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Fans don’t start


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Posted · Fans don’t start

Hello, I’m having the following problem every time I start a print. The cooling fans don’t start automatically. I have to turn them on from the printer’s menu. Is there a bug in cura or in printer’s firmware? I use cura 4.8 and marlin firmware. Thank you. 

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    Posted · Fans don’t start

    Yeah, it's hard to tell what's going on without seeing your settings.

    After posting your profile, on the right end of the "settings search" box is a drop-down for settings visibility.  One of the options is "All".  When they all show up go down to "Cooling" at look at all the settings.


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    Posted · Fans don’t start

    What model printer are you using?

    For most Ultimaker printers the hot end cooling fan turns on when your nozzle or Print Core heat to 50C. It cannot be controlled in the settings.

    For your model cooling fans--how long are you waiting for those to turn on? They don't kick on until the second or third layer, in order to prevent adhesion issues.

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    Posted · Fans don’t start

    Thank you all for the response but I know about the settings and what to they do and also about the delay until the second layer. I believe it is a software problem. My printer is Sapphire pro by TwoTrees. I attached a photo of my settings for you to see. 


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    Posted (edited) · Fans don’t start

    With the Initial Fan Speed set to 100% and Regular Fan Speed Height at 0 (Cura layer 1) you should see this in the Gcode as the fan should be at 100% right from the start.

    M106 S255  ;Layer cooling fan at 100%


    Using the settings you show you will see something like this.

    M107  ;Layer cooling fan off

    then later...

    M106 S255  ;Layer cooling fan 100%


    Open the Gcode file and search for M106.  The units are PWM so they can be from 0 (0%) to 255 (100%).  If they are there, and if you can turn the fan on using the LCD control, then it's a firmware problem.  If there aren't any M106 lines then it's a Cura problem because they are supposed to be there.


    EDIT:  The original 4010 layer cooling blower on my Ender 3 Pro would not start to spin until the M106 setting was 30% (PWM 77).  It had sleeve bearings.  The current ball bearing 5015 will start to spin at 12% (PWM  31) and will continue to spin as low as 8% (PWM 20).  So it's possible that the start-up speed of your layer cooling blower is high and the initial M106 settings are just to low to get it to spin.  With my original 4010 - if I asked Cura to increase fan speed to 28% over 5 layers the fan would get the signal, but it wouldn't start to spin. 

    Edited by GregValiant
    Another thought
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    Posted (edited) · Fans don’t start

    So I guess it is a firmware problem because the M106 code exists in the file, as you said. Can anyone provide me with a marlin firmware? Do you know if I can load a different firmware on my printer?

    Edited by faraso
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    Posted · Fans don’t start

    It depends on the printer.  Some need a bootloader installed first.  On others you can simply load from an SD card.  It's hard to believe that M106 and M107 weren't enabled in the firmware.  Controlling the fan is very basic to 3D printing.  You never mentioned the printer manufacturer or model.

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    Posted · Fans don’t start

    I'm having the exact same problem with a new Biqu B1. The M106 command is there. What I've tried is to erase de indexing of the fan. Instead of M106 S255 P3 I just leave M106 and this way the fans turn on when they should.
    Is there a way I can tweak the code Cura writes so I can avoid the indexing?

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    Posted · Fans don’t start

    The P parameter is the fan number.  If you have a single extruder/single hot end then P3 doesn't work because you don't have 4 layer cooling fans.  The stock B1 StartUp Gcode does not have any reference to a fan number.


    Check in Manage Printers / Machine Settings and on the Extruder tab there is a box for "Cooling Fan Number".  For most systems that should be a 0 indicating that you have a single layer cooling fan (fan numbers are base 0).

    Even with one of the fancy double blower layer cooling contraptions the blowers are usually wired together and so they are also single blower systems.

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