This guide will help you calibrate your probe offsets for X,Y,and Z axes.
The following is a typical config for a CRTouch:
[bltouch]
sensor_pin: ^PB1
control_pin: PB0
x_offset: 0 # Change to fit your printer
y_offset: 0 # Change to fit your printer
z_offset: 2.295 # Change to fit your printer
probe_with_touch_mode: True
stow_on_each_sample: False # Keep the probe extended between points
samples: 2 # Probe each point at least twice
samples_tolerance: 0.0125 # If those measurements aren't this close then
samples_tolerance_retries: 5 # Re-probe this many times and use the averageYou may find that your bl-touch requires slightly different configurations. There are many different variations and clones of the original bl-touch design.
This is explained in detail here in the docs.
Note that the samples_tolerance used in the above example is quite low so it frequently will probe a point several times and use the average.
You can change the samples and tolerance settings to fit your needs. These settings are explained in more detail in the docs here and here.
You will need to change the x and y offsets to be accurate for your probe's position relative to the nozzle. Follow the directions in the docs to measure those values.
Then you will also need to calibrate the z-offset. (Again, follow the docs)
It's important to configure a [safe_z_home] section so your probe knows to home in the center of your bed.
You can use the defaults:
[safe_z_home]
home_xy_position: 100, 100as a "good enough" on most beds, but it doesn't hurt to configure it a little better.
The simplest way to do this is to use the interface manually move the probe to what you believe to be the center of the bed and note those coordinates much like we did in previous guides.
Use those values for your home_xy_position.
This can be further tuned to the mathematical center, but I believe we will need to finish calibrating the offsets below first:
(I need to do more testing on the math for this, but the above will get you a reasonably close home_xy_position)
The basic idea is to compare the coordinates the printer registers for the nozzle and coordinates registered for the probe in the same physical location on the bed. The offset is the difference between those two sets of coordinates.
Run G28 to home the printer.
If your nozzle moves to 0,0 after homing then manually move the nozzle using the interface controls or gcode commands so that the probe's position is near the center of the bed. It doesn't need to be perfect.
Run the PROBE command. Mark the point on the bed where the probe pin touched using whatever method works for you.
You can use tape, your memory, a sharpie, it doesn't matter. Whatever works.
Run GET_POSITION and write down the coordinates as "probe coordinates".
Use the mainsail/fluidd interface to manually move the NOZZLE as close as you possibly can to that point you marked where the probe pin touched.
Run GET_POSITION again and note the new coordinates as "nozzle coordinates".
Then:
The probe x_offset is the X "nozzle coordinates" minus the X "probe coordinates"(This is typically a negative number if your probe is on the left of the nozzle)
The probe y_offset is the Y "nozzle coordinates" minus the Y "probe coordinates"
Put those values in your config and restart.
Done!
)
Klipper has a built-in function for finding the probe z-offset.
This is covered in the docs here.
It's also described in more detail here.
You will likely need to set your stepper_z position_min to a negative value:
[stepper_z]
position_min: -10during the calibration.
Afterwards, set it to -1 to allow a little room for later calibrations while preventing the nozzle from smashing through the bed if the probe fails catastrophically.
Run G28 to home the printer.
If your nozzle moves to 0,0 after homing then manually move the nozzle using the interface controls or gcode commands so that the probe's position is near the center of the bed. It doesn't need to be perfect.
Run PROBE_CALIBRATE
NOTE: You can use
Z_ENDSTOP_CALIBRATEto perform the same calibration procedure on a printer which doesn't use a probe for homing.
Then use TESTZ Z=-1 to bring the nozzle 1mm closer to the bed
Use TESTZ Z=+1 to bring the nozzle 1mm further from the bed
And of course you can do TESTZ Z=-0.001 to go 0.001mm closer, etc
Using these commands, adjust your nozzle height until you are about 100 microns from the (cold) bed. This is roughly the thickness of a sheet of paper, and the Klipper docs suggest it's also the approximate expected thermal expansion when the bed is heated.
When you are happy with it (0 is actually 0) run ACCEPT followed by SAVE_CONFIG
Some notes on calibration:
The + or - are necessary in the TESTZ commands! If you do TESTZ Z=1 it will move the nozzle to what it currently thinks 1mm from the bed is. We use the TESTZ Z=+1 and TESTZ Z=-1 to move it +1 or -1 from the current position.
Typically this is combined with "the paper test" where you use a sheet of paper (a standard printer paper is about 0.1mm thick) When you feel resistance from the nozzle pressing against the paper, that means you are about 0.1mm away from the bed. This way you don't have to actually contact the bed with the nozzle to do this calibration. (We need the exact 0 height, but obviously we never print that close to the bed or no filament would come out)
NOTE: The goal here is to get the nozzle to be literally resting on the bed at
Z=0. Despite some confusion on this topic,0means directly touching the bed. That's OK because we never actually print atZ=0. We print the first layer atZ=0+{first_layer_height}.So yes, we really are aiming to calibrate it so that
Z=0is nozzle just touching the bed, not so that the nozzle is one layer-height away from the bed. The slicer will manage the layer heights for you automatically.However, it's often easier to just get it close enough with the paper test (and a cold bed) Generally the expansion caused by heating the bed will make up the difference of your sheet of paper, but we can further refine the value during a print anyway (as shown below)
When you run TESTZ Z=-0.001 and other very small values then nozzle will lift a little before lowering in a kind of bouncing motion.
This often looks like it's hit a soft limit and not lowering, but it actually is still lowering.
Klipper does this to get more precise movements and hopefully do less damage if it does hit the bed.
The little bounce is normal, and it's still working!
(You'll understand when you see it)
I recommend to set your Z offset as best you can using the above methods, and then print a large 1-layer square.
Use that print to further refine your z-offset.
The process to do so is similar to what you'd call "baby-stepping" on Marlin.
If you don't have some manner of control interface to perform the baby-stepping, you can use gcode commands:
# Move the z-axis offset 0.2mm higher
SET_GCODE_OFFSET Z=0.2 MOVE=1
# Move the z-axis offset 0.3mm lower
SET_GCODE_OFFSET Z=-0.3 MOVE=1Reference: SET_GCODE_OFFSET
NOTE: It's important to include the
MOVE=1as that tells Klipper to apply the offset immediately instead of at the next Z-axis move.
Then use the following commands after the print completes to save the offset to your config:
Z_OFFSET_APPLY_PROBE
SAVE_CONFIGReference: Z_OFFSET_APPLY_PROBE
NOTE: If you don't have a probe, you can still apply baby-stepped adjustments to your endstop z-offset using
Z_OFFSET_APPLY_ENDSTOPandSAVE_CONFIG
Here are some images to help you recognize a properly calibrated first layer:
(These images were shamelessly borrowed from this site)