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G-code Offsets (Auto)

Automated calibration uses specialized tools to measure X/Y/Z offsets more precisely and efficiently. Refer to each tool's documentation for specific calibration procedures.

Available Methods

  • SexBall Probe – A modified Sexbolt Z Endstop that provides automated nozzle calibration. The hardware components for the SexBall Probe are included as a part of LDO's StealthChanger Base Kit.

  • Axiscope – Semi-automatic camera-based visual alignment. Gives you the ability to visually see and calibrate the XY offsets through a magnified lens. Z offset is handled by use of a Z endstop/probe.

  • Nudge – A DIY multi axis probe where the shaft is suspended in a wobbler that provides automated nozzle calibration.

  • KTAMV – Klipper Tool Alignment (using) Machine Vision. Uses machine vision to determine the XY nozzle calibration. Results may vary depending on camera choice, lighting and nozzles used.

  • NozzleAlign – A DIY multi axis probe.

Calibration With SexBall Probe

Define Switch Location

With the SexBall Probe mounted to the printer's bed extrusion, the absolute position of the ball needs to be added to the [gcode_macro _CALIBRATION_SWITCH] variables.

Calibration switch variables example.
  [gcode_macro _CALIBRATION_SWITCH]
  variable_x: 227.471875
  variable_y: 353.703125
  variable_z: 5.00
  gcode:
  1. Home the printer with G28.
  2. Run QUAD_GANTRY_LEVEL to level the gantry.
  3. Home z again with G28 Z.
  4. Manually move the gantry so that the tool is ~1mm over the ball.
  5. Run M114 to output the current position to console.
  6. Enter the positions in to the [gcode_macro _CALIBRATION_SWITCH] variables.

Enable Multi Axis Probing

  • Enable the multi-axis probe by defining the [tools_calibrate] section in toolchanger-config.cfg.
  • Set the pin variable to the pin that your calibration probe is connected to.
  • Calibrate trigger_to_bottom_z
[tools_calibrate] example.
  [tools_calibrate]
  pin:   #pin that your calibration probe is connected to.
  travel_speed: 20  # mms to travel sideways for XY probing
  spread: 7  # mms to travel down from top for XY probing
  lower_z: 1.0  # The speed (in mm/sec) to move tools down onto the probe
  speed: 2  # The speed (in mm/sec) to retract between probes
  lift_speed: 4  # Z Lift after probing done, should be greater than any Z variance between tools
  final_lift_z: 6 
  sample_retract_dist:2
  samples_tolerance:0.05
  samples:5
  samples_result: median # median, average
  probe: probe # name of the nozzle probe to use
  trigger_to_bottom_z: 0.25 # Offset from probe trigger to vertical motion bottoms out.

trigger_to_bottom_z

trigger_to_bottom_z is the travel distance from the point where the nozzle touches the top of the ball to the point where the switch not only triggers, but bottoms out.

  1. Move the gantry so that the nozzle touches the top of the ball.
  2. Using small increments, lower the gantry until you hear the switch trigger.
  3. Run M114 to log the gantry's current position to the console.
  4. Watching the tool on the shuttle, continue to lower the gantry. The point where the tool starts to lift, is the point where the switch has bottomed out.
  5. Run M114 again and the difference between the 2 logged values is your trigger_to_bottom_z value.

SexBall Nozzle Calibration

  1. Any debris on the tool will effect the accuracy of the results. Clean all of the tool's nozzles thoroughly.
  2. With tool 0 on the shuttle, home the printer with G28.
  3. Run QUAD_GANTRY_LEVEL to level the gantry.
  4. Home Z again with G28 Z.
  5. With your hand over the emergency stop, run CALIBRATE_ALL_OFFSETS.

CALIBRATE_ALL_OFFSETS

CALIBRATE_ALL_OFFSETS will move the tool over the probe and heat it to 150c before locating the probe. For the first run keep an eye on the printer and make sure the values entered in the config are correct and there isn't a crash.

After tool 0 has located the probe, it will turn off tool 0's heater and repeat the process for each subsequent tool. Tool 0 will be picked up again once the process has completed.

The values logged to the console are the offsets to be used in the [tool Tn]'s gcode_x_offset, gcode_y_offset and gcode_z_offset variables.

SexBall Probe Z Offset Calibration

  1. Any debris on the tool will effect the accuracy of the results. Clean all of the tool's nozzles thoroughly.
  2. With tool 0 on the shuttle, home the printer with G28.
  3. Run QUAD_GANTRY_LEVEL to level the gantry.
  4. Home z again with G28 Z.
  5. Run CALIBRATE_NOZZLE_PROBE_OFFSET.

CALIBRATE_NOZZLE_PROBE_OFFSET

CALIBRATE_NOZZLE_PROBE_OFFSET will move the tool over the probe and heat it to 150c before locating the probe. It will then bottom out the probe and use the tool's OptoTap sensor to determine the [tool_probe Tn]'s z_offset.

The value logged to the console is the value to be used for the [tool_probe Tn]'s z_offset.

Don't Trust the Robots

The [tool_probe Tn] z_offset should be verified using a small test print. Because this procedure depends on the accuracy of the trigger_to_bottom_z value, it is advisable to confirm the offset by performing a short test print and noting any adjustments required to achieve proper first-layer adhesion.

  • If you need to raise the nozzle during the test print, the z_offset must be adjusted closer to zero by the same amount.
  • If you need to lower the nozzle during the test print, the z_offset must be adjusted farther from zero by the same amount.