A clogged nozzle or hotend is a common issue for the FFF/FDM printers. If there are no issues, the filament is pushed in the hotend, melted, and then extruded through the nozzle. However, if the PTFE tube is damaged (scarred, distorted) or there are impurities in the filament it might get stuck in the hotend, clogging the printer.
Missing layers can be a sign of a partially clogged nozzle
Sometimes the clog is partial, meaning that the printer is able to push some filament through, but it is not enough to print the object properly, leading to visible gaps and missing layers. An early sign of a clogged nozzle is that the filament is not extruded consistently, curls up, and sticks to the nozzle.
The hotend or the nozzle is partially or fully clogged and the internal resistance against the flow of the filament is greater than what the gears are able to push. As a result, the gears are skipping leading to the “clicking” noise and in most scenarios also to grinding of the filament.
It is important to note, that the clogs can happen in multiple places across the filament path and each requires a slightly different approach. For example, changing the nozzle, while the clogs are happening due to the damaged PTFE tube, won’t solve the issue.
Choosing the right method depends on whether you are able to at least partially load/unload the filament or the printer is fully jammed and refusing the move the filament even a little.
Before you start fixing the printer, try unloading the filament and removing it completely. If you are unable to do it, it might indicate a more serious problem, but we will deal with this one as well.
Also, move the print head up from LCD Menu - Settings - Move Axis - Z-axis or by long-pressing the control knob, this way you will get better access to the parts, which are clogged.
The idler screw should be about flush with the plastic part, when the filament is NOT loaded.
If you are able to load and unload the filament, yet still experiencing partial clogs, try this technique first, which uses a partly melted filament to pick up the debris inside the hotend and pull it out. We have prepared a detailed article about Cold pull (MINI).
Once you finish, head to the point in this article to learn how to check for a dirty Extruder pulley.
Sometimes the gears are not able to push the filament through, but it doesn’t mean that you need to immediately start with the disassembly. By raising the temperature further above the melting point, you might be able to remove the clog together with the debris.
Try the following:
Some clogs can’t be removed easily and require you to partially disassemble the hotend. The filament is either stuck in the PTFE tube or in the nozzle. The filament can also be stuck due to a damaged or worn-out PTFE tube. If this is your case, we recommend replacing the PTFE tube for a new one. For disassembly and an inspection, we have outlined the procedure below.
|Orientation of brass fittings.||The end with the least threads into the heatsink.|
You can now reattach the Bowden tube that leads to the extruder. Before testing the printer we recommend checking the last two points below.
After doing maintenance on the print head we recommend doing a new First layer calibration, as hardware can slightly shift during the procedure. For more info, please see First Layer Calibration (i3).
All the issues mentioned above can participate in the filament being ground between the pulley and the bearing. Once the teeth on the pulley get full of filament debris, the extruder won’t be able to load the filament properly.
You can either use the inspection door (see the picture below) to check whether the pulley is clean. Use compressed air to get rid of the dust, for a more thorough cleaning, follow this guide How to access and clean the extruder-pulley (MINI/MINI+).
Use the inspection door to check the pulley
If you have a question about something that isn't covered here, check out our additional resources.
And if that doesn't do the trick, you can send an inquiry to [email protected] or through the button below.