I've got a clog in my nozzle/hotend! What do I do now?

It happens to the best of us. You've got a print running beautifully, then suddenly under-extrusion, clicking sounds, or nothing coming out at all. A clogged nozzle or hotend is one of the most common issues in 3D printing, and while it's frustrating, it's almost always fixable.

This guide will walk you through the most effective methods for clearing a clog with needles/unclogger tools to cold pulls. We'll start with the least invasive approaches and work our way up, as one you get nozzle flowing again, there some tips to prevent its occurring again in the future. 

⚠️ Important Note on Nozzle Types: Before you begin, check your nozzle material/type. Some manufacturers (e.g., E3D Revo, Micro Swiss FlowTech, diamond carbide, ruby-tipped, SIC) may have specific recommendations or warnings against certain cleaning methods like cold pulls or needle poking. Always refer to your nozzle manufacturer's guidance first. If in doubt, contact us, we're happy to advise.

TABLE OF CONTENTS

• Start Here: 
  • Cold Pull Videos:
  • Cold Pull Written Guide 
    • Example of good/bad cold pulls:
• Causes of Clogged 3D Printer Extruder Nozzles

Start Here: 

If the above does not resolve the issue, you may need just need new nozzle.

Cold Pull Videos:

All hotends can clog at times, and all-metal hotends can be more prone to clogging with PLA. There are "cleaning filaments" that can help to remove small clogs and debris. 

The simplest way to clear a clog in the heat break of any all-metal hotend is to perform a cold pull or atomic pull. 

Prusa MK3 (Cold Pull Video)

Prusa Article: https://help.prusa3d.com/article/cold-pull-mk3s-mk2-5s_2075

General Video:

Ender 3 Specific Video:

If that doesn't work, the Mosquito™ and Copperhead™ Hotends have been designed with high temperature materials in mind. Remove the hot block and heat break from the heat sink. Place the hot block and heat break into an oven or kiln (not one used for food consumption) preheated to 100°C above the melting temperature of the plastic. The goal is to incinerate the plastic. Please do not put the heat sink in the oven. It will deform. Also, please do not burn yourself.

If you clog is ABS or related plastic you can soak the component within acetone. 

Cold Pull Written Guide 

(For the best results, use Cleaning Filament or Nylon Filament, if not filament you print with may also work as long materials is not brittle such as any filled materials like GF/CF or wet PLA)

1. Heat up the nozzle to ~250°C, or ~300°C if printing with engineering materials.
2. Load the mentioned material through the hotend/nozzle, ensuring some material is purged before proceeding to the next step.
3. Set the hotend to cool down, then pull the filament out quickly when the temperature reaches around 85°C. You should see a result similar to the example of a cold pull below. (Hold the toolhead/extruder with your other hand for stability.)
4. Repeat the process until filament can be extruded/purged cleanly. If using cleaning filament, the extrusion should appear clear.

Example of good/bad cold pulls:

Expected Cold Pull Result (Regular Nozzle):

Credit: https://help.prusa3d.com/article/cold-pull-mk3s-mk2-5s_2075

Dirty:

Clean:

CHT Cold Pull: 

Source: https://www.bondtech.se/2021/09/30/the-bondtech-cht-nozzles-are-available-now/

Revo HF:

Credit: https://www.reddit.com/r/3Dprinting/comments/151xtf8/this_incredibly_satisfying_cold_pull_from_a_revo/

Causes of Clogged 3D Printer Extruder Nozzles

• Dust build up around filament path, considering running your printer via reverse bowden PTFE from filament to the extruder to reduce dust build up when filament is not used. Store in seal and dry/out of direct sunlight location when filament is not in use.
• Low quality filament, lower quality filament may have dust and other contaminants within filament from previous materials extrusion.
• Incorrect hotend temperature, this cause materials to crystallise and may cause build up within the nozzle, when changing materials from low to high, ensure the previous higher temperature materials are purge thoroughly before printing. 
• Incorrect nozzle size for filament, some with added additives (not limited to GF / CF / Wood / Sparkle / Glow In Dark) can be larger and its can build within nozzle, we suggest larger nozzle above 0.5mm for those materials or confirm with materials manufacturer for recommend nozzle size. 

If the above troubleshooting does not resolve the issue, you may need just need new nozzle, is simplest fix for clog or partial clog nozzle or hotend. If you using PTFE hotend, the other solution you may need replace the PTFE.