3 Piece Burr Puzzle

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About: I like to design and build random things.

I made a 12 piece burr puzzle shown here a while back and my friends/family enjoyed playing with it. This smaller/simpler version has only 3 pieces and is similar in construction to Sythe101's shown here. In addition to the wood version shown, I've created STL and STP files for a version that can be printed. As it is close to Christmas, I decided this would make a nice ornament as well!

Step 1: Tools/Materials

Tools:

  • Table Saw
  • Router and Router Table or Table Saw
  • Ruler
  • Pencil
  • Sand paper
  • File

Materials:

  • Wood: 2.25" x .75" x 12" (12" allows for extra pieces)
  • Paint/Stain (optional)

Step 2: Drawings

You will be building to this drawing. The parts are color coded for reference.

Step 3: Part 1

Start by cutting a piece of wood to 2.25" wide by .75" thick. For the notches, you could use a table saw with a dado blade or multiple passes with a standard blade. I chose to use my router table for this step. I passed a large piece of wood (~10" long) through and then went back and cut the pieces to length (.75"). I repeated the process on the second cut. However, since the pieces where smaller, I used scrap wood on both sides of the workpiece for stability.

You only need two of these. I made extras to allow for trial and error when fitting together.

Step 4: Part 2

This piece is similar to Part 1 except the center section is rounded. I started with one of the Part 1 pieces and rounded the corners. This was tedious and wasn't very nice looking in the end. I eventually broke the piece when trying to assemble the puzzle. The second version is shown here. For this one, I cut the blocks to .75" cubes and then glued a .375" diameter dowel between the blocks. This looks much nicer but I'm not sure how long it would hold up with kids.

Step 5: Part 3

Part 3 is similar to the other parts except that notches are cut into both sides. Again, I used the router table for these cuts.

Step 6: Finished Parts

Once built, you might need to do sanding to work out the fit. You want the puzzle together snugly. Once sanded, I finished the parts with Danish Oil.

Step 7: Solution

The solution isn't intuitive. However, the round piece (Part 2) should give you a hint about the solution.

  • Step 1: Insert Part 2 into Part 3 as shown. Note rotation.
  • Step 2: Insert Part 1 into the slot on Part 3 as shown
  • Step 3: Rotate Part 2 to center the puzzle

Solution Video:

Step 8: Assembled Pictures

I'm actually happy with how it turned out. With more care, I think I could have made the fit a little tighter.

Step 9: 3D Print

The parts are essentially the same except that I added rounded corners the outer edges. They serve no purpose except to make it feel nicer in your hand.

Step 10: 3D Print Files

Along with the STL files, I've included STP files for those that would like to modify the design.

Part3.stp

Part2.stp

Part1.stp

Step 11: 3D Print Part Pictures

I'm not sure I would have picked this color but that's what was loaded on the printer at the time.

Step 12: 3D Print - Assembled

I was very satisfied with how it printed. It's a balancing act between interference and being too loose. My print didn't require it but you might need to do a slight amount of sanding to adjust the fit. Below is a video of it being solved.

Step 13: Puzzle Comparison

Wood vs. print.

Thanks for viewing.

Step 14: Tis the Season

Ok, last pictures. I drilled a hole in one of the pieces to make a Christmas ornament. Maybe I will forget how to solve it by next Christmas.

Step 15: Final Thoughts

If made from wood, the puzzle takes time and requires tight dimensions for a proper fit. If I ever decide to build another, I think I will scale it up to double the size. Besides being an easier build, I think it would be more durable. The 3D print worked fine as expected. The one change I would make is to print in 3 different colors.

As always, thanks for viewing!

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