Stringing on parts coming from an Ender 3 can be a really annoying defect. Those little wisps of plastic can ruin the print’s surface and increase post-processing time. The good news is that you can solve this issue by correctly calibrating your Ender 3’s Retraction settings.
The best Retraction Settings for an Ender 3 is a Retraction Distance between 4-7mm and a Retraction Speed that’s in the 35 – 45mm/s range. For Direct Drive Ender 3 Printers, you can use a smaller Retraction Distance that’s between 0.5-1mm and a Retraction Speed that’s also in the 35 – 45mm/s range.
In this article, we’ll take a closer look at the Retraction Settings and how they affect the Ender 3. I’ll also show you some of the best slicer settings and how you can further calibrate these values for your Ender 3 Printer.
Let’s dive in!
What Causes Stringing on the Ender 3?
Stringing is caused by the molten oozing out of the printer’s nozzle while it moves over the print. This happens when the printer’s needs to move from one area of the print to another without depositing material.
Although the extruder stops feeding the nozzle with filament, the pressure inside it can lead to some material escaping from the nozzle. As a result, the nozzle deposits little strands of plastic over its path, which turn into stringing.
In the image above, we can see the little strands of plastic between the two towers.
How Does Retraction Fix This?
Retraction fixes this by reversing the direction of the extruder motor before the nozzle starts traveling. This pulls the filament out of the nozzle a bit and relieves the pressure inside it.
As a result, the nozzle doesn’t over-extrude any material when it moves from point to point. When the nozzle is ready to resume printing, the printer pushes the filament back into the nozzle via a process called priming.
Retraction in Bowden Tube Vs Direct Drive Extruders
Bowden and direct drive extruders are the two main types of extruders on Ender 3 printers. Older models like the Ender 3, Ender 3 V2, and Pro have Bowden extruders while newer ones like the S1 and Pro have direct-drive extruders.
Bowden extruders have the extruder motors farther away from the nozzle and they feed filament to it through a tube called a PTFE tube. This configuration means they have to pull the filament a farther distance during retraction.
The additional retraction distance helps compensate for friction and other forces, and even with that, retraction isn’t always accurate.
On the other hand, direct drive extruders are mounted directly on the print head, so retraction is faster and more accurate. Because the filament path is shorter, the motor pulls the filament through a smaller distance during retraction.
So, both extruders require different settings.
Best Ender 3 Retraction Settings
There are many parameters that control the retraction on Ender 3 printers. In this section, I’ll be explaining how these parameters work and the optimal value for them.
Note that I’ll be using the settings in the popular Cura slicer as that is what most FDM printer owners use. So, let’s look at these settings.
The Enable Retraction setting turns on retraction for your Ender 3 printer. If you do not enable this setting, the printer will not draw the filament back from the nozzle during travel moves.
So, you have to turn it on to be able to tune your retraction settings and solve stringing. This setting is turned on by default in Cura.
The optimal Retraction distance for the Ender 3 V2 is between 4–7mm while that for the Ender 3 S1 is between 0.5-1mm. This setting specifies the amount of filament the extruder will pull back from the nozzle in mm.
For example, if the retraction distance is set to 5mm, the printer will pull out 5mm of filament from the nozzle before the travel move. Once printing is about to start again, it pushes the same length of filament back in a process called priming.
The retraction distance should be kept to the lowest value possible, which eliminates stringing. This is because the longer the retraction distance, the greater the risk of under-extrusion.
Also, this can lead to filament grinding where the extruder’s gears gradually deform a section of filament as they go over it repeatedly. This can lead to clogs and even filament breaking.
Finally, drawing the filament in too far can also clog up your hot end as molten filament gets drawn up too far and solidifies. So, you’re going to have to strike a balance between preventing stringing.
The default value for Bowden tube Ender 3 printers is 5mm while for direct drive Ender 3s the value is 0.8mm.
The optimal retraction speed for Ender 3 printers is between 35-45mm/s. This value controls how fast the extruder pulls the filament back into the nozzle during extraction.
A faster retraction time speeds up printing and reduces the chances of filament leaking to cause stringing. However, it can also lead to the filament grinding as mentioned earlier in the previous section.
This speed is broken into two components in Cura: Retraction Retract Speed and Retraction Prime Speed. The former controls the speed at which the extruder pulls the filament in while the latter controls the speed at which the extruder pushes it back out while priming.
Some users recommend reducing the Retraction Prime Speed as the filament has a higher chance of grinding and breaking during priming. The default speed in Cura for both values is 45mm/s.
Retraction Extra Prime Amount
The optimal Retraction Prime Amount is 0mm. This setting compensates for any material lost from oozing by pushing extra filament through the nozzle during priming.
Most people recommend leaving this value at zero because it can cause blobs when the printer starts printing after retraction. If you calibrate your retraction distance and speed properly, you’re not going to need it.
The default value for this in Cura is 0mm.
Maximum Retraction Count
The recommended Maximum Retraction Count is 10. This specifies the maximum amount of retraction allowed along a particular section of filament.
The length of this section is specified in another setting called the Minimum Extrusion Distance Window.
For example, let’s say you set the Maximum retraction count to 20 and the Minimum Extrusion Distance Window to 2mm. After the 20th retraction on a 2mm length of filament, the printer will turn off all retractions for the next 2mm.
Reducing this value helps protect against filament grinding. However, it can also reduce retractions and lead to an increase in stringing
The default value is 100, which almost all users agree is way too high.
Minimum Extrusion Distance Window
The optimal Minimum Extrusion Distance Window should be the same value as your retraction distance. This is the length of the filament section over which the maximum retraction count will apply.
This user reduced theirs from 10mm to their Retraction Distance (4mm) and immediately got stringing-free prints.
The default value of this setting in Cura is 10mm.
Retraction Minimum Travel
The optimal retraction minimum travel value is 1.5mm. This setting specifies the minimum travel distance for retraction to be enabled. At travel distances below the set distance, the printer will not retract the filament.
This setting helps speed up printing as the filament doesn’t have time to ooze while the nozzle moves over short distances. As a result, retraction isn’t needed.
However, if you increase the distance, you run the risk of stringing between the delicate features of your model. On the other hand, if you decrease it you can increase the print time as the printer will retract the filament for even the smallest of travel moves.
The default value in Cura is 1.5mm.
The Optimal Combing mode for Ender 3 is the Within Infill option. This setting controls how the nozzle moves while traveling from one point to another while printing. It basically tries to keep the nozzle’s movement within the print so it doesn’t cross over any walls while printing.
This will reduce the need for retraction as the stringing will be restricted to the inner structure of the print. However, this can increase printing time, as the nozzle might take longer paths when traveling from path to path.
The default value for this setting is Not in Skin.
Print Temperature [Bonus]
If your print temperature is too high, it can result in stringing. The resulting flow will be too much for the nozzle to control, even with retraction, and this will lead to the plastic oozing uncontrollably out of the nozzle.
So, make sure you are using the correct, manufacturer-specified printing temperature for your filament.
How to Calibrate Your Retraction Settings
There are many calibration tests you can run to fine-tune your retraction settings and get them in the optimal range. Using the settings in the previous section as a starting point, you can gradually dial in your Ender 3 settings to their optimal values with these tests.
Two main tests you’ll want to look at are:
- Retraction Tower
- Temperature Tower
The Retraction tower is one of the most useful tests for a 3D printer. It’s basically a tower divided into various sections that represent a particular Retraction distance/speed. You can vary either your retraction speed or distance across these sections to discover their optimal value.
You can find the retraction tower in Cura’s calibration shape plugin. If you do not have the plugin installed, check for it in the Cura marketplace and install it.
After installing it, you’ll be able to see different towers for different materials and tests. Select the Retract Test tower, import it onto your build plate, and modify its G-Code using a post-processing script.
The tower will print with different retraction values for different sections. Once it’s done printing, look at each section and choose the one with the least stringing. CHEP provides a wonderful explanation of how you can configure and read this test in the video below.
Just like the retraction tower, the temperature tower is also divided into several sections. You can use a script with this tower to vary the temperature of each tower section to find out the best printing temperature.
You can find the temperature tower in the Cura calibration shapes plugin. Choose the right tower for your material and configure its post-processing script properly.
Once you’re done, print the model out and observe the tower sections. The one with the least stringing and the best layer adhesions is your optimal printing temperature.
You can learn more about this test in this video from Ricky Impey.
Calibrate Your E-Steps
The E-steps is a value that determines the number of steps the extruder motor needs to take to extrude 1mm of filament. If this value is out of order, it can affect both your extrusion and retraction.
In fact, many users have said that their stringing, over-extrusion, and under-extrusion stopped when they properly calibrated their extruder’s E-steps.
So, check your Extruder’s E-steps to make sure you have the correct value there. You can learn how to calibrate this value by checking out this article on How to Calibrate Your Extruder E-Steps & Flow Rate Perfectly
Other Ender 3 Retraction Tips
Here are some additional tips that can help solve any retraction issues you might be having on your Ender 3.
Check Your PTFE Tube
If your PTFE tube is worn out or incorrectly seated, it can hinder the movement of the filament. Check the tube to make sure it is properly seated in the hotend. Make sure it is pushed all the way in.
Also, check the clips to make sure they are holding the PTFE tube in place properly. Lastly, inspect the PTFE tube for any sign of wear.
If you notice any wear, cut off the worn parts, or if the damage is too much, replace the tube immediately.
Clean Your Nozzle
Build-ups and clogs in the nozzle can lead to stringing. These build-ups can interfere or mix with the filament flow, leading to stringing and other defects.
So, make sure you clean your nozzle regularly. You can use this article I wrote on nozzle cleaning as a guide to properly clean your machine.
Buy Quality Filament and Store It Properly
Low-quality and water-contaminated filaments can also be the root causes of stringing, oozing, and other print defects. In this scenario, no matter how much you fine-tune your Ender 3’s retraction settings, you might not be able to get rid of the stringing.
So, make sure you buy quality filaments and store them in a cool, dry location. You can also buy special dryer boxes to get rid of any moisture present in the filament.
Getting the best retraction settings for your Ender 3 is a big step towards printing impeccable 3D models. With this guide, you have everything you need to fine-tune your settings effectively.
As you embark on future printing projects, let these insights be your roadmap to printing excellence. Good luck and happy printing!