Floating Pooh: A Halloween Engineering Challenge

Every year, my girlfriend's family puts on an over-the-top, Disney-themed Halloween event. It's a huge production, with intricate decorations, special effects, and hundreds of visitors—last year, we had over 800 people come by. After spending the first three years helping with photos and candy, I wanted to contribute more.

This year, I set out to create an animate floating Winnie the Pooh—a practical effect where Pooh, holding onto a balloon, would float up and down as if caught in the wind. It sounded simple in theory: a stepper motor, some pulleys, fishing, and an arduino to control the movement. As I quickly learned, though, "simple in theory" is rarely simple in practice

The Iteration Process: Trial, Error, and a Bit of Soldering

I knew I'd need to prototype extensively, but I didn't realize just how many small issues would pile up along the way.

• The Motor Problem - I started with a small DC motor, only to realize it didn't have the torque to lift Pooh reliably. I upgraded to a higher-torque, stepper motor, but that also required me to upgrade to a 12V power supply, which introduced new wiring challenges.
• Current Draw - When I switched to the new power supply, I didn't think about the extra heat generated by using the thin wires from my little Arduino starter kit. Wires overheated, the insulationed started melting, and I had a fire hazard on my hands.
• The Motor Controllers - You only need one motor controller for the circuit, and yet I bought a 5 pack, thinking that'd be more than enough. I underestimated my ability to screw things up. Between short circuiting and blowing them up, running without the current limiter and melting them, and plain soldering fully working boards to broken circuits and not being able to remove them properly, I ended up needing 6 boards in total.

Finally, through extensive trial and error, I finally had a reliable system which stayed cool in testing. Except for one last thing I didn't test.

Six hours into Halloween night, the motor controller started overheating and throttling itself, turning off to protect the chip. This caused the stepper to unspool and drop Pooh a few feet before catching himself. So I ran over, hiding behind a wooden painting of Tigger, and started fanning the heatsink.

Also, when you spool a fishing line up and down for hours, it starts to fray. So after 8 hours, it snapped. Lucky for me, we were right about to take it down anyways.

Lesson Learned

Never underestimate the ability for things to go wrong.