“Hooped” - A Kinetic Sculpture

This kinetic sculpture is an advanced print. You’ll need good knowledge of optimal print settings for your machine and a willingness to do some post-print processing.

If you get it right, the spinning hoops whiz around the bobbing balls with clearances of only a fraction of a millimeter. If you get it wrong, you’re hooped.

See the machine in motion here: https://youtu.be/wQxTIqx9OIY
See here for assembly video: https://youtu.be/wfsd5Y0_sJE
The design was featured by magician "Palomares Magic": https://youtu.be/QKLskepYiOc

Printing

Print six each of “Followers (80mm),” “Hemisphere with Hole” and “Hemisphere No Hole.”

Print one of each of the remaining files. Carefully remove any burrs or imperfections in the print especially on surfaces that move against one another.

The critical bit of cleanup here is that the “followers” slide perfectly through the guides in the “lid.” If there is either too much friction or too much slack the machine will jam.

Lubricate any moving surfaces with Vaseline prior to assembly.

Assembly

1. Assemble the crank. Place the “grip pin” through the hole in the “crank” and secure it in place with the “grip.” The grip should be able to spin freely on the crank.

2. Insert the “cam” into the “base.”

3. Place the “drive bevel” inside the base against the hole in the side wall, ensuring that the teeth are properly meshed with the larger bevel gear. Attach the crank assembly from the outside.

4. The next step is the trickiest. Insert the ball end of one of the “followers” into the cam. You will notice that there are two flat face on the ball. These flat faces permit the ball to be pushed into the cam slot in one direction only, and then to be locked in place with a 90-degree turn. Hold the lid slightly above the top of the base and push the square end through. Do this with all six followers. It’s tricky but doable!

5. Once all the followers are in place, seat the “lid” onto the “base” and secure in place with the “lid screw top.”

6. The next step is to secure the “hoop” apparatus on to the visible end of the “cam”. Notice that there are identical ridges on the ends of both. These ridges need to line up in order for the “hoop” apparatus to be timed properly with the cam-driven balls. They also allow for the “compression collar” to hold them precisely and securely together. Slide the “compression collar” over one of the ends. Insert the male hex of the “hoops” into the female hex of the cam and twist the “compression collar” in place.

7. Glue the six “Hemisphere with Hole” and “Hemisphere No Hole” pieces together so that you have six balls with square holes. Place the holes on the square ends of the followers.

8. You may need to do some filing and shaping if the hoops and balls to not properly align.

You are ready to go!