Double Dovetail Puzzle with a twist

by damienb, published

Double Dovetail Puzzle with a twist by damienb Mar 20, 2013

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The double dovetail puzzle is a classical brain teaser that defy intuition at first... How the 2 pieces where assembled with these two dovetails? I've added a twist inside to raise the disassembly difficulty.

You can see the puzzle in action in this video:


This is my first brain teaser (and most complex assembly so far). You need 2 marbles (1/2inches diameter, STL provided) for the internal mechanism. I've added a 1mm clearance in the marble slots and the dovetails.

I finaly printed this one in PLA, 2 shells 20% infill, and got my first experience with warping on a non-heated bed... Only the external faces were warped, and the dovetail part was pretty flat, so I just had to do a little bit of sanding to make it slide nicely!

When doing the right actions there is a maximum of 4 steps to open the puzzle, but there are traps and dead-ends that will play tricks with anyone who's tempting to solve it. It's not an difficult puzzle probably 3/5 but should be challenging enough. You can check the solution here: http://wp.me/p3gI7M-2M at the end of the post.

To assemble the puzzle:
1/ push the 2 marbles in the holes (1 per piece)
2/ hold each marble/piece between the thumb and forefinger
3/ completly slide the the pieces starting with the corners with the arrows
4/ try to disassemble it!

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Where did you buy the single ball bearing? I am having difficulty finding online stores that sell just the metal ball.

Good day David,
I had to buy a whole lot of them actually :) If you (or anyone else) send me a private message with your email I'm sure we can arrange a shipment of a couple of ball bearing.
I've used them for my other puzzles (double key & padawan).

Printed this morning PLA 20% infill and it worked first time with out any sanding a little warped on one end which can be fixed by lowering the speed to 80% , A great puzzle which I have been meaning to make out of wood for the last 20 years ! A great twist to unlocking the puzzle aswell.

Dec 30, 2014 - Modified Dec 30, 2014
damienb - in reply to pilbara

Thanks for your comment, I'm glad you liked it!

Cool! I want to print one!

I've corrected the puzzle (V2) to:

  • enlarge it so it's not possible to lose the marbles in any situations
  • add 2 arrows to ease the assembly

The final size with 15.5mm marbles is a bit large for my taste (11711737mm) so I've generated a version for 10mm marbles (787826mm), you can find them for cheap as steel ball bearings in online stores.