3 Piece Burr Puzzle

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!

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)

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

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.

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.

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.

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.

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:

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

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.

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

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

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.

Wood vs. print.

Thanks for viewing.

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.

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!