3D Print Stringing. 5 Easy Ways to Fix It & Prevent It!

by Mike Brooks | Last Updated: March 5, 2022

3D printing professionals and hobbyists agree that stringing is a common issue they face in the ordinary course of their work. So, what is 3D print stringing?

Stringing occurs when filaments leak through your 3D printer nozzle in places where they shouldn’t.

It makes the 3D model look messy as the small wispy, and hairy bits of filaments occupy the print gaps. More significantly, stringing impacts the final print quality negatively.

Models with significant print gaps tend to experience stringing more than others. Thankfully, fixing stringing is easy as several print settings can help printers deal with this issue.

3D print retraction setting tops the list as it enables the 3D printer extruder nozzle to pull a filament backward when it finishes printing a section; thus, stopping filament oozing that causes stringing.

Also, retraction settings help the print head push back the filament into the nozzle when it is time to start printing again.

Why Does 3D Printing Stringing Occur?

Stringing or plastic oozing is a frequent occurrence in the 3D printing process. Also, you can quickly notice oozing because it leaves behind delicate strings similar to cobwebs or strands of hair.

Stringing or oozing happens because of a couple of reasons. The most typical reason why stringing occurs in 3D printing is filament oozing out of the print head while it travels.

As the print head travels over the build volume, tiny bits of filaments ooze, causing excessive stringing. These molten plastic filaments eventually solidify, sticking to the printed parts.

Ordinarily, stringing shouldn’t happen. However, it may also occur depending on the type of filament you are using. Likewise, hygroscopic plastic filament materials like TPU and Nylon tend to have stringing issues if not well stored.

Also, PETG remains one of the most notorious filament in the market with frequent stringing issues.

Another reason why oozing occurs is the use of filaments that need a high temperature to melt during 3D printing. You may need to edit process settings in a bid to achieve the correct temperature setting. It will aid your cause to stop excessive stringing.

What Does Stringing Do to 3D Print Models?

Stringing, oozing, or dribbling occurs when excess and unwanted material remains on the 3D print model after printing is completed. Still, it gets its name “stringing” as the unwanted material remaining on the print looks like strings.

Significantly, the extra materials remain stuck on the edges and sides of the finished model – it causes the finished object to look messy. Also, the thing lacks the exact dimensions it should, losing its envisioned quality in the process.

Some 3D printer users prefer removing strands of plastic with moderate stringing from finished 3D models. However, they find it difficult to remove the plastic strands using ordinary post-processing methods.

Notably, 3D printer users tend to leave behind unnecessary marks that hamper the surface quality. In fairness, these efforts aren’t worth it as, in the end, they tend to discard the model and re-print the model using updated or edited settings.

What Causes Stringing in 3D Printing?

Excessive Heat

If you heat a polymer material, it melts. The melted plastic is deposited layer by layer to build the 3D print object. If the printer engages a high printing temperature, it produces too much heat that causes stringing.

As the extruder temperature increases, the printer nozzle may leak bits of plastic material that cause stringing.

3D Printer Speed

The print speed at which a 3D printer works determines if it may cause oozing. Additionally, if the printer moves extremely fast, it causes holes and oozing along the way.

As such, most 3D printers have an adjustable speed to help avoid 3D printing stringing.

How to Fix Stringing/Oozing?

Stringing or oozing affects print quality. Therefore, it will be helpful if you find ways of combating it. Excessive heat in the extruder motor causes a high print temperature that results in stringing.

Also, a high 3D printer speed remains one of the most typical causes of stringing. If you are a 3D enthusiast looking for solutions to this readily noticeable phenomenon, you need to tackle these causes.

Retraction Distance

Retraction distance remains the most critical retraction setting. It determines the volume of plastic that is pulled in the printer nozzle.

As more plastic is retracted, it reduces the possibility of nozzle oozing.

Most standard drive direct extruders require a retraction distance of 0.5mm to 2.0mm. Therefore, if you experience oozing with your prints, try increasing your retraction distance by 1.0mm and test prints.

Check whether the test results in an increased performance devoid of oozing.

Retraction Speed

Another significant retraction setting is the retraction speed. Still, retraction speed determines how fast the filament retracts from the 3D printer nozzle.

So how does retraction speed affects oozing?

If you retract too slowly, plastic oozes too slow and may readily leak before the extruder moves to its next destination.

On the contrary, if you retract too fast, the filament may separate from the molten plastic inside the nozzle.

More significantly, an optimal spot is found in the range between 1200-1600mm/min.(20-100mm/s).

Extremely High Nozzle Temperature

The moment you have set your retraction settings right and find out that you still encounter stringing, check out your metal wires to ensure they operate optimally and don’t negatively affect temperature settings.

If the temperature setting is too high, the plastic inside the nozzle will be less explosive and will leak out of the nozzle easily.

By contrast, if the temperature is too low, the plastic will remain solid and may have a lot of difficulties extruding out of the nozzle.

So, if the extruder temperature is too high, decrease it by 5-10 degrees Celsius. Doing so will have a significant impact on your print quality.

Long Movement over Open Spaces

Extruder movement between two different locations carries with it the likelihood of 3D printing oozing.

During long extruder movement, that plastic starts to ooze out of the nozzle. Therefore, the longer the length of the direction, the more the oozing.

Short-distance moves mean the plastic has little time to drip out of the printer head nozzle.

More importantly, software that automatically adjusts the printer nozzle travel path, shortening it up, is now found in the market. The software helps eliminate the oozing problem.

Printer Movement Speed

You can reduce stringing by increasing the movement speed of your printer head nozzle. Furthermore, the amount of time that the extruder travels between two locations determines the number of strings.

You can always set your printer movement speed to reduce stringing as it travels over two locations.

Filament Material Drying

Always secure your 3D plastic filament to protect them from absorbing moisture from the environment.

Filament moisture tends to evaporate inside the printer nozzle and push the plastic out of the nozzle opening, as such, moisture evaporation inside the nozzle results in stringing with the poorly printed final products.

Is PLA More Susceptible to Stringing Than Other Filaments?

Different materials have different 3D printing temperature ranges. For example, PLA has a lower printing temperature range of 185-205 degrees Celsius.

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On the other hand, PETG has a higher print temperature range of 220-245 degrees Celsius.

The higher print temperature of PETG and the other materials reduces the fluid resistance to liquid flow or viscosity. It renders these other materials prone to stringing than PLA filament.

Easy Ways to Prevent 3D Print Stringing

1. Print at the Right Temperature

If you want to reduce stringing, print at the right temperature. Likewise, reduce your temperature setting to ensure minimal oozing in your 3D prints.

2. Increase the Retraction Settings

The retraction mechanism works like a pullback gear. If you activate the retraction setting, it will pull back the semi-solid plastics that push the liquid to extrude from the nozzle.

Retraction relieves the pressure of melted filaments. Thus, it stops plastic from dripping out of the nozzle when in motion.

3. Adjust Print Speed

Adjusting your print speed helps stop oozing in 3D printing. Significantly, the filament will take more time to melt and become ready to extrude as it only runs a little.

4. Protect Your Filament From Moisture

3D printing filaments absorb moisture from the environment. This moisture turns into bubbles as it evaporates when heated. Still, the bursting bubbles cause oozing.

Therefore, you need to store and secure your plastic filament away from moisture. It’s because leaving your filament in the open air for prolonged periods makes it absorb water.

5. Clean Your Printer Nozzle

3D printer nozzles often accumulate plastic particles during printing. If left for a long time without cleaning, the plastic gets stuck inside the nozzle.

It remains a common occurrence with high-temperature plastic filament, such as the PETG. So, you may consider switching to lower temperature filaments like the ABS and the PLA.

Cleaning your printer nozzle frequently to avoid clogging will help you to prevent stringing.

Conclusion

3D printing stringing remains a frequent challenge that needs addressing if you are to improve your print quality.

Stringing makes the 3D print look messy and ugly as unwanted plastic material settles in the edges and the object’s surface.

The object loses its original dimensions and impacts negatively on quality. Luckily, there exist numerous measures that you can take to tackle stringing that include retraction settings, adjusting the right speed, cleaning the extruder nozzle, and preventing filament moisture.

Michael Brooks is the founder of M3DZone.com. He sees a very bright future for 3D printing that's why his mission is to try and make this easy for everyone. Discover your hidden talent and creativity. You can follow here: Facebook, Twitter & Pinterest.