How to Fix Stringing Problem in 3D Printing | Tronxy 3D Printer

3D printing beginners usually encounter stringing issues during their printing process. Stringing issues is a very common issue in 3D printing. It generally does not cause printing failure, but it will make the model’s surface very unrefined. There are many small filament strings on the printed model, especially the intermittent strings in the gap part of the model, which seriously affects the appearance of the model.

What is the 3D stringing issue?

In the process of 3D printing, the print head needs to move constantly. In the process of travel move from point A to point B, it is easy for the print head to extrude a string BETWEEN point An and point B. According to our design, we only need melten filament to be printed at point and and Ponit B, there is no need to extrude/print any layers/strings Between pint A and paint B.

If the stringing phenomenon occurs inside the model, the model will look ok on the outside. However, if the stringing happens on the model’s surface, it will make the the product look fluffy, which significantly affect the appearance of the model.

Why this happens?

Generally speaking, no filament should come out of the print head of an FDM printer if no force is applied to the filament.

However, when the filament is fed into the heated aluminum block and melted at high temperatures,  the filament may “ooze” from the print head under the influence of gravity. The filament inside the print head is not completely solidified, and this melted filament is coming out from the print head automatically, which is the so-called “string phenomenon.”

When the printhead is moved from point A to point B, no filament is extruded, no substantial filament is printed, and no new layer is formed. This is called TRAVEL MOVE.

There are many reasons for stringing issues in 3D printers. When you encounter a stringing problem in the process of 3D printing, you can troubleshoot the problem in the following order and follow the suggested method below to solve the stringing problem.

Reason: poor quality filament

First, you can check your filaments to see if the poor quality filament causes this problem. If the quality of filament is not good, it will also cause stringing.

When purchasing filament, please choose large factories with quality assurance, and at the same time, you should pay attention to the storage method of filament to avoid dampness.

Reason: the printing temperature is too high.

Generally speaking, high temperature is the main cause of wire drawing.

Solution: the main reason for the stringing problem is the temperature of the extruder.

If the extruder’s temperature is too high, the filament in the print head/nozzle will become very sticky and flow out of the nozzle more easily.

But, if the temperature is too low, the filament will remain hard and difficult to squeeze out of the nozzle. If you think your retraction setting is correct on your 3D printer, but this stringing problem still occurs, please try lowering the extruder temperature by 5 to 10 degrees. Lowing the extruder’s temperature setting will have a significant impact on the final print quality.

The printing temperature of  PLA filament is generally about 200 °C. If the temperature is set too much, it will lead to stringing problems. We can reduce the printing temperature to solve this stringing problem.

In addition, filaments made by different manufacturers have different temperature requirements. You can try a few prints and figure out the best matching temperature between the filament and your 3D printer when using new filament.

Sometimes, we do not set a high temperature for the 3D printer, but the temperature of the print head is very high (higher than the pre-set temperature). What should we do?

Check whether the screws on the aluminum block are loose, or whether the temperature sensor is in poor contact with the aluminum block.

There are usually two lines on the aluminum block of the print head: one is a heating rod, and the other is a temperature sensing line. The function of the Temperature sensor is to sense the temperature of the print head.

Suppose the screw on the aluminum block is loose and the temperature sensing resistance head is not fixed on the aluminum block. In that case, the measured temperature will be lower than the actual temperature of the print head. At this point, you need to check to see if the screw is loose or the resistance head is detached from the aluminum block. If the screw is loose or the resistance head is detached from the aluminum block, please re-fix it.

Reason: insufficient retraction distance

What is retraction？

Retraction, the extruder is reversed, and the filament is pulled back in the opposite direction.

Under normal circumstances, the extruder extrudes melted filament at point A, and the extruder extrudes melted filament at point B, but the extruder does not extrude any filament between point A and point B. It is necessary to reverse the motor and rewind the filament to achieve no extrusion between point A and point A. this is retraction.

Solution: there is a retraction distance parameter in the slicing setting. If the value of this parameter is set too small, the extruder will be reversed, but the retraction distance does not reach the required distance. There is surplus melted filament in the print head/nozzle, which flows out along the nozzle. When sliding from point A to point B, the extruder is naturally drawn a string with the movement.

The most important setting of the retraction is the return distance, which determines how much material is withdrawn from the print head during the retraction. In general, the more filament is extracted from the nozzle, the less noticeable the string will be. Generally speaking, it is appropriate to set the retraction distance to 5~6mm when printing with PLA. If your printer has a stringing problem, try increasing the setting by 1mm each time to find the most suitable value for retraction distance.

Some 3D printer users have been using slicing software for a long time, but are not familiar with the retraction setting function of the software. The function of ” retraction setting” can effectively avoid the stringing problem on the model’s surface and improve the printing quality and forming effect.

In our 3D printer, we use Tronxy Slicing Software or Cura Slicing Software.

When you open the slicing software, you can find the “Retraction Distance.”

After setting the “Retraction Distance” value, print the actual model to observe whether the stringing phenomenon  is disappeared

Here are pictures to help you get a better understanding of retraction distance seeting:

Retraction Setting at Tronxy Slicing Software

Reason: the retraction speed is too slow.

Solution: another important setting in the retraction is the retraction speed. This setting determines how quickly the filament are retracted.

If the retraction speed is too slow, the melted filament will still flow out of the nozzle. If the filament is retracted too quickly, the unmelted part of the filament may be separated from the melted part, or the two dears may bite off a piece of the filament. There is usually an excellent retraction speed between 20 and 100mm/s. We need to do some tests with different retraction speeds to find the most suitable retraction speed and reduce the wire stringing situation.

Reason: The TRAVEL MOVE distance is too long

Solution: as we discussed above, stringing occurs when the extruder and print head moves between two different positions.

During the movement of the print head, the filament hangs down/prints in a position where it is not supposed to be. This is a suspended part, no need for any filament printing.

The distance that the print head needs to move has a significant influence on stringing. If it is a short distance, the print head can moves fast enough before the filament has time to fall from the print head. Then, the print head moving over a large distance is more likely to lead to a stringing problem.

To effectively reduce the stringing phenomenon, we can minimize the TRAVEL MOVE distance when designing the model.

To summarize:

Different filaments, different model designs and different printing environments will affect the setting of 3D printer and its printing effects. Therefore, when solving the stringing problems, we should understand the causes and adjust the solution from different situations.

You may need to try different methods to solve the stringing problem. Generally speaking, we should first check the quality of the filament, make sure it is in good condition, then set the appropriate printing temperature for the filament, and do not overheat the filament. Next, check the temperature of the print head, and make sure the temperature sensor is getting the actual temperature. Finally, check the printer’s parameter settings, such as retraction distance, retraction speed, and so on.

Compared with other 3D printing problems, the stringing problem is relatively easy to solve, right? As long as we understand the cause of the stringing problem, we can follow the above steps to solve the problem. We sincerely hope this article can be helpful to you.