Voron CPAP dual switchable intake

So you got your CPAP WS7040, and pondering on whether you're mostly wanting fresh cold air, or avoiding cold drafts? Let software handle it for you.

This (significant) mod of my favourite side bowden entry has been fitted with a 2 position air valve guide. The position of the valve decides whether you suck in warm chamber air (for abs/asa) or blast outside cold air directly onto your PLA. Put it in the start gcode with material conditions, and quit setting it by hand every time.

My build uses an old mainboard from my prusa MK3->MK4 upgrade, as well as one of the steppers. There are two variants of the driver cover - one blank and one with mounting holes for the MK3's board. The mount for the cpap driver fits the two boards provided in the Biqu universal turbo kit. Only STEP file provided and I highly recommend checking dimensions before printing. Use the STEP as a guide. I recommend configuring sensorless homing in CCW direction. Otherwise, ram it into the end stopper at low current for 180 degrees.

Pro tip: klipper rotation distance set to 360 means you can treat it like degrees.

All parts print support free. The "stepper spacer" may be printed in TPU if you want. All additional bolts are M3x10mm, except for the einsy rambo cover which uses two M3x16mm.

Do not forget the M3x10 (or x8, x4, as long as the head sticks out then all good) in the rotor:

That socket head will sit inside this groove on the stepper holder:

I recommend securing the stepper (don't forget spacer) to the stepper motor holder, flat shaft side facing away from the crescent groove, and press fitting the rotor on. Will be tight so it won't fall off. Once the assembly is complete, use the 4 outer holes to attach it to the main cover body.

This is what I use on my setup with the einsy rambo, and the hotend heater output controlling the PWM for the fan driver. Adapt it for your own use case.

[mcu exp]
serial: /dev/serial/by-id/{your device id}
[fan]
pin: exp:PE5
cycle_time: 0.01
off_below: 0.1
[gcode_macro HOME_VALVE]
gcode:
    MANUAL_STEPPER STEPPER=valve ENABLE=1
    MANUAL_STEPPER STEPPER=valve SPEED=200 MOVE=-400 STOP_ON_ENDSTOP=home
    MANUAL_STEPPER STEPPER=valve SET_POSITION=0
    MANUAL_STEPPER STEPPER=valve SPEED=300 MOVE=30
    G4 P1000
    MANUAL_STEPPER STEPPER=valve SPEED=200 MOVE=-400 STOP_ON_ENDSTOP=home
    MANUAL_STEPPER STEPPER=valve SET_POSITION=0
    MANUAL_STEPPER STEPPER=valve SPEED=300 MOVE=180
    MANUAL_STEPPER STEPPER=valve ENABLE=0
[gcode_macro COLD_AIR]
gcode:
    MANUAL_STEPPER STEPPER=valve ENABLE=1
    MANUAL_STEPPER STEPPER=valve SPEED=300 MOVE=90
    MANUAL_STEPPER STEPPER=valve ENABLE=0
[gcode_macro WARM_AIR]
gcode:
    MANUAL_STEPPER STEPPER=valve ENABLE=1
    MANUAL_STEPPER STEPPER=valve SPEED=300 MOVE=180
    MANUAL_STEPPER STEPPER=valve ENABLE=0
[tmc2130 manual_stepper valve]
cs_pin: exp:PG0
interpolate: True
stealthchop_threshold: 1
run_current: .281738
hold_current: .281738
sense_resistor: 0.220
diag1_pin: !exp:PK2
driver_IHOLDDELAY: 8
driver_TPOWERDOWN: 0
driver_TBL: 2
driver_TOFF: 3
driver_HEND: 1
driver_HSTRT: 5
driver_PWM_FREQ: 2
driver_PWM_GRAD: 2
driver_PWM_AMPL: 230
driver_PWM_AUTOSCALE: True
driver_SGT: 3
[manual_stepper valve]
step_pin: exp:PC0
dir_pin: !exp:PL0
enable_pin: !exp:PA7
microsteps: 4
rotation_distance: 360
endstop_pin: tmc2130_valve:virtual_endstop
velocity: 1000
accel: 200000
[delayed_gcode run_on_startup]
initial_duration: 1.0
gcode:
    HOME_VALVE