Stringing is one of the most frustrating problems with your 3d prints. Stringing not only makes the 3D model look messy, but also reduces the strength of the 3d print. Stringing occurs with many different types of filaments, from ABS to PLA, to Nylon but most commonly with PETG filaments.
In most cases, the main cause of stringing is the incorrect retraction settings and hot end temperature setting. However, there are also a number of other reasons that also cause stringing. Let’s find out the causes and solutions to handle and prevent stringing in this article
Contents
What is stringing in 3d printing
Stringing occurs when small strings of plastic are left behind on a 3D-printed model. This is typically due to filament dripping out of the nozzle while the extruder is moving to another location.
This is what happens when stringing occurs to your 3d print:
It’s very important to prevent Stringing in 3d printing as it not only makes your print look messy but also reduces the strength of the object.
Why stringing occurs to your 3d print & Solutions
In 3d printing, Stringing can happen due to several reasons. It can come from the wrong retraction setting in slicer software, or from physical causes like a wet filament.
It is very important to identify the cause of stringing because it will help you come up with the most effective solution.
I will list the most common causes as well as solutions for each below. Let’s take a look!
Wrong retraction setting
This is the most common cause of stringing. Wrong retraction settings may cause terrible stringing. The retraction settings that you should take into account are Retraction Distance, Retraction Speed, and Prime speed.
What is retraction setting ?
The retraction setting tells the extruder motor to pull the filament back before the nozzle moves to another place, preventing the filament from oozing out when the nozzle is traveling.
With proper retraction settings, you can prevent stringing for your future 3d print.
Retraction Distance
This is one of the most important settings for retraction. This setting determines the length at which the filament will retract before the nozzle moves to a new point.
If the retraction distance is not long enough, the filament will continue to flow out as the print head moves. However, if the retraction distance is too long, the filament will not be ready at the hotend and ready for the next meltdown.
If you increase the retraction distance, it will obviously reduce stringing on your print, however, if you increase it too much, the filament won’t be ready in time and will result in loss of detail in the print
Depending on the type of filament as well as the type of extruder you are using, there will be an appropriate retraction distance value. The best way to find the right Retraction Distance value is by performing printing tests with different settings.
Retraction Speed
Retraction speed determines how fast the filament retracts before the nozzle moves to another position. Basically, retracting speed will reduce stringing because the material won’t have enough time to ooze out while retracting.
However, if the speed is too high, the motor gear in the printer (the part that does the filament retraction job) will cause the filament to break or even crush the filament and cause nozzle blockage. This is also one of the common causes of under extrusion.
Similar to the retraction distance setting, by performing various printing tests you will find the optimal retraction speed for your 3d printer. Please note, the above principle will not apply to PETG filament because it is a very viscous filament. You should reduce the retraction speed when using PETG to avoid stringing.
Prime speed
Prime speed is the speed that the extruder pushes the filament into the hot end, making it ready for extruding.
If prime speed is too slow, the filament will have time to ooze out of the nozzle creating stringing and blobs. If prime speed is too fast, the printer may push too much plastic into the nozzle, which may cause over-extrusion.
If you notice that your current prime speed is causing stringing, I recommend you to use a speed 5-8 mm/s lower than the value you are using (this can be set in the slicer software). This is a safe level of reduction that both prevents stringing and ensures that the filament does not clog in the extruder.
Hotend temperature too high
Printing temperature is also a key factor in causing stringing. As the printing temperature increases, the filament becomes more liquid. If you set the print temperature too high, the filament in the liquefied state will easily flow out of the nozzle even if the filament is retracted.
After the liquid resin dries, it will create fibers on the printed product, also known as stringing in 3d print.
On the contrary, if you set the extruder temperature too low, the filament will not melt enough to flow out the nozzle. This can cause clogged nozzle, which leads to under extrusion.
The ideal print temperature varies depending on the type of filament you are using as well as the print configuration you set up in the slicer software. However, the best way to prevent stringing is to lower the print temperature slightly below the current temperature (which is causing stringing).
You should use the recommended printing temperature of the filament. Generally, you should use the following print temperature:
| PLA | 190°C – 220°C |
| ABS | 200°C – 240°C. |
| NYLON | ~240 ºC |
| TPU | 220ºC – 250ºC |
| ASA | 240°C – 260°C |
| PC | 220ºC – 265ºC |
Print speed to slow and combing turned off
Inappropriate Print speed settings will easily cause stinging, especially if the print speed is too slow. For example, you want to set the print speed to be quite slow to ensure the quality of the print. Sometimes the distance between the two printing points will be quite far apart and the nozzle will have to travel a long distance.
During this move, it will be easy to cause stringing as the filament will have enough time to ooze out of the nozzle.
To reduce stringing, if you see extra filaments during printing, try increasing the print speed a bit. Note that if the print speed is too high, the melted filament will not have enough time to flow out of the nozzle, causing under extrusion.
The ideal print speed is one that ensures the filament does not have enough time to ooze out while the nozzle moves between two points, but still ensures the filament extrusion speed. You will be able to find the optimal print speed for the filament you are using by experimenting with different print speed settings.
Also, there’s an awesome feature to fight stringing that’s called Combing. Combing keeps the nozzle within already printed areas when traveling. This results in slightly longer travel moves but it will help significantly reduce stringing.
Here’s how Combing work:
If combing is disabled, the material will retract and the print head will move in a straight line to the next point, which may cause stringing.
Fortunately, most of the best slicer software now supports automatic print speed calculation to minimize the risk of stringing during 3d printing. Here’s the recommended print speed for some popular types of filaments.
| PLA | ~60ms |
| ABS | 40-60ms. |
| NYLON | 30-60ms |
| TPU | 30-50ms |
| ASA | 55ms |
| PETG | 60-100ms |
If Combing is not turned on => turn on this feature in your slicer software and you will see an amazing result.
Wet filament
If you do not manage your filament properly, your filament may become wet from absorbing a lot of water vapor in the air. This is one of the common causes of stringing, especially with PLA because PLA has a rather high moisture absorption rate.
Here is an example of stringing due to wet filament
The reason wet filament may cause stringing is that when the moistured filament is melted in the hot end, in addition to the melted plastic, there will be a little bit of water vapor evaporated. This mixture causes the melted filament to become too viscous and watery and oozed out the print nozzle => stringing occurs.
When you notice stringing due to wet filament, stop printing and proceed to dry the filament before continuing. There are many ways to dry wet filament, one of the most effective is using a filament dryer.
In addition, it is also very important to preserve the filament well to prevent the filament from absorbing water vapor in the air
If you want to learn more about how to dry wet filaments as well as properly store filaments for future use, please refer to this article.
Clogged nozzle
When you use the 3d printer for a long time without regularly cleaning the nozzle, it is very likely that your nozzle will become clogged. Clogged nozzles are also a very common cause of stringing.
Clogged nozzle not only causes stringing but also many other serious errors that affect the quality of 3d prints such as under extrusion
The cause of stringing when the nozzle is clogged is that there will be a bit of plastic left in the nozzle. During the printing process, this residue will also be melted and flow out of the nozzle, sticking to the surface of the 3d printed object and causing stringing.
Solution
During 3d printing, if you notice stringing caused by a clogged nozzle, please stop printing and take the following steps and take the following steps to unclog and clean the nozzle.
Clean dust and excess melted material that got stuck around the nozzle.
Heat up your printer to the print temperature so that the leftover material is melted and use a cleaning needle to unclog the nozzle.
Also, if the nozzle blockage is severe, you can try using other methods such as using acetone, using a cleaning filament, or removing the nozzle completely and unclog it with a long, pointed needle. For more guidance, refer to my detailed and complete guide on how to clean nozzle.
The easiest way to fix 3d print stringing
If you finished your 3d print and noticed stringing but you don’t want to throw it away? Here is a quick easy fix for stringy prints
Things to prepare
| Flush Cutters: Flush Cutter is the main tool to cut supports around the object. It is recommended to use a Flush Cutter made from hardened steel with a plastic handle and, most importantly, with a sharp blade. | 
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| Blow torch: Used to heat the nozzle to a high temperature, it is very useful, especially for materials with a high melting point | 
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Step 1: Use flush cutters to remove excessive filament strands
First, use Flush cutters first to cut off the excess hairs lying around the 3d print
Step 2: Use a blow torch to remove the remaining hairs
If the remaining plastic is too short or too hard to remove with a flush cutter, then it’s time to use a blow torch to heat and soften the plastic
Remember not to burn a spot for too long with the blow torch, to avoid completely melting the plastic and completely ruining the 3d print.
Video for your reference
Wrapping up
Stringing is always a pain even with experienced 3d printing users. Hopefully, my tutorial will help you prevent and combat stringing in 3d print.
To get the best retraction settings and print speed, it’s best to try as many times as possible with a variety of media. You will accumulate a lot of experience and find the most suitable settings for you
If you find that there is an optimal and effective method that has not been mentioned in this article, please leave a comment below. It will be very useful and bring great value to users in the 3d printing community
