Impossible Dovetail Joint Puzzle




Introduction: Impossible Dovetail Joint Puzzle

A few years ago I saw a puzzle like this somewhere on the internet and I was really amazed. The only problem I had was my woodworking skills. Now I think I am ready to make one myself, although the handcrafted version of it is quite difficult. So why not make one using power tools for ease and precision? Fortunately the only power tools that I needed were the ones we all have in our workshops. No fancy stuff here!

Tools And Materials:

  • 4.5 x 4.5 x 30 cm oak wood
  • 4.5 x 4.5 x 30 cm iroko wood
  • 4.5 x 4.5 x 40 cm pine or other wood
  • 25 x 25 x 1.6 cm plywood
  • Router table
  • 13 mm dovetail router bit
  • Woodworking square
  • Sliding bevel
  • Pencil
  • Measure tape
  • Clamps
  • Jig saw
  • 10 mm drill bit
  • Countersink
  • Wood screws

Here is a video of the whole process, please check it out first:

Step 1: Making the Jig (Part A)

The basic concept behind the jig is that all the passes on the router should be made in 45 degrees angle. When we work with such a small work piece a jig is a must for ease and security!

So lets get started!

We will need a 25 x 25 cm piece of 16 mm thick plywood for the base, 2 pieces of lumber 4.5 x 4.5 x 4.5 cm and two more pieces of lumber 4.5 x 4.5 x 13.5 cm.

Take all your pieces of lumber and crew them in order to create a wooden square with a 4.5 x 4.5 cm hole in the center using some 7 cm wood screws. You can find the exact plan in the embedded PDF and also you can check how I made it by checking out the embedded video. Its really straight forward!

Step 2: Making the Jig (Part B)

Now take your 16 mm thick plywood and on top of it place the part of the jig that holds the work pieces (The one you have from the previous step) at 45 degrees angle. You can do this by using a sliding bevel set to 45 degrees.

Mark the inside of the square hole with a pencil.

Drill four holes, one on each corner of the square and use a jig saw to make the square hole.

Finally align the hole on the plywood and the hole on the upper part of the jig and secure them using some 5 cm wood screws. At this point you have to make sure that your screws are on a line. You do not want your router bit to hit any screw.

Step 3: Making the "Male" Part

Take your 4.5 x 4.5 cm piece of oak and divide each of its surfaces into three parts like in the picture 1 and 2, each part should be 1.5 cm. Now connect the markings like in the picture 3 again with your sliding bevel. You should have four parallel lines like it the picture 4.

Set your router bit 13 mm above the table and start routing.

Stay on the lines, remove the material from the two edges and in the middle and you should have something like this.

Step 4: Making the "Female" Part

The process is pretty much the same as the previous step. But this time instead of routing the two corners and the middle part of the wood, do the opposite!

In order to correctly mark your second work piece align it to the other one and transfer the markings from the dovetail corners.

Step 5: Finished!

Just slide the one part into the other and you are good to go!



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    22 Discussions


    1 year ago

    minimize tear-out by using a razor knife to trace the lines along the jig


    1 year ago

    Any thoughts on how to minimize tear-out?? After making one set (top and bottom) it looks like the entire area of the sled is sacrificed, so there's nothing left to keep tear-out on the next piece. Would making separate jigs for top and bottom prevent this?

    1 reply

    Hi, No you need only one jig. The only way to prevent tearout is to work the slowest you can on your router to give your router bit the time to remove as less material at every turn.

    This is what I call Thinkig out of the box. A nice mind is what you have.

    1 reply

    1 year ago

    Just a thought, if you make one side longer than the other, hollow out the center, insert a tube that is the same length as the longer (interior) section but can slide, and you have a stashbox that locks when turned over, allowing the tube to slide down.

    Great work!

    I think your Instructables are actually much better because you don't have a lot of fancy tools, since a lot more people can make them.

    1 reply

    Hi, thank you for your comment. Thats something I always think about before I start building something. It is not always easy though to use limited tools. Some operations require more fancy tools and I sometimes get too lazy to use hand tools instead. But I am working on it. I want everyone to be able to make what I make and that is the main reason I make instructables...

    This would make a very nice presentation box for wedding and engagement rings. Just make a cross wise cut in the dove tails and drill a hole in the upper part of the lower dove tail.

    1 reply

    Thats actually a really good idea. Never thought of it. Cool!!

    Very clever and great use of jigs, not sure if I'll make one but I know some folks who would like this as gift. Maybe time to go make some saw dust!

    1 reply

    1 year ago

    Really creative! I'm impressed with your hand made jigs and basic tool usage.
    Question for you... did you sacrifice a few pieces during the process? I always end up with a "test" piece or two when setting up my router table for height and width of joining pieces.
    PS: Very cool puzzle!!

    1 reply

    Hi, thank you for your question. Yes, actually this was my second jig and I had to sacrifice 3 more work pieces to get it right. Now with this jig and my homemade router table I can ever mass produce those puzzles.

    Thanks, go ahead its really easy. The only thing you need is to make sure that your jig is accurate.