"Filament Ramming Length" default adds 10mm of filament to all prime towers which it shouldn't #1615

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MrUnknownDE · 2026-04-05T18:41:29+02:00

MrUnknownDE commented

2026-04-05 18:41:29 +02:00

Originally created by @crpalmer on 11/16/2025

Is there an existing issue for this feature request?

I have searched the existing issues

The default value of "filament_change_length" ("Filament Ramming Length" in the UI) should be changed from 10 to 0.

At the moment, all prime towers have an extra 10mm of filament printed to them before starting a multi-material tool change. The tooltip claims that this helps avoid oozing. I'm not sure I understand how transitioning from printing in the model to printing in the tower to retracting and removing the filament is going to reduce oozing compared to just transitioning from printing to rectracting and removing the filament...

In particular, on a H2D printing which has dual nozzles, it adds 10mm of filament to every tool change which is completely unnecessary. Note that this is not doing anything to improve the quality post tool change, just pre tool change. Aka, if you switch from T0 to T1 and your prime volume is set to 2mm^3 then you will do:

T0: print about 7.65mm^3 (10mm) to the prime tower
switch tools, perform any necessary flushing of the nozzle
T1: print 2mm^3 volume
print your layer(s)
T1: print about 7.65mm^3 to the prime tower

FWIW, the only filaments which change this value from the default are the BBL PETG HF and PLA Tough+ / Basic which all reduce it from the default 10. This implies to me that BBL doesn't even know why they made this change in the first place and they don't like the default either!

Which printers will be beneficial to this feature?

All

Describe the solution you'd like

The default value of "filament_change_length" ("Filament Ramming Length" in the UI) should be changed from 10 to 0.

Describe alternatives you've considered

No response

Additional context

No response

*Originally created by @crpalmer on 11/16/2025* ### Is there an existing issue for this feature request? - [x] I have searched the existing issues ### Is your feature request related to a problem? The default value of "filament_change_length" ("Filament Ramming Length" in the UI) should be changed from 10 to 0. At the moment, all prime towers have an extra 10mm of filament printed to them before starting a multi-material tool change. The tooltip claims that this helps avoid oozing. I'm not sure I understand how transitioning from printing in the model to printing in the tower to retracting and removing the filament is going to reduce oozing compared to just transitioning from printing to rectracting and removing the filament... In particular, on a H2D printing which has dual nozzles, it adds 10mm of filament to every tool change which is completely unnecessary. Note that this is not doing anything to improve the quality post tool change, just pre tool change. Aka, if you switch from T0 to T1 and your prime volume is set to 2mm^3 then you will do: T0: print about 7.65mm^3 (10mm) to the prime tower switch tools, perform any necessary flushing of the nozzle T1: print 2mm^3 volume print your layer(s) T1: print about 7.65mm^3 to the prime tower FWIW, the only filaments which change this value from the default are the BBL PETG HF and PLA Tough+ / Basic which all reduce it from the default 10. This implies to me that BBL doesn't even know why they made this change in the first place and they don't like the default either! ### Which printers will be beneficial to this feature? All ### Describe the solution you'd like The default value of "filament_change_length" ("Filament Ramming Length" in the UI) should be changed from 10 to 0. ### Describe alternatives you've considered _No response_ ### Additional context _No response_

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Reference: github/OrcaSlicer#1615