CR-10/MKS Extruder Auto Fan

Did you know that Marlin can turn your extruder/hot-end fan on/off automatically depending on the temperature?

I find it annoying that the fan comes on as soon as you turn on the power. This is a description on how you can change that so that the fan is on only when needed.

Disclaimer
For this to work, your board need an available data pin. The Creality v1 boards (CR-10, CR-10 mini) does not have any available pins. I am not familiar with the v2 boards.

These instructions are primarily for those that have upgraded boards - I have upgraded my CR-10 mini to an MKS Gen L board.

You need to be comfortable with electronics and changing firmware. No soldering is required.

The mount is specific to the CR-10 power supply and the Mosfet Drive I chose, but the principles should be applicable to any printer as long as you have an available pin.

What you need:

• Printed mount (not required, but I don't like loose stuff in my control box)
• 1 Mosfet Driver
• 2x M4x6 to mount holder to power supply
• 2x M3x6 to mount Mosfet Driver to mount
• Wires to connect power output to Mosfet Driver
• 1 Female to female Dupont jumper wire to connect Mosfet signal pin to board

Instructions
Before you start, make sure power is off and USB disconnected. Take the power supply out of the box and screw the Mosfet mount onto the power supply with M4 screws (on the top, i.e. the side facing the inside of the control box). Put the Mosfet driver into the mount and secure with M3 screws.

Move the extruder fan wires from the board to the Mosfet Driver voltage output (Marked V+ and V-). Add wires from the Mosfet Driver voltage input to the board (where you removed the fan wires from). Make sure the polarity is correct (positive to positive and negative to negative).

The final step is to add a wire (Dupont female jumer wire) from the signal pin on the Mosfet driver to an available data pin on the board. On my MKS Gen L I use pin D64 (Aux2).

Note that on my CR-10 Mini the control box fans and extruder are connected - it is a good idea to separate the control box fans and put into the Mosfet input connectors - otherwise the control box fans will only be on when the extruder fan is on.

Marlin configuration
In Marlin, you need to edit the configuration_adv.h file. Go to the section called "Extruder cooling fans". Set the pin number to the pin number you connected the Mosfet signal pin to on your board (I used pin D64 from Aux2 on my MKS Gen L board)

#define E0_AUTO_FAN_PIN 64

Upload the firmware. You are now ready to test it out. When you power up the printer, the extruder fan should not be running. Heat up the hot-end, once the hot-end reaches 50 the fan should turn on automatically.

Amazon references:
Mosfet Drivers
Wires with connector
Set of Dupont jumper wires