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Before starting with Z Offset calibration, please make sure the bed is level following the steps in this article

To calibrate the Z offset with Klipper and BLTouch, we first start by homing all axis:

G28 #home all axis

Next we will send a probe calibrate command to tell the printer we want to calibrate the Z axis:

PROBE_CALIBRATE

Once this command is entered the printer will attempt to discover the Z offset and report back what it thinks it should be:

Z position: ?????? –> 6.025 <– ??????

We than need to start the manual calibration steps.  Grab a piece of paper and slide it between the nozzle and print bed and start lowering the nozzle until you feel a slight resistance when moving the paper back and forth.  To lower the nozzle enter the below command.  Adjust the value and repeat until you feel a slight resistance:

TESTZ Z=-.1

Once you feel a slight resistance, type accept to save your values:

ACCEPT

bltouch: z_offset: 1.099
The SAVE_CONFIG command will update the printer config file
with the above and restart the printer.

Now type SAVE_CONFIG and restart the printer to load the new config.

Next we need to verify the accuracy of the new settings.

G28 #home all axis

PROBE_ACCURACY

The printer will now run a series of tests to verify the repeatability of the probe results.

probe accuracy results: maximum 1.104000, minimum 1.091500, range 0.012500, average 1.099500, median 1.100250, standard deviation 0.004717

We are looking for a range of 0.0125 or better, but not worse than 0.025.  The Z Height is now calibrated.  For additional reading please reference the Klipper docs

Leveling your print bed is easy using Klipper and a probe such as the BLTouch.  First we need to verify the locations of the bed leveling screws are defined in your Klipper config:

[screws_tilt_adjust]
horizontal_move_z: 5
screw1: 70,213
screw1_name: back left
screw2: 235,213
screw2_name: back right
screw3: 70,47
screw3_name: front left
screw4: 235,47
screw4_name: front right

If this has just been added issue a restart so Klipper loads the new config.  Once Klipper is back online, we want to send a few commands to the terminal:

#Home All Axis

G28

#Adjust Bed Level

SCREWS_TILT_CALCULATE

The probe will now go the locations defined in the Klipper config file and probe for the distance to the bed.

In the terminal you will see the probe results and they will be followed up with something similar to the output below:

// front right : X 235.0, Y 47.0, Z 1.60750 : Adjust -> CW 00:02

// front left : X 70.0, Y 47.0, Z 1.65250 : Adjust -> CCW 00:04

// back right : X 235.0, Y 213.0, Z 1.58625 : Adjust -> CW 00:04

// back left (Base): X 70.0, Y 213.0, Z 1.62250

Adjust the bed according the output for each corner.  Once complete, run the SCREWS_TILT_CALCULATE command again and repeat the process until you are happy with the results.

From here you can proceed with issuing another G28 to home all axis and follow on with a calibration using BED_MESH_CALIBRATE