[Dave] just couldn’t take the ambient noise from his Lulzbot Mini anymore, so he built a fancy fan controller for it.
He measured some points on the printer’s Rambo controller board to see what actually got hot during a print. The hottest components were the motor drivers, so he taped a thermistor to them. He also placed one in the printer’s power supply. He replaced the main fan with a low noise model from Noctua (which have the most insanely fancy packaging you could imagine for a computer fan). The software on an Arduino Nano now idles the fan at an inaudible 650RPM, if an unacceptable temperature increase is detected, it increases the fan speed for a period, keeping everything nice and quietly cool.
The graphics display was added because, “why not?” A classic reason. The graphics runs on a hacked version of Adafruit’s library. It took him quite a while to get the graphics coded, but they add that extra bit of high-tech flair to keep the cool factor of the 3d printer up before they become as ubiquitous as toasters in the home. The code, fritzing board layout, 3D models, and a full build log is available at his site.
I just used a thermal switch to bypass a resistor on a PC fan that only allows it to run at a slow speed, when the NO switch gets to around 110-125 deg F it closes and gives full power to the fan. it opens back up at around 105 degrees. Found it surplus from electronics goldmine. It’s big but gluing it to the motor controller heatsink works great.
I would quickly get quite irritated by a fan only going between low-speed and full-speed. The mobo on my PC allows for the fan-speeds to be adjusted gradually instead of jumping between only a few hard breakpoints and it works quite well — the gradual increase in fan-speeds makes it somewhat less distracting.
That said, I am quite sensitive to such background noise.
….it’s really that easy? I’ve been trying to look into making a fan controller for months, and I keep getting scared off by how PC fans supposedly need some frequency of PWM other than the Arduino’s default one, and the lack of straightforward information about working it out… (Like I literally found far more information about controlling PWM fans with just a 555 than I did microcontrollers.) :S
I had no issues with the default PWM frequency in this project. However, you can change the default frequency in Arduino – you just have to be careful if using timers. In my case, yes, it was easy.
Dave
Wow this seems a lot easier than i thought. Maybe i will try and build one my self haha. Thanks for the great post and the idea. Is the controller mainly to reduce the noise or is there other advantages to having it?
Cheers!