Configuring Retraction Settings for PLA – Detailed Guide

While PLA isn’t exactly a type of filament that causes a lot of stringing (especially compared to PETG, which is practically notorious for it), retraction settings that aren’t configured correctly can still quickly turn your print into a stringy mess that doesn’t look very appealing.

In this guide, we will explain how you can configure your retraction settings as optimally as possible for printing PLA filament, both for Bowden and Direct Drive extruders, which should allow you to enjoy your prints without any issues related to over-extrusion in sight.

Additionally, as a bonus for Ender 3 users, we will be including example PLA-optimized retraction settings for both the regular Ender 3 models (Bowden extruder) and the Ender 3 S1 (Direct Drive extruder) that you can use to get into the action right away!

Configuring Retraction Settings for PLA

For this guide, we will be discussing retraction through the retraction distance, retraction speed, retraction extra prime amount, retraction minimum travel, and minimum extrusion distance window parameters in Cura due to it being the most commonly used slicer.

That being said, if you aren’t using Cura, you will likely still be able to find the same parameters in the slicer you’re using with similar names.

Retraction Distance

The retraction distance value is the distance that the filament travels away from the tip of the nozzle whenever your 3D printer performs a retraction.

When printing PLA with a Bowden extruder, a reasonable starting point for the retraction distance value is 6 mm, which should allow you to print without any glaring problems related to retraction in most cases.

On the other hand, if you’re using a Direct Drive extruder instead, a retraction distance value of 1 mm is what we would recommend as a starting point, as Direct Drive extruders don’t need as much retraction as Bowden extruders.

Once you complete a print, or a few prints, with this retraction distance value, you can reduce it if you’re observing under-extrusion on your prints due to filament grinding (which can even lead to extrusion stopping altogether in severe cases where the extruder completely loses grip on the filament), or increase it if you observe signs of over-extrusion such as stringing and blobs instead, preferably in increments or decrements of 0.5 mm at most.

That being said, to really dial your retraction distance value in as best as possible, we highly recommend using the Cura Calibration Shapes plugin, which allows you to print a retraction tower that uses different retraction distance values in a single print for testing purposes, making testing a whole lot quicker and easier.

You can find a more detailed guide on using the Calibration Shapes plugin in the following section.

Retraction Speed

The retraction speed value is the speed at which the filament travels whenever your 3D printer retracts or primes (unless the priming speed is defined separately through the Retraction Prime Speed parameter) the filament.

Regardless of whether you’re printing PLA on a Bowden or Direct Drive extruder, a retraction speed value of 45 mm/s should be quick enough to prevent any blobs from appearing but also not so fast that your 3D printer grinds the filament.

Once you have results from a print, you can increase this value if you observe the presence of blobs on the print or decrease it if there are signs of filament grinding, such as plastic pieces that are chipped away and under-extrusion, preferably in increments or decrements of 5 mm/s at most.

Once again, to really dial your retraction speed value in, we highly recommend using the Cura Calibration Shapes plugin, this time printing the retraction tower with different retraction speed values instead and observing the results to pick out the value that produced the best results.

You can find a more detailed guide on using the Calibration Shapes plugin in the following section.

Retraction Extra Prime Amount

The retraction extra prime amount value is the amount of extra filament that your 3D printer will prime after a retracted travel move, which fulfills the purpose of compensating for any material lost to oozing during travel.

As the retraction extra prime amount feature is designed for compensation purposes, we initially recommend setting this value to 0 mm^3 and observing how your 3D printer behaves during extrusions that take place right after retracted travel moves.

Once you get a few test prints in and gather results, you can increase this value in small increments (~0.05m^3 at a time) if you’ve noticed under-extrusion, specifically after retracted travel moves, as such a sign would clearly show that your 3D printer is losing material to oozing during travel moves despite retraction being enabled.

That being said, in most cases, it’s better to find ways to eliminate oozing (such as further increasing retraction distance) instead of using the retraction extra prime amount feature right away, as it’s usually considered to be a bit of a band-aid fix that is better saved to be the last resort.

Retraction Minimum Travel

The retraction minimum travel value determines the minimum distance the nozzle needs to travel (during a travel move) for a retraction to take place beforehand.

As the nozzle stops its movement before performing a retraction, not having such a limit would lead to the nozzle stopping way too frequently, which then would cause the printer to produce an excessive amount of blobs in scenarios where a lot of short travel move paths are present.

Additionally, as stringing is a lot less likely to happen during short travel moves due to the plastic not having enough time to ooze out of the nozzle before extrusion starts again, there is no benefit to retracting over short distances anyway.

With that said, we recommend keeping this value at its Cura default of 1.5 mm as a starting point when printing PLA and configuring it further based on your findings after a few prints.

If the appearance of an excessive amount of blobs is a frequent problem on your 3D prints, especially in areas that feature short travel moves, you will need to increase this value, which will further increase the required travel distance for a retraction to occur.

On the other hand, if you’re observing stringing between short distances, it’s a good idea to decrease this value instead, which will prompt your 3D printer to start retracting the filament over much shorter distances and hopefully eliminate stringing.

Finally, when experimenting with retraction minimum travel, it would be best not to decrease or increase the value more than 0.1 mm at a time, as this will allow you to obtain much more precise results from your tests.

Minimum Extrusion Distance Window (& Maximum Retraction Count)

The minimum extrusion distance window value, along with the maximum retraction count value, determines the maximum amount of retractions that your 3D printer will perform on a specific portion of the filament.

So, for instance, if your minimum extrusion distance window is set to 5 mm, and the maximum retraction count is set to 25, your 3D printer is only allowed to retract the same 5 millimeters of the filament 25 times in total.

As soon as the filament moves to a point where the 25th latest retraction was made farther than 5 mm away on the filament, a new retraction is allowed yet again.

With this limit in place, the filament is saved from getting worn out to a point where the extruder gear cannot successfully grip it anymore (this issue is known as filament grinding) as a result of the constant retractions, which otherwise would create a new set of problems for the print ranging from under-extrusion to extrusion stopping altogether.

When configuring the minimum extrusion distance window value, the rule of thumb to follow is pretty straightforward, regardless of the filament you’re printing, which is to set it to a value equal to or very close to the retraction distance.

With the minimum extrusion distance window tied to the retraction distance value at all times, it becomes possible to quickly modify the retraction limit by adjusting the maximum retraction count value alone, which makes the calculation & configuration process a whole lot more convenient compared to having two separate values to think about.

Finally, when it comes to configuring the maximum retraction count value, our recommendation would be to start off with the formula of 5 retractions per 1 mm of minimum extrusion distance window, such as a maximum retraction count value of 30 for a minimum extrusion distance window value of 6 mm, and work your way up in increments of 5 across each test print if you come across stringing due to a lack of retractions, as the lowest point where stringing doesn’t occur will always be the most optimal maximum retraction count due to it reducing wear & tear on the filament and preventing potentially unnecessary retractions.

Calibrating Retraction Speed & Distance with Cura Calibration Shapes Plugin

The Calibration Shapes plugin is a handy tool that includes different shapes and pre-configured post-processing scripts to allow you to print test shapes with varying print settings, making it perfect for testing retraction.

To start, click the Extensions option on the Cura menu bar, hover over the “Part for calibration” option, and choose “Add a retract tower” from the list, which should insert a retraction tower into the build area.

Following that, slice the model, and navigate to the Preview section in Cura.

Next, use the layer slider on the right to find out how many layers the base of the retract tower consists of and note this value, which will be our Change Layer Offset value for the script.

For instance, in the image above, you can see that the first section starts at the 4th layer (where the square and the circle first start appearing), so our Change Layer Offset value should be 3.

Moving on, bring the layer slider to its maximum to find the number of layers the entire retract tower consists of, and note it down as well.

For instance, in our example above, you can see that the tower consists of 141 layers.

Now, subtract the number of layers that create the base from the total number of layers, and divide this number by the number of sections in the tower to find the Change Layer value, which will equal the layer count of a singular section of the tower.

So, in our example, we would subtract 3 from 141 to find 138 and divide 138 by 5 to find 27.6. Since this is not a whole number, we will round it up to 28, which will be our Change Layer value.

Next, click Extensions again, but this time, hover over “Post Processing” and click “Modify G-Code”.

Now, click the “Add a script” button, and choose “RetractTower” from the list.

Finally, insert the Change Layer and the Change Layer Offset values you have found by following the earlier process, configure the rest of the RetractTower script according to your needs, and print the retract tower as you would print any other model.

For instance, if you’re experiencing stringing with a retraction distance value of 5 mm/s, you can choose Distance from the Command dropdown, set the Starting Value to 5.5 mm, and set the Value Increment to 0.5 mm for your initial test of higher retraction distance values.

Since the test model consists of 5 different sections, this will prompt your printer to use retraction distance values of 5.5 mm, 6 mm, 6.5 mm, 7 mm, and 7.5 mm, in order, for each of the sections, allowing you to easily spot the value that eliminates stringing without causing under-extrusion in a single test print.

Once your 3D printer finishes printing the tower, locate the section that looks the best and enter the value that corresponds to that section as your new retraction distance/speed in Cura, which concludes the calibration process.

Additionally, you can re-print the retraction tower with the new retraction distance/speed you have found as the starting value and a much smaller value increment value, which will allow you to see the effects of small changes to retraction in a clear way and further fine-tune the values for even better results.

Example PLA Retraction Settings for Ender 3 (Pro & V2 & Neo)

Below, you can find an example set of PLA-compatible retraction settings for all Bowden extruder Ender 3 models:

• Retraction Distance: 6 mm
• Retraction Speed: 45 mm/s
• Retraction Extra Prime Amount: 0 mm^3
• Retraction Minimum Travel: 1.5 mm
• Maximum Retraction Count: 30
• Minimum Extrusion Distance Window: 6 mm

Example PLA Retraction Settings for Ender 3 S1

Below, you can find an example set of PLA-compatible retraction settings for the Ender 3 S1:

• Retraction Distance: 1 mm
• Retraction Speed: 45 mm/s
• Retraction Extra Prime Amount: 0 mm^3
• Retraction Minimum Travel: 1.5 mm
• Maximum Retraction Count: 30
• Minimum Extrusion Distance Window: 1 mm

Conclusion

Now that you know how you can precisely configure the retraction settings for printing with PLA filament, the problems that over-extrusion brings to prints, with stringing being the most famous one, should be a thing of the past forever.

That being said, as finding the optimal retraction settings that work the best for the 3D printer you’re using and the filament you’re printing with can take some trial and error, it’s usually a good idea to run a few test prints to get your settings completely dialed in before moving on to the actual print.