M425 - Backlash compensation

calibration Enable and tune backlash compensation BACKLASH_COMPENSATION BACKLASH_GCODE

Description

Backlash compensation will add extra steps to one or more segments whenever a motor reverses direction.

By default, steps are added to the first segment after a direction change. This gives the best dimensional accuracy but may cause marks to appear in the print. Smoothing spreads the added steps over multiple consecutive segments to prevent blemishes in the print, at the expense of dimensional accuracy.

Backlash compensation can be configured at either compile-time or run-time. Enable BACKLASH_GCODE to turn on M425 and a “Backlash” menu item.

Backlash can be measured automatically on all axes with G425 or on Z only with G29 when MEASURE_BACKLASH_WHEN_PROBING is enabled.

Notes

Requires BACKLASH_COMPENSATION, BACKLASH_GCODE and the following parameters:

BACKLASH_DISTANCE_MM specifies the default backlash on the X, Y and Z axis.
BACKLASH_CORRECTION specifies the default backlash correction (0.0 = none; 1.0 = 100%).
BACKLASH_SMOOTHING_MM enables backlash smoothing over a specified distance.
BACKLASH_GCODE enables M425 for run-time tuning of backlash.
MEASURE_BACKLASH_WHEN_PROBING turns on Z backlash measurement when probing with G29.
Use BACKLASH_MEASUREMENT_LIMIT, BACKLASH_MEASUREMENT_RESOLUTION and BACKLASH_MEASUREMENT_FEEDRATE to configure G29 backlash measurement.

Usage

M425 [F<value>] [S<linear>] [X<linear>] [Y<linear>] [Z<linear>] [Z]

Parameters

`[F<value>]`	Enable or disables backlash correction, or sets an intermediate fade-out (0.0 = none; 1.0 = 100%)
`[S<linear>]`	Distance over which backlash correction is spread
`[X<linear>]`	Set the backlash distance on X (mm; 0 to disable)
`[Y<linear>]`	Set the backlash distance on Y (mm; 0 to disable)
`[Z<linear>]`	Set the backlash distance on Z (mm; 0 to disable)
`[Z]`	When `MEASURE_BACKLASH_WHEN_PROBING` is enabled, loads the measured backlash into the backlash distance parameter

Examples

Manually configure backlash compensation:

M425 X0.1 Y0.2 Z0.3 ; Set backlash to specific values for all axis
M425 F1             ; Enable backlash compensation at 100%

Use smoothing for best print surface quality:

M425 F1 S3

Use no smoothing for best dimensional accuracy:

M425 F1 S0

Automatically measure X, Y, and Z backlash using G425:

G425                ; Perform a full calibration
M425 F1             ; Use full measured value of backlash on X, Y and Z

G425 automatically loads the measured backlash into the backlash distance, but will not enable backlash compensation.

To automatically measure Z backlash when probing with MEASURE_BACKLASH_WHEN_PROBING:

G29                 ; Perform probe and measure backlash on Z
M425 F1 Z           ; Use full measured value of backlash on Z

MEASURE_BACKLASH_WHEN_PROBING measures backlash, but does not update the configured backlash distance. The measured value should be activated by using the Z argument without a value. This differs from the behavior of G425.

Report the current backlash configuration:

M425