The most reliable way to clear a clogged nozzle is the cold pull: heat the hotend to 240–250 °C, let it cool to about 90 °C and pull the filament out in one firm move — the clog comes out together with the tip of the material. For lighter blockages, a thin 0.35 mm needle inserted from below into the heated nozzle is enough. In this guide we will walk through both methods step by step, plus nozzle disassembly for when nothing else works. Before you start, make sure the problem is not simply your temperature settings — our article on PLA printing temperature will help you rule that out.
The good news: in more than 90% of cases the nozzle can be saved without replacement and without tearing down the whole hotend. All you need is a few minutes, a bit of patience and — ideally — a piece of nylon or cleaning filament. The bad news: if you do not remove the cause of the clog, it will come back sooner than you think. That is why, alongside the cleaning itself, we will also cover prevention.
Starting settings for clearing a nozzle — table
| Parameter | Value | Comment |
|---|---|---|
| Cleaning needle | 0.35–0.38 mm | for a 0.4 mm nozzle; always a few hundredths thinner than the bore |
| Soak temperature before the cold pull | 240–250 °C | must melt everything sitting in the nozzle, including PETG residue |
| Pull temperature — PLA | 80–100 °C | the filament should be rubbery but no longer fluid |
| Pull temperature — PETG | 100–120 °C | PETG is stretchier, pull decisively |
| Pull temperature — nylon / cleaning filament | 120–140 °C | the best material for a cold pull, comes out in one piece |
| Number of cold pull repetitions | 2–4 | until the tip comes out clean, with the nozzle shape imprinted on it |
| Test extrusion after cleaning | 100 mm | measure whether the extruder feeds exactly as much as it should |
| Nozzle tightening against the heater block | hot, at 250 °C | tightening cold ends in leaks and the next clog |
| Nozzle tightening torque | 1.5–2 Nm | gently, with feel — brass strips easily |
You will find soak temperatures for specific materials in our printing temperature table — cold pull values are always 10–20 °C higher than the normal printing temperature of a given filament.
Why nozzles clog
The most common scenario is not a single particle that “got stuck”, but a gradual build-up of contamination. Dust settling on the spool is dragged in with the filament, chars inside the nozzle and forms hard, carbonised specks. Those specks narrow the bore gradually — which is why a clog almost never appears suddenly; instead, for a few days “something is off” with your print quality.
The second frequent culprit is moisture. Wet filament steams inside the hotend, and the water vapour causes micro-bubbles and material degradation — instead of flowing in an even stream, the plastic sizzles and leaves deposits. If your filament crackles while printing, start by drying it — we covered this in detail in our guide on storing and drying filament.
The third group of causes is thermal mistakes: printing at too low a temperature (the material cannot melt fast enough), switching materials without purging (PLA residue carbonises at PETG or ABS temperatures) and heat creep, i.e. heat spreading up the hotend so the filament softens where it should stay solid. The quality of the material itself matters too — filament with uneven diameter or cheap fillers clogs nozzles more often. Consistent diameter and clean raw materials are one reason why Porima PLA performs so well in everyday printing.
How to tell your nozzle is clogged
Symptoms of a partial clog
A partial clog is the sneakier opponent, because the printer keeps printing. Watch out for: a thinner-than-usual extrusion line, missing material in individual layers, weaker infill, filament curling out of the nozzle at an angle instead of straight down, and the characteristic clicking of the extruder (click-click) when the motor cannot push the material through the narrowed bore. Surface quality drops, and part strength can fall by tens of percent before you even notice the problem.
Symptoms of a full clog
With a complete blockage things are obvious: nothing comes out of the nozzle even though the extruder is working. The motor skips steps or grinds a notch into the filament — you will see plastic dust on the drive gear while the filament does not move a millimetre. If a print stopped halfway and the feeder is grinding in place, 9 times out of 10 you are dealing with a clog or heat creep.
Method 1: the needle — the fastest rescue
Start with the simplest option. Heat the nozzle to the printing temperature of the last material you used plus 10 °C (about 220 °C for PLA, about 250 °C for PETG). Insert a 0.35 mm needle from below into the nozzle bore and move it gently up and down while rotating it. Do not force it — the needle is meant to break up and dislodge the clog, not widen the bore. After a dozen or so seconds, command an extrusion and check whether the material flows in a straight, even stream. The needle handles soft clogs very well, but it will not remove carbonised deposits from the melt chamber walls — that is what the cold pull is for.
Method 2: the cold pull step by step
Preparation
Nylon or a dedicated cleaning filament gives the best results, because they are ductile and come out of the nozzle in one piece, taking contaminants with them. Have neither? Use light-coloured PLA — white material shows best what came out of the nozzle. Remove the PTFE tube from the hotend inlet (on a Bowden setup, release the coupling) so you can pull the filament directly. Also disengage the extruder or release its idler tension so nothing holds the material back.
Execution
Heat the hotend to 240–250 °C and manually push a few centimetres of filament through until it starts flowing from the nozzle (if the clog is complete, simply keep the pressure on for a dozen seconds). Then set the pull temperature: 90 °C for PLA, 110 °C for PETG, 130 °C for nylon. Wait for the temperature to drop while keeping light pressure on the filament. When the display shows the target value, grip the filament firmly and pull it out in one decisive, smooth motion straight up. Do not yank sideways — the nozzle and heatbreak will not thank you.
How to judge the result and how many times to repeat
Inspect the tip of the pulled filament. If you can see dark specks, burnt spots or a rough, torn surface — the cleaning is working, but something is still sitting in the nozzle. Repeat the whole cycle. Success looks like this: the tip is clean, uniform in colour and carries a perfect imprint of the nozzle interior, including the tiny spike cast in the bore itself. Usually 2–4 repetitions are enough. Finally, load normal filament and run a 100 mm test extrusion — the stream should be straight and even.
Method 3: removing the nozzle when nothing else works
When disassembly is the only way out
If after four cold pulls the tip still comes out dirty, or the material refuses to flow at full temperature, the clog is probably carbonised solid or sits higher up, in the heatbreak. Then the nozzle has to come out. Heat the hotend to 250 °C (a nozzle is only ever unscrewed hot!), hold the heater block with a flat spanner and unscrew the nozzle with a socket wrench. Be careful — everything is above 200 °C.
Cleaning the removed nozzle
You can heat the removed nozzle with a heat gun and clear it with a needle from both ends, soak it in acetone (effective only for ABS and ASA — PLA and PETG do not dissolve in acetone) or simply replace it. A brass nozzle costs very little, and sometimes replacement is quicker than fighting a carbonised clog. When refitting, screw the nozzle in warm and give it the final tightening at 250 °C — gently, with feel, so you do not strip the thread.
Heat creep — when the blockage sits above the nozzle
If the filament jams not in the nozzle itself but a few centimetres higher, and after removal shows a characteristic teardrop-shaped bulge, that is not a classic clog — that is heat creep. Heat travels up the heatbreak, the filament softens too early and wedges itself in the zone that should stay cool. Check that the heatsink fan (not to be confused with the part cooling fan!) runs at full speed throughout the print, that the heatsink is not covered in dust and that the thermal paste on the heatbreak has not dried out. Heat creep gets worse when printing PLA in an enclosed chamber and with very long retractions that drag molten material upwards.
Settings for popular configurations
| Configuration | What to watch for | Recommendation |
|---|---|---|
| Bowden | the clog can also sit in the PTFE tube, not just the nozzle | before the cold pull, disconnect the tube at the hotend and check it separately |
| Direct drive | easy access, but a short filament path | release the extruder tension and pull the filament directly above the hotend |
| CoreXY with an enclosed chamber | heat creep with PLA in a hot chamber | open the door or run chamber ventilation when printing PLA |
| Printer with an AMS / CFS system | frequent material changes leave residue in the nozzle | after a series of swaps, run a preventive cold pull with cleaning filament |
| Hardened nozzle (steel, CHT) | conducts heat worse than brass | raise the soak temperature by 5–10 °C before cleaning |
How to prevent clogs
Prevention comes down to three things: cleanliness, dryness and correct temperatures. Fit a dust filter (a piece of sponge clipped onto the filament before it enters the extruder is enough) and replace it regularly — you will be surprised how much dirt it collects in a month. Store filament in sealed containers with a desiccant, and dry hygroscopic materials before printing. When switching to a material that prints at a lower temperature, always purge the nozzle: heat it to the previous material's temperature and push through 10–15 cm of the new one before you start the actual print.
Every few dozen hours of printing it is worth running a preventive cold pull with cleaning filament — it takes five minutes and removes deposits before they grow into a clog. Keep your calibration in order too: a nozzle set too close to the bed on the first layer can block the flow and push pressure back into the melt zone — a straight road to a clog right at the start of a print.
Most common mistakes
Pulling filament out cold. Yanking the material at room temperature can snap the filament inside the heatbreak or damage the hotend — always heat the nozzle before any intervention.
Drilling the nozzle out. A drill bit widens and ruins the calibrated bore — a 0.4 mm nozzle prints like a 0.5 mm one after such treatment, only worse. Use only needles thinner than the bore.
Cold pulling with flexible TPU. Flexible filament stretches instead of coming out in one piece and can snap inside, making things worse. Use nylon, cleaning filament or PLA for cleaning.
Tightening the nozzle cold. Metal shrinks as it cools — a nozzle tightened cold starts leaking once heated, and the leak bakes onto the thread. Always tighten at 250 °C.
Ignoring the first symptoms. A clicking extruder and a thinner extrusion line are an invitation to a five-minute clean. A week later the same clog will require taking the hotend apart.
Switching materials without purging. PLA residue left in the nozzle carbonises at ABS or PETG temperatures and forms hard deposits that a regular cold pull may no longer remove.
Printing with wet filament. Sizzling and steam are not just a worse print surface — the degradation products of wet material build up in the nozzle and speed up the next clog.
Frequently asked questions
Can I burn the clog out with a lighter or a torch?
A removed brass nozzle can be carefully heated with a heat gun, but an open flame easily overheats brass and destroys the coating on coated nozzles. It is safer to soak the nozzle (ABS/ASA in acetone) or use a needle on a heated hotend. Never burn out a nozzle that is still mounted in the printer — you will damage the thermistor and the heater cartridge.
How often should I do a preventive cold pull?
With daily PLA and PETG printing, once every 100–150 hours of operation or at every change of material type is enough. If you print filled materials (wood, CF, glow), shorten the interval to 30–50 hours, because additives speed up deposit build-up.
Will acetone dissolve the clog in my nozzle?
Only if the clog comes from ABS or ASA. PLA, PETG and nylon do not dissolve in acetone to any practical degree, so soaking the nozzle will achieve nothing — mechanical or thermal cleaning is your only option.
How do I know the nozzle needs replacing rather than cleaning?
When the bore is oval or visibly enlarged (you can tell by the extrusion line width), when the flat face of the nozzle is worn down, or when clogs keep returning every few prints despite successful cleaning. A brass nozzle printing abrasive materials can wear out after just 1–2 kg of filament.
Can wet filament clog a nozzle?
Yes, and it does so more often than you would expect. Moisture causes material degradation and deposits in the melt chamber, and additionally hurts extrusion consistency. If your filament crackles while printing, dry it first — and only then look for a problem in the nozzle.
Summary
A clogged nozzle looks scary but in practice almost always ends with a five-minute fix: a needle for light blockages, a cold pull for the serious ones, disassembly only as a last resort. The key is to react at the first symptoms — a clicking extruder and a thinner material line — instead of waiting until the printer stops mid-print.
The other half of the battle is prevention: dry, clean filament, correct temperatures and material with consistent diameter and predictable composition. If clogs keep coming back, take a closer look at the filament you print with — the proven PLA filaments in our range hold a diameter tolerance that lets you forget about this problem for a long time.