Hi.
In the name of the adventure of adding active chamber heating, I decided to start by taking care of the initial requirements I set for myself.
The first one is adding an exhaust fan to take the hot air out from the microcontroller board.
I bought the NF-A4x10 12v Noctua fan.
I created a Y splitter cable that connects to the header of the stock Bambulab MC fan.
Using a Noctua fan mount designed by someone from Makerworld site, I mounted the fan on the MC heatsink to such the hot air out.
Upon placing my hand at the back, I barely feel the movement of air.
So my question to anyone who reads this is, do you think that because I added a 2nd fan on the same header, instead of just using a single fan, there’s less power reaching the Noctua fan?
Not having the necessary knowhow isn’t a shame. You should seek an electronics engineer or technician among your friends or colleagues, show/explain to him/her what you did, and ask for a pre- and post- fan install power output measurement. However, based on what you have described, I think you’ve split the nominal power output between the two fans, and as result neither performs at nominal power output, but I might be wrong, which is why I suggest bringing in an electronics expert (which I’m not).
Likely an aero issue. Noctuas are never going to turn fast, so if you think the fan speed is reasonable but its still not moving much air, I’d bet you are dealing with bad airflow from two fighting fans.
Personally, if the exhaust fan is close to the board, I’d disconnect the BBL fan. Its possibly sucking air from the point the Noctua fan is also sucking from.
A Y splitter should behave like a parallel circuit so there should be no change in voltage.
Here’s a simple low tech test you might try with paper and Scotch tape. If you suspect your fans are wired in series, therefore cutting power in half, unplug one fan to verify. For a non-technical outflow test, tape pieces of paper of varying weights loosely along the fan housing. Experiment with thickness. If the fan is in single fan mode, you should see different paper deflection compared to dual mode, confirming your suspicion. If you confirm that it is lower in outflow, then look at your wiring to rerun the wire in parallel.
I’ll give that a try.
I’m pretty sure the Y splitter I did is correct. It’s not the first time I’ve created a Y splitter, but it could also be that two fans on the same header are too much.
The BBL fan is pushing air over the heatsink while the noctua fan is pulling the hot air out of the case. I’m convinced it’s something wrong that I’ve done and not an issue with the fans. But thanks for the insight… this is something worth remembering for future sake.
I had a look at my spare control board fan, it’s a 4 wire fan. So what I think may be happeningis:- If your Y-splitter is connecting all 4 wires then it would mean that 2 tacho signals could be asserted on to the same same line. (They are open collectors so it would still work) This would make the controller the think the fan is going twice as fast depending on how the 2 fans are syncing up. Try to remove/cut the tacho wire from your new fan and see if it changes the speed.
Ok then try removing the PWM signal to the noctua fan. This should make the noctua run at 100% (if you connect the noctua’s pwm wire to ground it will stop or run very slowly). I’m thinking the signal from the printer’s control board is not strong enough to drive both fan’s PWM inputs. (because they have similar RC integrators inside)
Normally fan with PWM run at max speed when no PWM signal is present, connecting it to 0V makes it stop. Maybe the noctua works differently, Try powering the fan and touching the pwm wire to 12V and 0V and see what affect it has.
I would avoid Noctua. You have to pay close attention to the number of revolutions per minute. These are usually fans with fewer revolutions and a different blade design because they are supposed to be quieter.
