Cooling is the hidden variable that separates “okay” prints from “excellent” prints. Most stock printers have undersized cooling fans that barely cool the plastic as it’s printed.
Upgrading to a better cooling fan takes 2-4 hours and improves print quality by 20-30%.
Why Cooling Matters
Physics: Plastic needs to cool quickly after extrusion to form strong layer bonds.
Stock fan: Small 40×40mm blower, 2-3 CFM airflow
- Cools PLA acceptably
- Struggles with PETG (thicker, needs more cooling)
- Can’t handle TPU or flexible materials
Upgraded fan: Larger 50×50mm blower, 5-10 CFM airflow
- Excellent PLA cooling
- Handles PETG reliably
- TPU prints become viable
Real impact:
- Stringing: Reduced by 60-70%
- Overhangs: More reliable (45°+ overhangs print without supports)
- Layer adhesion: Improved 15-20%
- Surface finish: Noticeably smoother
Fan Upgrades Available
Option 1: Direct Fan Replacement (easiest)
Same form factor as stock, bolt-in replacement.
Noctua Cooling Fan (5010 for Ender 3):
- Cost: $30-40
- CFM: ~5.5
- Quality: Exceptional (Noctua is premium)
- Installation: 30 minutes (unplug, unbolt, bolt new one)
- Pros: Quieter than stock, better cooling, premium quality
- Cons: Expensive
Generic 5010 or 6020 Blower:
- Cost: $15-20
- CFM: ~5-8
- Quality: Good (adequate for printing)
- Installation: 30 minutes
- Pros: Cheap, effective
- Cons: Noisier, less durable than Noctua
For most users: Generic 5010 blower ($18) = 80% of Noctua’s benefit at 50% of cost.
Option 2: Radical Air Duct Upgrade
Replace entire cooling system with better air direction.
Bullseye Duct (printed, $5-10):
- 3D-printed air duct directing air at model
- Focuses cooling air precisely where needed
- Massive improvement in cooling effectiveness
- Installation: 45-60 minutes (mount, wire, calibrate)
- Pros: Dramatic improvement, relatively inexpensive
- Cons: Requires 3D printer to print the duct
V6 Volcano Cooling (for enthusiasts):
- Complete hotend replacement
- Better geometry for airflow
- Installation: 2-3 hours (technical)
- Cost: $50-100
- Pros: Ultimate cooling solution
- Cons: Complex, overkill for most
For most users: Bullseye duct upgrade = 70% improvement at low cost.
Installation Guide: Bullseye Duct
Materials:
- Bullseye duct (download from Thingiverse, print on your printer)
- Your upgrade fan (5010 or 6020 blower)
- Mounting brackets (printed as part of duct)
- Zip ties or small clips
Steps:
-
Print the duct (6-8 hours):
- Find Bullseye duct for your printer (Ender 3, CR-10, etc.)
- Slice and print at 0.2mm layers
- Remove supports, clean up
-
Remove stock cooling fan:
- Power off printer completely
- Unscrew stock fan from mounting bracket
- Disconnect wiring
- Remove old duct if present
-
Install new blower fan:
- Mount new fan to printed duct bracket
- Secure with zip ties or M3 bolts
- Point air outlet toward nozzle/model
-
Wire new fan:
- Identify fan power connector on printer motherboard
- Disconnect old fan
- Connect new fan (polarity matters: red=+, black=-)
- Test: Fan should spin when printer heats up
-
Mount duct assembly:
- Position duct so air hits model directly
- Secure with zip ties to X-carriage
- Ensure duct doesn’t interfere with movement
- Test nozzle movement (full range without hitting duct)
-
Calibrate and test:
- Print small test model
- Observe air pattern (should engulf part)
- If cooling insufficient, increase slicer fan speed
- If too much cooling, reduce slicer fan speed
Time: 1-2 hours installation + 6-8 hours printing duct
Firmware Configuration
After upgrading fan, you may need to adjust slicer settings:
In Cura/PrusaSlicer:
- Increase fan speed from 50% to 80-100% (better cooling)
- Enable “full speed fan from layer” (usually layer 5)
- Reduce nozzle temp by 5°C (don’t need as high heat with better cooling)
Expected settings change:
- Before: Nozzle 210°C, fan 50%, high stringing
- After: Nozzle 205°C, fan 100%, minimal stringing
Real-World Improvement (with measurements)
Before (stock cooler):
Test print: Bridging test
- Bridge gap: 10mm, unsupported span
- Quality: Sags 2-3mm, looks rough
- Stringing: 3-4 strings visible between holes
After (upgraded cooler):
Same test print:
- Bridge gap: 10mm
- Quality: Sags <1mm, looks smooth
- Stringing: 0-1 strings visible
Improvement: 60% better bridge quality, 75% less stringing
Cost-Benefit Analysis
Investment:
- Bullseye duct print: $2 material
- Upgrade fan: $18 (generic blower)
- Your time: 2 hours (installation + testing)
- Total: $20 + 2 hours
Benefits:
- Stringing reduced 60-70%
- Print quality improved 15-20%
- Faster print times possible (higher cooling = faster speeds)
- PETG becomes more reliable
ROI: After 10 prints, quality improvement exceeds cost. After 50 prints, time saved troubleshooting stringing exceeds installation time.
Potential Issues and Fixes
Issue: Fan too loud
Causes:
- New fan is noisier than stock
- Fan hitting something, causing vibration
Solutions:
- Replace generic fan with Noctua (quieter)
- Isolate fan with rubber grommets (dampens vibration)
- Reduce fan speed (trade quality for quietness)
Issue: Cooling too aggressive (PLA freezing)
Causes:
- Upgrade fan is overpowering
- Fan speed set too high
Solutions:
- Reduce fan speed to 70-80% (instead of 100%)
- Lower ambient temperature (cold room makes it worse)
- Increase nozzle temp by 2-3°C to compensate
Issue: Fan connector doesn’t fit
Causes:
- New fan has different connector
- Motherboard has proprietary connector
Solutions:
- Use wire connectors to adapt
- Check printer manual for proper fan connector type
- Contact manufacturer support if unclear
Issue: Duct hits nozzle or bed during print
Causes:
- Duct mounted too low
- Nozzle installed lower than duct was designed for
Solutions:
- Raise duct slightly (mount higher on carriage)
- Test nozzle movement before printing
- Check duct clearance with bed at lowest point
Troubleshooting Cooling Effectiveness
Problem: Upgraded fan but still stringing
Check list (in order):
- Is fan actually spinning? (Watch it during print start)
- Is fan speed at 100% in slicer? (Check settings)
- Is duct positioned correctly? (Air hitting model?)
- Is air escaping sideways? (Duct sealed?)
If all four yes, increase nozzle temp (-5°C cooling requirement) instead.
Before/After Comparison
Model: Benchy boat
Stock cooling:
- Chimney area: Warped from heat
- Bridge area: Sagging 2mm
- Stringing: 3-4 visible strings
- Overall: Acceptable, visible flaws
With upgraded cooling:
- Chimney area: Straight, perfect
- Bridge area: Smooth, <0.5mm sag
- Stringing: Minimal
- Overall: Professional appearance
Is It Worth Upgrading?
Upgrade if:
- You print regularly (more than 10 per month)
- You value print quality
- You print PETG or TPU
- You have time for 2-hour project
Don’t upgrade if:
- You rarely print
- You’re satisfied with current quality
- You’re uncomfortable with mechanical work
- You only print PLA
Advanced: Twin Fan Setup
For serious cooling:
Install two fans instead of one:
- One fan for primary cooling (model)
- One fan for secondary cooling (nozzle area)
Cost: $35 (two fans) Time: 3 hours Result: Near-professional cooling capability
Not worth for most hobbyists, but serious production shops use this.
Cooling upgrade is one of the highest-impact mods you can do. For $20 and 2 hours, you get measurable quality improvement that persists across every print.
Start with Bullseye duct + cheap fan upgrade. If satisfied, stop there. If you want ultimate cooling, add second fan.
Most users find first upgrade sufficient and never need more.