What Is the Optimal Extrusion Multiplier for PLA Filament?

The extrusion multiplier parameter, also known as flow rate, holds a significant place in the configuration of your 3D printer, as it’s the primary decider of how much plastic comes out of the nozzle at any given time of the printing process.

As it can directly control the rate of extrusion in terms of percentages, the extrusion multiplier parameter offers a quick and easy way to perform slight adjustments on the amount of plastic that goes into the model in scenarios of under and over-extrusion.

In today’s article, we will be diving into the topic of optimally configuring the extrusion multiplier parameter specifically for printing with PLA, which is especially vital to configure between different spools of filament due to differences between filaments.

So, what is the optimal extrusion multiplier for PLA filament?

The optimal extrusion multiplier value for printing PLA largely depends on your observations of how your prints come out, as increasing or decreasing it slightly (5-10%) from its default value of 100% should only be necessary if you’re facing under-extrusion or over-extrusion.

In the upcoming sections of the article, we will further analyze the optimal extrusion multiplier values for PLA filament, find out how to calculate the extrusion multiplier value for a new spool of PLA, and discuss how different extrusion multiplier values affect the printing process with PLA filament.

What Is the Optimal Extrusion Multiplier for PLA Filament?

Due to it having a direct impact on how much filament the 3D printer will extrude at any given time, configuring the extrusion multiplier parameter as correctly as possible is paramount to ensure that the printer extrudes the correct amount of plastic during the printing process.

Considering that you have configured every other parameter that affects extrusion correctly, the default extrusion multiplier value of 100% should be the optimal figure that allows your 3D printer to conduct the PLA printing process without over-extrusion or under-extrusion.

On the other hand, sometimes it can be necessary to perform slight tweaks to the extrusion multiplier value to quickly fix the problem of under-extrusion or over-extrusion, such as scenarios where you switch to PLA from a different filament for the first time, or you can’t find anything else that could be the culprit.

In such scenarios, we recommend keeping the extrusion multiplier value between 90% and 110% for PLA, as needing to go lower or higher than these values will most likely add to your problems rather than fix them.

As always, the best way to figure out the optimal extrusion multiplier value in your case is to perform experiments, which we will talk about in the upcoming section.

How to Calculate the Extrusion Multiplier Value for a Fresh Spool of PLA Filament?

Calculating the optimal extrusion multiplier value for each fresh spool of filament is a vital process to avoid issues related to under or over-extrusion after a filament change, as even different spools of the same material can behave differently.

You can use two methods to perform the calculations: basic calibration and precise calibration.

Basic Calibration

Basic calibration is the more accessible (and less precise) method of the two, as it allows you to perform the calculations without the need for any extra tools.

Here are the steps we recommend following to perform basic calibration:

  1. Print a test cube with the dimensions and the PLA filament of your choice. As there is no need for a large print, a 20x20x20 cube will be fine for our purposes.
  2. Thoroughly inspect the cube for imperfections caused by over or under-extrusion, such as blobs and stringing or gaps and holes.
  3. Increase or decrease the extrusion multiplier value by 1% based on your observations.
  4. Repeat the steps until you don’t experience any issues.

Please note that this method may not always yield the best results, so we recommend the precise calibration method whenever possible.

Precise Calibration

Precise calibration offers the best way of performing the calculations, but it requires you to have access to calipers for taking accurate measurements.

Here are the steps we recommend following to perform precise calibration:

  1. Print a test cube with the dimensions and the PLA filament of your choice. We recommend going for a standard 20x20x20 test cube here.
  2. Measure the wall thicknesses of the model from multiple points with calipers, and note the values.
  3. Calculate the average thickness from the values you have gathered. (Add all values together, then divide by the number of values.)
  4. Divide the line width (or the wall thickness if your model has multiple wall lines) value you have used in your slicer by the figure you have found in step 3, which should give you the next extrusion multiplier value you should use.
  5. Input the new extrusion multiplier value into the slicer.
  6. Repeat the steps until the value you find in step 3 equals your line width or wall thickness value.

As this method uses measurements to approximate the optimal extrusion multiplier value, we recommend using this method whenever possible.

How Does the Extrusion Multiplier Value Affect Printing with PLA?

Having a good understanding of how different extrusion multiplier values affect your printing experience is a significant portion of getting the value correct, as the signs that appear as a result of a misconfigured extrusion multiplier are usually pretty detrimental to the final product.

To start, let’s talk about the issues that a too high extrusion multiplier value can create while printing with PLA.

A too high extrusion multiplier will cause your printer to extrude more PLA than necessary, causing over-extrusion-related problems, such as stringing, blobbing, and an overall loss of quality on the model due to excess plastic gathering on the details.

On the other hand, here are the problems you would observe on the prints you have printed with PLA if the extrusion multiplier value is too low.

With a too low extrusion multiplier value, your printer will extrude less PLA than necessary for printing your model, which will bring under-extrusion-related issues such as poor bed and layer adhesion, gaps and holes, and missing or thin layers.

Since the extrusion multiplier parameter has the final say on how much plastic the 3D printer will extrude, it’s one of the parameters that will have an immense impact on your prints, making it vital to configure it correctly for a healthy printing process.

How to Set the Extrusion Multiplier Parameter for PLA in Cura?

Setting the extrusion multiplier parameter specifically for PLA filament in Cura is a process that won’t take more than a few minutes of your time, which we have outlined the steps for below:

  1. Click the Prepare tab on the top of the Cura window.
  2. Click the middle pane to bring up the Material dropdown.
  3. Click the Material dropdown, and choose PLA from the Generic tab. This process will load the default Cura PLA settings as a baseline before configuring the extrusion multiplier.
  4. Click the pane on the right, which should bring up the Print Settings menu.
  5. Switch to Custom mode if you haven’t before by clicking the Custom button.
  6. Click the three lines icon next to the search input in Print Settings, and choose All from the dropdown menu. This process will allow you to see all the advanced settings Cura offers.
  7. Type “flow” into the search input, which will allow you to see and configure the Flow (extrusion multiplier) parameter.

After following these steps, you can save your settings into a new profile by clicking the Profile dropdown and choosing the “Create profile from current settings/overrides” option.

Wrapping Up

While extrusion multiplier is not something you will need to configure on a print-by-print basis, it’s vital to ensure that you optimize it whenever you switch between different spools of filament to avoid issues with under or over-extrusion.

To quickly recap, while it’s best to keep the extrusion multiplier at its default value of 100% and optimize other parameters that can contribute to under or over-extrusion issues, such as the nozzle temperature or the print speed, using a value in the range of 90% to 110% is usually acceptable for printing PLA.

As modifying the extrusion multiplier value acts as a quick and dirty solution to fix under or over-extrusion problems due to its direct impact on the amount of filament that the 3D printer extrudes, it’s usually best to use it as a last resort in most cases.

Happy printing!