3DPrinting

3. Adjustments and corrections.

• Make sure your probe offset is correct

I’m assuming you’ve done the BLTouch config checks here

https://www.klipper3d.org/BLTouch.html

Take a piece of painters tape and place it in the middle of the bed and using a fine tip pen out a small dot on it.

Now home your printer and then do the following

In the console enter the following

PROBE

Now move the tool head until you have the deployed probe over the dot on the tape. Then slowly baby step it down while adjusting the X and Y to put the probe directly over the dot.

Once you’re sure it’s directly overhead baby step down until the probe triggers and then enter the following in the console.

GET_POSITION

And note the toolhead X and Y

 Recv: // toolhead: X:46.500000 Y:27.000000 Z:15.000000 E:0.000000

Note the X and Y values.

Now move the toolhead so that the nozzle is over the dot and then bring it down slowly making sure it’s over the spot. When you’re sure it is do another GET_POSITION in the console.

 Recv: // toolhead: X:41.500000 Y:29.000000 Z:15.000000 E:0.000000

Now you can calculate the new X and Y offset.

Your probe X offset will be nozzle_x_position - probe_x_position

Or in our hypothetical example above

41.5 - 46.5

Or x_offset: -5

And the probe Y offset will be

 nozzle_y_position - probe_y_position

Or in our hypothetical example above

29 - 27

Or y_offset: 2

Remove the tape and then restart Klipper and we should now have a reliable X and Y position. So when you home it Klipper should move the probe over the center of the bed and then move the nozzle over that same spot when asked to move to the same location.

• Z offset

You don’t have to heat the bed for this since we’re only calculating the distance between when the probe activates and the tip of the nozzle. Well be doing the Z offset as documented here

https://www.klipper3d.org/Probe_Calibrate.html

You can test this with the nozzle heated (that’s more accurate) but you don’t need to. That’s because we’re going to get close and then use a print to get the final detail.

So home your printer and then issue the following

PROBE_CALIBRATE

Then we’ll use the same method as we did for the screws with paper or a feeler gauge.

Follow the prompts and once you have the slightest grab then you have the right spot.

Since we’re using a piece of paper we aren’t actually at 0 and you can adjust it down 0.1 (or whatever the thickness of your feeler gauge is)

Then you’ll enter

ACCEPT
SAVE_CONFIG

Now restart Klipper.

• Bed Mesh

Let’s warm the bed to your printing temps. Since we know the bed is trammed we don’t have to worry about adjusting the screws with it hot

In the console enter the following

G28
BED_MESH_CALIBRATE

When it’s done look at the bed mesh in the UI. What’s the range? If it’s less than your layer height you should be good. Focus more on the range and less on the visual since the scale can be confusing. It’s incredibly useful for seeing if there’s warping, or the bed is way out of tram but we’ve already physically confirmed that we have the kinematics fixed

Now save the config which will save this mesh SAVE_CONFIG

• Make sure your start print macro calls it

Here’s what mine looks like with a few things removed to avoid confusion

[gcode_macro START_PRINT]
variable_material_printed: ""
variable_material_retract: 1.2
gcode:
  {% set BED_TEMP = params.BED_TEMP|default(60)|float %}
  {% set EXTRUDER_TEMP = params.EXTRUDER_TEMP|default(180)|float %}
  {% set DO_ABL = params.DO_ABL |default(1)|int %}
  {% set MATERIAL = params.MATERIAL|default('PLA')|string %}

  ;Reset state
  G90 ; Absolute Positioning
  
  CLEAR_PAUSE

  M117 Starting {MATERIAL} Print with Bed Temp of {BED_TEMP} and Extruder Temp of {EXTRUDER_TEMP}, ABL set to {DO_ABL}
  PLAY_START

  # Save material used   
  SET_GCODE_VARIABLE MACRO=START_PRINT VARIABLE=material_printed VALUE="'{MATERIAL}'"
   
  SFS_ENABLE ; Turn on filament runout

  G90 ; use absolute coordinates
  SET_PART_FAN PERCENT=20 ; Fan on approx. 20% to protect cooling ducts

  ;Start heating bed
  M117 Start > Heating Bed
  SET_HEATER_TEMPERATURE HEATER=heater_bed TARGET={ BED_TEMP } ; set bed temp

  G28 ; home all

  ;Move up to keep toolhead away from heating bed
  G1 Z75 F3000 
  TEMPERATURE_WAIT sensor=heater_bed minimum={BED_TEMP} ; wait for bed temp 
    
  {% if DO_ABL == 1 %}
    ;Pre-heat the extruder while we build the mesh so it'll be ready
    SET_HEATER_TEMPERATURE HEATER=extruder TARGET={ EXTRUDER_TEMP-50 } ; set first layer extruder temp

    M117 ABL
    BED_MESH_CALIBRATE PROFILE=default; calibrate bed mesh leveling

  {% else %}
    ; Load the existing mesh
    M117 Loading Default ABL
    BED_MESH_PROFILE LOAD=default ; Use default mesh
  {% endif %}

  ;Turn part fan off unless otherwise requested
  SET_PART_FAN PERCENT=0 

  ;Home z after bed is heated
  G28 Z 

  ;Park the head at the right location
  ;;Smart_Park

  ;Prepare
  M117 $MR$:Preparing to Print

  ;Heat extruder to final temp
  
  SET_HEATER_TEMPERATURE HEATER=extruder TARGET={ EXTRUDER_TEMP } ; set first layer extruder temp

  ;Turn on Nevermore filter
  SET_FAN_SPEED FAN=Nevermore SPEED=.8

  ;Wait for everything to be ready
  TEMPERATURE_WAIT sensor=heater_bed minimum={BED_TEMP} ; wait for bed temp 
  TEMPERATURE_WAIT sensor=extruder minimum={EXTRUDER_TEMP} ; wait for extruder temp 

  M117 Start > Priming
  
  ;Draw Primer Line
  NOZZLE_PRIME_LINE

  G92 E0.0

Don’t copy this but it can be useful to see the order of how I have my mesh and heating, etc.

• Final adjustment of your Z offset with a print

In your slicer of choice we just need a patch that’s the same height as your layer height (such as .2) you can find one online, create one or even download this one from Andrew Ellis’ GitHub.

https://github.com/AndrewEllis93/Print-Tuning-Guide/tree/main/test_prints

As it’s printing watch it and use the baby step ui to move it .01 up (if it’s over extruding and there’s ridges) or down (if it’s obviously too far and there’s gaps)

Then, when it’s done you hit the save icon or enter this in the console

Z_OFFSET_APPLY_PROBE

Then save_config to save the value.

Run the print again and verify that you have a smooth solid print that matches what you see here in the phenomenal Ellis print tuning guide

https://ellis3dp.com/Print-Tuning-Guide/articles/first_layer_squish.html

Hopefully that helps and if it doesn’t there’s more that can be accounted for and adjusted but it’s always good to make sure we have the fundamentals.

The skewed and twisted X gantry took me a week of frustrating prints and tweaks before I stopped, redid the frame, etc and identified the issue.