Physical Computing Series
Zoetrope & Praxinoscope
An exploration of persistence of vision, 3D printing, and iterative design.
Project Overview
This project was a two-part physical computing journey. It began as a challenge to create a simple interactive object using a servo motor, a 3D printed component, and an external button—resulting in a classic Zoetrope.
Through iteration and feedback, the project evolved. The second phase focused on refining the visibility and mechanics, ultimately converting the shutter-based Zoetrope into a mirror-based Praxinoscope.
Brainstorming
As part of the design process, it is important to quickly explore as many ideas as possible. Deviations often lead to a richer final product.
I utilized a combination of traditional sketching on paper and collaborative digital mind-mapping on Miro. My initial concept involved a 3D printed character jumping into a portal and re-emerging as a 2D drawing in an infinite loop.
Planning & Development
My initial concept involved a 3D printed character jumping into a portal and re-emerging as a 2D drawing in an infinite loop.
To help figure out the action of the character in the limited "frames" alloted, I animated the subject in 2D using Toon Boom Harmony.
Design & Modeling
I quickly discovered my "portal" idea was too complex for the frame rate of a Zoetrope. I scaled the action down to a single 3D printed character.
I animated the subject in Autodesk Maya, carefully considering the 360-degree silhouette so the animation would be legible from any angle.
Prototyping & Wiring
The physical build involved preparing models in ZBrush and Cura for 3D printing. The core mechanism relied on a servo motor controlled by a microcontroller.
I experimented with different input methods, including a potentiometer to control speed and even a sound sensor, though I ultimately focused on stability for the final presentation.
Design Challenges
Zoetrope Feedback: The shutters (slits) of the Zoetrope obstructed the view of the animation too much. Additionally, the push-button activation was physically uncomfortable to hold down for extended periods.
Scope Creep: I attempted to add an animatronic servo controlled by a potentiometer for the second iteration but had to abandon it to focus on perfecting the core animation experience.
The Solution: Praxinoscope
To solve the visibility issue, I converted the Zoetrope into a Praxinoscope. This device replaces the slits with a central ring of mirrors.
- Mirrors: I used 12 mirrors to match the 12 frames of animation 1:1. This reflects the image to the viewer, creating a brighter, clearer persistence of vision.
- Interaction: I swapped the momentary push button for a robust toggle switch, improving user comfort.
- Fabrication: I designed a new base in Carbide Create and cut it using a CNC machine for a cleaner finish.
Final Design
The final result is a functional Praxinoscope that smoothly animates the 3D printed figure. The mirrors successfully stabilize the image, and the toggle switch allows for hands-free viewing.
Lessons Learned
Occam's Razor
I initially designed a very ornate base in Maya, but realized "Occam's razor is always in effect." A simpler, cleaner outcome was more achievable and aesthetically pleasing.
Persistence of Vision
The number of mirrors must correspond exactly 1:1 with the animation frames. Even a slight misalignment breaks the illusion of motion.