Exceeding the maximum flow if you add an unused filament #1122

New Issue

MrUnknownDE · 2026-04-05T16:52:02+02:00

MrUnknownDE commented

2026-04-05 16:52:02 +02:00

Originally created by @Dalvikk on 1/10/2026

Is there an existing issue for this problem?

I have searched the existing issues

OrcaSlicer Version

2.3.1

Operating System (OS)

macOS

OS Version

macOS 26.1

Additional system information

No response

Printer

Anycubic Kobra S1

How to reproduce

Preparations

Download my 3MF archive and open it in OrcaSlicer.
You will see that:
- The printer “Anycubic Kobra S1 0.4 nozzle (my version, hardened steel)” is selected.
- 4 filament is selected.
- The process “0.20mm Standard KS1 0.4mm” is selected.
- A 20 mm cube is placed on the build plate.

Please note: this process uses a high print speed (200 mm/s) and the filament setting “Do not slow down on external perimeters” is enabled. This is required in order to exceed the max flow rate of the filament used for printing.

Test 1

Remove all filaments except GeekFilament PLA 0.4 nozzle, which has a 12 mm³/s max flow rate. They will be needed in the next tests, but not at this stage.
Slice it.
Check the flow on external perimeters on any layer of your choice.

Test 2

Return to the Prepare tab. Add 3 unused filament spools of “Anycubic PLA Silk 0.4 nozzle”
(users with AMS should add the spools so that they correspond to the AMS order).
Make sure the spool order is:

1–3: “Anycubic PLA Silk 0.4 nozzle”
4: “GeekFilament PLA 0.4 nozzle”
Change the filament for the cube model to spool 4 (“GeekFilament PLA 0.4 nozzle”, the same filament as in Test 1).
Slice it and check the flow on external perimeters again.

Test 3

Return to the Prepare tab. Change the 3 unused filaments from “Anycubic PLA Silk 0.4 nozzle” to “Anycubic PLA 0.4 nozzle”.
Double-check that the cube is still assigned to filament 4 (“GeekFilament PLA 0.4 nozzle”).
Slice it and check the flow on external perimeters again.

Actual results

Test 1

In all tests, the external perimeter on layer 80 is inspected
(although in practice all external perimeters are identical).

Speed: 152 mm/s
Flow: 12.00 mm³/s

Test 2

Speed: 167 mm/s
Flow: 13.20 mm³/s

For some reason, the external perimeter speed increased and exceeded the maximum flow limit, even though we only added filament spools that are not used for printing.

Test 3

We only changed the profiles of the unused filament spools, but the speed and flow changed again.

Speed: 162 mm/s
Flow: 12.80 mm³/s

Notes

Line width and layer height remained unchanged across all three tests:

Line width: 0.42 mm
Layer height: 0.20 mm

Expected results

Unused filament spools should not affect the slicing result.
Print speed, line width, layer height, and therefore the resulting maximum flow rate, should remain identical and must not exceed the value defined in the filament settings (no more than 12 mm³/s).

The results for external perimeters should be the same as in Test 1, where only one filament spool is present:

Flow: 12.00 mm³/s
Speed: 152 mm/s
Line width: 0.42 mm
Layer height: 0.20 mm

Project file & Debug log uploads

Issue_orca.3mf.zip

Checklist of files to include

Log file
Project file

Anything else?

No response

*Originally created by @Dalvikk on 1/10/2026* ### Is there an existing issue for this problem? - [x] I have searched the existing issues ### OrcaSlicer Version 2.3.1 ### Operating System (OS) macOS ### OS Version macOS 26.1 ### Additional system information _No response_ ### Printer Anycubic Kobra S1 ### How to reproduce #### Preparations 0. Download my **3MF archive** and open it in **OrcaSlicer**. You will see that: * The printer **“Anycubic Kobra S1 0.4 nozzle (my version, hardened steel)”** is selected. * 4 filament is selected. * The process **“0.20mm Standard KS1 0.4mm”** is selected. * A **20 mm cube** is placed on the build plate. Please note: this process uses a **high print speed (200 mm/s)** and the filament setting **“Do not slow down on external perimeters”** is enabled. This is required in order to **exceed the max flow rate** of the filament used for printing. --- #### Test 1 1. Remove all filaments except **GeekFilament PLA 0.4 nozzle**, which has a 12 mm³/s max flow rate. They will be needed in the next tests, but not at this stage. 2. Slice it. 3. Check the flow on external perimeters on any layer of your choice. --- #### Test 2 4. Return to the **Prepare** tab. Add **3 unused filament spools** of **“Anycubic PLA Silk 0.4 nozzle”** (users with AMS should add the spools so that they correspond to the AMS order). Make sure the spool order is: 1–3: **“Anycubic PLA Silk 0.4 nozzle”** 4: **“GeekFilament PLA 0.4 nozzle”** 5. Change the filament for the cube model to **spool 4** (**“GeekFilament PLA 0.4 nozzle”**, the same filament as in Test 1). 6. Slice it and **check the flow on external perimeters again**. --- #### Test 3 7. Return to the **Prepare** tab. Change the **3 unused filaments** from **“Anycubic PLA Silk 0.4 nozzle”** to **“Anycubic PLA 0.4 nozzle”**. Double-check that the cube is **still assigned to filament 4** (**“GeekFilament PLA 0.4 nozzle”**). 8. Slice it and **check the flow on external perimeters again**. #### Actual results **Test 1** In all tests, the **external perimeter on layer 80** is inspected (although in practice all external perimeters are identical). * **Speed:** 152 mm/s * **Flow:** 12.00 mm³/s <img width="1514" height="855" alt="Image" src="https://github.com/user-attachments/assets/3c506b09-a4d3-471a-af54-9444410fb501" /> --- **Test 2** * **Speed:** 167 mm/s * **Flow:** 13.20 mm³/s For some reason, the **external perimeter speed increased** and **exceeded the maximum flow limit**, even though we **only added filament spools that are not used for printing**. <img width="1510" height="862" alt="Image" src="https://github.com/user-attachments/assets/408178a4-2bea-4029-adb6-2d8b7b5e5780" /> --- **Test 3** We only changed the **profiles of the unused filament spools**, but the **speed and flow changed again**. * **Speed:** 162 mm/s * **Flow:** 12.80 mm³/s <img width="1511" height="864" alt="Image" src="https://github.com/user-attachments/assets/5495ec6a-6bc0-4bda-8d54-ed2be7bdc09e" /> --- **Notes** **Line width** and **layer height** remained unchanged across all three tests: * **Line width:** 0.42 mm * **Layer height:** 0.20 mm --- ### Expected results Unused filament spools should **not affect the slicing result**. Print speed, line width, layer height, and therefore the **resulting maximum flow rate**, should remain **identical** and must **not exceed** the value defined in the filament settings (**no more than 12 mm³/s**). The results for **external perimeters** should be the same as in **Test 1**, where only one filament spool is present: * **Flow:** 12.00 mm³/s * **Speed:** 152 mm/s * **Line width:** 0.42 mm * **Layer height:** 0.20 mm ### Project file & Debug log uploads [Issue_orca.3mf.zip](https://github.com/user-attachments/files/24545921/Issue_orca.3mf.zip) ### Checklist of files to include - [ ] Log file - [x] Project file ### Anything else? _No response_

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Reference: github/OrcaSlicer#1122