✨ M423 X-Axis Twist Compensation

MarlinFirmware/Marlin#23745

_gcode/M422.md

@@ -63,7 +63,7 @@ parameters:
 videos:
   - 6UgT9YqY3UA
 
-example:
+examples:
   -
     pre: Set a probe position for aligning the first Z stepper
     code:

_gcode/M423.md

@@ -0,0 +1,79 @@
+---
+tag: m0423
+title: X Twist Compensation
+brief: Modify, reset, and report X-Axis Twist Compensation data
+author: thinkyhead
+
+requires: X_AXIS_TWIST_COMPENSATION
+since: 2.0.9.4
+group: calibration
+
+codes: [ M423 ]
+related: [ G29 ]
+
+notes:
+
+parameters:
+  -
+    tag: R
+    optional: true
+    description: Reset the Twist Compensation array to the configured default values.
+    values:
+      -
+        type: flag
+  -
+    tag: A
+    optional: true
+    description: Set the X-Axis Twist Compensation starting X position.
+    values:
+      -
+        tag: linear
+        type: float
+  -
+    tag: I
+    optional: true
+    description: Set the X-Axis Twist Compensation X-spacing.
+    values:
+      -
+        tag: linear
+        type: float
+  -
+    tag: X
+    optional: true
+    description: Zero-based index into the Twist Compensation array. Requires a `Z` value.
+    values:
+      -
+        tag: index
+        type: int
+  -
+    tag: Z
+    optional: true
+    description: A Z-offset value to set in the Twist Compensation array. Requires an `X` index.
+    values:
+      -
+        tag: index
+        type: int
+
+examples:
+  -
+    pre: Report the current X-twist data to the host console.
+    code:
+      - M423
+  -
+    pre: Reset X-twist data to the configured defaults.
+    code:
+      - M423 R
+  -
+    pre: Set the 5th value in the Twist Compensation array to -0.03.
+    code:
+      - M423 X4 Z-0.03
+  -
+    pre: Set the X-start position to 0 and the X-spacing distance to 50.
+    code:
+      - M423 M423 X0 I50
+
+---
+
+Use `M423` to reset, modify, or report X-Twist Compensation data.
+
+X-Twist Compensation is applied to the mesh on [`G29`](docs/gcode/G029)) to correct for a twisted X gantry. Meaningful X-Twist Compensation data is generated using a guided procedure in the LCD menu that compares measurements taken by the bed probe to readings taken manually at the nozzle. Since manual measurements are prone to inaccuracy, a metal feeler gauge is recommended over a paper test. If the first layer is still imperfect, `M423` can then be used to correct for small errors.