Apparently Impossible Cube

by richgain, published

Apparently Impossible Cube by richgain May 17, 2012

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Iwahiro's Apparently Impossible Cube is an example of a coordinate motion puzzle - all the pieces have to be moved into place at the same time.
You can find the original at http://puzzlewillbeplayed.com/444/IwahiroAIC/1/


Print of 2 of each piece at a fine resolution. I used a layer height of 0.2 mm from a 0.3 mm nozzle.
The pieces have been designed with a small bevel on the edges and a slight offset to give a snug fit (but this may vary on your printer).
You can watch a video of the puzzle in action (including the solution, so don't watch it if you want to try and solve it yourself) at http://www.youtube.com/watch?v=1J8fA3t3Y78

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Thank you for building in the 0.2mm clearances between the faces! Using thermally calibrated filament (this system: https://www.thingiverse.com/thing:1037301) these puzzles go together straight off the printer. Once the stair stepping on the 45 degree slopes wear in it goes together very easily but stays snug. Great puzzle. Thank you for replicating it and sharing.

3D Printer Calibration Piece
by JP1

The question is: Can I use high temperatures to solve it :D
Super puzzle. Brillant mind who designed it!

Made one in PLA. My printer has E-step calibrated, and edge extrusion calibrated with this: https://www.thingiverse.com/thing:1622868
But when I read eveything here, I went to 96% extrusion, and mine is a little too lose.

Dropping it, and it will go apart. Pulling at two opposite small rectangles at some sides will move it apar.

So to all that has issues, please calibate e-steps and then calibrate edge extrusion with the above model.Here I need to underextrude most filaments by 3-15% (PETG most). Maybe because my nozzle is a few percent too large ? The roll of PETG I have which needs huge underextrusion is a brand I will not buy again, it gives me other trouble as well.

Fast edge over/under extrusion test

You can also print the left parts with 0.01 more! That it will make it pretty tight but still movable

Like others, it's a VERY tight fit. I was able to get it together, but it won't come apart without mechanical intervention. I'm planning on printing another, and will clean-up the parts a bit before assembling...

If you’re planning to print again, please try turning your extrusion multiplier down 5-10%. Many printers push out too much plastic and this severely impacts on the precision necessary for making interlocking puzzles. You can’t see it because it’s only 1 or 2 tenths of a millimetre but it will jam up a puzzle.

I couldn't find that setting on my Makerbot software. What I did eventually is spray the parts with a bit of WD-40. That seems to have helped a good deal--that plus assembling and disassembling the puzzle a few times.

I think my grandkids are going to enjoy this! Thanks for providing it.

mine are to tite to fit together will scalinig it up work or is ther one with bigger tolorances

Yes, scaling up the size will also increase the size of the gap between the pieces.
However, the usual cause of the parts being too tight to fit together is 'over-extrusion' of plastic. If your printer is over-extruding, the only place the excess can go is outwards and this can easily fill the 0.1 mm gap between parts.
Try lowering the extrusion multiplier in your slicer, perhaps to 95% or even 90% and have another try.
Adjacent lines of filament should only just touch each other in a solid filled layer. It is a good idea to decrease the extrusion multiplier until you start to see gaps between the lines and then increase it just a little bit to make them touch again.

does non comerciaal mean i cant sell the file or that i cant sell one i 3d printed to my freinds

Yes, I’m afraid non-commercial means you cannot profit from selling printed copies of this design. I did not invent the puzzle, so I cannot give you permission. Puzzle designers are entitled to receive a royalty payment (usually 5-10 % of price paid) when copies of their designs are sold.

ok thanks i did not want to do anything illegal

These turned out great. Like some of the others, mine was a bit too snug at first. However, after putting it together and taking it apart a few times, it has worn down into a perfect fit. I think I had a tiny bit of Z wobble that contributed to the tightness. Thanks for a great puzzle!

I printed one. It turned out very well. I managed to put the 4 pieces together, which was a little tricky, but it's even trickier to get them apart.

There is a knack. The video might help.

I didn't watch the video, but after a little more fiddling, I got it apart. After two or three times of putting it together and taking it apart, you see there is an easiest way to do it. Good puzzle to pass around at work. Oh, and thanks for the link to the original, I had visited that site many years ago, and had completely forgotten it. Now that I have a 3D printer, I'll probably make more puzzles from that site.

First attempt is very tight. I eventually got them to fit together but I don't think I can get them apart. Too much friction. Might try another set

Sorry to hear that. Maybe try turning down your extrusion multiplier by 5 - 10% and have another go.

Great thing man! At first try the fit was very very tight, I hardly got it open with my hands, but after assembling and opening 2-3 times, it worked great. Still, I did some experiments with the tolerances. The most interesting thing I found is that printing the pieces oriented on one of the smaller sides (with the thinnest point on the bed, so there's even less cleaning, plus the "tower" is stronger as it's no longer perpendicular to the layers) the result is much looser. In fact, it's too lose if you'd like the cube to never shake loose on its own, on my printer. But maybe it's a solution for those with too-tight prints or very tall layer heights...

With the Makerbot at my work it prints and assembles great. With my new Printrbot at home, however, the pieces are too tight: they go together with effort, but require pliers and great force to get apart again. I'm wondering if different printers (and/or settings) could cause this, and whether an adjustment with my software could compensate.

Puzzles like this require printing to very accurate tolerances. What slicer are you using? Do you have a set of digital calipers that you can measure expected and actual dimensions with? Slightly reducing your extrusion multiplier might help if you are over-extruding. Printing a larger version will increase the effective tolerance gap and give a looser fit.

Thanks for your help. I am using Cura. I don't (yet) have digital calipers, but it sounds like a good idea. I'll try reducing my extrusion multiplier. Printing larger versions only worked slightly better than the smaller ones (which I couldn't assemble as easily).

Great, fits in the first print, however, I recently changed to a new bowden system and my retract isn't great yet, so this was a good testpiece to see if my retract would be right.

Going to raise it and retry it later :) Nice puzzle!

Worked 1st try with PLA on our MakerGear M2, but a really tight fit. Too tight.

This is really good! I am so pleased with this thing for two reasons. First of all it is a great puzzle (not that I am any sort of expert when it comes to puzzles!).  I give it to people fully assembled and ask them to take it apart before putting it back together - how easy is that? (Not very!). Secondly, after much tweaking with my RepRapPro Huxley and its 0.3mm nozzle, I got this printed and working without very much filing at all. (Must admit that in order to satisfy myself that I had tuned my printer properly, I took a peek at the YouTube video - excuse is that there was no point twiddling with these four pieces if the printer hadn't done its job properly .... am I excused? 

Very nice! Absolutely excused.

Had some trouble getting figuring it out......even more frustration getting it apart. Well worth the effort though. Liked it so much I printed two - scaled the second one up 1.5. Took about 30-35 minutes to print each scaled up piece on a TOM with default settings.

The set screw on the driver gear of the stepstruder let go half way through one of the pieces - that's the half finished one in the background. 3 minutes left in the print - GRRRrrrr :)

This is a great puzzle to give to friends/family!

This is awesome! I printed all the pieces, but apparently my printer isn't calibrated very well and I'm having a hell of a time fitting them together (even with sanding). I don't suppose by chance this you created this in OpenSCAD or something similar so I fiddle with settings?

Still awesome though, I will be vigilant and keep sanding until it works (:

Great puzzle took me a while and I resisted looking at the youtube video :)

Printed at .27 layer heigh / .4 nozzle on a Replicator fits together without any sanding.

Great little puzzle. Everyone in the house says thanks for the challenge/frustration..

Sorry that I asked before searching; pretty noobish of me :-(

I found a very nice video demonstration about acetone finishing by andrewupandabout here: http://youtu.be/r3nJbU9OInkhttp://youtu.be/r3nJbU9OInk.

I am curious about your method of finishing with acetone. How do you apply it; with a cloth or in a "bath"? Can you describe the result? Will it be like chemical deburring of cast metal parts?

I love so it was super fun to just print this out and try and figure out how it goes together with no idea where to start.

Awesome, nice job. Took me a fair while to puzzle it out, but I got it together.

Great fun!

I printed this on my ToM with 0.5mm nozzle. No problem but it is a bit of a tight fit. It will be a great challenge for my friends.

My first prototype was a little tight as well. Nothing that a bit of sandpaper couldn't fix though ;)

this is fun, needed a tiny bit of tidying up with a sharp knife (0.5mm nozzle) but works great :)

I've "Liked it" Now I'm printing it right now... Results to follow =-X