thankfully, there were instructions on how to put the pieces together (for one of the solutions). Honestly, not being good at these sort of puzzles, I would not have been able to solve it without help. Even if the sticks were quad-coloured and I had completed puzzle photo to follow, it may still have eluded me.The instructions are in Japanese but the accompanying photos were clear enough for me to follow without resorting to trying to figure out the text.

I found that after the first solve and re-doing it second time, I could repeatedly solve it without the instructions after some practice. With 9 identical pieces to start with at the beginning, it is not too difficult to memorize where each piece goes where after a few tries. Completed, it displays very well and truly looks the part as a very serious and complicated puzzle indeed!

Both Brian Pletcher and  Kevin Sadler have solved their respective Hexsticks and Hectix Revisited copies and you can read about their experiences here and here. These guys are super-solvers, so it wasn't too difficult for them.

For those interested, there are several places where the Hexsticks is sold, one is a Japanese online retailer while the other is a US based home accessories store called Monolier, the latter which incidentally sells the same puzzle I have here but at nearly twice the price! And of course Amazon and Ebay as well, just do a search for "Hectix". And for those hard-core puzzle fans that like to know even more about burrs and polyhedral puzzles, read Stewart Coffin's very interesting and informative book here.

Checking In

Steward Coffin's designs are typically not known to be easy and my puzzle of choice this weekend was no different.In fact it is probably one of the harder ones I have played with, considering the amount of time it took me to solve. This puzzle was Jerry Slocum's IPP34 Exchange Puzzle called "Checking In" and its Coffin's design #223.

Checking In was made by Brian Young of Mr Puzzle and comprises of Western Australian Jarrah for the tray and a combo of Jarrah and Queensland Silver Ash for the eight pieces. The puzzle measures about 10cm x 10cm x 1.5cm. According to Brian, this design has never been made before so its the first time design #223 has been produced. As usual, quality and construction is very good and the pieces with its two-tone colours looks fabulous.

The puzzle comes "semi-solved" and the goal is to fit one of the pieces packaged at the bottom of the frame flat into the tray together with the rest of the other seven pieces. Not only that but to also form a checkerboard pattern as well. Each of the eight pieces consist of dark and light squares and half squares (triangles) glued together. One look and it is obvious right from beginning that this one wasn't going to be easy. The pieces don't look like they can all fit into the tray. And the fact that its eight pieces already ups the the difficulty quotient by a few notches. 

I spent around two hours or so over several sessions trying to figure this one out. At first, random sort of packing, but usually this won't work when there are a large number of pieces. Then I tried logical deduction/reasoning, which I would say helps to some extent for this puzzle. Many a times, it was always the last one or two pieces that couldn't fit. But eventually the a-ha moment came when I adjusted the last few pieces and the tray accepted the last piece nicely...and in a checker board pattern too! A rather "interesting" solution I might add!

Not at all easy but not unduly frustrating either...although I would imagine that those who don't often play with packing puzzles could spend hours on Checking In and get no where. Mr Puzzle rates it a 6/10 for difficulty but I think it deserves a 6.5 or 7. If you are into packing puzzles (and given this is a Coffin design which is not easily available), Checking In should be on your must-have list. Available only from Mr Puzzle at a price of A$50/- 

For anyone who might want to take a look at the solution, please PM me via my blog email here.

Restricted Area

This "crooked" shaped box puzzle is Saul Bobroff's IPP35 Exchange Puzzle. For those serious puzzlers, you may know Saul as the guy behind the very unusual and unique impossible object; 4 Street Elbows, which I never quite figured out how to take apart although I have heard stories of puzzlers who have.

When I first un-packaged this puzzle and saw the blue box, I thought it was made by Brian Young, who had produced something physically similar (but straight at right angles) called the Restricted Soma. But its actually manufactured by "Here To There", which I believe its Saul's own puzzle company. 

Now back to Restricted Area - it's a Stewart Coffin design, #270-A and the goal is to pack eight pieces into the box which has a restricted opening, reminiscent of Lacika Kmolnar's L-I-Vator Cube. What is unusual about this puzzle is that the box is slanted at an angle from all sides (not obvious from the photo). Whichever side you look at, you will see a "pararellogram" shape on each face of the box. Consequently the pieces inside; each piece comprising of two glued-together "slanted" squares are also at an angle. Quality is good with all the pieces cut and fitting nicely. Dimensions wise, the box is 6.5cm x 6.5cm x 7cm.

If this was a "normal" packing puzzle with straight edges, I don't think it would have been that difficult; but because of the angle that the pieces have to go into the box and with the different shapes, the packing becomes consequently much harder. 

I fiddled with the pieces, taking each one out very slowly with several involving 2-step orthogonal movements because of the restricted opening. Took a bit of time and practice but after a while I memorized where each piece was suppose to go. I can say its not easy. I didn't want to scramble the lot because knowing my lack of packing skills, I probably won't be able to get them all back in later. I suspect Burr Tools could help here (configuring the pieces in the normal way) but I didn't bother to try. I am also not sure but there could be more than one way to solve this puzzle.

Not an easy packing puzzle by any means and certainly different from your normal box packing puzzles with the angles and all. Hardcore packing fans would most certainly love this one.

Multi-Grain 275-AS

Name
Multi-Grain 275-AS.

Designer
Stewart Coffin was the designer of the original Multi-Grain 275-A. This version, the 275-AS with a modified grain pattern was by Jerry Slocum.

Manufacturer & Availability
Manufactured by Brian Young of Mr Puzzle Australia. Available for AU$66/-.

Type & Classification
Interlocking solid

Dimensions
7cm x 7cm x 7cm.

Materials & Construction
Papua New Guinea Rosewood. Overall very good quality and finish with a nice snug fit.

Overview
This dissection puzzle was Jerry Slocum's IPP35 Exchange Puzzle.

The object is to take it apart and then re-assemble it. Even though its only 4 pieces, the taking apart was pretty tricky, given its symmetrical assembly. The pieces all fit very snugly and I had to pull and push a bit, here and there everywhere before something finally moved. It took me a bit of time to release the first piece.

Like all burr puzzles, I try to take apart the rest of the pieces slowly and memorizing the moves, and placing them in a systematic manner on the table, so that assembly wouldn't be such a pain later. Brian encourages puzzles who want a real challenge to scramble the pieces and "...go for a walk round the block or something..." and then try to fit the pieces back to its symmetrical pyramidal shape, the latter which of course I didn't.

Thankfully I managed to put the 4 pieces back together, and this is after some trial and error which got me a bit worried in the beginning. But I would imagine that if I had followed Brian's advice, the pieces would have looked so confusing later that I would not have been able to put it together correctly.

If it had come un-assembled, it would certainly have been very difficult indeed. Again quoting Brian from his site:

"Even though it’s a symmetrical shape when it's done; visualising that shape while you're assembling the puzzle is extremely difficult even with the supplied photo of the finished puzzle.

An extension of the famous 'Three Piece Block' puzzle that Stewart is famous for; this one is just as hard if not harder than the original"

Difficulty
It is rated as 7/10 by Mr Puzzle but comes assembled so the difficulty quotient is lower.

TetraHexed

Now isn't this a handsome looking puzzle? The TetraHexed shown here is Stan Issacs' IPP35 Exchange Puzzle.

The TetraHexed is a Stewart Coffin design that dates back to 1971. The original copy called Cetus was made by a company called Skor-Mor. It was made of Styrene and Stan's mother had bought it for him from the Museum of Modern Art in New York.

This beautifully crafted version is made by Wayne Daniels and comprises of three woods, one which is Paduak, and the other two likely to be Cherry and Mahogany (although I can't be sure). Dimensionally, each triangular edge is 10cm x 10cm x10cm. All the pieces are very precisely cut with sharp edges and fit is perfect. The puzzle is just loose enough for the pieces to slide nicely yet the puzzle holds itself together properly. Really nice quality here.

In the packaging Stan has also provided 4 classifications for this puzzle:-

1. Hordern-Dalgety - INT-POLY
2. Slocum: 3.2 - Interlocking solid, geometric
3. Hajek Big Six - Packing 3-d
4. Houlis - +BU+GE+IN+MA+WD+04+TE

Now #4 above has me stumped; what do the letters and numbers mean? If anyone knows, please feel free to add a comment here.

The object of the TetraHexed is take the puzzle apart and put it together again with an additional challenge of putting three colours on each face.

This is a 6-piece co-ordinate motion puzzle. Dis-assembly and re-assembly is not too difficult as you manipulate the pieces. My way is to split it into two halves and then further split each of the halves. But putting it together with three different colours for each face is more tricky and requires some thinking and experimenting. All the 6 pieces are identical save for one different colour for each pair.  

Not difficult from the puzzling standpoint, but certainly this is one of those puzzles that would look really good on the coffee table!

Lockdown

Is Lockdown a packing puzzle? Well, I guess it probably is. It's also my first puzzle comprising of pieces in the shape of linked spheres. 

LockDown is a Stewart Coffin design (#271-A). Also made by Stewart Coffin for Rob Jones' Exchange Puzzle at IPP35 in Ottawa, Canada this last August. I am not sure the species of the woods used but the puzzle is well made and feels solid and sturdy. It measures about 10cm wide and 7.5cm tall in the assembled state. The spheres are around 2.3cm in diameter.

The puzzle consists of 3 different pieces, each formed by linked spheres. The puzzle came un-assembled and the object is to pack all 3 pieces into the triangular tray to form a pyramid. One edge of the tray has a curved recess to facilitate access of the pieces. 

To form the pyramid outside of the tray is not too difficult. With some thinking, you can probably figure out how the final shape would look, given that there are just 10 spheres. Its the packing that requires a lot more effort. The instructions are also explicit that no force is required.

While I figured out the shape of the pyramid pretty soon, it took me the better part of an hour before I managed to get the pieces into the tray. Some experimentation is required to get the right orientation of the pieces and aside from this, the movements also require twisting and rotation. Indeed once the pieces are inside the tray, you could grab the top few balls and lift the entire puzzle off the surface it's on. Truly "locked down".

There are not too many moves involved to solve this puzzle; no need actually since the shapes of the mutil-sphere pieces are enough create a good deal of confusion.  Although there are only 3 pieces, the packing is more than moderately challenging and pretty tricky.
To put it another way, the Lockdown is just the right level of difficulty for an Exchange Puzzle. None commercially available but Rob may have some extra copies for sale, just maybe.

CCC-1 & Diamond Engagement

Over the weekend, I played with another two IPP35 Exchange Puzzles, of which only one I was able to solve.

Well I will start with the unsuccessful one first, which was the CCC-1 ("Coffin-Cutler Collaboration"). This was Bill Cutler's exchange puzzle and it was designed in collaboration with Stewart Coffin and based on Coffin's Design #177A. The CCC-1 was made by Coffin.

It's a packing puzzle and the object is to fit the 5 polyminoes (ranging from 4 to 6 units) into the tray. The puzzle came with its accompanying literature/explanation. I think both Cutler and Coffin knew that this was no easy puzzle so they also including a note containing a clue on how to solve it. But even with the clue, I was hopelessly lost and had to asked fellow Sinaporean puzzle collector/designer Goh Pit Khiam for help. 

Goh is quite an expert on these sort of packing puzzles having designed many of them himself including the IPP33 award winning Dancing Shoes. Goh had earlier borrowed the CCC-1 from me and solved it rather quickly.

Like always, only with the benefit of hindsight after seeing the solution, I felt perhaps I could have done better with the CCC-1. Very difficult puzzle indeed (at least for me) and I think the solving aid provided is probably quite necessary. Definitely would be of much interest to packing puzzle enthusiasts, and since its a Coffin/Cutler puzzle, a great addition to any puzzle collection. If the CCC-1 could be made with exotic woods, even better still. As far as I can tell, the CCC-1 is not available commercially so the only source is from Bill Cutler.

Diamond Engagement

I had much better luck with the Scott Elliot's Diamond Engagement Exchange Puzzle. Last year his exchange puzzle was "Join The Club". This year his exchange puzzle borrows the same theme as Join The Club with a similar solving method. Scott produced his puzzle via 3D printing. 

Although the puzzle consists of only 2 pieces, getting them together still required some effort and experimentation. But once you find the correct " entry" point, the pieces slide themselves nicely into each other. The solution is actually quite easy once you figure out what to do and the solving becomes very repeatable; ust a couple of seconds is all it takes. 

Diamond Engagement is one of those highly pocketable puzzles that you can easily take with you anywhere and have a play while waiting for someone, travelling on public transport etc to keep your fingers occupied. it is available for sale by PuzzleMaster of Canada for CA$24.99.

Diamond Engagement solving bears similarities to the Hanayama Cast Dot. The Cast Dot came out mid 2016.

Supersymmetry

Here's another put-together puzzle that I got nowhere with. Supersymmetry is Stewart Coffin's #247 design and was Tom Rodger's IPP30 exchange puzzle in Osaka, Japan in 2010.

I saw the Supersymmetry during one of Nick Baxter's puzzle auctions and there were around seven copies available for sale. It looked really cool (and had such a cool name too!) being made of walnut, with its own plastic container and "appeared" quite do-able for me. After all, there are only 6 pieces and they didn't look like complicated burr pieces with multiple notches and grooves, so how tough could it be right? wrong, I should have know better that a Coffin puzzle would not be easy. So I went for it and made sure I won a copy.

Looks symmetrical, but is not and can't fit into the container

Well, when it arrived a couple of weeks later, I had problems from day one. While only 6 pieces consisting of equal length rods, the notches were cut diagonally. The object was to form a symmetrical shape and there were 8 solutions for this. I would have been happy to just find one solution, never mind it didn't fit into the plastic container. But unfortunately, I could not even get the rods to interlock together to form any sort of shape at all!

Burr Tools of course was no help for puzzles like these. But I happen to know that fellow puzzler and collector, Oli Sovary-Soos had a copy of the same puzzle (and Oli is quite a super-solver). So I promptly shot him a message for help. He very kindly responded with photos of the solved Supersymmetry from different angles. After quite a good number of days of on-and-off trying, I still got nowhere and asked if he had a step by step solution. The orientation of the rods and how they interlocked I just couldn't figure out from the photos. He sent a second round of photos, this time one photo showed a partial dis-assembly. With this I managed to get an interlocking puzzle, but still not a symmetrical one. Finally after several more tries, I got the right solution; which slipped nicely into the container.

Very difficult, even looking at photos. Trying to get the pieces just to come together properly (without force) is very hard in itself (and even Oli says he doesn't dare to fully take apart his copy). I doubt I will be removing and disentangling the pieces anytime soon, just happy to leave it in its container.

Three Coffins

This week saw the arrival of three "coffins" to my home! Three Coffin-designed packing puzzles to be accurate. They are:-

1. The Cruiser
2. Five Fit - Stewart Coffin #177A
3. Martin's Menace - Stewart Coffin #217

The Cruiser

All three puzzles came to me from Creative Crafthouse. Creative Crafthouse has a very extensive catalog of wooden puzzles and games and the company manufactures most of their puzzles in their shop in Florida, USA. They also design their own puzzles. 

All of the three packing puzzles are precision laser cut. Quality, fit and finish is very good. The pieces and tray are made from different hardwoods (and I have asked Creative Crafthouse what these are) while the base of the trays are made of floorboard. Don't let the word "floorboard" put you off; it is extremely sturdy, scratch resistant and durable and can withstand a lot of abuse. You can even clean it, tho I won't recommend using any floor cleaner! Other nice touches include the names and other details etched onto the tray. 

Ranging from US$12 to US$21, these three puzzles represent excellent value for money. Cruiser and Five Fit also come in larger sizes.. What I also really like is that all three puzzles came to me upgraded with tray covers; which makes the puzzle look nicer and storage much neater.

Five Fit - Stewart Coffin Design #177A

I started with what appeared to be the easiest of the lot; Cruiser. Only four piece made up of two congruent pairs of shapes. Not too difficult and I managed to solve it in under five minutes. According to the grading given by Creative Crafthouse for time it takes to solve (less than 1 min - Gifted, less than 5 mins - Smart, less than 10 min - Normal, less than 20 min - Slow,  Never - Sad Situation), I fall into the smart category; for this puzzle only!

My next attempt was with Five Fit. This one consist of five pentominoes. And much tougher than the Cruiser. I must have played with this for nearly half an hour before I finally figured it out. I don't want to have any spoilers here but suffice to say there is a "trick" to this puzzle. You will go around in circles (even tho only five pieces) if you don't discover the trick. Again I have some experience with such packing puzzles and this helped my solving.

Two packing puzzles is enough for one day. I am leaving the last; Martin's Menace for another time and will post a review once I have played with it. It is supposedly a very difficult puzzle from the description. I don't know how to do the "hide/show" thing here, so if any reader wants to see the solutions for the first two puzzles, please PM me and I will send you a photo.

For anyone interested in packing puzzles, these three are great to collect and for beginner and experienced puzzlers alike, its definitely worth checking out Creative Crafthouse's range of products, which judging from these three puzzles, are both high quality and affordable. 

Convolution's Cousin

Convolution's Cousin ("CC") designed by Stewart Coffin, was Dave Rossetti's IPP34 Exchange Puzzle. It's the "cousin" because it looks and behaves very similar to Coffin's Convolution. Except that this cousin is the smaller cousin, has only five pieces versus Convolution's seven. While I don't have a copy of the Convolution, I do have the Convolution Ball, which is spherical shaped and based on the former's cube design.

The CC is made from African Mahogany. Dave made the puzzle himself under the mentor-ship of Tom Lensch. The mentoring appears to have paid off as the CC is very well constructed with high quality fit and finish. In fact the fit is so good that the join lines of the separate pieces are very well hidden and pretty difficult to find.

This is an interlocking puzzle and the object is to disassemble and re-assemble the pieces. First task of course is to find the "locking" piece that keeps the rest together. Not too difficult as I pushed and prodded and after a short while, figured out how to move the first piece. Once the first piece is sorted out, its a matter of finding which piece comes next and so on. Despite the snug fit, all the pieces slide smoothly and no force is required. 

The dis-assembly takes 6 steps and there are two ways to take the puzzle apart; so it would not really count as a sequential movement puzzle. A bit of rotation is also involved in the process. While dis-assembly is not hard, the re-assembly is, especially if you forget the order and orientation of the pieces and how they interact with each other. It can then pose a huge challenge to get it back to the solved state. That's why its always advisable to document the steps with photos as you play.

Involute

Name
Involute

Designer
Stewart Coffin. Check out his over 250+ designs here.

Manufacturer
Brian Menold. Online retail shop Wood Wonders.  My copy priced at US$26 (unavailable). But available in Red Oak for US$22.

Type & Classification
Interlocking, sequential movement

Dimensions
6.7cm (Length) x 6.7cm (Width) x 6.7cm (Height).

Materials & Construction
The 8 pieces of the puzzle which interlock to form the cube is made of Tasmanian Rose Myrtle with the corners made from Rosewood. Construction fit and finish is very good; solid quality and value for US$26.

Overview
This is my third puzzle from Brian after Twin Pentominoes and Stacks Of Sticks both reviewed earlier in this blog. I had received this from him a while back but only got around to it this week.

This one is a real beast! Looks innocuous; just like any other 4x4x4 cube out there but a nightmare to solve, especially the re-assembly. Although only 4x4x4, it comprises 8 pieces all of irregular and non-identical shapes.

Initially I didn't think it would be that difficult; especially after I got the 1st piece out (easy) and even the 2nd and 3rd piece was removed pretty quickly with the right moves...thereafter I was stuck. I had dried the puzzle in my dry box to make sure there was no tightness due to wood expansion (and its a really good thing I did, because this puzzle probably cannot be solved if the pieces fit too snugly). 

Although I am generally lousy at interlocking burrs, I have enough experience to know that some interlocking burr pieces don't disengage in the way one would normally expect them to. So I tried a different angle...and yes, my alternate approach did work and I managed to free up pieces #4 and #5. The rest came out pretty easily thereafter. Here is where the intimidation started!

But I made one serious misstep. I forgot to document my steps with photos which I usually do, especially with burrs. After all the pieces had come apart and I had photographed them for this blog post, I started to reassemble them. Horrors! I had forgotten the orientation of the pieces and sequence. I spent a long while trying to fit the pieces together but nothing worked. General confusion pervaded.

I activated Burr Tools. While the programme did not reveal a solution (because you can't use Burr Tools on this particular type of puzzle), the final assembly of the Involute (combined with my photo of the disassembled pieces) gave me clues as to where the different pieces were positioned, relative to one other. (Those who know how to use Burr Tools would know what I mean). Aided by this, I was able to slowly piece everything back to together. Whew!

Difficulty Level
Extremely difficult; particularly the re-assembly. And Burr Tools doesn't work here either, except perhaps for the way I have described above.

Summary
For anyone who enjoys a really difficult challenge with interlocking burrs, this one is a must- have. Just remember to document your steps as you play to save you a ton of headache and frustration later. A real gem from Stewart Coffin. And for the price paid, excellent value for money too!

Convolution Ball

Name
Convolution Ball

Designer
Stewart Coffin. The Convolution Ball is based on Coffin's Convolution. For a list of his puzzle designs, click here.

Manufacturer
Pelikan. For their website (which you will probably require Google Translate), click here. Mr Puzzle of Australia also retails the Convolution Ball on behalf of Pelikan for A$135/-.

Type & Classification
Interlocking.

Dimensions
8.5cm (diameter) x 10.5cm (Height with stand)

Materials & Construction
The puzzle comes in different wood combinations which include exotic woods from the following; maple, walnut, birch, ash, apple, pear, cherry, oak, beech, plum, acacia, mahogany, ebony, wenge, walnut, paduak, rosewood, amaranth, bubinga, owango, jarah, meranti, and iroko. Pelikan is well known for their solid craftsmanship and the Ball is no exception; really excellent quality. Fit and finish is snug without being too tight and pieces move smoothly against each other. 

Overview
The Convolution Ball consist of seven interlocking pieces forming a perfect sphere. Each of the seven pieces comprise of different smaller pieces glued together. The object is firstly to disengage the pieces and thereafter, reassemble them. As the puzzle is very well made, all the joint lines are virtually invisible. I spent a fair amount of time figuring out how to get the first piece loose. It was all trial and error pushing at various points of the sphere to see what could or could not move.

Once the first piece slid out, the rest came out pretty naturally. Just to be sure, I rested my Convolution Ball in my camera dry box for a couple of days to ensure there was no lock-up.

Reassembly was just as challenging. The pieces are all of varying shapes and sizes. Everything now had to go back in reverse order. I had taken the liberty of arranging all the pieces nicely on my desk in the same order which they were disengaged, so that I would have a easier time assembling. This plus photo documentation, just to play it safe. 

The first three pieces came back together quite nicely and easily. However, I took much longer with the subsequent four. But since every piece had curved edges, this helped since I was trying to form back a sphere which can only take place if the pieces were in their general right orientation. Still I had to refer to my photos for assistance for one or two of the pieces.

One point to note about the Ball; be very carefully while you are handling it. All the pieces have been cut to very exacting tolerances and have sharp corners. One accidental drop would almost certainly twist off or blunt a corner and damage the puzzle for good. Worse still if you dropped the whole ball or it rolled off your table...

The Convolution Ball right with the Pelikan Egg

Difficulty Rating
Difficult overall. Finding that one first piece that moves is the key to "unlocking" the Ball. For those living in high humidity countries, find a way to "dehumidify" the Ball first before playing. Otherwise if the pieces are too tightly pressed together, you may end up not finding the first piece that is intended to move.

Summary

Aside from being a challenging interlocking puzzle, the Convolution Ball, with its multi-coloured exterior, is also really a handsome work of wood art that would stand out well amongst your multitude of similar/same looking burrs. A must-have indeed!

The Decoy

Name
The Decoy

Designer
Stewart Coffin (Design #187-A). To-date he has done 258 puzzle designs. For a list of his designs, click here.

Manufacturer
Eric Fuller. Website www.cubicdissection.com. 42 copies were made, each priced at US$59, but all have been sold out.

Type & Classification
3D packing puzzle (with a twist)

Dimensions
9.5 cm (Length) x 9.5 cm (Width) x 2.8 cm (Height)

Materials & Construction
The puzzle comes in a several wood combinations. The box frame is made of Sapele with a laser-cut acrylic transparent top. The bottom is made of either Spalted Wormy Holly or Canarywood. The six loose pieces are either Cocobolo or Ebony. Construction fit and finish is excellent and all the edges well cut. Tolerances between the pieces are tight; in fact a little too tight in the case of my copy. The high humidity in Singapore doesn't help either.


Overview
The Decoy was shipped to me in the solved state. So the object is to first remove all the six irregular-shaped individual pieces up through the similarly irregular-shaped cut-outs in the acrylic cover, and then to re-pack them back into the box frame. Looking at the shapes of the cut-outs on the acrylic cover, it is obvious the pieces can only come out after being orientated in a certain way. This is a packing puzzle with a slight difference here compared to the traditional "open-top" ones. And in some ways similar to The Rattle reviewed earlier in this blog.

Removal of the first three pieces was a cinch. After taking out the first one, it was just a simple matter of sliding the other two into position and removing them through the cut-out on the cover. Then comes the real challenge. So challenging indeed that I was stuck in the same position for a couple of days. Extraction of the 4th to 6th pieces by way of simple (linear) sliding would not do. I experimented with rotations. One piece could be turned in a certain direction while the other two wouldn't budge. I tried all sorts of ways but no avail.

I wondered if the tolerances were too tight so in went the puzzle into my camera dry box overnight. Eric crafts his puzzles at around 55-58% humidity, so I set my dry box to 42% humidity which I thought would do the trick. Alas, even after over 18 hours of de-humidification, there was no still improvement, so I assumed (wrongly here) that perhaps the puzzle was just too difficult for me. In situations like that, normally I would ask for help (after all, is there any point in trying to be a hero and frustrate myself indefinitely?). I emailed Eric and he promptly replied with a solution PDF.

Now here is the clincher...after studying the solution, I discovered that one of the pieces that I tried to rotate but could not, IS actually suppose to rotate....no wonder I was stuck for so many days. The problem was the tolerances were indeed too tight. I emailed Eric again about this and he gave me some information about compression shrinkage; basically it may take a while for wood to expand and then take just as long for the wood to shrink. Here's the excerpt from a post on a woodworking forum Eric had contributed to:-

"I've read several posts lately about wood movement and thought I would post this up in case anyone didn't know about it. It's near and dear to my heart because I work to stupidly tight tolerances when I make my puzzles, and my work gets shipped all over the world (i.e. different climates).

Compression shrinkage occurs when wood tries to expand but is constrained by its surroundings (i.e. locked into a puzzle or a drawer inside a frame). When that happens the wood absorbs moisture but cannot expand. The cells then take on an oval shape, and when the wood dries, it is permanently smaller then before it tried to expand. So, if you make something a little too tight when it's dry and you find it has locked up in humid weather, best thing to do is store it somewhere for a few dry/humid cycles. It might surprise you by working itself out via compression shrinkage!

As far as movement in general, I keep a close eye on humidity in my shop and adjust my work accordingly. If it's super humid I'll make the puzzle as tight as possible while still being assembled. If it's dry I'll make sure key joints or places where pieces will interact have a few extra thousandths to move around. I recommend putting a decent hygrometer in your shop and getting into the habit of checking it if you do any precision work. I bought mine at a cigar shop for $20 and calibrated it using a zip-loc bag and some damp salt in a soda pop cap."

In went the The Decoy into my camera dry box for a second time but this round, I kept it inside for a full week. Yes, when the seven days were up, compression shrinkage had taken place; this time when I tried to solve it, all the pieces slid and rotated smoothly and I got every piece out of the box.

Difficulty Rating
Tough! As quoted from Eric's site, Stewart Coffin says:

"The Decoy (#187-A) is by far the most difficult and my favourite. It is the only one that requires a slightly loose tray or rounding of corners to solve."

However, it is not so unduly difficult that you can't repeat solving it. As I mentioned above the first three pieces come out quite easily, its the next three that will pose the challenge. But you will only be working with three pieces. With some practice, the moves can be memorised and you will be familiar with the sequence after a while.

Summary

The Decoy starts off easy and gives you the impression that you are doing well. But along the way, the trickiness comes into play and here's where the difficulty begins. That's why its called the "Decoy". If you like packing puzzles (with a twist), this one is a real gem!