PETG Stringing – Causes & Possible Solutions

If you have printed with PETG, you must have encountered the Stringing issues and seen the kind of negative impact it has on the final print. In this article, you will see how to prevent the stringing problems to get high-quality prints. 

Why does the PETG Stringing problem arise? How to solve it?

The PETG stringing problem can be solved by optimizing the retraction settings as below:

  • Increase the retraction 
  • Increase the nozzle traveling speed 
  • Reduce the Nozzle Temperature 

So, let’s dive into how to minimize / totally reduce stringing in PETG. Take your time and test out each of the solutions that we discuss here. Keep trying until you win over the problem.

Know PETG Characteristics To Reduce PETG Stringing:

Before finding a solution for PETG stringing, it’s essential to understand its characteristics. Firstly, PETG is a thermoplastic filament modified with glycol, because of which it turns to be transparent and slightly viscous.

The melting point of PETG is low and thus minimizes the crystallization. Glycol treatment makes it easier to print. 

PETG turns to complete liquid when heated, this boosts up the printing process and makes it reliable. Today, PETG is classified as Food Safe and hugely used by many private 3D nerds. 

3D Stringing

3D Stringing happens when the nozzle emits excess filament in the form of a thread while traveling from one point to another point. These threads show up in the final result and are difficult to remove. 

So, take measures to prevent the Stringing problem. 

PETG Stringing

If you are printing with PETG, then you need to be extra careful of Stringing. Because of the high melting temperature and high viscosity, the excessively melted material spills out from the Nozzle tip while it is moving. This drags the spilled PETG thermoplastic in the form of a thread or strings. These strings will ruin the end result. 

How to Reduce PETG Stringing

There are many methods to overcome Stringy PETG and are listed below:

1. Increase the retraction values and reduce the Nozzle travel distance

If you observe more threads on your model, then you need to increase the retraction value. Most often, this alone fixes the problem by enabling the extruder motor to suck the melted filament from the nozzle during retraction. This prevents the plastic from spilling out from the Nozzle. 

Start increasing the retraction values to 1 mm and the traveling speed to 5 mm per second. Play with these values until threads are totally eliminated. There are no patented or standard values, they vary based on different PETG rolls and brands. 

How to Prevent Stringing in 3d Printing: Minimizing the travel distance is another effective method of preventing PETG Stringing in 3D printing. These values define how long the nozzle will move before the filament is retracted. If low values are set, 3d stringing will not occur even during shorter distances.

2. Increase the Nozzle traveling speed

Increasing the print head traveling speed is another effective method of preventing 3D Stringing. The faster the print head moves, the less time the filament has before it spills out from the Nozzle. This is advantageous when working at higher temperatures.

Start increasing the speed gradually in terms of 10mm per second. As you increase, you will reach the precise value based on the chosen filament on a selected printer. Once the precise value is reached, you can make the test print and check if any more threads are coming.

3. Reduce the Nozzle Temperature

As we’ve already discussed, the viscosity of the filament varies based on the temperature of the Nozzle. Especially with PETG, it turns to fluid quickly when its melting point is reached. 

If you’ve tried all the above remedies and didn’t find any improvement, then Nozzle temperature is the culprit. Too much high Nozzle temperature will contribute to stubborn PETG stringing. The best way to test and avoid stringing is to do a test print of the tower. This tower is designed in such a way to help determine the perfect nozzle temperature setting within a single print. Thingiverse here has this test model in a downloadable format. 

Bear in mind not to reduce the temperature too much nor increase it too much. Find a healthy point that ensures the proper surface structure without stringing.  

PETG Stringy Nature: Does PETG Suit Me?

Usage of PETG in your printing is dependent on many factors. Before deciding, analyze the model you want to print and the characteristics it should have. PETG has many helpful properties and leveraging it depends upon the purpose of the model for which it is used. If you are looking for durability, flexibility, and transparency in your model, then PETG is the right choice for you. 

Bheema Shankar
Author | Website

I am Bheema Shankar. I have worked on SLS, CJP, DLP, SLA and FDM technologies at Think3D. Currently working as Process and application engineer at VEER-O-METALS PRIVATE LIMITED. I am always fascinated by the process of creating things layer by layer. This fascination led me to pursue a career in 3D printing technology. I am passionate about how 3D works and enjoy exploring new ways to improve the 3D printing process.

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