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Weak or Spongy Infill

Easy to Fix

The internal infill structure is weak, spongy, or poorly formed, weakening the entire print.

What Does It Look Like?

Print feels weak or flexible
Infill pattern poorly formed
Gaps in infill structure
Print crushes easily

Common Causes

Infill speed too fast
Under-extrusion
Infill percentage too low
Wrong infill pattern

Solutions (Try in Order)

Start with Priority 1 solutions. Make one change at a time and test between changes.

1
Slow Down Infill Speed

Allows proper material deposition

Infill speed: 60-80mm/s (or match perimeter speed)
1
Increase Infill Percentage

More material creates stronger structure

Use 20-30% for functional parts
2
Increase Extrusion for Infill

Compensate for under-extrusion

Infill extrusion multiplier: 102-105%
2
Change Infill Pattern

Some patterns are stronger

Try Grid, Triangle, or Gyroid for strength
3
Increase Infill Overlap

Better bonding with perimeters

Infill/perimeter overlap: 25-30%
Prevention Tips
  • Save working settings for each filament type
  • Perform regular printer maintenance
  • Keep filament dry and stored properly
  • Re-level bed before important prints
  • Start with manufacturer-recommended settings
At a Glance
Severity: MEDIUM
Difficulty: Easy
Category: Extrusion Issues
Solutions: 5
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