Practical Flow Ratio Calibration Test #1897

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MrUnknownDE · 2026-04-05T20:58:17+02:00

MrUnknownDE commented

2026-04-05 20:58:17 +02:00

Originally created by @pi-squared-studio on 10/16/2025

Practical Flow Ratio Calibration Test

What is this Practical calibration test for?

This minimalistic test is used to quantify and calibrate the actual flow rate of the extruder for the required filament with its typical printing conditions.

This test uses the current settings of the filament profile, printer, and printing conditions and builds its model based on them.
The model is a rectangular block with a solid unidirectional filling on a leveling substrate. The filling density is dynamic and depends on the current filament settings. In other words, the 1.0 consumption coefficient in this test will be equal to a solid infill of 100% density and it corresponds to the internal Orca math algorithm for flow rate calculating. The change in flow is determined by the volume of the outgoing extruder material, and it linearly depends on the line width.

Now, knowing the linear rate of flow change along the length of the model and using a conventional ruler, we can determine the required flow rate of the extruder with an accuracy of one thousandth.

By only one this test, it is possible to really select the required filament consumption not only to ensure the maximum allowable strength of infill, but also to ensure the highest quality surface. Thanks to the flexible configuration of this calibration test, it is possible to perform both fast evaluation tests with minimal consumption of material and printing time and rather complex and accurate ones.

Test conditions

Caution

To perform the test successfully, first calibrate the temperature of the hotend and the cooling conditions of the filament. The printing surface should be as smooth and even as possible (perhaps even shiny). Poor adhesion between layers and lines can lead to objective defects that complicate the readability of the test.

Model Width & Depth

You can specify the desired size of the model for the test in order to conveniently evaluate the quality of the result.
The width (along X axis) of the model varies in values: 100, 150 and 200 mm.
The depth (along Y axis) of the model varies in values: 10, 15 and 20 mm.

Note

Larger sizes entail a higher consumption of filament and the time spent on printing.

Number of calibration layers

Since this test is with cumulative effect, a larger number of layers will increase the visual effect of internal overflow with excess material. You can specify a minimum value of 4 and a maximum value of 40. The default value is 10.

Note

Larger number entail a higher consumption of filament and the time spent on printing.

Tip

Use a smaller flow range and a larger number of calibration layers to compensate for the loss of readability.

Start & End flow rate values

These are the numbers of the variable flow range for the test.

Tip

For easier interpret the result later use values of comparable rank to make it. For example, pairs of values like 0.95 and 1.05 (or 0.8 and 1.0) will be easier to recalculate with ruler. The best option would be to enter numbers that are separated from 1.0 with positive and negative delta.

Warning

Please note that the current flow ratio for the extruder/filament will be applied for the actual value of 1.0 for this test. What will remind you the notice label in the dialog box and on the printed ruler.

Interlaced

This setting changes the printing mode from progressive to interlaced. However, these methods give slightly different results.

Progressive - The filling is performed from line to line from the low flow value to the high one. Simulates the conditions closest to the usual ones in 3D printing. The results are slightly smoothed out, as there is a degree of freedom where the plastic can move without causing overflow. The flow detection zone is also well formed to ensure the best geometry of the object.
Interlaced - The printing mode for high-strength products, when the lines are filled through one. 2 passes are formed. The first is the free application of lines, the second is cementing in a limited space. In this mode, the slightest overflow of plastic causes a clearly visible defect.

Use Z-Hop

Enables the Z-axis lifting mode when changing the line on upper surface. It is used to keep the its clean. For the lowest layer, Z-Hop is switched on constantly to ensure the formation of a more reliable base.

Note

If Z-Hop mode on, the nozzle lift every time when a new line will draw. But in this case, the formation of retract threads or strings is possible upon surface.
If Z-Hop mode off, for the upper surface determines the test option when the transfer nozzle to a new line leaves a mark on the excessively extruded material. This helps to visually highlight the slightest defects.

Print Scale

You can print a scale along with the test on the bed surface, which will help you immediately assess the range of flow rate applied to the test.

In the corners there are labels with the start and end values of the flow rate.
It is also possible to display labels with intermediate flow values.
The applied scale contains major and minor divisions for easy reading.

Print Ruler

You can print a ruler along with the test on the bed surface, with which you can easily calculate the actual flow rate value. Each major division shows a distance of 1 cm. Minor divisions show the fractional parts of this dimension.

- it resembles a shortcut for recalculating values. If possible, it will show a convenient fractional formula for recalculation.
- the label of material type and some printing conditions. Specifies the type of used filament, the printing speed, the method of applying infill (p - progressive, i - interlaced), as well as the current flow coefficient for the selected filament.
- the scale ratio bar.
The applied scale contains major and minor divisions for easy reading.

Note

The printable scale and ruler can display a triangular mark that indicates the mechanical extruder/filament flow ratio equal to 1.0. In other words, there would the position of the normal flow ratio of the extruder be if it didn't normalize in any way. Let's say the current filament flow rate is set to 0.96, then this mark would be point to the value 1/0.96 = 1.042.

How to make the Practical Flow Ratio Test

Open a new project in Orca.
Install the needed print, printer, and filament profiles. Make all necessary changes to the profiles settings.

Warning

When generating a model, this test will make changes to some settings (for example, disabling Fuzzy Skin) for successful testing. Do not save these settings under already saved profile names, as they may not be desired.

Select from the menu "Calibration" > "Flow Ratio" an element "Practical Flow Ratio Test".
In the dialog box that opens, set the necessary test settings.
Click "OK" and the required model will be generated.
Slice the model, then transfer the generated G-Code to the printer for testing.
For remake new test, you can change the settings in print, printer, and filament profiles, then run a new test instance without saving the old one.

Caution

Applying to the conditions of this test will changes a some of the print, printer and filament profiles settings. Do not save these profiles, as this may lead to their loss. After finish the test, memory the measured values, and then set them in needed project after completely resetting or unloading the test.

How to perceive the results obtained

The visible manifestations may vary depending on the filament used and the printing conditions.
It can be noted that increasing the number of calibration layers cumulative highlights any visual defects better.

Visible signs:

The area with the best filling. Smooth and even. It does not always have a gloss, it can be matte or gradient.
Loose area with cavities, depressions and uneven lines. There is a clear shortage of material.
Plowed and raised surface. Its level is noticeably higher than normal. Obvious signs of an excess of material.
Visible curbs protruding above the surface.
Visible excess material collected by the nozzle.
Top roller of excess material. This is where the printing line ends, and all the excess printing material accumulates here.
Bottom roller of excess material. Surface material accumulates here, which is collected during the return stroke of the nozzle. It is not always a sign of overflow.
Deformation of the side wall caused by the pressure of excess material.

The test readings can be divided into 3 boundaries:

I zone. A clear lack of flow (flow < 1.0).

With this filling, the lines do not affect each other, so it allows you to keep the shape of the printed surface. This area usually has a smooth, even, and often glossy surface. The surface quality does not suffer from the number of calibration layers, as the material will not be enough to deform in any case. With large values of material shortage, it is possible for it to hole upwards, as the lines lose their lateral support in the form of neighboring lines, or the formation of shrinkage cavities.

II zone. The flow is normal (flow about 1.0).

In this area, the empty pores are filled with additional material. Since the process becomes complex due to the use of excessive pressure, and the formation of lines may not be as stable. The print surface is still strait, but it is no longer as glossy and a little rough. You can determine any number of nominal flow rate in this range for yourself, depending on the desired result - from comply with the size and quality of the surface to ensure maximum rigidity. Or you can leave the average value.

Note

The magnitude of this transition zone can vary from a complete absence to a few percent of flow change. If it is impossible to clearly define the boundaries, focus on the "for rigidity" indicator.

III zone. Overflow (flow >1.0+)

This is an extremely high amount of plastic that can ruin your prints. Excessive amounts of plastic tend to be squeezed out through the printed walls or come out onto the top surface. The lines turn out to be shapeless, and the excess may collide with the nozzle when printing an adjacent line. This leads to the formation of shapeless flakes of plastic on the surface, the formation of tracks from the nozzle on it, and in the worst case, the model may peel off from the bed.

The boundaries between these zones are the most optimal values for printing:

Zones I/II - they show the optimal flow ratio for the formation of smooth and even surfaces. Choose this indicator to ensure the best geometry and appearance of the model.
Zones II/III - determines the best filling of the material between the lines. With this flow rate, conditions are provided for printing the most durable models.

Tip

If it is possible to adjust the flow rate separately for the surface and for the internal continuous filling, then you can set the value II/III for the main flow of the extruder/filament, and for the surface the value is lower by this difference.
For example: II/III =1.05, I/II = 0.96
The resulting flow value for the surface will be 1 - (1.05 - 0.96) = 0.91

Tip

To determine the flow rate for the maximum strength of the solid infill, it is sufficient to perform a test with the number of calibration layers equal to the maximum the number of solid layers for the printed model. Such a test will show the optimal possible infill density that does not lead to critical consequences.

Assessment methods

visual: surface quality assessment
for gloss: it is possible to determine where the smoothest surface is without gaps between tracks and micro-jaggs or ripples on the surface caused by excessively extruded plastic.
side light: highlights minor visual defects well
nail or toothpick test: detects the grooves between the lines very well. Swipe your fingernail over the surface, and in the most optimal place you will feel almost no vibrations. The same can be done with the side surface, or with the edge between them.
a "roller" made of excessive material: since printing takes place in one direction, this excessive material can pile up at the end of the path, which leads to its increase during the test.
outer wall test: аs mentioned above, too much material can deform the outer perimeter.

Measurements

Photography often cannot convey that fine line of transition from one measuring zone to another. This line is more clearly visible to the eyes. Use a small, bright source of contrasting light, such as a flashlight, to make these visual differences more visible. It is a good idea to direct a beam of light along the surface of this sample so that the minimum printing defects in height become as readable as possible.

There are 2 main ways to determine the required value:

use the ruler (physical or printed on the bed)

Attach a regular ruler (or use the printed one) to measure the distance from the edge of the dough to the desired point.
Let's say we liked 2 points: 2.2cm for position 1|2 (for geometry), and 6.1cm for position 2|3 (for rigidity);

knowing the initial flow value of 0.9 and the conversion factor of 1cm = 0.02, we are easily calculating the 2 necessary values:

0.9 + (0.02 * 2.2) = 0.9 + 0.044 = 0.944 (for Geometry)

0.9 + (0.02 * 6.1) = 0.9 + 0.122 = 1.022 (for Rigidity)

0.9 + 0.02 * (2.2 + 6.1) / 2 = 0.9 + 0.083 = 0.983 (Average)

use the printed scale on the bed, and directly read the readings from it

*Originally created by @pi-squared-studio on 10/16/2025* # Practical Flow Ratio Calibration Test <img width="600" alt="image" align="center" src="https://github.com/user-attachments/assets/9d64cf7f-2803-4aea-a819-7ff38c92096f" /> ## What is this Practical calibration test for? This minimalistic test is used to quantify and calibrate the actual flow rate of the extruder for the required filament with its typical printing conditions. <img width="1000" alt="image" src="https://github.com/user-attachments/assets/114aa8c3-084f-4ebd-83c0-c41512402cfa" /> This test uses the current settings of the filament profile, printer, and printing conditions and builds its model based on them. The model is a rectangular block with a solid unidirectional filling on a leveling substrate. The filling density is dynamic and depends on the current filament settings. In other words, the 1.0 consumption coefficient in this test will be equal to a solid infill of 100% density and it corresponds to the internal Orca math algorithm for flow rate calculating. The change in flow is determined by the volume of the outgoing extruder material, and it linearly depends on the line width. Now, knowing the linear rate of flow change along the length of the model and using a conventional ruler, we can determine the required flow rate of the extruder with an accuracy of one thousandth. By only one this test, it is possible to really select the required filament consumption not only to ensure the maximum allowable strength of infill, but also to ensure the highest quality surface. Thanks to the flexible configuration of this calibration test, it is possible to perform both fast evaluation tests with minimal consumption of material and printing time and rather complex and accurate ones. ## Test conditions <img width="428" height="591" alt="image" src="https://github.com/user-attachments/assets/576e2993-1e23-4fee-9095-2dec493d2ec3" /> > [!CAUTION] > To perform the test successfully, first calibrate the temperature of the hotend and the cooling conditions of the filament. The printing surface should be as smooth and even as possible (perhaps even shiny). Poor adhesion between layers and lines can lead to objective defects that complicate the readability of the test. ### Model Width & Depth You can specify the desired size of the model for the test in order to conveniently evaluate the quality of the result. The width (along X axis) of the model varies in values: 100, 150 and 200 mm. The depth (along Y axis) of the model varies in values: 10, 15 and 20 mm. > [!NOTE] > Larger sizes entail a higher consumption of filament and the time spent on printing. ### Number of calibration layers Since this test is with cumulative effect, a larger number of layers will increase the visual effect of internal overflow with excess material. You can specify a minimum value of 4 and a maximum value of 40. The default value is 10. > [!NOTE] > Larger number entail a higher consumption of filament and the time spent on printing. > [!Tip] > Use a smaller flow range and a larger number of calibration layers to compensate for the loss of readability. ### Start & End flow rate values These are the numbers of the variable flow range for the test. > [!TIP] > For easier interpret the result later use values of comparable rank to make it. For example, pairs of values like 0.95 and 1.05 (or 0.8 and 1.0) will be easier to recalculate with ruler. The best option would be to enter numbers that are separated from 1.0 with positive and negative delta. > [!WARNING] > Please note that the current flow ratio for the extruder/filament will be applied for the actual value of 1.0 for this test. What will remind you the notice label in the dialog box and on the printed ruler. ### Interlaced This setting changes the printing mode from progressive to interlaced. However, these methods give slightly different results. - **Progressive** - The filling is performed from line to line from the low flow value to the high one. Simulates the conditions closest to the usual ones in 3D printing. The results are slightly smoothed out, as there is a degree of freedom where the plastic can move without causing overflow. The flow detection zone is also well formed to ensure the best geometry of the object. - **Interlaced** - The printing mode for high-strength products, when the lines are filled through one. 2 passes are formed. The first is the free application of lines, the second is cementing in a limited space. In this mode, the slightest overflow of plastic causes a clearly visible defect. ### Use Z-Hop Enables the Z-axis lifting mode when changing the line on upper surface. It is used to keep the its clean. For the lowest layer, Z-Hop is switched on constantly to ensure the formation of a more reliable base. > [!NOTE] > If Z-Hop mode on, the nozzle lift every time when a new line will draw. But in this case, the formation of retract threads or strings is possible upon surface. > If Z-Hop mode off, for the upper surface determines the test option when the transfer nozzle to a new line leaves a mark on the excessively extruded material. This helps to visually highlight the slightest defects. ### Print Scale You can print a scale along with the test on the bed surface, which will help you immediately assess the range of flow rate applied to the test. <img width="823" height="146" alt="image" src="https://github.com/user-attachments/assets/43a73fbc-75e4-42f6-974b-e429e01f61dd" /> - In the corners there are labels with the start and end values of the flow rate. - It is also possible to display labels with intermediate flow values. - The applied scale contains major and minor divisions for easy reading. ### Print Ruler You can print a ruler along with the test on the bed surface, with which you can easily calculate the actual flow rate value. Each major division shows a distance of 1 cm. Minor divisions show the fractional parts of this dimension. <img width="823" height="131" alt="image" src="https://github.com/user-attachments/assets/a7d99462-7886-4142-9bdb-8ed426bc7aa9" /> - <img width="359" height="47" alt="image" src="https://github.com/user-attachments/assets/4613cba1-a4d2-41ce-8108-ce125c3d7eb8" /> - it resembles a shortcut for recalculating values. If possible, it will show a convenient fractional formula for recalculation. - <img width="376" height="54" alt="image" src="https://github.com/user-attachments/assets/253a78a6-1e99-41a6-88d7-5a4389d5e3d5" /> - the label of material type and some printing conditions. Specifies the type of used filament, the printing speed, the method of applying infill (p - progressive, i - interlaced), as well as the current flow coefficient for the selected filament. - <img width="251" height="65" alt="image" src="https://github.com/user-attachments/assets/d26a700a-d366-410c-a238-34e773c5d5ac" /> - the scale ratio bar. - The applied scale contains major and minor divisions for easy reading. > [!NOTE] > The printable scale and ruler can display a triangular mark <img width="37" height="34" alt="image" src="https://github.com/user-attachments/assets/b6f31fc1-aaff-4bd5-b8ff-989cd316362b" /> that indicates the mechanical extruder/filament flow ratio equal to 1.0. In other words, there would the position of the normal flow ratio of the extruder be if it didn't normalize in any way. Let's say the current filament flow rate is set to 0.96, then this mark would be point to the value 1/0.96 = 1.042. ## How to make the Practical Flow Ratio Test 1. Open a new project in Orca. 2. Install the needed print, printer, and filament profiles. Make all necessary changes to the profiles settings. > [!WARNING] > When generating a model, this test will make changes to some settings (for example, disabling Fuzzy Skin) for successful testing. Do not save these settings under already saved profile names, as they may not be desired. 3. Select from the menu "Calibration" > "Flow Ratio" an element "Practical Flow Ratio Test". 4. In the dialog box that opens, set the necessary test settings. 5. Click "OK" and the required model will be generated. 6. Slice the model, then transfer the generated G-Code to the printer for testing. 7. For remake new test, you can change the settings in print, printer, and filament profiles, then run a new test instance without saving the old one. > [!CAUTION] > Applying to the conditions of this test will changes a some of the print, printer and filament profiles settings. Do not save these profiles, as this may lead to their loss. After finish the test, memory the measured values, and then set them in needed project after completely resetting or unloading the test. ## How to perceive the results obtained The visible manifestations may vary depending on the filament used and the printing conditions. It can be noted that increasing the number of calibration layers cumulative highlights any visual defects better. <img width="1864" height="480" alt="image" src="https://github.com/user-attachments/assets/4c0b08ce-fe4d-4e66-bde5-bc14c1fc07d8" /> Visible signs: 1. The area with the best filling. Smooth and even. It does not always have a gloss, it can be matte or gradient. 2. Loose area with cavities, depressions and uneven lines. There is a clear shortage of material. 3. Plowed and raised surface. Its level is noticeably higher than normal. Obvious signs of an excess of material. 4. Visible curbs protruding above the surface. 5. Visible excess material collected by the nozzle. 6. Top roller of excess material. This is where the printing line ends, and all the excess printing material accumulates here. 7. Bottom roller of excess material. Surface material accumulates here, which is collected during the return stroke of the nozzle. It is not always a sign of overflow. 8. Deformation of the side wall caused by the pressure of excess material. The test readings can be divided into 3 boundaries: - I zone. A clear lack of flow (flow < 1.0). > <img width="400" alt="image" src="https://github.com/user-attachments/assets/6700714a-cb7d-478d-b1e5-66be635667ed" /> > > With this filling, the lines do not affect each other, so it allows you to keep the shape of the printed surface. This area usually has a smooth, even, and often glossy surface. The surface quality does not suffer from the number of calibration layers, as the material will not be enough to deform in any case. With large values of material shortage, it is possible for it to hole upwards, as the lines lose their lateral support in the form of neighboring lines, or the formation of shrinkage cavities. - II zone. The flow is normal (flow about 1.0). > <img width="400" alt="image" src="https://github.com/user-attachments/assets/acf3f16f-7de0-4d94-bf99-94aeb24063af" /> > > In this area, the empty pores are filled with additional material. Since the process becomes complex due to the use of excessive pressure, and the formation of lines may not be as stable. The print surface is still strait, but it is no longer as glossy and a little rough. You can determine any number of nominal flow rate in this range for yourself, depending on the desired result - from comply with the size and quality of the surface to ensure maximum rigidity. Or you can leave the average value. > [!NOTE] > The magnitude of this transition zone can vary from a complete absence to a few percent of flow change. If it is impossible to clearly define the boundaries, focus on the "for rigidity" indicator. - III zone. Overflow (flow >1.0+) > <img width="400" alt="image" src="https://github.com/user-attachments/assets/c854a3c8-b71f-4fb3-806c-ee88b25cbf83" /> > > This is an extremely high amount of plastic that can ruin your prints. Excessive amounts of plastic tend to be squeezed out through the printed walls or come out onto the top surface. The lines turn out to be shapeless, and the excess may collide with the nozzle when printing an adjacent line. This leads to the formation of shapeless flakes of plastic on the surface, the formation of tracks from the nozzle on it, and in the worst case, the model may peel off from the bed. The boundaries between these zones are the most optimal values for printing: - Zones I/II - they show the optimal flow ratio for the formation of smooth and even surfaces. Choose this indicator to ensure the best geometry and appearance of the model. - Zones II/III - determines the best filling of the material between the lines. With this flow rate, conditions are provided for printing the most durable models. > [!TIP] > If it is possible to adjust the flow rate separately for the surface and for the internal continuous filling, then you can set the value II/III for the main flow of the extruder/filament, and for the surface the value is lower by this difference. > For example: II/III =1.05, I/II = 0.96 > The resulting flow value for the surface will be 1 - (1.05 - 0.96) = 0.91 > [!TIP] > To determine the flow rate for the maximum strength of the solid infill, it is sufficient to perform a test with the number of calibration layers equal to the maximum the number of solid layers for the printed model. Such a test will show the optimal possible infill density that does not lead to critical consequences. ## Assessment methods - visual: surface quality assessment - for gloss: it is possible to determine where the smoothest surface is without gaps between tracks and micro-jaggs or ripples on the surface caused by excessively extruded plastic. - side light: highlights minor visual defects well - nail or toothpick test: detects the grooves between the lines very well. Swipe your fingernail over the surface, and in the most optimal place you will feel almost no vibrations. The same can be done with the side surface, or with the edge between them. - a "roller" made of excessive material: since printing takes place in one direction, this excessive material can pile up at the end of the path, which leads to its increase during the test. - outer wall test: аs mentioned above, too much material can deform the outer perimeter. ## Measurements Photography often cannot convey that fine line of transition from one measuring zone to another. This line is more clearly visible to the eyes. Use a small, bright source of contrasting light, such as a flashlight, to make these visual differences more visible. It is a good idea to direct a beam of light along the surface of this sample so that the minimum printing defects in height become as readable as possible. There are 2 main ways to determine the required value: - use the ruler (physical or printed on the bed) <img width="400" alt="image" src="https://github.com/user-attachments/assets/7dfcf1a4-7ee8-457f-8e80-85134434a268" /> > <img width="800" alt="image" src="https://github.com/user-attachments/assets/f572eb61-eff2-41cb-9f27-4b0ad9c00f6f" /> > Attach a regular ruler (or use the printed one) to measure the distance from the edge of the dough to the desired point. > > Let's say we liked 2 points: 2.2cm for position 1|2 (for geometry), and 6.1cm for position 2|3 (for rigidity); > knowing the initial flow value of 0.9 and the conversion factor of 1cm = 0.02, we are easily calculating the 2 necessary values: > 0.9 + (0.02 * 2.2) = 0.9 + 0.044 = 0.944 (for Geometry) > 0.9 + (0.02 * 6.1) = 0.9 + 0.122 = 1.022 (for Rigidity) > 0.9 + 0.02 * (2.2 + 6.1) / 2 = 0.9 + 0.083 = 0.983 (Average) - use the printed scale on the bed, and directly read the readings from it <img width="400" height="626" alt="image" src="https://github.com/user-attachments/assets/c5f24b1e-33d4-4a67-8404-9627e62a0058" />

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Reference: github/OrcaSlicer#1897