G425 - Backlash Calibration

calibration Use a conductive object to calibrate XYZ backlash CALIBRATION_GCODE

Description

This command performs an automatic calibration of backlash, positional errors, and nozzle offset by touching the nozzle to the sides of a bed-mounted, electrically-conductive object (e.g., a cube, washer or bolt).

This command measures backlash but doesn’t enable backlash correction. Use M425 to enable backlash correction.

Notes

Requires CALIBRATION_GCODE and the following parameters:

CALIBRATION_MEASUREMENT_RESOLUTION determines the increments taken in mm when performing measurements.
CALIBRATION_FEEDRATE_SLOW, CALIBRATION_FEEDRATE_FAST and CALIBRATION_FEEDRATE_TRAVEL determine the speed of motion during the calibration.
CALIBRATION_NOZZLE_TIP_HEIGHT and CALIBRATION_NOZZLE_OUTER_DIAMETER refer to the conical part of the nozzle tip.
CALIBRATION_REPORTING enables G425 V for reporting of measurements.
CALIBRATION_OBJECT_CENTER and CALIBRATION_OBJECT_DIMENSIONS define the true location and dimensions of a cube/bolt/washer mounted on the bed.
CALIBRATION_MEASURE_RIGHT, CALIBRATION_MEASURE_FRONT, CALIBRATION_MEASURE_LEFT and CALIBRATION_MEASURE_BACK define the usable touch points. Comment out any sides which are unreachable by the probe. For best results, all four sides should be reachable.
CALIBRATION_PIN, CALIBRATION_PIN_INVERTING, CALIBRATION_PIN_PULLDOWN and CALIBRATION_PIN_PULLUP configure the pin used for calibration. For example, if the nozzle is grounded, the calibation cube would be connected to a digital input pin with a pull-up enabled.

Usage

G425 [B] [T<index>] [U<linear>] [V]

Parameters

`[B]`	Perform calibration of backlash only.
`[T<index>]`	Perform calibration of one toolhead only.
`[U<linear>]`	Uncertainty: how far to start probe away from the cube (mm)
`[V]`	Probe cube and print position, error, backlash and hotend offset. (Requires `CALIBRATION_REPORTING`)

Examples

Check positional accuracy before calibration (Requires CALIBRATION_REPORTING):

T1                  ; Switch to second nozzle
G425 V              ; Showing positional report for T1
T0                  ; Switch to first nozzle
G425 V              ; Showing positional report for T0

Perform automatic calibration:

G425                ; Perform full calibration sequence
M425 F1 S0          ; Enable backlash compensation at 100%

Check positional accuracy after calibration (Requires CALIBRATION_REPORTING):

T1                  ; Switch to second nozzle
G425 V              ; Validate by showing report for T1
T0                  ; Switch to first nozzle
G425 V              ; Validate by showing report for T0