Hotend clogs are relatively common for FDM 3D printers and they can occur due to various reasons, exemplified below:
- The filament used has a low glass transition temperature (gets softened when printing in an enclosure) - More information about heat creep available in this Wiki article.
- The filament has an inconsistent diameter, usually larger than the regular 1.75 mm, getting stuck in the hotend.
- Debris present on the filament or inside the extruder has reached the hotend and clogged the nozzle completely or partially
- Particulates from filament have blocked the nozzle tip of the hotend (common when printing with carbon fiber infused filament, glow in the dark or sparkling filament)
- When very different filament types were used and the previous filament was not purged completely (PLA and PC, ASA and TPU, etc)
How to resolve a filament clog?
Simple Clog / Partial Clog
A simple clog or partial clog is considered when the tip of the hotend is clogged with particulates inside the filament (carbon fiber, sparkling filament, etc). These particulates could be larger than the nozzle hole and will block it from being extruded.
Most of the time, these particulates could either clog the hotend completely, where there is no filament being extruded anymore, or a partial clog generated by debris on the filament which manifests itself by filament not flowing straight from the hotend and curling when extruding manually from the hotend.
When such a clog occurs the model is not printing as expected, with inconsistent extrusion leading to bad print quality.
It can also manifest itself with a badly calibrated K value for Flow Dynamics due to the inconsistent nozzle pressure and flow.
The easiest procedure to follow in this case is to try and dislodge the small piece blocking the hotend using the included pin you received with the printer.
Tools needed
- Unclogging Pin Tool
- Plier
- Oven glove
- H1.5 or H2.0 Allen key
- Filament
Notes before you start
Please note that some of the operations within this guide could be hazardous if not performed with care as they involve high nozzle temperatures. Please take all precautions necessary when performing these tasks. For some of these procedures, the machine should be powered off and the nozzle should be completely cooled down for most of these procedures.
When it is necessary to hold the hotend in your hand, please wear an oven glove and make sure that the floor or tabletop below the hotend is free of flammable materials or furniture or flooring that can be easily damaged by the heat.
1. Manually extrude the filament
This is the simplest method to unclog the hotend. Switch to the left nozzle on the screen, increase the hotend temperature slightly higher than the filament's recommended temperature, and then extrude the filament by clicking the loading button on the screen.
Step 1. Heat the hotend
Increase the temperature of the hotend to a temperature slightly higher than that required by the filaments (PLA for example, set the hotend temperature to 250°C);
Step 2. Manually extrude
Click the loading button on the screen to extrude the filament manually. If using TPU, the loading button cannot be clicked more than three times. And avoid rapidly clicking the unloading button multiple times to prevent jamming or filament entanglement.
Observe whether the nozzle is extruding properly. As shown in the picture below, the filament should come out straight and consistently.
2. Unclog with a pin tool
It is important to note that this method does not work with nozzles smaller than 0.4mm.
If the filament cannot be extruded from the nozzle, or if the filament extruded from the nozzle does not become newly loaded filament, it will be necessary to use a through-needle to unclog the hotend and manually re-extrude the filament (cycling the unclogging with a pin tool and extruding process).
Heat the hotend to a temperature slightly higher than that required by the filament inside the hotend , following the instructions in Step 1 of the “1. Manually extrude the filament” section above. After reaching the temperature, insert the needle into the nozzle and unclog it up and down several times.
Warning! When using a cleaning needle, sudden release of internal nozzle pressure can cause hot filament to spray unexpectedly. Always wear protective gloves and keep your head clear of the printer chamber during cleaning.
3 Unclogging with a pin tool and cold pull
We have provided a complete video tutorial along with written instructions and images. Here is the complete video of unclogging with a pin tool and cold pull:
Step 1：Preparation before starting
Move the Z-axis to the appropriate height, and also move the tool head to the appropriate height; and remove the front cover of the tool head for the next step
Step 2：Heat the hotend and remove the filament
Heat the hotend to 100°C (PLA for example) and remove the hotend while it is heated (Please operate with oven glove!).
image | image |
Remove the filament at the entrance of the hotend with a plier.
Step 3：Placing the hotend and reheat it
Placing the hotend back in, set the hotend temperature to 220°C and load another colour of the same filament；
image | image |
Step 4：Manually extrude the filament and cold pull
If the extruded filament from the nozzle becomes completely freshly loaded, the hotend temperature can be lowered to 100°C and cold pull can begin.
image | image |
Step 5. Reconnect the PTFE tube and test extrusion
Reconnect the PTFE tube and load the filament and test the extrusion. If there is still no extrusion or under extrusion, several more attempts to clear the hotend will be required.
4. Hot hex wrench unclogging method
The images in this section feature the H2 nozzle. Since it is very similar to the A1 nozzle, the procedure is identical.
A common clog that occurs on A1 series is the filament getting stuck inside the hotend due to heat creep issues. This phenomenon was covered in detail in this article, and we recommend reading it to understand how to avoid this type of clog.
For the next steps, you will need to remove the nozzle. This wiki page covers the full removal and reinstall of the A1 nozzle, in case you need it
Caution! We recommend using heat-protective gloves for this operation. The molten filament can drip on your fingers causing burns.
Step 1. Heat up the hex wrench
Start by heating a hex wrench for approximately 10 seconds. Use a set of pliers to hold the hex wrench firmly and prevent burning yourself.
Step 2. Insert the hex wrench on the nozzle inlet
While the tip of the wrench is hot, quickly push it in the hotend, through the top end of the heatsink.
The hot wrench will go inside the filament, as shown in the image below. Then, wait for about 30 seconds for the hex wrench to get cold.
Step 3. Heat the tip of the hotend and pull filament clog
The hex wrench is now stuck inside the hotend, with filament around it. To remove the wrench with the filament clogging the hotend, you will need to heat the tip of the hotend.
First, remove the silicone sock of the hotend, then apply heat using the lighter to the tip of the nozzle for about 20 seconds (when using a regular lighter).
Caution!: Avoid heating the nozzle for a longer period or using a high power butane torch. A regular gas lighter is recommended.
The hot side of the nozzle needs to only be hot enough so you can remove the hex tool with the filament.
Overheating the nozzle can lead to the filament dripping or popping from the tip. Carefully follow the instructions and don't point the nozzle tip towards you when doing this procedure.
After heating the tip of the nozzle for 20 seconds, you can pull slowly on the wrench. You will notice that the filament comes out from the hotend in a single piece, clearing the clog.
Step 4. Reinstall the nozzle
You are now ready to reinstall the nozzle. This wiki page covers the full removal and reinstall of the A1 nozzle, in case you need it
How to verify completion/success
Reinstall the nozzle, connect the PTFE tubes, and reload the filament to test the extrusion. If there is still clogging or insufficient extrusion, it is necessary to repeatedly attempt cleaning the hotend.
Confirm the nozzle is flowing correctly
After moving the pin through the nozzle tip a few times, remove the pin and extrude some filament using the on-screen buttons. The filament should flow in a straight line and should not curl during extrusion, as shown in the image below.
While the above methods tend to clear out 99% of clogs, there might be cases where a nozzle simply needs to be replaced, as it could be damaged. If after all these, your machine can print normally, then you have successfully unclogged your nozzle.
Note
0.2mm nozzles are much more difficult to clear clogs from and might require the above steps several times over. On the other hand, nozzles larger than 0.4mm tend to clog a lot less than 0.4mm ones as the opening of the nozzle allows for larger particles to go through.
End notes
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