Note: Back feeding voltage to tacho wire will kill the fan, is this not covered under warranty if wired incorrectly. We highly suggest wiring to dedicated fan tacho port where possible, the below guide using end stop with 1n4148 diode is not user friendly, if you don't need tacho or have tacho port, we suggest using 2 wire variants on older tool boards such as EBB36/42. If you have toolboard that supports Tacho header, it won't be an issue as long you wire and connect to header.



TABLE OF CONTENTS


Klipper Guide:

Credit: https://ellis3dp.com/Print-Tuning-Guide/articles/useful_macros/hotend_fan_monitoring.html

Credit: https://www.klipper3d.org/Config_Reference.html#heater_fan


Requirements: 

  • Machine running klipper
  • Spare endstop port/pin (data pin, not GND/5v/3.3v), please refer to your toolhead board pinout or wire to tacho specifically for tacho, as these will have built in diode required.
  • 1n4148 diode is required general end stop port, otherwise wire to dedicated tacho header which should have 1n4148 wire inline (double check board schematic)  

Setup: 

Download Ellis Macro: https://github.com/AndrewEllis93/Print-Tuning-Guide/blob/main/macros/fan_tach_monitor.cfg

LDO Tacho Configuration: https://github.com/MotorDynamicsLab/Nitehawk-SB/blob/master/Firmware/Klipper%20Configs/tacho_macros.cfg


  1. Under your hotend fan, set "tachometer_pin" (Remember to set pull up to the pin "^" (example: tachometer_pin: ^P1.29 )
  2. Place fan_tach_monitor.cfg in the same directory as your printer.cfg.
  3. Add [include fan_tach_monitor.cfg] to your printer.cfg.
  4. Change min_rpm and max_consecutive_stops in the HOTEND_FAN_CHECK macro to your desired values. (The default value 3000 works well in our testing, you may want test yourself by stopping/slowing the hotend fan when hotend is heated up to pass your minimal toggle fan speed.)
  5. Place your desired hotend fan failure g-code in FAN_STOPPAGE_ROUTINE




Marlin Guide:


Requirements: 

  • Machine running Marlin
  • Spare endstop port/pin (data pin, not GND/5v/3.3v), please refer to your toolhead board pinout or wire to tacho specifically for tacho, as these will have built in diode required. 
  • 1n4148 Diode is required general end stop port, otherwise wire to dedicated tacho header which should have 1n4148 wire inline (double check board schematic)  


Within Configuration_adv.h (Find tachometers section)


Find and define E0 fan (in most case, hotend fan setup would be E0 (Extruder 0/1) with endstop/data pin. 


Example: 

#define E0_FAN_TACHO_PIN PIN19




RepRap Guide:


Requirements: 

  • Machine running RepRap 
  • Wire to Tacho Fan Port, most duet toolhead or main board will have suitable header.


More Information: https://docs.duet3d.com/User_manual/Connecting_hardware/Fans_connecting


Example:

M950 F2 C"out4+out4.tach" ; Fan 2 uses out4, and using out4.tach as a tacho input