What is nozzle clogging, how to fix it and how to prevent it
It’s every 3d printing enthusiast’s worst nightmare. You are minding your own business, but suddenly you hear it. The horrible clicking sound… You look over and realise it: Filament stopped extruding, your nozzle is moving around in thin air and your print failed… Your nozzle is clogged!
In this article, we are going to wind back time, see what exactly clogging is, what causes it and how we can fix it and go back to printing.
What is nozzle clogging?
The best indicators for a clogged 3d printer nozzle is a sparse springy print, or simply the fact that your nozzle is suddenly printing in thin air. This means that a clog of material or other contaminants has formed in your nozzle, preventing the filament from extruding correctly.
A clogged nozzle can be the cause of more obvious problems down the line. That’s why it’s sometimes difficult to identify it as the root culprit of your issues.
A clogged nozzle can, for example, cause your extruder to grind into the filament, causing a dent in the filament which can stop the filament from being extruded correctly even after the nozzle is unclogged. So make sure to inspect your filament thoroughly and if you notice any dent, simply cut the filament at that place with a pair of pliers.
What causes a clogged nozzle?
In order to understand why your 3d printer nozzle is blocked you need to understand what can cause clogging.
There are many possible factors that can cause nozzle clogging:
Nozzle height to low. Your nozzle is to close to the print surface. This will cause plastic to back up in your hotend, which can cause a clog
Print temperature too low. You print temperature is too low causing the plastic getting liquified to little. Your extruder will have trouble pushing the material out of the nozzle and this will eventually cause a clog.
Poor filament quality. If you get poor quality filament it’s material properties may vary across the spool and may cause a clog.
Dirty filament. If there is dirt entering your hotend alongside your filament this may simply block the tiny hole of your nozzle
Fiber filled material. Fiber filled material will highly increase the chance of your nozzle clogging by simply getting the fibres stuck in the hole.
Over cooked filament. If you leave your nozzle too hot for a while without extruding, this may cook and char the filament which is currently in the hotend. This will not only clog your nozzle, but it also is a fire hazard.
How to fix a clogged nozzle?
There are multiple ways to clean a clogged 3d printer nozzle. Some use acupuncture needles or tiny drill bits, others dissolve the plastic using acetone or heat guns. The probably best way to clean a clogged nozzle is the cold pull method.
The cold pull method
The cold pull method requires no additional equipment except a piece of filament. Simply follow these simple steps:
Remove the material
Remove the bowden tube (if you have one)
Heat up the nozzle to your normal printing temperature. While your nozzle is heating you can cut off an approximately 20 cm (or 8 inch) long piece of filament and straighten it as much as possible.
Insert the piece of filament until some of it comes out of the nozzle or it can’t be pushed in any further.
Lower the temperature. For PLA I recommend 80-90°C, for ABS 110°C
Remove the piece of filament with a quick pull
Repeat the steps 2 – 6 until the filament comes out clean
Reassemble your bowden tube and insert filament again
Get back to printing!
How to fix a clogged nozzle?
There are multiple ways to clean a clogged 3d printer nozzle. Some use acupuncture needles or tiny drill bits, others dissolve the plastic using acetone or heat guns. The probably best way to clean a clogged nozzle is the cold pull method.
The cold pull method
The cold pull method requires no additional equipment except a piece of filament. Simply follow these simple steps:
Remove the material
Remove the bowden tube (if you have one)
Heat up the nozzle to your normal printing temperature. While your nozzle is heating you can cut off an approximately 20 cm (or 8 inch) long piece of filament and straighten it as much as possible.
Insert the piece of filament until some of it comes out of the nozzle or it can’t be pushed in any further.
Lower the temperature. For PLA I recommend 80-90°C, for ABS 110°C
Remove the piece of filament with a quick pull
Repeat the steps 2 – 6 until the filament comes out clean
Reassemble your bowden tube and insert filament again
Get back to printing!
Acupuncture needles
Another very common way to unclog a nozzle is using an acupuncture needle, a tiny drill bit or even a B guitar string.
First you need to make sure that your unclogging tool is going to fit into your nozzle. For example a 0.35 or 0.4mm tool works great on a 0.4mm nozzle.
Then it’s really easy: simply heat up your hotend and push the tool into the nozzle from the bottom. Then simply move it back and forth breaking up the clog.
Be very careful not to hurt yourself with the tool or burn you on the hot nozzle!
Dissolving a clog
Important note: this method only works with abs filament clogs. Acetone won’t dissolve pla.
This method uses solvents in order to dissolve the material. Obviously the use of solvents can be dangerous for the environment and you!
Only use this method if you know what you are doing and only do it outside or in a well ventilated area.
That said, this method is suited for very tough clogs.
For this method you need to remove your nozzle. Once your nozzle is removed put it into a closed glass mason jar half filled with acetone. Leave it in there for 24 hours agitating it every few hours.
After that use the acupuncture needle method to remove as much of the clogg as possible. If necessary repeat this method a few times.
Other options
Some people use specialized cleaning filament which chemically cleans the inside of your nozzle. We might follow up with an article about it.
After that you are left with very few options, you could try using a heat gun or a blowtorch in order to burn the plastic in the nozzle, but we highly discourage you from trying this, it’s not only dangerous for you and the environment, it also can physically damage and deform your nozzle.
If all of these methods still have failed you are left with only one option: Buy a new nozzle.
We could recommend you trying our titan nozzle. Its special internal geometry greatly reduces the risks of further clogging.
How to prevent nozzle clogging
An easy way to prevent your nozzle from clogging is to make a cold pull every time you switch from a filament with a higher melting point to one with a lower melting point, like for example switching from ABS to PLA. This has the other benefit that it prevents colour contamination, especially if you switch from a dark to a bright colour.
Another good practice is to keep your filament stored as clean and dry as possible, in order to prevent contaminants from entering your hotend. It’s also important to buy good quality filament, especially for critical prints. Also make sure to double check your print temperature before using a new material.
It’s also recommended to avoid fibre filled material if possible and use a separate nozzle for it in order to avoid problems further down the line.
We also offer a solution which can greatly reduce the chance of clogging your nozzle, while also reducing wear and colour contamination: it’s our Titan nozzle. A unique 3d printer nozzle made out of a titanium alloy with a unique internal flow geometry, which reduced the risk of anything getting lodged in the hole of the nozzle.
