I recently completed a jigsaw puzzle (too cute kittens perched upon a tree looking very cute and innocent) only to realise their wide eyed smirks were not due to some previous feline frolic - but because they knew all along that there were three pieces missing to the jigsaw!

I propose a system when buying a secondhand jigsaw puzzle of confirmation that it is in fact a full set. As far as I can tell, the proprietors of said goods do in certain cases label the box (two pieces missing or as is) - having either done the jigsaw themselves or used some sort of system that I am proposing.

My first suggestion would be to go on weight - a fairly precise scale would need to be involved, but could effectively pinpoint how many were actually in the box in contrast to how many each set should weigh before leaving the factory. A similar device could be used for actually counting all pieces, quite like a bank money/note counting machine - but could be somewhat expensive to secondhand shops.

Secondly, a system of length. If each piece is stacked on top of each other, it should measure X distance.

The only other possibilty i can think of outside of individual GPS devices in each piece, is for the manufacturer to provide two of the same puzzle in each box - one with a different coloured back so as to distinguish which is the back up set.
-- benfrost, Dec 12 2001

Bastards Incorporated http://www.halfbake...rporated#1008112883
Wonder how *that* happened? [phoenix, Dec 12 2001]

Coinstar http://www.coinstar.com
As advertised in my anno below. [bristolz, Dec 13 2001]

For [ravenswood] http://www.talkorig...s/homs/mleakey.html
Mary Leakey, fossil hunter [angel, Dec 14 2001]

The iButton keeps track of inventory http://www.ibutton....tions/tracking.html
such as the different pieces of a jigsaw puzzle. [neelandan, Dec 14 2001]

JigZone http://www.jigzone.com/
A fully-computerised jigsaw. A bunch of them, actually, variable difficulties. [StarChaser, Dec 15 2001]

Perhaps you could buy a missing-piece(s) insurance policy that paid you for your time spent building the defective puzzle.

Maybe each puzzle piece could have a little inductance element in it, like those security card entry systems, where each piece would respond to an electronic scan. A hash total could be computed for all the pieces that responded and compared against what hash the puzzle manufacturer states the puzzle should have. This system may have an adverse effect on puzzle prices.

Another way to do it is to only buy used puzzles that are assembled.
-- bristolz, Dec 12 2001


I'd be worried about going on weight, because pieces would gradually become lighter with time, as fluids in the glue and inks evaporate, and as wear and tear takes its toll.

If you were really serious about knowing if all the pieces were there, the company could number each piece (in a random order around the puzzle), and you could simply check that every number was there. This has an advantage over counting the pieces in that is works even if you don't know how many pieces there are (just look for gaps in the numbering), and it protects against stray pieces from other puzzles getting in the box. Perhaps a computer could sort and check the numbers for you.
-- pottedstu, Dec 12 2001


pot, I love the idea that the pieces are numbered in a random way and then you check that each piece is there i.e. you set them all out in an ordinal fashion say in lines starting with no 1 on top left hand side and 1000 on bottom right hand side. (to see if they are all there) in other words you are doing the puzzle on the reverse side... love it mate...
-- po, Dec 12 2001


It would actually probably be easier to get a "counting" machine. Many exist already, but probably not for puzzles. Run it through the cheaply-made but still-working "puzzle piece counter" and you'll know how many pieces are in the puzzle as compared to the box.
-- jimithing, Dec 13 2001


Coinstar for puzzles! (link)
-- bristolz, Dec 13 2001


We need to refine UnaBubba's approach. If you put five copies of each piece in the box, then the odds are you'll be able to get at least one completed puzzle out of it, even if a few are missing.
-- pottedstu, Dec 13 2001


<only vaguely relevant> Mary Leakey could do jigsaw puzzles with the pieces picture-side down.</only vaguely relevant>
-- angel, Dec 13 2001


Bristolz, since Coinstar keeps ~10% for itself, that would make the problem even worse! <grin>
-- StarChaser, Dec 13 2001


Discard one piece. What remains is confirmed to be not a full set. O(1) complexity.
-- prometheus, Dec 14 2001


StarChaser: well the PuzzleStar would have no commission because they would adjust that out in the conversion from coins to puzzle pieces, see?
-- bristolz, Dec 14 2001


Yeah, but it wasn't FUNNY like that.
-- StarChaser, Dec 14 2001


Incidentally, do many people do jigsaws? I can't really imagine benfrost doing jigsaws, least of all of kittens, but I know lots of people who have unexpected hobbies.

Maybe the answer's a fully-computerised jigsaw on a desk screen (of the sort that someone suggested before).
-- pottedstu, Dec 14 2001


Embed chips (link) with rf transceivers in each piece, use a rf coupler and PC to verify that none are missing (from information stored in each chip) and you have a high tech solution to a low tech problem.

At least make those ibutton people happy.
-- neelandan, Dec 14 2001


Spread the pieces out on a desk, photograph them with a high resolution digital camera, and you might be able to have a computer work out if they all fit together. (This would save ravenswood having to pay someone to assemble it to check there are no pieces missing.)
-- pottedstu, Dec 14 2001


There are CAD applications that work out the most efficient way to lay out (eg) clothing patterns. Such a thing would probably suffice.
-- angel, Dec 14 2001


Am I the only one to find the image of benfrost patiently whiling away the hours by doing jigsaws of fluffy kittens somewhat disturbing? Exactly which institution is it that you're in, ben?

Meanwhile, back on topic. Clearly this is a complex technical issue, so perhaps it's better to avoid it altogether and have an 'Emergency Puzzle Completion Kit' containing pieces of every shape and colour, so that you can always find the right bit to finish the puzzle with.
-- DrBob, Dec 14 2001


My mate Mr X (the inglybinglydinglys will know him as my companion on the great Croydon expedition), lives in Eastbourne. He would say that you were lucky to find anything that exciting there, Peter.
-- DrBob, Dec 14 2001



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