Failure guide
Clogged Nozzle Fix
A clog is a feeding problem you can see: the strand curls, thins, sputters, or stops. Clear the path before changing slicer flow.
Independent third-party notes. Verify firmware, heater, electrical, and vendor-specific work against official documentation for your exact printer.
Start here
Debris, overheated residue, worn nozzle geometry, or an assembly gap is restricting plastic flow.
A clog is a feeding problem you can see: the strand curls, thins, sputters, or stops. Clear the path before changing slicer flow.
- Check first
- Heat to the material temperature and extrude into free air; watch whether the strand exits straight and full-size.
- Change only this
- Clear the nozzle path before changing flow, speed, or extruder tension.
- Verify with
- A free-air extrusion test followed by a short single-wall print.
- Time
- 5 min setup
- Risk
- Caution: hot parts
- Needs purchase
- Maybe, if cleaning fails or the nozzle is worn.
Visual diagnosis
Match the visible pattern before changing settings.
Original synthetic diagnostic reference plus licensed look-alike references; confirm with the test or log evidence below.
Looks like this
- Extruder clicks, strand curls upward, extrusion thins, or flow stops suddenly.
- Walls show missing lines or weak infill after feeding was previously normal.
- Issue may start after abrasive filament, heat soak, nozzle swap, or old filament.
Not this
- Poor first layer with good free-air extrusion is Z/plate, not clog.
- Random stringing with strong walls is heat/moisture/retraction first.
- Layer shift is motion hardware, not nozzle flow.
Common look-alikes
- Partial clog
- Heat creep
- Worn nozzle
- PTFE gap or hotend assembly leak
- Abrasive filament wear
- Spool path drag
Inspect in the photo
- Are missing lines random or after retractions?
- Does extrusion curl as it exits nozzle?
- Any clicking/grinding marks on filament?
- Any nozzle buildup or heat block leak?
Photo cannot prove
- Nozzle internal blockage
- PTFE tube gap
- Exact wear diameter
- Whether extruder tension is correct
Original visual references
Synthetic examples for fast pattern matching.
These are Print Fixes synthetic diagnostic references, not user-submitted photos. Use them to compare shape and location, then confirm with the test or log evidence on this page.
Licensed reference photos
Compare against real-world photos before changing settings.
These are externally licensed reference photos, not vendor images or scraped forum posts. Use them as pattern checks, then confirm with the small test model on this page.
Before / after
Compare one small test, not a whole print.
This is a look-alike reference, not proof of a clog. Confirm with free-air extrusion and the single-wall flow box.
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
- Material
- PLA for baseline after clearing; use the failed material if diagnosing material-specific clogging.
- Dimensions
- 35 x 35 x 25 mm.
- Footprint
- 35 x 35 mm
- Height
- 25 mm
What it testsWhether the nozzle/extruder can feed a continuous single wall after free-air extrusion passes.
When to use itAfter clicking, curling strand, missing lines, suspected partial clog, or nozzle maintenance.
Keep unchanged
- Same material
- Same nozzle temperature unless testing clearing temp
- Same flow value
- Same print speed unless testing volumetric limit
Expected good resultContinuous walls with stable extrusion and no clicking.
Failure result meaningGaps after clean free-air extrusion point to volumetric speed/path drag; curling free-air strand points to nozzle restriction.
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.
Field guide
Follow the branch that matches your print
Free-air extrusion curls, thins, or exits sideways
- Likely cause
- Partial clog or debris in nozzle.
- First test
- Heat to material temp and extrude slowly into free air.
- Change only this
- Clear nozzle path with cold pull/cleaning or nozzle swap if needed.
- Verify with
- Free-air strand drops straight and full-size.
- Stop when
- Strand is consistent and single-wall test prints cleanly.
Flow starts OK then fades/clicks after heat soak
- Likely cause
- Heat creep or filament softening too high in the path.
- First test
- Run short extrusion after idle heat soak and inspect hotend fan/path.
- Change only this
- Hotend cooling/path temperature issue, not slicer flow.
- Verify with
- Extrusion remains stable after heat soak.
- Stop when
- Clicking no longer appears after idle/slow print.
Abrasive filament printed through brass and holes/walls are oversized or inconsistent
- Likely cause
- Nozzle is worn, not simply clogged.
- First test
- Compare extrusion/wall width with a known-good nozzle or inspect nozzle history.
- Change only this
- Replace with hardened/wear-resistant nozzle for abrasive materials.
- Verify with
- Single-wall width and surface become consistent.
- Stop when
- New nozzle restores stable width.
Under-extrusion after nozzle or PTFE work
- Likely cause
- PTFE gap, nozzle seating issue, or hotend leak creates drag/debris.
- First test
- Inspect hotend assembly for gap/leak using printer maker procedure.
- Change only this
- Reseat nozzle/PTFE/hotend interface.
- Verify with
- Free-air extrusion and single-wall box are stable.
- Stop when
- No leak/debris returns after heat cycle.
Extruder grinds but free-air strand is clean after reload
- Likely cause
- Spool drag, extruder tension, or filament path resistance.
- First test
- Pull filament path by hand and run free-air extrusion with spool path isolated.
- Change only this
- Spool/path drag or extruder grip.
- Verify with
- No grinding during single-wall flow box.
- Stop when
- Extrusion stays clean without raising flow.
Concrete Parameter Range
| Setting | Start | Range | Change when | Stop when | Too far looks like |
|---|---|---|---|---|---|
| Free-air extrusion speed | Slow manual extrusion | 20-50 mm filament at slow feed | Strand curls, thins, or clicks | Strand drops mostly straight and full-size | Forcing fast extrusion can skip even on a healthy hotend. |
| Nozzle temperature for clearing | Material normal print temp | +5 to +10 C only for clearing if safe for material/hotend | Residue softens poorly at normal temp | Flow clears and normal temp works again | Too hot can degrade filament and create more residue. |
| Print speed / volumetric repeat | Current profile | Reduce 20-30% for one single-wall test | Free-air flow is clean but print still under-extrudes | Walls become continuous at realistic speed | Too slow hides a worn nozzle or path drag problem. |
| Retraction after clog | Profile default | Use normal material range; avoid aggressive increases | Clogs follow heavy travel/retraction sections | No clicking after travel and restarts are full | Too much retraction can trigger heat creep or jams. |
| Nozzle replacement threshold | Clean existing nozzle first | Replace when cleaning fails, abrasive wear is likely, or opening is damaged | Same clog/wear repeats after clearing | New correct nozzle restores consistent single-wall extrusion | Replacing parts before diagnosis can hide PTFE or extruder issues. |
Material / Machine Differences
PTFE-lined hotendA small tube/nozzle gap can create repeated clogs after maintenance.
All-metal hotendHeat creep and cooling are more likely if retraction or fan setup is wrong.
Abrasive filamentUse hardened or wear-resistant nozzle; brass wear can mimic bad flow.
Flexible filamentPath drag and extruder grip often look like clogs.
Bambu/Prusa quick-swap nozzleFollow vendor seating and hot-tightening guidance; do not force cleaning needles sideways.
Wrong Turns
Raising slicer flow to push through a clogPressure rises and grinding/clicking can get worse.
Replacing nozzle before free-air testYou may miss spool drag, PTFE gap, or heat creep.
Using cleaning needle aggressivelySmall nozzles can be scratched or enlarged.
Stop tuning when
Do not keep chasing perfection after the signal is clear.
- Free-air strand is straight and stable.
- Single-wall flow box prints continuous walls.
- Extruder stops clicking/grinding under the same material.
- A clog returns after clearing, pointing to hotend assembly or filament path.
Common setups
Jump to the branch that matches your machine or material
After abrasive filament Carbon fiber, glow, glass-filled, or hardened-material use Check nozzle material/history and single-wall width. Inspect nozzle wear and extrusion strand before increasing flow. After nozzle change New nozzle/hotend work followed by under-extrusion Inspect seating/PTFE gap before raising flow. Check nozzle seating and PTFE gap before replacing the hotend. PETG nozzle buildup PETG strings, glossy blobs, material on nozzle Dry/temp check before calling it a clog. Clean buildup and lower temp 5 C before changing retraction restart.
Copy before changing more settings
Clogged-nozzle diagnostic brief
Fill this out after the first test so the next branch is based on evidence, not memory.
Submit this failure patternPrinter:
Slicer:
Firmware:
Material:
Nozzle size/material:
Bed surface:
Exact symptom:
Recent change:
First test run:
One change tested:
Result:
Next branch:Still not matching?
Jump to the next likely diagnosis
Problem Pattern
Clogs often follow a material change, abrasive filament, old PLA cooked in the nozzle, a cold pull gone wrong, or printing too cool for the requested flow.
Likely Causes
- Burnt residue, dust, or material contamination inside the nozzle.
- Abrasive or filled filament has worn the nozzle opening.
- Heat creep softened filament above the melt zone and jammed the path.
- Nozzle, heatbreak, or PTFE path is assembled with a small gap that traps plastic.
Print Context
- Applies to
- FDM hotends, brass nozzles, hardened nozzles, filled filament
- Best first move
- Confirm flow into free air before replacing the nozzle.
- Do not start with
- Extruder tension changes when the nozzle cannot pass plastic.
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
- Plastic exits straight down in a smooth strand at normal temperature.
- The extruder no longer clicks or grinds during slow manual extrusion.
- A short single-wall print has continuous lines with no sudden gaps.
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.
Warnings
- Nozzle and heater block work can burn skin; use the printer maker's hot-tightening and replacement instructions.
- Cleaning needles can damage small nozzles if forced sideways.
- Do not bypass thermal or heater warnings to push through a clog.
Useful when
- A print that clearly shows clogged nozzle, 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
Page: Clogged Nozzle Fix
Printer / firmware:
Slicer profile:
Filament brand and material:
Nozzle size:
Bed surface:
Recent changes:
First check run:
One change tested:
Result:FAQ
Is every under-extrusion issue a clog?
No. Check spool drag, extruder grip, temperature, and speed too, but a bad free-air strand strongly points to a nozzle or hotend restriction.
Can I just raise temperature?
A small temperature increase can help diagnosis, but it should not become a workaround for debris, assembly gaps, or a worn nozzle.
When should I install a hardened nozzle?
Use hardened or other abrasion-resistant nozzles when printing carbon fiber, glow, glass-filled, or other abrasive materials.