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Activity 002: Temperature Profile Calibration & Filament Change Exercise

Activity ID: U1M2-ACT-002 Duration: 35 minutes Objective: Practice filament loading/unloading, material changeover, and temperature tower interpretation Group Size: 2-3 students per printer station Materials Cost: ~$3 (filament samples)

Overview

Students perform a complete filament changeover from one material to another, purging correctly to prevent contamination. They then print a temperature tower to identify the optimal nozzle temperature for the new material. This exercise builds practical proficiency in one of the most common daily printer operations.

Key Topics Covered

  • Filament unloading procedure (at correct temperature)
  • Filament loading procedure (preheat, cut tip, purge)
  • Material changeover protocol (purging between materials)
  • Temperature tower interpretation (identifying optimal print temperature)
  • Drive gear tension verification

Materials & Equipment Needed

  • FDM printer with loaded PLA filament — 1 per group
  • PETG filament spool (for changeover target) — 1 per group
  • Temperature tower G-code file (pre-sliced, PLA or PETG appropriate)
  • Side cutters / flush cutters for filament tip cutting
  • Magnifying glass or loupe (for examining drive gear marks on filament)
  • Printed temperature profile reference card

Instructions & Procedure

Phase 1: Unloading Current Material (8 min)

  1. Identify current loaded material (PLA) and note its printing temperature (200°C)
  2. Preheat nozzle to PLA temperature (200°C)
  3. Once at temperature, use printer's "Unload Filament" command
  4. Observe filament tip after removal — it should have a clean, tapered end
  5. If tip is blobbed or thick, the retraction was too slow or temperature too low
  6. Examine the filament surface near the drive gear area — note the tooth marks
  7. Store removed filament in sealed bag with desiccant

Phase 2: Loading New Material (12 min)

  1. Cut the PETG filament tip at a 45-degree angle using side cutters
  2. Preheat nozzle to PETG temperature (230°C) — must be at new material's temp
  3. Insert PETG filament into the guide tube and through the drive gear
  4. Use printer's "Load Filament" command or manually push until resistance is felt
  5. Continue extruding until the output changes from PLA (previous) to PETG (new)
    • Color change is the primary indicator (if different colors)
    • Texture change is secondary (PETG is slightly glossier than PLA when extruded)
  6. Extrude an additional 50mm after color change to ensure complete purge
  7. Verify: extrusion should be straight, consistent, and the correct color/material

Phase 3: Temperature Tower Print (15 min)

  1. Start the pre-sliced temperature tower print
  2. Observe each temperature section as it prints (tower changes temp every 5°C)
  3. For each section, evaluate:
    • Surface quality (smooth vs. rough)
    • Overhang performance (drooping vs. clean)
    • Bridging quality (sagging vs. straight)
    • Stringing between features (less = better)
  4. After print completes, physically examine each section
  5. Identify the optimal temperature: best balance of surface quality, overhangs, and minimal stringing

Discussion Points

  • "How did you know the purge was complete and the old material was fully flushed?"
  • "What temperature section of the tower looked best? Why?"
  • "What would happen if you loaded PETG at PLA temperature (200°C) instead of 230°C?"
  • "Look at the drive gear marks on the filament you removed — what do they tell you about tension?"

Expected Outcomes

  • Students successfully change material without contamination
  • Temperature tower clearly shows quality differences across temperature range
  • Students can identify optimal temperature within ±5°C for PETG
  • Understanding that different materials require different handling procedures

Assessment Rubric

Criterion Excellent (5) Proficient (3) Needs Improvement (1)
Unload Procedure Clean unload; correct temp; properly stored old filament Successful unload with minor procedural errors Failed unload or incorrect temperature
Load Procedure Clean 45° cut; correct temp; complete purge verified Successful load; purge may be incomplete Loading failure or contamination visible
Temperature Tower Analysis Correctly identifies optimal temp with reasoning; notes tradeoffs Identifies best section but limited analysis Cannot identify optimal temperature
Filament Examination Correctly reads drive gear marks; assesses tension quality Attempts examination with prompting Does not examine or cannot interpret marks
Material Handling Proper storage of removed material; clean workspace Adequate handling; minor storage issues Poor material handling; contamination risk

Safety Considerations

  • Nozzle reaches 230°C+ during PETG loading — maintain safe distance
  • Extruded purge material is hot — let it cool before handling
  • Side cutters are sharp — proper grip and supervision required
  • Filament under tension can spring back — hold securely during cutting

Time Breakdown - Briefing and material check (2 min) - Unloading PLA (8 min) - Loading PETG (12 min) - Temperature tower print and observation (10 min) - Analysis and discussion (3 min)

Deliverable: Completed temperature tower with annotated optimal temperature, and filled evaluation rubric

Learning Connection: This activity directly supports Slide 002-002 on filament loading and temperature profiles.

Last Updated: 2026-03-19