Disentanglement Puzzle

This is my take on a classic rope and ring disentanglement puzzle. The goal is to separate the ring (the light colored one) from the puzzle strings. As with most disentanglement puzzles, the solution isn't intuitive. Can you figure it out from the pictures? If not, refer to the video for the solution.

I think this puzzle was pretty easy to make since it only requires basic woodworking skills. If you are not up to it, similar versions can be purchased online.

Tools:

• Table Saw
• Drill Press
• 2 3/8" & 1 1/4" Hole Saws
• 1 1/4", 1/2" & 3/8" Forstner Bits
• 1/2" Reverse Counterbore Bit
• 3/8" Drill Bit
• Router (optional)
• Sander
• Scissors
• Lighter
• Ruler
• Pencil

Materials:

• Wood: 5"x5" x 1" Thick
• Wood: 5"x5" x 1.25" Thick
• Wood Dowel: 1.25" Diameter x 6" Long
• Wood Dowel: 1/2" Diameter x 1" Long
• Paracord: 4'
• Wood Glue
• Paint/Stain/Oil (optional)

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

Cut a 1" thick (or thicker) piece of wood to 5" x 5". Use a 1.25" Forstner Bit to make the hole in the center. Drill the string holes as shown. I used a 1/2" Forstner Bit for the counterbore. The chamfers on edge are optional - just me playing with the router :).

Cut a 1.25" diameter dowel to 6" long.

You will be building to this drawing. Each step is detailed below.

Use a 2 3/8" hole saw (or larger) to cut the disc. Make two of these.

As with the base, this step is optional. I used a router to cut the chamfer.

I pushed a 1/4" dowel into the hole and then inserted the part into a drill press. While running, I used sandpaper to smooth the edges.

Use a 1 1/2" hole saw to cut the inner diameter.

Unfortunately, I didn't take pictures when making these holes but I did learn something at this step. The first (3/16") hole on the outside was straightforward. Since I needed the paracord to be flush on the internal diameter, I had to come up with a way to add a counterbore to the inside of the cylinder. My machinist buddy had an interesting tool called a "Reverse Counterbore" that worked perfectly. It has a shaft that you push through hole and then you add the reverse bit. Using a drill, you pull the bit towards the outer diameter.

Below is a similar example of the technique. Note that this is a spot face and doesn't require the addition of the reverse bit but the concept is similar.

The cap is similar to the spacer. I used a 1 1/4" Forstner bit for the hole.

This part was built like the spacers except with thinner wood (arbitrary) and no hole for the rope.

This is a picture of the materials I used for this project. Ignore the small wood beads - I scrapped that idea.

Glue the post into the base.

Cut the paracord to 16" length. Feed one end of the cord through the hole. Tie a knot at one end of the cord and pull it into counterbore. I used a lighter to smooth out the knot.

Drop the spacers over the post.

Cut the paracord to 30" and feed it through the base. This is similar to threading the cord for the spacers.

This is optional but I used 1/2" dowels to fill the holes on the bottom side of the stand.

Finally, glue the cap to the top of the post. Note that my cap has a 1/4" hole in the center from the hole saw. Filling it with a 1/4" diameter dowel is optional.

I used danish oil on all the pieces for the finish.

I'm happy how it turn out. Thanks for viewing!