Snap-Fit Clip - Teacher Template (Extension Project)

Briefing

Students design a snap-fit connector that joins two 3D-printed parts without fasteners. This project emphasizes tolerance engineering, material properties, and mechanical design validation.

Key Learning: Tolerance engineering; snap-fit mechanics; non-destructive assembly testing.

Real-world Connection: Snap-fits are ubiquitous in consumer products. Designing them requires understanding material stress, geometry precision, and repeated-use durability.

Constraints

• Snap-fit must connect two printed parts without external fasteners
• Design must be parametric (tolerance variables clearly labeled)
• Assembly must be testable (connection strength, reusability)
• Design must account for material properties (PLA creep, flex limits)

Functional Requirements

• Parts snap together securely without over-constraint
• Connection withstands intended use without permanent deformation
• Snap mechanism is reusable (at least 5+ assembly cycles)
• Design demonstrates understanding of tolerance and material behavior

Deliverables

• .scad with parametric snap-fit module
• Completed documentation template
• Assembly testing log (snap strength, cycle durability)
• Tolerance analysis documentation
• Reflection on mechanical design trade-offs

Rubric

Category 1: Problem & Solution (0-3)

Snap-fit works reliably; parts assemble and disassemble as designed.

Category 2: Design & Code Quality (0-3)

Code shows tolerance thinking. Design is mechanically sound.

Category 3: Documentation (0-3)

Assembly testing documented. Tolerance rationale explained.

Assessment Notes

• Strong submissions: Show evidence of tolerance testing, multiple assembly cycles documented, and reflection on material limits
• Reinforce: Snap-fit design principles; tolerancing for manufacturability
• Extension: Material property analysis; cost-benefit comparisons