Activity 002: Print Defect Diagnosis Challenge

Activity ID: U1M4-ACT-002 Duration: 45 minutes Objective: Students will identify, diagnose, and propose corrective actions for intentionally-introduced FDM print defects using a systematic troubleshooting methodology. Group Size: 2-3 students per station Materials Cost: ~$5-8 (pre-printed defect samples, reusable across sections)

Overview

Students rotate through a set of 6 stations, each containing a pre-printed FDM part with an intentionally-introduced defect. At each station, they examine the sample, identify the defect, determine the root cause, and prescribe a corrective action. This activity develops diagnostic skills critical for independent makerspace operation.

Materials & Equipment Needed

• 6 pre-printed defect samples (prepared by instructor in advance):
• Sample A: Severe stringing between two towers
• Sample B: Warped corners on a flat rectangular part
• Sample C: Layer shift at mid-height
• Sample D: Under-extrusion (thin walls, gaps in infill)
• Sample E: Pillowing on top surface
• Sample F: Elephant's foot on first layers
• Magnifying glass or loupe (one per station)
• Digital calipers (one per station)
• Defect Reference Guide (laminated, at each station)
• Diagnostic worksheet (one per student)
• Timer or clock visible to all students

Instructions & Procedure

Phase 1: Introduction and Methodology Review (5 min) 1. Review the 5-step troubleshooting framework: Observe → Categorize → Hypothesize → Test → Verify 2. Each station has a defective print sample — your job is a forensic analyst 3. You will spend 5 minutes at each station (instructor will call rotations) 4. Do NOT discuss your findings with other groups during rotations

Phase 2: Station Rotations (30 min, 5 min per station)

At each station, complete the following on your worksheet:

1. Observe (1 min): Examine the part from all angles. Use calipers to measure any dimensional anomalies. Use the magnifying glass to inspect surface details.
2. Identify (1 min): Name the specific defect. Write a 1-sentence description of what you see.
3. Root Cause (1 min): List the most likely root cause and one alternative possible cause.
4. Corrective Action (1 min): Specify the exact slicer setting, hardware adjustment, or process change that would fix this defect. Include specific values where possible (e.g., "increase retraction from 1mm to 2mm").
5. Severity Rating (30 sec): Rate the defect:
6. Cosmetic: Part is functional but visually flawed
7. Structural: Part integrity is compromised
8. Critical: Part has completely failed and cannot be used
9. Rotate to the next station when called

Phase 3: Group Discussion and Scoring (10 min) 11. Instructor reveals the correct defect identification, root cause, and intended fix for each sample 12. Students self-score their worksheets: - Correct defect identification: 2 points per station - Correct root cause: 2 points per station - Correct/reasonable corrective action: 2 points per station - Correct severity rating: 1 point per station - Maximum: 42 points (7 per station × 6 stations) 13. Discuss any surprising findings or disagreements as a group 14. For any station where >50% of students got the wrong answer, the instructor provides a detailed walkthrough

Discussion Points

• Which defects were easiest to identify? Which were hardest? Why?
• Could any of the defective parts still be used for their intended purpose? Where do you draw the line?
• How would you build a troubleshooting checklist for a new makerspace operator?
• What information would a print log need to capture to help diagnose these issues retroactively?

Expected Outcomes

• Students should correctly identify at least 4 of 6 defects
• Students should demonstrate understanding that each defect has specific, addressable causes
• Students should be able to prescribe actionable fixes with specific setting values
• Group discussion should reveal that experienced troubleshooters use pattern recognition, not random guessing

Assessment Rubric

Criterion	Excellent (5)	Proficient (3)	Needs Improvement (1)
Defect Identification	5-6 correct identifications	3-4 correct identifications	0-2 correct identifications
Root Cause Analysis	Correct root cause for 5+ defects with plausible alternatives	Correct root cause for 3-4 defects	Correct root cause for 0-2 defects
Corrective Actions	Specific, actionable fixes with values for 5+ defects	General fixes for 3-4 defects	Vague or incorrect fixes
Severity Assessment	Correct severity for all 6 samples	Correct severity for 4-5 samples	Correct severity for 0-3 samples

Safety Considerations

• Handle pre-printed samples carefully — some may have sharp edges from failed prints or support removal
• Do not attempt to flex or break the samples to test structural integrity (they are reused across sections)
• Calipers have sharp measuring tips — close them when not actively measuring
• Keep workstations tidy to prevent samples from being confused between stations

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Last Updated: 2026-03-19