Professor Mark Csele

Witch and Boiling Cauldron

In 2006, the display combined the witch from 2003 and the coffin from 2005. Upon triggering the sensor (visible in the lower left of the photo) the coffin opened, and following a short time delay, the witch turned to greet the trick-or-treaters! Turning the witch was accomplished by mounting her on a piece of wood with a large bolt as a pivot. A pneumatic cylinder actuates the mount.

In 2004, the display featured a boiling cauldron ‘stirred’ by a witch. A hand, operated by a pneumatic cylinder, comes out of the cauldron when triggered. The display was improved two years later to feature the witch on a turntable allowing it to move quickly to face oncoming trick-and-treaters.

Mechanical Details

For the witch and cauldron display, the cauldron was made from paper-mache (I used strips of paper soaked in drywall compound) and is 22 inches in diameter. It features a moving hand which comes out of the cauldron when kids cross the laser-sensor (details below) by pneumatic power. The cauldron also features a moving stirring-spoon driven by a windshield-wiper motor inside – when attached to the witch it appears that the witch is stirring the brew. Pumped full of fog from a fog machine underneath, the addition of a red spotlight and a load of plastic bones on top gives the illusion of some sinister brew of bones!