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Connecting BL-Touch

Once you've hooked up the BL-Touch servo connector to a control_pin according to the BL-Touch documentation or of your MCU. Using the original wiring, the yellow wire from the tripple is the control_pin, the white wire from the pair is the sensor_pin. You need to configure these pins according to your wiring with Klipper:

[bltouch]
sensor_pin: P1.24
#   Pin connected to the BL-Touch sensor pin. This parameter must be
#   provided.
control_pin: P1.26

Calibrating the BL-Touch

Z Offset

In order to make klipper work properly you need to tell it in which relation to the nozzle the probe is exactly located. Lets start with the z_offset - the height of the probe when its expanded:

Make sure the probe is above the bed by moving the head into an appropriate x/y position:

g0 x0 y0

Now make klipper aproach the bed until the probe triggers using:

PROBE

This should deploy the BL-Touch probe, stop the run when it triggers by touching the bed. Now acquire the current position from the reached z_offset using:

GET_POSITION

In the output lines the toolhead line with the Z: contains the required value.

X/Y Offset

In order to find the propper vertical offset of the probe you need to know a certain point of your bed. X/Y = 0 may be a good point for this, any other will do as long as you know it. Find it by lowering the nozzle next to it using g0 z0.5. Create a removeable mark on your bed by i.e. using a non permanent marker.

Now move the tip of the BL-Touch over that point by jogging there with the conrols in the control tab of OctoPrint. Once the BL-Touch is roughly over the point acquire it using the GET_POSITION command. The difference to your marked point is your x_offset and y_offset to configure in the printer.cfg.

BL-Touch gone bad

Once the BL-Touch is in inconsistent state, it starts blinking red. You can force it to leave that state by issuing:

BLTOUCH_DEBUG COMMAND=reset

This may happen if its calibration is interrupted by the probe being blocked from being extracted.

However, the BL-Touch may also not be able to calibrate itself anymore. This happenes if the screw on its top is in the wrong position, or the magnetic core inside the probe pin has moved. If its moved that way up that it sticks to the screw, it may not be able to lower its pin anymore. With this behaviour you need to open the screw, pick i.e. a ball-pen and push it gently back in place. Re-Insert the pin into the BL-Touch so that it falls into extracted position. Carefully readjust the headless screw into place. You need to find the right position so it is able to lower and raise the pin, and the red light turns on and of. Use the reset, pin_up and pin_down commands to achieve this.

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