# Sienci ATC spindle cooling fan action **URL:** \ **Category:** ❓ Something's Up\ **Created:** [May 20, 2026, 4:44pm UTC](https://forum.sienci.com/t/sienci-atc-spindle-cooling-fan-action/26432 "2026-05-20T16:44:25Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![aksiuchenka](https://forum.sienci.com/letter_avatar_proxy/v4/letter/a/b782af/32.png) [@aksiuchenka](https://forum.sienci.com/u/aksiuchenka)\ **Post date:** [May 20, 2026, 4:44pm UTC](https://forum.sienci.com/t/sienci-atc-spindle-cooling-fan-action/26432/1 "2026-05-20T16:44:25Z")
The ATC spindle cooling fan is always on, never turns off. It makes noise even when the machine is idle, when SLB-EXT is powered on. The blog post “Everything You Need to Know about the ATC” from 12/03/25 says: “Additionally, since we can turn the fan on and off as needed, this impacts the overall noise of the spindle as well. It should be noted that the fan will primarily turn on when the spindle is running and cutting, where the sound of the spindle is masked by the sound of cutting anyway.” So, I expect the cooling fan to be off when there is no need for a cool-down. What is the community experience with this? ---
**Author:** ![aksiuchenka](https://forum.sienci.com/letter_avatar_proxy/v4/letter/a/b782af/32.png) [@aksiuchenka](https://forum.sienci.com/u/aksiuchenka)\ **Post date:** [May 20, 2026, 8:54pm UTC](https://forum.sienci.com/t/sienci-atc-spindle-cooling-fan-action/26432/2 "2026-05-20T20:54:31Z")
Here is the response I got from Sienci Labs support. ☹ " The cooling fan always being on is intensional for safety, the information you found on our website isn’t correct, i will have it edited right away. Thank you, Danial " ---
**Author:** ![Jens](https://forum.sienci.com/letter_avatar_proxy/v4/letter/j/d2c977/32.png) [@Jens](https://forum.sienci.com/u/Jens)\ **Post date:** [May 20, 2026, 10:27pm UTC](https://forum.sienci.com/t/sienci-atc-spindle-cooling-fan-action/26432/3 "2026-05-20T22:27:52Z")
That is rather disappointing for those of us who leave their Altmill powered up always. What aspect of safety requires the fan to be on all the time? Could there not be a choice in the setup to allow the fan action be ‘constant’ (default) or ‘when spindle is on’ ? ---
**Author:** ![guy559](https://forum.sienci.com/letter_avatar_proxy/v4/letter/g/50afbb/32.png) [@guy559](https://forum.sienci.com/u/guy559)\ **Post date:** [June 9, 2026, 10:30am UTC](https://forum.sienci.com/t/sienci-atc-spindle-cooling-fan-action/26432/4 "2026-06-09T10:30:53Z")
Is this spindle dependent? I just built a 2x4 AltMill with Sienci’s 2.2kW spindle. No sound from spindle when at idle. Unless I’m missing something, I thought the spindle fan is attached to rotating part within spindle–i.e., the cooling fan rotates as the armature does…? ---
**Author:** ![aksiuchenka](https://forum.sienci.com/letter_avatar_proxy/v4/letter/a/b782af/32.png) [@aksiuchenka](https://forum.sienci.com/u/aksiuchenka)\ **Post date:** [June 15, 2026, 5:02pm UTC](https://forum.sienci.com/t/sienci-atc-spindle-cooling-fan-action/26432/5 "2026-06-15T17:02:05Z")
Is your 2.2kW spindle ATC one? ---
**Author:** ![guy559](https://forum.sienci.com/letter_avatar_proxy/v4/letter/g/50afbb/32.png) [@guy559](https://forum.sienci.com/u/guy559)\ **Post date:** [June 17, 2026, 9:32pm UTC](https://forum.sienci.com/t/sienci-atc-spindle-cooling-fan-action/26432/6 "2026-06-17T21:32:59Z")
Thanks - missed that crucial detail! ---
**Author:** ![LightBurnSupport](https://forum.sienci.com/user_avatar/forum.sienci.com/lightburnsupport/32/10249_2.png) [@LightBurnSupport](https://forum.sienci.com/u/LightBurnSupport)\ **Post date:** [August 6, 2026, 6:14pm UTC](https://forum.sienci.com/t/sienci-atc-spindle-cooling-fan-action/26432/7 "2026-08-06T18:14:44Z")
Would just like to add a vote towards being able to control the spindle fan. Trying to work next to the machine is _very_ annoying with the ~60DBa fan running constantly. I’ve poked at the firmware settings and have yet to find a solution. ---
**Author:** ![Altmillal1114](https://forum.sienci.com/letter_avatar_proxy/v4/letter/a/f6c823/32.png) [@Altmillal1114](https://forum.sienci.com/u/Altmillal1114)\ **Post date:** [August 7, 2026, 10:28am UTC](https://forum.sienci.com/t/sienci-atc-spindle-cooling-fan-action/26432/8 "2026-08-07T10:28:21Z")
yep very annoying and for now no control of it. I asked support about it as well and no fix yet. hopefully they will turn it off while its not in use ---
**Author:** ![LightBurnSupport](https://forum.sienci.com/user_avatar/forum.sienci.com/lightburnsupport/32/10249_2.png) [@LightBurnSupport](https://forum.sienci.com/u/LightBurnSupport)\ **Post date:** [August 7, 2026, 2:38pm UTC](https://forum.sienci.com/t/sienci-atc-spindle-cooling-fan-action/26432/9 "2026-08-07T14:38:31Z")
Does anyone else experience an air leak once the SLB is turned off? Persistent, from the ATC spindle. Now with shutdown I have to turn off air to the machine as well. ---
**Author:** ![Altmillal1114](https://forum.sienci.com/letter_avatar_proxy/v4/letter/a/f6c823/32.png) [@Altmillal1114](https://forum.sienci.com/u/Altmillal1114)\ **Post date:** [August 8, 2026, 10:56am UTC](https://forum.sienci.com/t/sienci-atc-spindle-cooling-fan-action/26432/10 "2026-08-08T10:56:58Z")
if i do emergency stop it does that. try doing m65 p0 from the console when that happens. see if that stops leaking. There is a small amount of airflow during job run to keep spindle’s internals clean during cutting. its activated via m64 p0 and m65 p0 stops it ---
**Author:** ![LightBurnSupport](https://forum.sienci.com/user_avatar/forum.sienci.com/lightburnsupport/32/10249_2.png) [@LightBurnSupport](https://forum.sienci.com/u/LightBurnSupport)\ **Post date:** [August 13, 2026, 9:17pm UTC](https://forum.sienci.com/t/sienci-atc-spindle-cooling-fan-action/26432/11 "2026-08-13T21:17:53Z")
I tried that, but no dice. On eStop it’s silent, but after removing power from the SLB via the power switch on the back, I get the air leak.