Activity 002: Support Structure Design Challenge¶
Activity ID: U1M3-ACT-002 Duration: 45 minutes Objective: Students will evaluate and optimize support structures for a complex geometry, then print the part to validate their slicer configuration. Group Size: 2-3 students per station Materials Cost: ~$2-3 (PLA filament for small test print)
Overview¶
Students receive a challenging STL model featuring multiple overhang angles (30°, 45°, 60°, 75°, and a full 90° horizontal bridge). They must orient the model to minimize support material, configure support settings, and then print the part to evaluate real-world results against their slicer predictions.
Materials & Equipment Needed¶
- Computer with slicer software (Cura or PrusaSlicer)
- FDM 3D printer (pre-calibrated and leveled)
- PLA filament (any color)
- Provided STL file: "ProtoLab_Overhang_Test_v1.stl"
- Digital calipers
- Flush cutters or pliers for support removal
- Safety glasses
- Comparison worksheet
Instructions & Procedure¶
Phase 1: Model Analysis (10 min) 1. Import the overhang test model into your slicer 2. Identify all overhang features by rotating the model in the 3D viewport 3. Document each overhang angle and its location on your worksheet 4. Try at least THREE different model orientations and record the support material estimate for each: - Orientation A: Default (as imported) - Orientation B: Rotated 90° on X-axis - Orientation C: Student's choice optimized orientation 5. Select the orientation that minimizes support volume while maintaining print quality
Phase 2: Support Configuration (10 min) 6. Using your chosen orientation, configure support settings: - Set overhang threshold to 45° initially - Enable support interface layers (2-3 layers at 80% density) - Set support Z-distance to 0.20mm (1 layer gap at 0.20mm layer height) - Set support X/Y distance to 0.7mm 7. Switch to tree supports and compare: record material estimate and examine contact points 8. Select your preferred support type and document your reasoning 9. Add a brim (5mm width) for bed adhesion 10. Verify in layer preview that all overhangs are adequately supported
Phase 3: Print and Evaluate (20 min) 11. Export G-code and start the print (estimated 15-25 minutes depending on orientation) 12. Monitor the first 3-4 layers to confirm bed adhesion and first layer quality 13. While the print runs, predict on your worksheet: - Which overhang angle will show the worst quality? - Will the bridge section sag or succeed? - How difficult will support removal be (easy/moderate/difficult)? 14. Once the print completes, allow 2-3 minutes cooling before removing from bed
Phase 4: Post-Print Analysis (5 min) 15. Carefully remove support structures using flush cutters 16. Measure surface roughness qualitatively: rate each overhang section 1-5 (1=rough, 5=smooth) 17. Compare predicted vs. actual results on your worksheet 18. Photograph the finished part showing all overhang surfaces
Discussion Points¶
- How did model orientation affect the total support volume? What percentage reduction did the best orientation achieve?
- At what overhang angle did print quality noticeably degrade?
- Did tree supports or linear supports produce better surface quality at the contact points?
- How could the original model be redesigned to reduce or eliminate the need for supports?
Expected Outcomes¶
- Students should find that optimal orientation reduces support material by 30-60%
- Overhangs at 60° and beyond should show visible quality degradation
- Bridge sections under 40mm should succeed with adequate cooling
- Support removal should leave minimal scarring with properly configured interface layers
Assessment Rubric¶
| Criterion | Excellent (5) | Proficient (3) | Needs Improvement (1) |
|---|---|---|---|
| Orientation Optimization | Tested 3+ orientations, selected optimal with clear reasoning | Tested orientations but selection reasoning unclear | Only tried default orientation |
| Support Configuration | All settings properly configured with documented rationale | Settings configured but missing documentation | Incorrect or default settings used |
| Print Quality | Clean print with minimal support scarring, all features intact | Acceptable print with some defects | Failed print or significant quality issues |
| Analysis Accuracy | Predictions closely matched results with insightful observations | Some predictions correct, basic observations | Predictions inaccurate, no meaningful analysis |
Safety Considerations¶
- Wear safety glasses when removing support structures — small pieces can snap and fly
- Do not touch the print bed or nozzle during or immediately after printing (bed: 50-60°C, nozzle: 200°C+)
- Use flush cutters carefully — cut away from your body and keep fingers clear of the cutting edge
- Dispose of support material waste in the designated recycling bin
Last Updated: 2026-03-19