FLSUN Super Racer 5015 Fan Duct for Mainboard Stepper Drivers

I had some extra 24V 5015 blower fans lying around that I used to upgrade my FLSUN Super Racer's part cooling, so I figured I'd upgrade the mainboard cooling too! This drop-in replacement directs the air flow over the stepper driver heatsinks, which are really the only part of this board that need cooling. Mine has the MKS Robin Nano v3, but this might work with the other SKR variant too (let me know if you try).

These 24V 5015 blower fans already have the correct plug, so this was an easy swap! Print with the flat side down, no supports needed. I printed mine in black PETG.

To install:

• Remove the stock 60mm 24V mainboard fan from the two posts
• Unplug the stock fan, making a note of where it was plugged in (corner socket closest to the fan on the MKS board, pictured)
• Mount the 5015 fan to the shroud using two M3x25 bolts & nuts
• Plug in the 5015 fan to the mainboard where the stock fan was (or read below about controlling the fan with klipper!)
• Mount the shroud as pictured to the two posts using two M3x6 bolts

Note that this fan is quite a bit louder and higher-pitched than the stock fan. If, like me, you've klipper-ized your Super Racer, you can control the fan speed and turn it off while the printer's idle! I moved the fan to the unused FAN2 connector instead, then added the following section to my klipper printer.cfg:

[controller_fan MCU_Fan]
pin: PB1 #MKS Robin Nano v3 FAN2 connector, double check this for other boards
max_power: 1 #Max 100% duty cycle PWM
fan_speed: 0.6 #60% speed, adjust as desired
idle_timeout: 30 #Seconds to leave the fan running after all steppers have turned off to give them time to cool down
stepper: stepper_a,stepper_b,stepper_c,extruder #Turn on the fan when any stepper is active

This will only turn on the fan if any of the steppers are active. Gcode M84 (usually in end gcode) will turn the motors off, then you should hear the fan turn off 30 seconds later (configured with idle_timeout). You can adjust the fan_speed as desired to quiet the fan.

There's probably a way to set this up in Marlin, too, but I haven't used it in a while.

Poblopuablo did most of the work with the excellent and easy-to-print shroud. I added a plate to mount it to the stock Super Racer mainboard fan posts in the correct position. Poblopuablo had added a cutout to the duct to access ports for a BLTouch… which this printer doesn't use, so I blocked it back off to prevent air leakage there.

While I was at it, I added one of mightynozzle's fan grills to hopefully prevent the fan from eating any nearby wires or fingers, but mostly because it looks cool :)