🎯 Lesson: Troubleshooting Common Issues
🧠 Focus: Diagnose and fix common 3D printing problems like bed adhesion failures, stringing, under-extrusion, layer shifting, and more.
✅ Lesson Summary
Even the best-prepared print jobs can run into issues. This lesson walks learners through identifying and resolving frequent FDM and resin printing problems, helping them recognize visual symptoms and apply quick, effective fixes.
🎓 Learning Objectives
By the end of this lesson, students will be able to:
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Identify visual signs of common 3D printing issues
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Understand the root causes behind failed prints
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Apply proper adjustments in hardware, slicer, or materials
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Maintain a troubleshooting mindset to improve over time
📘 Lesson Content
🟨 1. Poor Bed Adhesion
Symptoms:
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First layer not sticking
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Corners lifting (warping)
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Print detaches mid-print
Causes & Fixes:
| Cause | Solution |
|---|---|
| Bed not level | Re-level the bed or rerun auto-leveling |
| Incorrect Z-offset | Adjust Z-offset for proper nozzle height |
| Dirty bed surface | Clean bed with isopropyl alcohol |
| Too cold bed/nozzle | Raise bed temp (e.g., PLA: 60°C, ABS: 100°C) |
| Printing too fast | Lower first layer speed to 20–30 mm/s |
| Use adhesion aids | Add glue stick, painter’s tape, or PEI sheet |
🟧 2. Stringing / Oozing
Symptoms:
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Thin “hairs” or strands between parts
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Blob-like artifacts on retractions
Causes & Fixes:
| Cause | Solution |
|---|---|
| Retraction too low | Increase retraction distance/speed |
| Nozzle too hot | Lower nozzle temp in 5–10°C steps |
| Poor filament storage | Use dry filament; avoid moisture |
| Travel moves slow | Enable “Combing” and increase travel speed |
🟥 3. Under-Extrusion
Symptoms:
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Gaps between lines or layers
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Thin or missing walls
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Clicking sound from extruder
Causes & Fixes:
| Cause | Solution |
|---|---|
| Partially clogged nozzle | Clean nozzle or replace with a fresh one |
| Inaccurate E-steps | Recalibrate extruder (see Module 6.3) |
| Filament diameter mismatch | Check filament size (1.75mm vs 2.85mm) |
| Too low flow rate | Increase flow rate in slicer |
🟩 4. Over-Extrusion
Symptoms:
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Bulging layers
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Blobby corners
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Overly thick walls
Causes & Fixes:
| Cause | Solution |
|---|---|
| E-steps too high | Recalibrate extruder |
| Flow rate too high | Reduce flow % in slicer (e.g., Cura: 90–95%) |
| Incorrect filament diameter | Double-check slicer setting vs real diameter |
🟦 5. Layer Shifting
Symptoms:
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Sudden or repeated lateral shifts in the print
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Jagged walls or misaligned parts
Causes & Fixes:
| Cause | Solution |
|---|---|
| Loose belts or pulleys | Tighten X/Y belts and pulley grub screws |
| Printing too fast | Reduce print speed in slicer |
| Stepper motor overheating | Add cooling or lower stepper current |
| Obstructions on bed path | Check cable routing and smooth axis motion |
🟫 6. Nozzle Clogging
Symptoms:
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No filament extruding
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Clicking extruder
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Gaps or weak first layer
Causes & Fixes:
| Cause | Solution |
|---|---|
| Debris or burnt filament | Perform a cold pull or clean with needle |
| Low-quality filament | Use reputable filament brands |
| Incorrect temp settings | Check material’s recommended print range |
| Over-retraction | Reduce retraction distance/speed |
🟪 7. Resin Printing-Specific Issues
| Problem | Symptom | Solution |
|---|---|---|
| Layer Separation | Delaminated prints | Increase base layer exposure and bottom layers |
| Supports failing | Model falls off supports | Add more supports and increase support tip size |
| Suction forces | Warped or broken layers | Use hollow models with drain holes |
| Incomplete curing | Soft or tacky surface | Extend UV exposure or cure time |
🔁 8. How to Troubleshoot Systematically
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Observe the issue clearly (take photos)
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Identify the most likely root cause
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Apply ONE change at a time (e.g., change temp or retraction)
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Re-test and document the result
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Use calibration models (e.g., stringing test, cube, benchy) to compare
🛠️ Tip: Keep a print log to track slicer settings, materials, and problems.
🧠 Summary
3D printing isn’t just plug-and-play—it’s part printing, part diagnosing. Troubleshooting builds your technical intuition. Most common problems have clear visual symptoms and proven fixes once you learn what to look for.
🧩 With time and patience, every failed print becomes a valuable lesson.
📂 Optional Activities
Assignment:
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Choose a print that failed or had a quality issue
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Identify and document the problem (photos encouraged)
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Describe what setting or hardware adjustment you used to fix it
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Re-print and share the before/after results