Wednesday, September 28, 2011

Triangular Dovetail Joint

Woodworkers have made trick dovetails for years, probably centuries.  I designed this trick joint because I hadn't seen any triangular dovetail joints.  Not surprisingly, it has been done before.

All three exterior sides show identical dovetail-like joints, which makes it look impossible to open.

But the pieces don't slide like a conventional dovetail.

The two pieces rotate until they gently let go of each other.

There's a hollow cavity inside, so it can be used as a puzzle box.  Not that anyone would be terribly puzzled--it looks odd, but it's easy for anyone to open once they pick it up.

This is a simple, traditional puzzle box so I've posted the STL files at Thingiverse for anyone who wants to play with it.

5 comments:

  1. That looks very nice! If you wanted it to be more difficult as a puzzle you could always give it a simple gravity pin lock. Then if the fit was tight enough it could be much more puzzling.

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  2. Ordinarily I don't like to add locks or other complications unless it's consistent with the premise of the puzzle. But while watching colleagues open this joint I noticed a subtle psychology which suggested a feature that would be counter-intuitive yet elegantly simple. It's worth building a successor to test that idea.

    In the meantime I've found other designers who've worked with similar three-sided dovetails.

    Buried in Rob's Puzzle Page is a picture of R.D. Rose's "Triple Dovetail Triangle" in which Rose took the same basic dovetail mechanism and added locking cylinders to it.

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  3. Gravity pins and the like should be banned from puzzles, IMHO. Those things drive me nuts.

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  4. Adding a slot half way round the dovetail, requiring the halves to be lifted apart, then rotated back on themselves to open would make for a nice puzzle with no pins. Almost a maze, but not quite.

    Given your familiarity with threads, putting a left handed thread onto the centre hollow would also make things interesting.

    Neither would be difficult puzzles, but they would slow people down. (especially a left handed thread)

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  5. I just found this post. I have been struggling with an old design that i want to renew. It involves puzzles, made of plastic, that can be made to change the final shape, but fit together as a cohesive, solid unit.
    Are you still working on such puzzle matters (?) since this post is a # of yrs old...

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