Lei Feng Fab Academy 2025

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Week 17: Wildcard Week ​

Course Overview ​

Wildcard Week is a unique component of the Fab Academy curriculum that allows students to explore digital fabrication technologies not covered in previous courses. This week is characterized by students' freedom to choose which digital fabrication techniques they want to learn, departing from the pattern of previous weeks where all students learned the same skills. The chosen technique must meet the following conditions: it must involve a digital design and manufacturing process, be documented in detail for others to replicate, and must be a skill not covered in other assignments. The flexibility of this week enables students to utilize special equipment available in their lab or introduce new manufacturing capabilities.

The course is divided into two parts: the first half introduces various optional digital fabrication technologies, while the second half delves deeply into composite materials technology (which was previously a separate course week). When choosing projects, students need to balance the allocation of time and attention, as the final project deadline is approaching.

Check out the Wildcard Week inventory for more information.

Detailed Course Content Introduction ​

Part One: Wildcard Week Optional Technologies Overview ​

1. Multi-axis Machining ​

  • Three-axis Machining: Although previous courses introduced 2.5D machining (XY plane movement plus Z-axis stepping), full three-axis synchronous machining (simultaneous control of XYZ axes) is an optional new skill
  • Four-axis/Five-axis Machining: If conditions permit, more advanced multi-axis machining can be learned, where the workbench can rotate (four-axis), or a combination of workbench rotation and tool head pivoting (five-axis)
  • Specific Example: 5-axis Machining Center

2. Special Cutting Technologies ​

3. Welding ​

  • Welding alone does not meet the requirements for digital manufacturing, but can be combined with other digital tools
  • Parts can be designed by computer, cut using CNC tools, and then connected using MIG, TIG, or spot welding techniques
  • Technical Reference: Welding Technology Fundamentals

4. Special Molding and Casting Techniques ​

5. Folding Techniques ​

6. Robotics Technology ​

7. Electronic Manufacturing ​

8. Special Applications for Embedded Programming ​

  • Embedded AI: Implementing machine learning on microcontrollers using platforms like TensorFlow Lite, TinyML, ESP-DL, or Edge Impulse - Embedded AI Resources
  • Machine Vision: Using OpenCV or AI cameras for facial recognition, tracking moving objects, etc. - Image Processing in Input Devices

9. Food Manufacturing ​

10. Materials Science ​

11. Biotechnology ​

12. Textile Technologies ​

Composite Materials Composition ​

  1. Fiber Material Selection:
    • Chopped Fibers: Easy to use but lower performance, as they cannot effectively transfer forces
    • Filaments: Can be used for wrapping
    • Tape: Can be laid up
    • Fabrics: Most commonly used in Fab Labs, can be fiberglass, carbon fiber, or natural fibers (cotton, silk, bamboo, wood, flax, jute)
  2. Matrix Material Selection:
    • Epoxy Resin: Commonly used but requires safety precautions
    • Phenolic Resin: Used for FR1 circuit boards, etc.
    • Cement: Used for construction
    • Natural Resins: More environmentally friendly plant-based resins
    • Supplier Resources: Entropy Resins (Bio-based Epoxy), McMaster-Carr, West System
  3. Lamination Materials:

Composite Materials Design Principles ​

  • Bending Stiffness Principle: Outer layer fibers bear tensile forces, inner layers contribute less to the structure
  • Core Material Usage: Using honeycomb structures or cardboard as core material in the middle section to reduce weight
  • Sandwich Structure: Combination of bottom composite layer, core material, and top composite layer
  • Digital Design Methods: Using computers to design the shape and performance of composite structures - Digital Composite Materials Research

Composite Materials Manufacturing Process ​

  1. Mold Making:
  2. Layup Process:
    • Wet Layup: Layering fabrics and applying resin progressively - Wet Layup Example
    • Prepreg: Fabrics pre-impregnated with resin
    • RTM (Resin Transfer Molding): Injecting resin under pressure
    • Material Ratio Control: Testing fiber-to-resin ratios under different compression conditions - Composite Coupon Testing
  3. Compression Methods:
    • Vacuum Bag Compression: Using vacuum bags, breather layers, and release layers, compressed by atmospheric pressure - Detailed Guide to Vacuum Bag Techniques
    • Press Molding: Using mechanical clamping with two-sided molds to squeeze out excess resin
    • Water Bag Pressure: A simple method using garbage bags filled with water to provide weight - Vacuum Storage Bag Example
  4. Post-processing:
    • Surface Treatment: Final composite materials often require varnish or other post-processing for a smooth, glossy surface

Safety Considerations ​

  • Fiber Hazards: Carbon fiber and fiberglass produce short fibers when cut, drilled, or sanded, which can cause lung disease if inhaled
  • Protective Measures: Full protective equipment is needed when working with carbon fiber (respiratory, eye, and skin protection)
  • Resin Safety: Common epoxy resins are highly volatile, requiring good ventilation; low-volatility bio-based resins (like Entropy Resins) are recommended
  • Thermal Reaction: Large composite materials may generate significant heat during curing, requiring cooling measures

Recommendations and Best Practices ​

  • For Beginners: Avoid fiberglass and carbon fiber; use natural fibers and low-volatility resins
  • Material Ratio: Beginners might use a 50:50 fiber-to-resin ratio, while advanced composites can reach 90% fiber and 10% resin
  • Test First: Make small samples ("coupons") to test the process before making large components - Composite Coupons Collection
  • Combine with Other Skills: Composite material techniques combined with "Making Large Items" and "Molding and Casting" week skills can greatly expand a lab's manufacturing capabilities

Assignment Requirements ​

The assignment for this week requires students to define and complete their own project:

  1. Design and Manufacture: Create an item using a digital manufacturing process (including computer-aided design and manufacturing) - Reference Example Project
  2. Uniqueness Requirement: The chosen technology must not be covered in other assignments
  3. Documentation:
    • Clearly state which requirements your assignment meets
    • Document all necessary steps in detail so others can replicate your project
    • Explain your chosen technology and process
  4. Digital Process: The project must involve computer design and manufacturing, not just manual skills
  5. Time Management: Balance this new project with work on the final project, allocating time wisely

Official Fab Academy Resources ​