What Was Happening
A customer in Wandsworth SW18 contacted us about their Creality Ender 3 V3 SE, which had stopped extruding filament during prints. The printer powered on normally, homed correctly, and the print head moved through its path as expected — but nothing came out of the nozzle. The customer described it as the printer “moving around in the air” whilst the bed stayed empty.
The problem had developed over about two weeks. Initially, prints started showing thin, inconsistent lines and gaps in the walls. Within a few days, extrusion became intermittent — some sections would print normally whilst others were missing entirely. By the time the customer contacted us, the printer had stopped extruding altogether. The customer had tried changing filament and raising the nozzle temperature, but neither made any difference.
Our Diagnosis
We started with a manual extrusion test — heating the nozzle to 200°C and manually pushing filament through the extruder by hand. This confirmed two things: filament could be forced through, but it required significantly more pressure than normal, indicating a partial blockage in the hotend. We also noticed the extruder gear was not gripping the filament firmly — when we commanded extrusion through the printer’s menu, the gear slipped against the filament rather than driving it forward.
We removed the nozzle and inspected it under magnification. The 0.4 mm bore was partially blocked with carbonised PLA — a dark, hardite plug that had built up over time. This type of clog doesn’t block the nozzle completely at first; it gradually reduces the bore diameter, increasing the back-pressure the extruder has to overcome.
Next, we inspected the extruder gear. The teeth showed visible wear — they had been ground smooth on one side from months of use, reducing the gear’s ability to grip the filament. A new extruder gear can push filament through a partially clogged nozzle for a while by gripping harder, but once both components degrade past a threshold, the gear slips and extrusion fails entirely. That was exactly what had happened here.
We also checked the PTFE Bowden tube where it seats into the hotend. The tube end had started to deform and pull back slightly from the nozzle seat, creating a small gap. This gap is where molten filament pools and eventually carbonises, which is the root cause of the recurring nozzle clog.
How We Fixed It
We replaced the 0.4 mm brass nozzle with a new one, ensuring it was tightened to the correct torque whilst the hotend was at printing temperature. Tightening a nozzle cold leaves a gap that opens up when the metal expands during heating — this is a common cause of leaks and clogs on Creality printers.
Before fitting the new nozzle, we performed a cold pull to clear any remaining carbonised material from the heat break. We heated the hotend to 200°C, inserted a short length of Nylon filament, let it cool to 90°C, then pulled it sharply. The plug came out with a dark, discoloured tip, confirming carbonised residue had been present in the heat break above the nozzle.
The worn extruder gear was replaced with a new hardened steel drive gear. We also trimmed approximately 5 mm from the degraded end of the PTFE Bowden tube and reseated it firmly against the back of the new nozzle, eliminating the gap that had caused the clog to form in the first place.
With new components fitted, we recalibrated the E-steps. The previous value of 93 steps per millimetre had been set when the extruder gear was in better condition. After calibrating against a measured 100 mm extrusion test, the correct value came out at 101.6 steps per millimetre. We also re-levelled the bed using the CR Touch auto-levelling sensor and fine-tuned the Z offset.
Finally, we updated the printer’s firmware to the latest stable release, which included improvements to the CR Touch probing routine and thermal management.
The Result
The Ender 3 V3 SE was extruding consistently within minutes of the repair. We ran a full test print — a calibration cube followed by a small functional prototype the customer needed — and both printed cleanly with smooth walls, consistent layer adhesion, and no gaps or under-extrusion. The customer was printing their own PLA prototypes within 30 minutes of us finishing. The entire repair and calibration took approximately 2.5 hours onsite, completed the same day.
We documented the final extrusion settings and maintenance intervals so the customer could keep output stable between service visits.
Why This Happens
Nozzle clogs and extruder gear wear are the two most common mechanical failures on budget FDM printers like the Ender 3 series. They tend to happen together because each problem accelerates the other. A partially clogged nozzle increases the force required to push filament through, which wears the extruder gear teeth faster. A worn gear slips more often, which means filament sits in the hot zone longer than intended, increasing the chance of carbonisation and further clogging.
The PTFE-lined hotend design used in the Ender 3 V3 SE (and most Creality printers) is particularly prone to this cycle. The PTFE tube must sit flush against the nozzle with zero gap. Over time, heat cycling causes the tube end to soften and retract slightly. Even a gap of 0.5 mm is enough for molten filament to pool, degrade, and form a partial blockage. All-metal hotends avoid this problem but are not fitted as standard on the Ender 3 series.
Regular nozzle and Bowden tube maintenance can prevent this failure mode entirely, but most users don’t know that these are wear items with a finite lifespan.
Local Help in Wandsworth SW18
We provide 3D printer setup, calibration and repair across Wandsworth SW18 — either onsite at your home or workshop, or at our Putney base which is a short trip from Wandsworth Town or East Putney. Whether you’ve got a new printer that needs assembling or an established machine that’s developed a fault, we work with Creality, Prusa, Bambu Lab, Anycubic and most other consumer FDM printers.
Prevention Tips
- Replace brass nozzles every 3–6 months if you print regularly. Brass nozzles are a consumable — they cost under £2 each and prevent the gradual bore narrowing that leads to partial clogs. Keep a pack of spares next to the printer.
- Check the PTFE Bowden tube seating every time you change a nozzle. Push the tube in firmly and check that it sits flush against the nozzle. If the tube end is discoloured or deformed, trim 5–10 mm from the end or replace it entirely.
- Perform a cold pull every 50–100 print hours. A cold pull with Nylon filament clears early-stage carbonisation before it develops into a full clog. It takes five minutes and saves hours of troubleshooting.
- Listen for clicking from the extruder. A clicking or knocking sound during printing means the extruder gear is skipping — the gear teeth can’t push filament through the resistance. This is an early warning sign of a clog, worn gear, or both.