Automated Cooling System for Bambu A1 3D Printer

My 3d printing setup is located in my dusty woodshop, which has led me down the rabbit hole in which i have created this probably overly elaborate system for temperature/air management.

The Bambu A1 is the printer that I settled on for my first printer, and I'm really happy with it, however I realized in my research that Bambu does not recommend enclosing this printer (with no further explanation), so after consulting the meme-lords of reddit I learned that it is because there is no internal cooling fan for the motherboard. I have a pair of small fans cooling the A1 directly, a set of larger fans exchanging air from outside the enclosure through a filter to keep wood dust out (and maybe some plastic cancer out of the air? please? probably not.) These fans are controlled by a Raspberry Pi Pico using a DHT11 module to sense the enclosure temperature. I was able to use the auxiliary AMS plug to pull 24V to power everything, and it all fits in a nice enclosure I made.

These are some of the very first 3d prints I've designed and printed so there are definitely improvements that could be made, but it's a functional and fun project. Enjoy!

1. Rasberry Pi pico
2. 2 Relay module
3. Switch
4. 24v 40x40mm fan (x2)
5. 120v fan (x2)
6. Male molex connector
7. Air filter
8. Buck converter
9. DHT11 (temperature sensor)

Print the left and right side port fan housings. One side is sculpted to accommodate the touch screen and not interfere with it's pivoting motion. I've attempted to sculpt them so that the air is directed towards the air inlets present on the side and underneath the A1. My initial intent was to have the fans positioned so that air would flow in one direction, but I ended up making it so that they both just blew air towards the printer and this seems to work fine.

I'm using 40x40mm 24v fans so they can be directly powered from the auxiliary AMS plug (through a relay, but we'll get to that later) The fans fit tightly into the housing, and I did not have to use any screws, although screw holes are present if yours are a looser fit.

The side ports slide underneath the printer, with it's rubber feet slotting into the notch. All you have to do is push it up against the printer and it should be aligned with the holes. There is still room on the left side for a reasonably sized poop bucket.

The idea of this part of the project stemmed from a concern that my enclosure would become too warm, and the fans to cool the motherboard would become useless since they were just blowing hot air onto it. This part is probably not necessary, but I made it, so here's how I did it.

Cut a 9.5" x 8" opening in the side of your enclosure, and attach the filter housing to the inside wall of the enclosure.

Install the fans into the split fan duct print. These fans fit tightly, but I still put a couple metal screws to secure them. One should be air intake and the other should be exhaust, placement does not matter.

The fan duct mates with the filter housing, and I glued it in place. There is definitely room for improvement in this part of the design. Use the grill to locate the placement of the brackets that hold it in place, and screw them in. The grill should slide easily in and out for filter installation. You may need to cut a slit in the white walls of the filter to slide it over the divider separating the intake/exhaust.

If you wanted to omit this step, you could just wire the 40mm fans into the 24v AMS plug with a switch in line and do it manually. The large fan for the air filter has an inline switch already.

What I've done here is have the Pico monitor the temperature in the enclosure, turn on the cooling fans if it goes above 65F, and have the air filter fans cycle on/off every 3 minutes when it is >75F. There is some additional code in there for a future project where I'll be using this same system to control a versions of Ricky Impey's Sunlu S1 mod with another 24v 40mm fan. Pin 16 on the pi is coded to control this future project.

Save the file A1_V3.0.py as main.py so it automatically runs, and you'll need to have dht11.py and temp_sensor.py on the pi as well. This is all in micropython, so I would assume it could be easily adapted to a different platform.

Start by using the molex connector to pull 24v out of the second AMS plug. I learned about this from this project, who apparently learned about it from this project. There is a picture below to diagram which of the four molex terminals are + and -, the other two will be unused.

Wire the 24v to the buck converter, and take it down to 5v for the pi and the relay module to use. The 24v will also go to power the small fans, via the relay. That relay will be switched by the pi on pin 28.

The large fans for the exhaust system will be on the second relay and controlled by pin 27.

GPIO 0 will be used for the DHT11 module