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How to Build a Pulley for a Marble Machine

People who build complex marble machines invoke the memory of Rube Goldberg. Goldberg worked as a cartoonist who became famous for his drawings of incredibly complex machines designed to perform simple tasks. Webster's New World Dictionary even lists his name to describe " a comically involved, complicated invention, laboriously contrived to perform a simple operation." A functioning marble machine requires multiple moving parts. One of those parts, a pulley, can be constructed from common household items.

Things You'll Need

Wire hanger
Wire cutters
Empty thread spool
Twine or string

Instructions

- 1
  Use the wire cutters to cut the straight length of wire off the bottom of the hanger. Cut that piece in half.
- 2
  Pass the wire piece through the center of the spool. Bend the ends of the wire downward so that the spool stays in place. Make sure the spool can spin freely.
- 3
  Wrap a length of string or twine around the spool, leaving tails on both ends. One end of the tail should attach to a hook or basket that will catch the marble or other object and pull it downward. Attach the other end to the opject that needs to be lifted. The length of the twine depends on the size of the marble machine. Experiment with different lengths to get the torque you desire.
- 4
  Insert the other half of the wire hanger piece into the pulley. Use it to mount the pulley inside the marble machine by securing the ends to a wall or hanging it across an open space. After mounting make sure the spool can rotate freely; if not, readjust.

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