How to unclog a hotend

In this article you will find how to proceed if you have a clog on the hotend





Nozzle cleaning needle
Allen key 2mm


Hotend clogs are one of the most frequent issues in FFF (Fused Filament Fabrication) 3D printing. Here we will talk about why the hotends get clogged and the different ways you can solve this. 

How to know if the hotends are clogged?

There are many reasons why the hotends get clogged, so it is important to take in consideration that changing the hotend in the first place is not the definitive solution on this matter. Locating the issue is important to find the best solution to this issue. 


Clogs can happen partially or totally, and you can diagnose if it's a partial clog or a total one by observing the prints:

Partial Clog Total Clog


Partial clogs happen normally in the middle of the printjob, even if the extrusion is regular and good, you spot that there are layers missing in the print.

Total clogs, in the other hand, present a sudden interruption of the extrusion, and are a bit more difficult to fix. 


Another sign that can tell you the hotends are clogged is clicking sounds coming from the extruder motor. The clicking sound means that the motor itself doesn't have enough force to push the filament through them, this can also have many other causes, check out this guide to know them all:

How to fix underextrusion


You can prevent clogs if you see that the filament curls up while it is extruding or it is not extruded consistently by simply cleaning the hotend. Keeping a good maintenance of the hotend is key to not have clogs in a long time.

Removing the clog

There are two main methods of dealing with this issue. To choose the right method, see whether or not it is possible to load/unload the filament. Partial clogs can usually be melted out or be removed with a simple Nylon clean , more complex clogs that prevent even loading of the filament call for more unorthodox methods. 


Clean the Hotend: If you can load and unload the filament, but you are still experiencing some clogs, try cleaning the hotend with Nylon. Here's how to clean them on all the models:

How to clean the hotend (Epsilon series)

How to clean the hotend (Sigma series)

How to clean the hotend (BCN3D Sigma)

How to clean the hotend (BCN3D Sigmax)


Purging the clog: When you experience clicking noises and the filament still doesn't come out the nozzle, try the following method:

1. Unload the filament. If you can't unload it, these unloading filament articles will help you on this:

How to unload filament (Epsilon series)

How to unload the filament (Sigma series)

How to manually unload filament (BCN3D Sigma)

How to manually unload filament (BCN3D Sigmax)


2. Go to Utilities/Filament/Purge and raise the temperatue about 40-50º above the default printing temperature.


3. When the temperature is reached, wait for 3 minutes, the filament should start oozing out. Use a fine, nozzle cleaning needle for 3D printing and push it through the nozzle from below. Push in and out in multiple directions.



4. Try loading the filament again and see if the issue is solved or the clogging persists. If the needle didn't help in this, take out the bowden tube and push some nylon through the hotend.



5. Let the hotend cool down and pull out the nylon when it goes down to 70ºC and pull it out as in a normal Nylon Cleaning.



If none of this works, swap the hotends from one head to the other, if the issue moves to the other head, it's time to replace the hotend. If the clogs persist on the same head, get in contact with the support team by filling this form.

Forum community 

Repair didn’t go as planned? Check out our forum community for troubleshooting help.


It's important to keep your printer in good shape to make the most out of it. In this chart you can find a list of the extruder maintenace procedures and how frequently these should be done. 

Maintenance Plan (Epsilon series)

Maintenance Plan (Sigma Series)

Maintenance Plan (BCN3D Sigma)

Maintenance Plan (BCN3D Sigmax)


bcn3d-recycle  Take your e-waste to a certified recycler. Check how we do it in BCN3D.



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