Wooden Lock Puzzle




Introduction: Wooden Lock Puzzle

About: I like to design and build random things.

This simple wooden lock puzzle will challenge your mind. You are given three wooden blocks. The goal is to assemble them in the cross pattern shown.

I started this as an "I made it" project but since I changed the size and building techniques, I thought I would include detailed build instructions. The original versions are shown here and here. Also, I think this was pretty easy to build. However, it you are not up to it, similar version can be purchased from online.

This video gives away the solution. Skip it and don't go past Step 10 if you would like to try to figure it out from the drawings.

Step 1: Tools/Materials


    • Table Saw
    • Router
    • 3/8" Roundover Router Bit
    • 3/4" Straight Router Bit
    • Band Saw
    • Pencil
    • Calipers
    • Sander


    • 1x4 by 20" Long
    • Paint/Stain (optional)

    Step 2: Drawings

    This is the top level drawing. Detailed part drawings are included for the three pieces.

    Step 3: Blocks

    I used a scrap piece of 1x4 cedar for the blocks. I started by cutting it down to the desired width (2.25"). Note that I cut a board long enough to make six pieces (vs. the required three). Knowing myself, the extras come in handy when I mess up, which is quite common.

    Step 4: Rounded Edges

    I used a 3/8" roundover bit and routed the board from both sides. This was done for both ends.

    Step 5: Cut Blocks

    I set the table saw to 6" and sliced the board down. Edit - This is the wrong way to make cuts. Although easy, you should not use the table saw rip fence as a guide for cutting wood to length. The wood can become trapped between the fence and the saw blade and pose a kickback hazard.

    Step 6: Block 1

    With the router centered on the workpiece, I cut the groove with a 3/4" straight router bit to the dimensions shown.

    Step 7: Block 2

    Cut the same groove for the all three parts. The only difference is the notch cut in the center. I used a band saw for this cut.

    Step 8: Block 3

    Same as before except I used the 3/4" router to make the additional notch.

    Step 9: Finished Parts

    Step 10: Solved Puzzle

    Can you figure out how it went together?

    Step 11: Solution


    1. Start with Block 1 (green piece)
    2. Slide Block 2 (purple piece) through slot
    3. Slide Block 3 (cyan piece) down and through notch
    4. Slide Block 2 towards the center to complete the puzzle

    Step 12: Pictures

    I'm pretty happy with how it turned out. Thanks for viewing.

    Pocket-Sized Contest

    Participated in the
    Pocket-Sized Contest

    Trash to Treasure

    Participated in the
    Trash to Treasure

    Epilog Challenge 9

    Participated in the
    Epilog Challenge 9

    2 People Made This Project!


    • For the Home Contest

      For the Home Contest
    • Make It Bridge

      Make It Bridge
    • Big and Small Contest

      Big and Small Contest



    Question 3 years ago on Step 5

    In the router step, I see that from one direction you use the router fence to cenenter the work, do you just free hand to a mark for the long direction or are you able to set up stops?


    Answer 3 years ago

    I just used freehand for the distances. Stops would be better if I was making more than one.


    4 years ago on Step 5

    Your picture also shows a rip blade being used to make cross cuts. Using a crosscut or combination blade will provide much better results. As you mentioned, it would be better to use a stop block on your miter gauge or at the very least, clamp a block onto the rip fence so that the block is 6 inches from the blade and set the block well ahead of the blade.