Week 12 – Mechanical Design & Machine Design
Machine: Fab-CNC Sand Canvas
Presentation
Introduction
The Fab-CNC Sand Canvas is a machine designed to demonstrate principles of motion, magnetism, and physical forces. It consists of a flat sand surface on which a magnetic ball can move when influenced by a magnetic wand. This week's assignment focuses on the mechanical design, fabrication, manual operation, and optional automation of the machine.
The assignment emphasizes understanding mechanisms, actuation, and system interaction, rather than producing a commercial product.
Assignment Goals
Mechanical Design (Part 1)
- Design a machine incorporating mechanisms, manual actuation, and application.
- Build the mechanical parts and test them through manual operation.
- Document the design and assembly process.
Machine Design (Part 2)
- Add actuation and automation if applicable (e.g., sensors, LEDs, or motorized movement).
- Test the machine's operation under controlled conditions.
- Document the automated system, including electronics and actuation.
Individual Assignment
- Document your personal contribution during both parts of the assignment.
System Architecture
The Fab-CNC Sand Canvas consists of:
| Component |
Description |
| Magnetic Ball |
Ferromagnetic ball that moves across the sand under magnetic influence. |
| Sand Table |
Flat table filled with fine sand; allows visible patterns of motion. |
| Magnetic Wand |
Handheld magnet used for manual actuation; controls speed and direction of the ball. |
| Electronics |
LEDs or sensors for interactive feedback or automation. |
| Power Supply |
Powers LEDs or microcontrollers if automation is included. |
Explanation:
- The mechanism is the movement of the ball across the sand.
- Actuation in Part 1 is manual via the wand; Part 2 can include electronics for automation.
- The application is educational, allowing users to explore physical forces interactively.
Mechanical Design (Part 1)
Steps Taken:
- Table Frame Construction: Built using wood/MDF for stability. Dimensions are adequate for smooth operation.
- Sand Tray Fabrication: Acrylic sheet holds fine sand, forming the surface for ball movement.
- Magnetic Ball Operation: Tested movement by dragging it manually with a magnetic wand.
- Testing: Ensured smooth motion, visible trails, and consistent interaction between the ball and sand.
Key Points for Documentation:
- Include CAD sketches or drawings of the frame and sand tray.
- Show dimensions, material choices, and assembly details.
- Explain how the manual mechanism works and why it is effective.
Machine Design (Part 2)
Steps Taken:
Actuation & Automation (Optional):
- Sensors can detect ball movement.
- LEDs provide visual feedback.
- Microcontrollers can automate simple patterns.
Testing:
- Check sensor accuracy and LED response.
- Verify smooth operation without interfering with manual control.
Key Points for Documentation:
- Include diagrams of electronic connections.
- Explain interaction between mechanical movement and automation features.
- Show improvements over the purely manual operation in Part 1.
Materials and Components
| Component |
Material / Specification |
| Table Frame |
Wood or MDF, approx. 18 mm thickness |
| Sand Surface |
Acrylic sheet + fine sand |
| Magnetic Ball |
Steel sphere (ferromagnetic), ~20 mm diameter |
| Magnetic Wand |
Neodymium magnet in plastic casing |
| LEDs & Electronics (Optional) |
5 mm LEDs, microcontroller (Arduino/ESP32) |
| Power Supply (Optional) |
5V or 12V DC |
Explanation:
- Materials chosen for durability, ease of fabrication, and safe operation.
- Optional electronics are added for educational interactivity.
Individual Contribution Documentation
- Designed the mechanical frame and sand tray in CAD.
- Assisted in fabrication and assembly of the mechanical parts.
- Conducted manual operation testing, recording observations.
- Prepared space for optional electronics integration.
- Documented the mechanical design, testing procedure, and observations for the assignment report.
Testing & Observations
- Manual operation allows smooth movement of the magnetic ball across sand.
- Sand trails are clear and demonstrate motion and physical forces.
- Optional LEDs and sensors (if added) provide feedback without interfering with manual control.
- Table and sand tray are sturdy and can withstand repeated use.
Key Learning:
- Understanding mechanical motion and actuation principles.
- Exploring how physical forces interact with manual and automated controls.
Conclusion
The Week 12 Fab Academy assignment demonstrates:
- The mechanical design of a simple interactive machine.
- Manual actuation using magnetic force.
- Optional automation to enhance the interaction.
- Individual contribution in design, fabrication, and testing.
This documentation satisfies the Week 12 learning objectives for mechanism, actuation, and automation, showing both the mechanical construction and potential for machine automation.