Part cooling fan always on at low speed | Rat Rig Community [Unofficial] | Page 1

rough parcel May 29, 2023, 11:00 AM

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Hello, I have an issue with my Rat rig C-Core 3.1 priter (400x400) cooling part fan. I changed the part cooling fan with this one "https://www.distrelec.ch/fr/ventilateur-axial-dc-bille-40x40x28mm-12v-48-6m-sanyo-denki-9ga0412p3k01/p/30154445". It seems to work quiet well. I can change the speed with PWM control correctly. The only problem is that when the value of the fan speed is set to 0 (when not printing or while first layer) it still blows some air. The speed is very slow but not at zero as expected. I have trouble understnding the issue...

This is my klipper config for part cooling (pretty standard configuration) :

[fan]
pin: !fan_part_cooling_pin
cycle_time: 0.00004

Did anyone have the same issue ?

quaint osprey May 29, 2023, 12:00 PM

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Yup that is a known issue, see https://os.ratrig.com/docs/guides/4028#my-fan-doesnt-shut-off-at-0

Connecting a 4028 fan | RatOS

4028 server fans are becoming a popular option for part cooling because of their light weight and great pressure and flow rates. In this guide we'll go over how to connect one and use it for part cooling. 4-pin fans usually aren't used in 3d printers, and many boards only provide 2-pin ports, but fear not! There's always a way.

rough parcel May 29, 2023, 12:23 PM

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Oops, I will try that... I thought that issue was only at printer startup.

rough parcel May 29, 2023, 12:57 PM

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What pin would it be on the "BIGTREETECH Octopus v1.1" (PA9) ?

quaint osprey May 29, 2023, 1:11 PM

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rough parcel What pin would it be on the "BIGTREETECH Octopus v1.1" (PA9) ?

if you read the instructions, you must wire it differently to use the enable pin. Did you first do that?

rough parcel May 29, 2023, 1:22 PM

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Yes exactly, I was thinking of connecting the gnd cable of the fans power intpu to HE1 - pin but I am not sure if I should keep the + wire on the HE1 + pin or leave it at its current position..

rough parcel May 29, 2023, 2:17 PM

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Sorry for the stupid question

keen nimbus May 29, 2023, 2:17 PM

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rough parcel Yes exactly, I was thinking of connecting the gnd cable of the fans power intpu ...

you can leave + wire where it is. Only gnd is controlled

keen nimbus May 29, 2023, 2:17 PM

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rough parcel Sorry for the stupid question

no worries

rough parcel May 29, 2023, 2:17 PM

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Yeah it is the PWM that is put on HE1..

keen nimbus May 29, 2023, 2:18 PM

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You can connect PWN cable to fan octopus gnd pin, and GND of fan to HE1 GND

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Does that make sense? I am not the best in explaining, so don't be ashamed to ask. 8)

rough parcel May 29, 2023, 2:20 PM

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On this image, the blue wire would be connected to the HE1 Negative pin right ?

keen nimbus May 29, 2023, 2:20 PM

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black to HE1

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gnd is black

rough parcel May 29, 2023, 2:20 PM

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Oh okay

keen nimbus May 29, 2023, 2:21 PM

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blue is PWN - you can leave it as on picture

rough parcel May 29, 2023, 2:21 PM

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Ahh I got confused..

keen nimbus May 29, 2023, 2:21 PM

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PWN does not need a lot of current - that is why fan pin is good enogh, but ground of power full fan should be controlled by powerful transisor, as in HE1

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That is basically the main reason of not using another fan header for gnd of the fan

rough parcel May 29, 2023, 2:23 PM

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Okay, but then I dont understand really why the red wire souhld not be connected to the HE1 positiv...

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My electricity nowledge is not ideal ^^

keen nimbus May 29, 2023, 2:24 PM

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You can connect red to HE1 + too, it just doesn't matter, transistor control only the GND(black, -) pin, +(red) is always on

rough parcel May 29, 2023, 2:32 PM

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Okay I get it 🙂

#Part cooling fan always on at low speed