How to Clean 3D Printer Nozzles and Prevent Clogs

Updated

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Using a needle to clean the nozzle on an Anycubic Kobra 2 FDM 3D printer

Cleaning your 3D printer nozzles is essential to ensure consistent extrusion and high-quality prints. Dirty and clogged 3D printer nozzles lead to poor print quality, failed prints, and damage to your printer.

3D printing nozzles are important because they regulate material flow. Cleaning and maintaining your nozzle extends its lifespan and ensures excellent print results.

This article looks at when and how to clean 3D printer nozzles. And when to replace old parts.

Identifying Clogged Nozzles

In 3D printing, understanding the difference between a partial clog and a full clog in the nozzle is crucial for diagnosing and fixing issues effectively. Here’s how they differ:

Partial Clog

  1. Symptoms:
    • Inconsistent Extrusion: The most common sign of a partial clog is inconsistent extrusion. Your printer will extrude the filament, but there are gaps with sudden bursts of material.
    • Under-Extrusion: Under-extrusion occurs when a partially blocked nozzle restricts filament flow. You’ll notice gaps, thin layers, and weak or spongy prints.
    • Surface Quality: The print’s surface may appear rough or uneven.
    • Slight Nozzle Leakage: There might be minor leakage or oozing of filament from the nozzle.
  2. Cause:
    • Partial clogs often occur due to the accumulation of filament residue inside the nozzle.
  3. Impact on Printing:
    • The printer can still operate, but the print quality is significantly reduced. Continuous printing with a partial clog can lead to a fully clogged nozzle.

Note: Make sure you check that your filament is dry. Printing with wet filament causes similar print defects as partial obstructions.

If you clean the nozzle and still have issues, try drying your 3D printer filament or using a new spool.

Conversely, if you dry your filament and still have issues, it’s a sign you have a partial clog.

Full Clog

Green PLA filament oozing out of the hotend of a 3D printer due to a full nozzle clog
The extreme effects of a full clog. (Source: u/BrilliantPrimary2385 via Reddit)
  1. Symptoms:
    • No Filament Extrusion: The most apparent sign of a full clog is when no filament is extruded from the nozzle at all, even when the printer is trying to print.
    • Clicking Sounds from Extruder: The extruder motor might make clicking or grinding noises as it struggles to push filament through the completely blocked nozzle.
    • Visible Filament Grinding: The extruder gear might grind into the filament without being able to push it through. You may find filament dust around the extruder.
  2. Cause:
    • Full clogs are caused by solidified filament completely blocking the nozzle. This can happen due to overheating, using improper filament, or leaving the printer idle at high temperatures.
  3. Impact on Printing:
    • A full clog halts printing entirely, as no filament can be extruded. Printing in this state can damage the printer, especially the extruder motor, gears, and hot end assembly.

Exterior Debris on the Nozzle

A dirty 3D printer nozzle covered in exterior debris
(Source: u/sdhoigt via Reddit)
  1. Symptoms:
    • Visible Debris: You might notice filament or burnt material visibly sticking to the outside of the nozzle.
    • Irregular Print Patterns: Debris on the nozzle can drag across the print, causing the pattern or surface finish irregularities.
    • Filament Adhesion Issues: The presence of debris can affect the first layer’s adhesion to the print bed, as the nozzle cannot lay down the filament smoothly.
  2. Cause:
    • Exterior debris typically arises from excess melted filament adhering to the printer’s nozzle. The common cause of dirty nozzle exteriors is setting the nozzle height too low so that it bumps into the part. Filament tends to adhere to itself, so as the plastic extrudes from the nozzle, a portion adheres to the nozzle’s outer surface. Subsequently, as more filament emerges, it accumulates on the already-adhered material, exacerbating the problem.
  3. Impact on Printing:
    • While exterior debris doesn’t block material extrusion, it negatively affects print quality. The debris can interfere with the precise placement of filament, leading to defects in the print. Extruded material can bond to the exterior debris rather than the 3D printed part. And if there’s enough exterior nozzle debris, it can collide with the print, knocking it over.

Addressing nozzle clogs and dirty nozzles as soon as it’s identified is important. It’s important to clean and maintain your 3D printer to prevent issues like clogs.

If you suspect your printer nozzle is obstructed, use one of the methods below to clean a clogged nozzle.

How to Clean 3D Printer Nozzles

There are several effective nozzle cleaning methods, each with its benefits. All the options work well, so I recommend trying all of them and then deciding which you like best.

Remember, safety is essential when working with heated elements. Always wear appropriate personal protective equipment and exercise caution. Wear heat-resistant gloves when working with a hot nozzle.

Here’s how to clean a 3D printer nozzle

Method 1: Cold pull

A 3D Printer Cold Pull on a 3D printer

Cold pulling filament is one of the easiest and most effective methods to clean a partially clogged nozzle.

Follow the steps below to perform a cold pull technique:

  1. Prepare your 3D printer: Detach the Bowden tube from the hotend if your machine has one.
  2. Heat the nozzle: Set the nozzle temperature to the regular printing temperature for your filament material. For PLA, heat it to 220°C; for other materials like ABS, nylon, or PETG, set a temperature of 240-260°C.
  3. Wait for the hotend to reach the set temperature.
  4. Insert the filament: Once the nozzle reaches the desired temperature, gently push it into the extruder until it begins to ooze out the nozzle. Ensure you have enough to grab onto for later.
  5. Cool down the nozzle: Reduce the temperature to 90°C and wait for the nozzle to cool. Apply a small amount of downward pressure on the filament to ensure it takes the shape of the nozzle’s interior. This step is crucial because we want the filament to solidify inside the hot end, attaching to the nozzle debris.
  6. Pull the filament: As soon as the print nozzle reaches a temperature of 90°C, slowly pull the filament back up through the extruder. It’s best to use the pliers to have better control. Be especially careful when using PLA, as it is brittle and has a high risk of snapping.

Note: The cold pull method is most effective with dedicated cleaning or nylon filament. The nylon filament is strong yet flexible and won’t break when pulling.

Method 2: Cleaning filament

eSUN Cleaning Filament
  • Designed to adhere to any stray material left in the nozzle and remove it along with the cleaning filament. It can clean a variety of 3D printer materials.
  • Wide Cleaning Temperature Range 160°C-300°C. Clean the nozzle and extruder of the 3D printer regularly, ensuring it feeds smoothly and constantly without clogging.
  • Works to clear residue from PLA, ABS, PETG, and more.
  • Use before and after printing; change material with different melt points, colors, and properties for better extruder protection and printing effect.

Cleaning filaments are specially designed to clear debris and partial clogs in 3D printers. Cleaning filament is very easy to use, but it’s costly.

Follow the steps below to prevent wasting expensive cleaning filament on your 3D printer nozzle cleaning:

  1. Inserting the Cleaning Filament: Feed the filament into the hot end, as you would with regular 3D printing filaments.
  2. Heating the Nozzle: Heat the nozzle of your 3D printer to the printing temperature of the cleaning filament, typically 200°C to 230°C.
  3. Extruding the Cleaning Filament: Use the printer display to extrude 10mm of filament.
  4. Inspect the Extruded Filament: Inspect the filament. The end of the extruded filament should be white, indicating that there is no more obstruction.
  5. Repeat as Necessary: Sometimes, multiple passes with the cleaning filament might be needed to clean the nozzle fully. If the extruded filament has colors from previous prints or is a shade of grey, you’ll want to repeat the steps above until the clog is clear and the filament extrudes in a pearl white.

Cleaning filament effectively cleans the nozzle and restores the quality of your 3D prints. Regular use of cleaning filament helps maintain your 3D printer nozzle and prevent future clogs.

Method 3: Needle Cleaning

Using a needle to clean a 3D printer nozzle from partial and full clogs caused by filament residue, dust, and debris

A simple method to unclog your 3D printer nozzle is using a needle.

  1. Preheat the nozzle to soften the filament, making it easier to remove.
  2. Carefully insert a thin, flexible needle into the nozzle to dislodge the clogged material.
  3. Gently rotate and move the needle until the obstruction is cleared. Ensure you are cautious throughout the process to avoid damaging the nozzle.

Make sure the needle is correctly sized for your nozzle. You’ll stretch the nozzle diameter if you use a sewing needle or a too big needle. A slight diameter increase affects extrusion rates and print quality.

I recommend using this nozzle cleaning kit from Amazon because it has pre-sized needles 0.4 mm and 0.35 mm.

It’s important to be sure to be very gentle while unclogging the nozzle.

Soft brass 3D printer nozzles scratch easily. Scratches on the nozzle’s interior cause resistance in the filament flow and may increase the nozzle diameter and/or change the filament flow direction.

Scratches also create more places for the filament to catch, leading to more clogs in the future.

Regardless of which method you choose to use, I always recommend heating the nozzle to the material’s printing temperature after the nozzle is cleaned. Then, manually push the new filament through the nozzle before printing. I find this helps purge the nozzle and helps to remove any small contaminants that are left in the nozzle.

Method 4: Acetone

Acetone is an effective solvent for cleaning clogs formed by ABS filament residue.

Acetone quickly dissolves ABS filament, but it’s not great for cleaning other filament materials like PLA or PETG. One major benefit is that acetone cleaning is non-abrasive, which reduces the likelihood of causing damage to the nozzle.

Acetone cleaning is one of the easiest ways to clean 3D printer nozzle clogs.

Simply unscrew the nozzle and submerge it in acetone for two hours. After two hours, you can dry the nozzle and re-install it on your 3D printer.

However, the chemical nature of acetone poses risks due to its flammability and strong odor.

Method 5: Brushing the nozzle

Exterior debris is the most visible nozzle issue. The debris is caused by excess material sticking to the nozzle’s surface.

Here’s how to clean the nozzle exterior:

  1. Heat the nozzle to the printing temperature.
  2. Use a damp cloth or alcohol wipe to clean the nozzle.
  3. Carefully brush the nozzle’s exterior with a brass wire brush.

If your nozzle is covered in debris, it’s best to remove it. After unscrewing the nozzle, gently brush the exterior to remove the debris.

Editor Note

Use a brass wire brush, as steel wool and steel wire brushes can scratch brass nozzles.

Method 6: Replace the Nozzle

A small diameter nozzle beside a large diameter nozzle

It might be time to replace your 3D printer nozzle if all else fails. If you’ve tried cleaning your nozzle but continue to run into issues, it’s time for a nozzle replacement.

Sometimes, cleaning a nozzle just isn’t worth the effort. Swapping to a new nozzle every few months of regular printing is important, especially when using brass nozzles, which wear easily.

Nozzles degrade over time. If you’ve been printing for a long time or using abrasive filaments, the wear on your nozzle isn’t fixable with nozzle cleaning.

How to Prevent Clogged Nozzles

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SUNLU Filament Dryer Box
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Prevention is the best way to eliminate debris and prevent clogged nozzles. Remember, regular cleaning and maintenance save you from frustration and failed prints.

Here are some things you can do to prevent clogged nozzles:

  1. Keep your filament clean and dry: Ensure that your filament is stored in a dry, cool place and sealed in a sealed container or bag with a desiccant to absorb moisture. Proper storage prevents filaments from absorbing moisture from the air. The moisture in the wet filament evaporates in the hotend, causing extrusion issues and clogging. If you suspect your filament has absorbed moisture, you can dry wet filament in a filament dryer or oven.
  2. Set the correct printing temperature: Ensure you use the recommended temperature settings for your type of filament. If the printing temperature is too low, the filament won’t melt properly, forming clogs in the print head. On the other hand, excessive heat can cause filament degradation, which catches filament, creating clogs.
  3. Keep your nozzle clean: Cleaning your nozzle as part of your regular 3D printing maintenance prevents filament residue, debris, dust particles, and dirt from accumulating. I recommend cleaning out the nozzle any time you swap out materials.
  4. Purge the nozzle between material changes: Always purge excess material when switching between different filament types or colors. When you swap filaments, there’s always some old material left in the nozzle. Perform a few purges with the new filament by preheating the nozzle and pushing through some new filament. Or use the extrusion option on the printer’s interface.
  5. Keep the extruder gear clean: The extruder gear pushes the filament through the nozzle. Regularly inspect and clean the gear to remove any filament debris or dus. Fine shavings and dust can clog the extruder gears, impacting the filament flow.

Following these guidelines can effectively prevent clogged nozzles in your 3D printer and ensure a smooth, successful printing experience.

Check Your PTFE Tube

One unlikely culprit of nozzle clogs is gaps in the PTFE tube. PTFE tubing on the Bowden tube 3D printer guides filament from the extruder gear into the hotend.

If the Bowden tube isn’t fully inserted, the gaps can catch excess filament and create clogs. As plastic filament heats and pushes through the tool head, it can leak out into these spaces. The leaked plastic builds up, slowly obstructing the path and requiring more force to extrude the filament.

Eventually, so much plastic accumulates in the gaps that the filament gets completely jammed. To prevent clogs caused by the PTFE tube, ensure it is properly seated from the extruder into the hotend with no gaps.

The heat from the print head can damage the tubing over time. Especially when printing high-temperature filaments. In extreme cases, you may need to replace old tubes. 

Marcello De Lio
Marcello De Lio

Marcello co-founded 3D Print Mentor to share his love of 3D printing. Marcello used to own an online 3D printing company, where he sold unique designs and customized novelty gifts. After closing the business, Marcello’s new passion is 3D printing replica movie props and cosplay items.

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