Improved Cooling - Link Aux Fan to Part Cooling Fan, or Add Checkbox "Cooling Boost" for Short Layer Times #1664

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MrUnknownDE · 2026-04-05T19:00:34+02:00

MrUnknownDE commented

2026-04-05 19:00:34 +02:00

Originally created by @Fuzzyl0g1x on 11/10/2025

Is there an existing issue for this feature request?

I have searched the existing issues

When printing small objects or when printing an object that has a narrow feature, it is sometimes impossible to slow down enough to ensure adequate cooling. When this happens, parts will have a "melted" look or fail outright. Below is an example of a model that has a tab that cannot be slowed enough to avoid melting.

This problem occurs frequently when printing high-warpage materials such as ABS and ASA, where you have to keep the chamber temperature way up and the cooling fan speeds very low to avoid warpage. Because the fan speeds are lower and the air they're blowing is so hot, cooling is less effective, and slowing down to ensure adequate cooling is impractical (e.g. you would have to print at < 5 mm/sec, which is extruder jam territory).

These materials, however, will tolerate (and indeed require) vastly higher fan speeds on small objects (which are stiffer and warp less) and when the bed moves away from the aux fan. However, with only one setting for all prints, users have to check layer times and manually adjust speeds at the proper time during a print, which is not ideal.

Which printers will be beneficial to this feature?

Marlin

Describe the solution you'd like

What I'm suggesting is Orca should implement one or both of the following options for users:

Simple option: scale the aux fan with the part fan speed. This could be implemented using a "Link Part Fan and Aux Fan Speeds" checkbox.
Complex option: Boost the auxiliary fan speed when the layer time limit cannot be achieved with slowdowns alone. This could be implemented with a checkbox and a fixed "boost" speed (e.g. "Override Aux Fan Speed during Fast Layers" checkbox and a percentage value).

If you want get really fancy, you could scale the aux fan speed from the user-defined setpoint to a maximum value based on how far below the minimum layer times the print needs to go (e.g. at 10 seconds = default aux speed, 1 second = 80% aux, and linearly interpolate between those points for everything between).

Ultimately, I think that both options should be implemented--being able to scale both fans during normal printing will benefit everybody, and boosting the fan speeds on small parts / small sections will benefit engineering prints. For users that prefer the old way, they can leave the features disabled thanks to the enable/disable checkboxes.

Describe alternatives you've considered

No response

Additional context

No response

*Originally created by @Fuzzyl0g1x on 11/10/2025* ### Is there an existing issue for this feature request? - [x] I have searched the existing issues ### Is your feature request related to a problem? When printing small objects or when printing an object that has a narrow feature, it is sometimes impossible to slow down enough to ensure adequate cooling. When this happens, parts will have a "melted" look or fail outright. Below is an example of a model that has a tab that cannot be slowed enough to avoid melting. <img width="1155" height="922" alt="Image" src="https://github.com/user-attachments/assets/7e62d5a4-7c4b-4cec-b969-144730352033" /> This problem occurs frequently when printing high-warpage materials such as ABS and ASA, where you have to keep the chamber temperature way up and the cooling fan speeds very low to avoid warpage. Because the fan speeds are lower and the air they're blowing is so hot, cooling is less effective, and slowing down to ensure adequate cooling is impractical (e.g. you would have to print at < 5 mm/sec, which is extruder jam territory). These materials, however, will tolerate (and indeed require) vastly higher fan speeds on small objects (which are stiffer and warp less) and when the bed moves away from the aux fan. However, with only one setting for all prints, users have to check layer times and manually adjust speeds at the proper time during a print, which is not ideal. ### Which printers will be beneficial to this feature? Marlin ### Describe the solution you'd like What I'm suggesting is Orca should implement one or both of the following options for users: 1. Simple option: scale the aux fan with the part fan speed. This could be implemented using a "Link Part Fan and Aux Fan Speeds" checkbox. 2. Complex option: Boost the auxiliary fan speed when the layer time limit cannot be achieved with slowdowns alone. This could be implemented with a checkbox and a fixed "boost" speed (e.g. "Override Aux Fan Speed during Fast Layers" checkbox and a percentage value). If you want get really fancy, you could scale the aux fan speed from the user-defined setpoint to a maximum value based on how far below the minimum layer times the print needs to go (e.g. at 10 seconds = default aux speed, 1 second = 80% aux, and linearly interpolate between those points for everything between). Ultimately, I think that both options should be implemented--being able to scale both fans during normal printing will benefit everybody, and boosting the fan speeds on small parts / small sections will benefit engineering prints. For users that prefer the old way, they can leave the features disabled thanks to the enable/disable checkboxes. ### Describe alternatives you've considered _No response_ ### Additional context _No response_

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Reference: github/OrcaSlicer#1664