Fan noise printing PETG still unsolved?!  

Re: Fan noise printing PETG still unsolved?!

Anyways, sounds like a fix has been made, coz that would've driven me up the wall in a quiet environment as well.

Looks like it. Let's hope this fix makes it into the official branch!

So, you just installed the 3.4.1 zip file from the github page, this one for anyone not on github:
and flashed it just like a Prusa official update and it worked, yes?

Correct. Although I have to say I did not test it extensively, I just flashed it using Slic3r PE and printed a few parts.

Re: Fan noise printing PETG still unsolved?!

After 2 weeks printing PLA with fantastic results on my new printer, I tried PETG for the first time and the sound of the fan drives me crazy. I already have tinnitus and hyperacusis for some years and bought the prusa printer because of the reviews that mentioned how quiet the printer is. I am sitting in the room where the printer works with a bose noise canseling headphone on my ears and can still hear the hissing sound of the fan. Terrible. I also noticed on the internet that this is an ongoing problem with the prusa MK3 so I am very surprised they could not fix this. Come on Prusa with all the knowledge you have...

Re: Fan noise printing PETG still unsolved?!

Send an email to Prusa. The more they hear about it, the more likely it will get that they incorporate the fix into the main branch.
In the meantime install the firmware from the github 460 thread: https://github.com/prusa3d/Prusa-Firmware/issues/460 . I am just printing with the modified 3.5.0 firmware (PLA though), looks like it works.

Re: Fan noise printing PETG still unsolved?!

I don't think they care too much about this. Was on chat with support and the answer is "yeah, the fan noise is normal".
I'm guessing here but there are 2 factors:
- Probably not all fans are the same, and some fans tends to whine more (resonant PWM freq.)
- Not all ppl hear the noise the same way, somebody is bother with it, somebody not

I will however test the 3.5.0 modified firmware as I have a bunch of PETG printing to do.

Re: Fan noise printing PETG still unsolved?!

I am thinking of trying a low pass filter into a common collector transistor to basically convert the PWM into DC V but don't know if the rpm sense would work below say 2.5 v dc, but this would silence the fan from the PWM noise. (A firmware change could ignore rpm sense below an operating threshold, but would still operate during startup, self checks or above the threshold).

Quick calculations show PWM into a 4k7 resistor which is connected to a 2.2 uF capacitor which has one leg to ground gives a nice smooth quick responding output from 0 to 5 v with a 0 to 100 % duty PWM at 480 Hz, this would then be fed into a 2n2222 transistor base through a current limiting resistor, with the collector connected directly to +5v and the emitter to the +ve of the fan.
The transistor like this is a voltage follower, basically what you put in comes out but with a much higher current (2N2222 can output 600mA).

There is a +5v and a -0v available on connector j7 which is unused if I am not mistaken.
A small board could be made to plug into the existing fan socket on the controller board, sit a 90 deg down (As looking fitted on the printer) over Q2 and Q5 and have the 3 pins for the fan to plug onto sticking out of the side towards and underneath the filament sensor, a two wire lead would also come from the board and be plugged into j7 to pick up power (-0V is nearest the top).
For the component count and space available this is easily do able, I just need some free time to do this myself, most likely could be done on a small piece of veroboard, no need for custom PCB. I have everything to do this except time ATM.

Re: Fan noise printing PETG still unsolved?!

I had pretty much the same thought - lowpass with voltage follower. There are some problems though. You lose max RPM because of diode drops, you need some extra wiring because GND is not available on the fan pins (only +5V, PWM switched to GND, sense). It is doable, but rather a big effort for a solution that should be done in software (btw 3.5.0 modified in Github works fine for me).
If the software mod would not work, I'd probably connect the fan to my lab power supply and let it run on a lower voltage for PETG prints.

Re: Fan noise printing PETG still unsolved?!

??? (only +5V, PWM switched to GND, sense) 😕

I was about to say you must be wrong, but no, I checked the circuit diagram 😳
Good job I did, else I would look a right fool.

Re: Fan noise printing PETG still unsolved?!

So I finally decided yesterday that I want this noise gone and went and got the latest firmware (3.5.1) source code, manually merged the pull request 1193 https://github.com/prusa3d/Prusa-Firmware/pull/1193 that basically solves this problem, compiled the firmware myself and flashed the printer.

... I can only say: WOW!
Now it's the printer it should have been. No more whining noise.
I have printed with PLA, PETG, does not make much difference now (PETG is even more silent now since it keeps the fan without whining at 30%)

If anyone wants to give it a shot, you can find the firmware zip on the very bottom of the infamous 460 issue https://github.com/prusa3d/Prusa-Firmware/issues/460 . I wish you all best of luck, for me at least until this is addressed by Prusa (if ever), I will just get the latest firmware source code and patch it myself, as long as it's possible (forked repo here: https://github.com/zoltanf/Prusa-Firmware/releases ).

Re: Fan noise printing PETG still unsolved?!

If anyone wants to give it a shot, you can find the firmware zip on the very bottom of the infamous 460 issue https://github.com/prusa3d/Prusa-Firmware/issues/460 . I wish you all best of luck, for me at least until this is addressed by Prusa (if ever), I will just get the latest firmware source code and patch it myself, as long as it's possible (forked repo here: https://github.com/zoltanf/Prusa-Firmware/releases ).

I know I was a naysayer at first, but after using this FW without the noise...I definitely like it that way 😀 cheers