Flow Test in 3D Printing: Quick Solution

Filament flow calibration is one of the most important settings in 3D printing. This calibration is done by one or several flow tests.

To make it simple: the flow rate is the amount of filament coming out of the nozzle, and it is usually measured as a percentage.

When the flow rate is too high (above 100%), problems appear such as:
✔ Excess material in the layers.
✔ Rough surfaces with visible lumps.
✔ Errors in fine details and incorrect dimensions.

On the other hand, if the flow rate is too low (below 100%), it is common to notice:
✔ Poorly adhered layers and separation between extrusion lines.
✔ Brittle parts with poor mechanical strength.
✔ Irregular surfaces with voids.

To avoid these problems, it is recommended to perform a Flow Test, which allows determining the ideal setting for each material and printer configuration . One of the most commonly used methods is the Flow Tower, a test that prints a model with different extrusion values along its height, helping to identify the optimum setting.

In this guide, we will explain how to perform a flow test on the most popular slicers: Ultimaker Cura, OrcaSlicer and BambuStudio.

Ultimaker Cura Flow Test or Calibration Test

Preparation of Ultimaker Cura for Flow Testing

Before performing the flow test, we must prepare Ultimaker Cura with the necessary tools. For this test, we will use the Auto Towers Generator plugin, which will allow us to automatically generate a Flow Tower with variations in the extrusion percentage along its height.

Auto Towers Generator Plugin Installation

This plugin facilitates flow calibration without the need to manually modify each layer of the model. To install it, follow these steps:

1. Opens Ultimaker Cura.
2. Go to the Marketplace section (located at the top right of the interface).
3. Search for Auto Towers Generator and click Install.
4. Wait for the installation to finish and then restart Cura for the plugin to activate correctly.

📌 Note: If the plugin does not appear in Cura after installation, verify that you are using a compatible version of the software and that you have an internet connection.

What exactly does this plugin do?

The Auto Towers Generator automatically generates a Flow Tower, similar to the Temperature Tower, but in this case, varying the extrusion flow in each section. This allows to visualize how the print quality changes according to the percentage of flux used.

If you have not yet calibrated the temperature of your filament, we recommend doing the Temperature Tower Test first, as a bad thermal setting can affect the results of the flux test. You can learn how to do this in our complete guide: Temperature Tower in PLA for 3D Printing..

The Flow Tower will print with extrusion values ranging from 115% to 85%, allowing you to identify which setting is best suited for your filament and printer configuration.

Now that we have Cura ready, the next step is to create the Flow Tower and adjust the print parameters.

Cura Flow Tower Creation and Configuration

Once we have Ultimaker Cura ready and the Auto Towers Generator plugin installed, we can proceed to generate and print the Flow Tower.

This test is quite simple: a tower is printed with different sections, each with a different percentage of flow. By analyzing the result, we can identify which is the most suitable setting to improve the quality of our prints.

Generating the Flow Tower at Cura

1. Open Cura and make sure that the Auto Towers Generator plugin is correctly installed.
2. Go to the menu:
   • Extensions > Auto Towers > Flow Tower 115 to 85.
3. Select the “Flow Tower 115 to 85” option.
   • This will generate a tower with flow values ranging from 115% to 85%, with a progressive reduction in each section.

📌 Note: This test is ideal for any type of filament, but if you use flexible materials such as TPU, it is advisable to make additional adjustments to the shrinkage settings.

Print Parameters Configuration

For accurate results, it is recommended to use the following settings on the slicer:

• Layer height: 0.2 mm (a good combination of precision and speed).
• Print speed: 50-70 mm/s (adjust according to your printer’s usual settings).
• Temperature: Use the optimum temperature for your filament (according to the Temperature Tower test if you have performed it).
• Initial flow: 100% (do not modify it manually, as the tower will change it automatically).

Once these values are set, save the file and send it to your printer.

How much material is needed for the test?

One of the benefits of this test is that it consumes very little filament. The Flow Tower requires approximately 6 grams of material, making it an efficient and waste-free test.

With the Tower ready and the parameters well configured, it is time to start printing and evaluate the results.

Printing and Evaluation of the Flow Tower

Now that we have generated the model and adjusted the parameters in Ultimaker Cura, it is time to print the Flow Tower and analyze the results.

Printing the Flow Tower

• Make sure the printer is properly calibrated before starting.
• Use the same filament you normally use, as different brands or batches may affect the result.
• Start the print and watch the process to make sure there are no problems with the extrusion.

📌 Tip: If you notice that the first layer does not adhere well to the bed, check the levelness of the base and adjust the temperature of the first layer.

How to Analyze the Flow Tower

Once the tower is printed, examine each section to identify which has the best finish.

1. High Flow (115%-110%)
   • If you notice lumps, filament strands or excess material, it means that the flow is too high.
   • Parts with overextrusion tend to lose detail and have incorrect dimensions.
2. Low Flow (90%-85%)
   • If gaps appear between layers or poor adhesion between extrusion lines, the flow rate is too low.
   • These parts tend to be weak and less mechanically resistant.
3. Ideal Flow
   • Look for the section where the surface is cleanest and smoothest.
   • Look at the overhangs and small details: if they are well defined and without excess or lack of material, that is the right value.

Example: If you notice that the best quality is in the 95% flow section, this is the setting you should apply in Cura.

Final Flow Adjustment in Cura

Now that we have determined the optimal flow rate through the Flow Tower, the next step is to apply this setting in Ultimaker Cura.

Configuring Global Flow in Cura

To set the new flow value in Cura, follow these steps:

1. Open Ultimaker Cura and load the print profile you usually use.
2. Go to the Material settings (you can find it in the right sidebar).
3. Find the “Flow” option and change it to the percentage that the test yielded (e.g., 95% or 0.95).
4. Save this setting to ensure that it is applied to future prints.

This adjustment affects the entire print flow, ensuring that the correct material is extruded in each layer.

Additional Flow Adjustments (Optional)

In addition to the overall flow, Cura allows you to modify the flow in specific areas to further improve the impression. Here are some recommendations:

✅ Flow for External Walls

• If you notice that the walls do not meet perfectly, you can increase the wall flow by 2-5% (e.g., from 95% to 98-100%).
• This helps to improve the bond between lines without affecting the rest of the part.

✅ Flow for Skirt/Brim

• If the first layer does not adhere well to the bed, you can raise this parameter to 105%.
• This ensures that the printer purges the filament well before starting the actual printing.

✅ First Layer Flow.

• If the first layers look too compacted or flattened, keep it between 100% and 105%.
• Too high a value can cause the elephant’s foot effect (flared edges at the base of the part).

📌 Tip: Always test these settings on a small test print before applying them to larger parts.

Now, if you use OrcaSlicer or BambuStudio, you can also perform this calibration in them. Select your slicer from the buttons above to continue with the test in other software.

Bambulab flow test

Bambu Lab printers have an advanced automatic calibration system, but for optimal results, it is recommended to perform a manual flow calibration in BambuStudio. Correctly adjusting these parameters helps to avoid problems such as over-extrusion or under-extrusion, improving the accuracy and quality of your prints.

In this tutorial, you will learn how to calibrate:
✅ Flow Dynamics: Adjusts the K parameter to improve the dynamic extrusion.
✅ Flow Rate: Determines the optimal flow rate for each material.

Both tests ensure that the filament extrudes correctly in any printing situation.

Flow Dynamics Calibration in BambuStudio

The Flow Dynamics calibration adjusts the K parameter, which defines how the extruder responds to speed changes during printing. An incorrect value can cause inconsistencies in the extrusion, affecting part quality.

This procedure helps to improve the stability of the flow, avoiding abrupt variations in the amount of material deposited in different sections of the print.

Accessing the Calibration Tab in BambuStudio

To start manual calibration:

1️⃣ Open BambuStudio and go to the Calibration tab in the main interface.
2️⃣ Select Flow Dynamics Calibration and then Manual Calibration to access the advanced settings.

📌 Note: This option will allow you to make more precise adjustments than the automatic calibration.

Initial Adjustments Before Testing

Before running the calibration, make sure that the following parameters are set correctly:

🔹 Nozzle Diameter: Should be at 0.4 mm (factory default).
🔹 Build Plate Type: If you are using a Textured Plate, select it instead of the “Cool Plate”.
🔹 Material Profile: If the filament does not have a specific profile (example: Figutech ONE PLA), use the generic PLA profile.

These settings ensure that the test is performed under optimal conditions.

Execute Calibration and Evaluate Results

✅ Running the Test:
1️⃣ Click Calibrate.
2️⃣ The printer will print a continuous line by varying the K value automatically.
3️⃣ After printing is complete, observe the consistency of the printed line.

✅ O utcome Evaluation:

• If the line shows thickening or inconsistencies, it means that the K parameter is not well adjusted.
• If the line is uniform and without variations, you have found the optimum value.

📌 Example: In an actual calibration, it was determined that the best result was obtained with K = 0.02.

Updating the Flow Value in BambuStudio

When you identify the best fit, follow these steps to apply it to the printer:

1️⃣ Select the optimal K value in the calibration interface.
2️⃣ Click Next to save the settings to the device.

💡 Tip: If you change filament or nozzle, repeat this calibration to make sure the value is still correct.

With this, the Flow Dynamics calibration is complete. Now, we will move on to the Flow Rate calibration, which further refines the amount of extruded material in the print.

Calibration of Flow Rate in BambuStudio

Flow rate calibration adjusts the amount of extruded filament to avoid problems of underextrusion (weak layers) or overextrusion (excess material). This process optimizes extrusion uniformity in detailed prints.

Reset Manual Calibration

1️⃣ Open BambuStudio and go again to Calibration > Manual Calibration.
2️⃣ Make sure that the values for nozzle, printing plate and material profile are correct.

Running the Test and Evaluating the Results

✅ S tart calibration by clicking Calibrate.
✅ The printer will print a 3×3 grid with different flow rate settings (30 min process).

🔎 Evaluation:

• Visually examine each sample and run your finger over it to check the smoothness of the extrusion.
• Discard extreme values (-10, -20) if irregularities are present.
• Choose the optimum fit with the best surface quality and no defects.

📌 Example: Two similar samples were compared and it was determined that -5% was the best choice.

Fine Calibration and Profile Saving

🔹 If you want more precision, repeat the calibration with finer settings.
🔹 In the second round, the 0 (zero) setting proved to be ideal.

✅ S ave the profile with a custom name (example: PLA Figutech ONE).

OrcaSlicer flow test

Before starting the test, it is important to make sure that OrcaSlicer is properly configured:

1️⃣ Open OrcaSlicer and go to the Filament Settings section.
2️⃣ Select the filament to calibrate with.
3️⃣ Verify that the Flow Rate is set to 1.00 (100%) so that the first test is the starting point without previous corrections.

📌 Note: Do not adjust the flow rate manually before testing, as this will alter the results.

Flow Test – Step 1

Now we will perform the first calibration print to evaluate how the material is extruding.

✅ Running the Test:
1️⃣ Go to Calibration within OrcaSlicer.
2️⃣ Select Flow Test – Step 1.
3️⃣ Click on Transfer / Apply settings, so that the test values are applied to the current configuration.
4️⃣ Slice the model and send it to print.

Analysis of the Printed Part (Step 1)

Once the printing is finished, check the quality of the part.

🔎 Factors to be evaluated:

• Surface: It must be uniform and without irregularities.
• Clarity of numbers/marks indicating flow.
• Reference values:
  • 0 = Flow without adjustment (100%).
  • +5 = 105% flow.
  • -5 = 95% flow.

✅ Choose the best fit:

• If the best quality is set to 0, the flow remains at 1.00 (100%).
• If you prefer +5, set the Flow Rate to 1.05 (105%).
• If you prefer -5, change to 0.95 (95%).

📌 O nce the best value is defined, apply it as the base Flow Rate for the next test.

Flow Test – Step 2

We will now refine the flow with a second, more precise test.

✅ Running the Test:
1️⃣ Returns to the Calibration section in OrcaSlicer.
2️⃣ Selects Flow Test – Step 2.
3️⃣ Verifies that the flow obtained in the previous test is applied.
4️⃣ Laminates and prints the new test model.

Printed Part Analysis (Step 2) and Final Adjustment

🔎 Repeat the analysis:

• Evaluates the homogeneity of the surface and the legibility of the numbers.
• Select the best value and adjust the Flow Rate based on the difference.

📌 Example:
If in Test 1 you chose 1.05 (105%) and in Test 2 the best result is -1, then:
1.05 – 0.01 = 1.04 (104%) → This will be your final Flow Rate.

Orcalicer Images: Magicraft3D

If you prefer to see the process in action, here is a Magicraft video explaining the OrcaSlicer flow calibration step by step: