PF Print Fixes

Failure guide

Under Extrusion Fix

The printer is laying down too little plastic: thin walls, gaps, weak infill, or clicking. Prove the nozzle and extruder can feed before raising flow.

Independent third-party notes. Verify firmware, heater, electrical, and vendor-specific work against official documentation for your exact printer.

Start here

The hotend or extruder cannot feed the requested plastic volume consistently.

The printer is laying down too little plastic: thin walls, gaps, weak infill, or clicking. Prove the nozzle and extruder can feed before raising flow.

Check first
Unload, cut the filament tip, reload, and extrude into free air while watching for a straight consistent strand.
Change only this
Clear the path or lower speed before increasing flow percentage.
Verify with
A single-wall cube with consistent walls and no extruder clicking.
Time
5 min setup
Risk
Medium
Needs purchase
Maybe, if the nozzle or drive gear is worn or blocked.
Under Extrusion Fix visual diagnosis

Visual diagnosis

Match the visible pattern before changing settings.

Looks like this
  • Lines look skinny or broken instead of touching.
  • Top surfaces have gaps that never close.
  • The extruder clicks, grinds, or leaves dust on the filament.
Not this
  • The printer is showing a firmware, heater, or electrical safety warning.
  • You are copying numbers from a different printer as final values.
  • Several slicer values have already been changed without a repeatable test.
Look for Thin walls, missing lines, clicking, or a weak free-air strand.
First test Extrude slowly into free air at normal print temperature.
Do not do Do not raise flow to hide a clog or slipping drive gear.

Before / after

Compare one small test, not a whole print.

Use the same small test before and after the change so the comparison means something.

Before: broken or skinny extrusion lines
Before: broken or skinny extrusion lines
After: continuous single-wall lines
After: continuous single-wall lines
Illustration by Print Fixes.
Single-wall flow box STL preview
Preview diagram, not a printed result.

Download a quick test

Single-wall flow box

Verify whether the nozzle and extruder can feed consistently before changing flow.

File
STL
Typical time
10-18 min
Dimensions
35 x 35 x 25 mm.
Footprint
35 x 35 mm
Height
25 mm
Download STL
What it testsVerify whether the nozzle and extruder can feed consistently before changing flow.
When to use itUse when the same symptom repeats and you need a small proof print.
Keep unchanged
  • Material
  • Nozzle
  • Bed surface
  • All slicer values except the one variable being tested
Expected good resultThe symptom improves on the same test without creating a new failure.
Failure result meaningIf the result does not change, stop tuning that variable and switch branch.
Slicer notes
  • Use one wall and no infill if your slicer supports it.
  • Keep temperature fixed while checking flow consistency.
  • Measure only after the filament path is mechanically clear.

Still not matching?

Jump to the next likely diagnosis

3D Print Stringing Fix Fix 3D print stringing by checking temperature, moisture, and retraction in the right order. Start with one small test before changing the whole slicer profile. 3D Print Warping Fix Fix 3D print warping by checking plate cleanliness, first-layer squish, bed temperature, cooling, and enclosure needs in the right order. Poor First Layer Fix Fix poor first layers by checking plate cleanliness, Z offset, bed mesh, probe setup, and first-layer speed with one simple patch test.

Problem Pattern

Under extrusion shows as missing material, not just ugly texture. Free-air extrusion may come out thin, curl hard, stop, or trigger clicking if the path is restricted.

Likely Causes

  • Partial nozzle clog, heat creep, or debris restricts flow.
  • Extruder gear is dirty, slipping, tensioned poorly, or grinding the filament.
  • Print speed or volumetric flow is too high for the hotend and material.
  • Nozzle temperature is too low for the material, color, or nozzle size.

Print Context

Applies to
Bowden, direct drive, PLA, PETG, TPU, hardened and brass nozzles
Best first move
Confirm free-air extrusion before adjusting slicer flow.
Do not start with
Large flow increases that hide a clog or slipping extruder.

Recommended Checks

0/4 done
Start with the first check. Keep this page open while you test. The checklist saves on this browser so you can come back after the print finishes.

Verification

  • Free-air extrusion forms a smooth strand with no clicking or repeated thinning.
  • Single-wall thickness is consistent around the cube.
  • Top surfaces close without gaps at the same speed and temperature.

After the test

Use the result, do not keep changing random settings.

If one check clearly changes the print, repeat that exact test once before moving on. If nothing changes, switch diagnosis instead of stacking more slicer edits.

Try next diagnosis Open full checklist

Warnings

  • Do not force cold filament through a hotend; heat it to the correct material temperature first.
  • Raising flow can mask the symptom while pressure builds and the extruder keeps slipping.
  • Flexible filament needs a clean path and slower speeds before aggressive tension changes.
Useful when
  • A print that clearly shows under extrusion, especially if the same failure repeats.
  • You want one next move instead of five profile edits.
Skip if
  • The printer is showing a firmware, heater, or electrical safety warning.
  • You are copying numbers from a different printer as final values.
More traps to avoid
  • Changing several slicer settings at once and losing the actual cause.
  • Ignoring filament condition or bed cleanliness while tuning advanced values.
  • Keeping one global profile for different materials, brands, colors, and nozzle sizes.

Bench Note

Print-failure log to keep beside the printer
Page: Under Extrusion Fix
Printer / firmware:
Slicer profile:
Filament brand and material:
Nozzle size:
Bed surface:
Recent changes:
First check run:
One change tested:
Result:

FAQ

Should I increase flow first?

No. Confirm the nozzle and extruder can feed normally before using flow calibration.

Is clicking always a clogged nozzle?

No. Clicking can come from a clog, low temperature, high speed, spool drag, or extruder tension.

When should I replace the nozzle?

Replace it when cleaning and correct temperature still produce a thin, curling, or inconsistent strand.

Sources

Prusa Knowledge Base - Print quality troubleshooting Accessed 2026-05-18

Related Pages

3D Print Stringing Fix Fix 3D print stringing by checking temperature, moisture, and retraction in the right order. Start with one small test before changing the whole slicer profile. 3D Print Warping Fix Fix 3D print warping by checking plate cleanliness, first-layer squish, bed temperature, cooling, and enclosure needs in the right order. Poor First Layer Fix Fix poor first layers by checking plate cleanliness, Z offset, bed mesh, probe setup, and first-layer speed with one simple patch test. 3D Print Layer Shift Fix Fix 3D print layer shifts by checking belts, pulleys, collisions, cable drag, acceleration, and motion limits before changing slicer cosmetics. Clogged Nozzle Fix Fix a clogged 3D printer nozzle by confirming free-air extrusion, checking filament residue, cleaning safely, and replacing only when the nozzle is worn or blocked.