Part fan needs a push



  • My part fan seems to need a push (by hand) to get it started and I have very little control over the speed of it. Any ideas?

    Cheers



  • Look at https://duet3d.dozuki.com/Wiki/Gcode#Section_M106_Fan_On
    Specifically loook at "blip" time to get the fan started.
    What are the rest of your M106 parameters?



  • @Sakey said in Part fan needs a push:

    My part fan seems to need a push (by hand) to get it started

    Even at 100% or just at lower percentages?



  • Assuming it also happens at full power, that is a normal mode of failure for fans. The friction on the sleeve bearing is higher than the power of the motor portion. I have one fan that I re-lubricate the bearing about every three months on.
    One of the labels in the center of the fan hides access to the bearing and a single drop of sewing machine oil will get it going like new. Cover the bearing access after re-lubricating to prevent dust ingress.



  • Another thing is that some fans don't like/work well being powered by PWM (pulse width modulation) which is how the duet controls fans. You may just need to try a different brand fan.



  • To add to all the other suggestions, you can also try using a lower PWM frequency (the "F" parameter in M106). I use some very small blower fans and the only way I can control the is by using a really low frequency of 10 Hz (I think the default is 250). .



  • And just to make things extra confusing, some fans won't spin unless the frequency is set much higher. Up to F30000 is viable.



  • Thanks everyone for the suggestions!

    Will try each one and get back. Just annoying that I keep having to open the case on my printed to give it a shove. It's a Noctua 40mm fan. It has to be on 100% and then give it a flick any lower and it wont keep spinning.



  • Oh yeah... What voltage is the fan and how is the fan power jumper set and what voltage is Vin? Try moving the fan to one of the "Always On" fan headers and see what happens.


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