From 8e6a130e52be6766edb3aadc99126eb3d03045f8 Mon Sep 17 00:00:00 2001
From: Scott Lahteine <thinkyhead@users.noreply.github.com>
Date: Fri, 11 Mar 2022 15:13:15 -0600
Subject: [PATCH] =?UTF-8?q?=E2=9C=A8=20M423=20X-Axis=20Twist=20Compensatio?=
 =?UTF-8?q?n?=
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MarlinFirmware/Marlin#23745
---
 _gcode/M422.md |  2 +-
 _gcode/M423.md | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 67 insertions(+), 1 deletion(-)
 create mode 100644 _gcode/M423.md

diff --git a/_gcode/M422.md b/_gcode/M422.md
index 2b66b5052..b7325c6c4 100644
--- a/_gcode/M422.md
+++ b/_gcode/M422.md
@@ -63,7 +63,7 @@ parameters:
 videos:
   - 6UgT9YqY3UA
 
-example:
+examples:
   -
     pre: Set a probe position for aligning the first Z stepper
     code:
diff --git a/_gcode/M423.md b/_gcode/M423.md
new file mode 100644
index 000000000..b5e4f7fe2
--- /dev/null
+++ b/_gcode/M423.md
@@ -0,0 +1,66 @@
+---
+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: Set the 5th value in the Twist Compensation array to -0.03.
+    code:
+      - M423 X4 Z-0.03
+---
+
+Use `M423` to modify your 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.