Add a fade factor for mesh leveling

Marlin/Configuration.h

@@ -745,6 +745,11 @@
     #define MBL_Z_STEP 0.025  // Step size while manually probing Z axis.
   #endif  // MANUAL_BED_LEVELING
 
+  // Gradually reduce leveling correction until a set height is reached,
+  // at which point movement will be level to the machine's XY plane.
+  // The height can be set with M420 Z<height>
+  #define ENABLE_LEVELING_FADE_HEIGHT
+
 #endif  // MESH_BED_LEVELING
 
 //===========================================================================
@@ -802,6 +807,13 @@
   // Probe along the Y axis, advancing X after each column
   //#define PROBE_Y_FIRST
 
+  #if ENABLED(AUTO_BED_LEVELING_BILINEAR)
+    // Gradually reduce leveling correction until a set height is reached,
+    // at which point movement will be level to the machine's XY plane.
+    // The height can be set with M420 Z<height>
+    #define ENABLE_LEVELING_FADE_HEIGHT
+  #endif
+
 #elif ENABLED(AUTO_BED_LEVELING_3POINT)
 
   // 3 arbitrary points to probe.

Marlin/Marlin_main.cpp

@@ -2270,6 +2270,30 @@ static void clean_up_after_endstop_or_probe_move() {
     #endif
   }
 
+  #if ENABLED(ENABLE_LEVELING_FADE_HEIGHT)
+
+    void set_z_fade_height(const float zfh) {
+      planner.z_fade_height = zfh;
+      planner.inverse_z_fade_height = RECIPROCAL(zfh);
+
+      if (
+        #if ENABLED(MESH_BED_LEVELING)
+          mbl.active()
+        #else
+          planner.abl_enabled
+        #endif
+      ) {
+        set_current_from_steppers_for_axis(
+          #if ABL_PLANAR
+            ALL_AXES
+          #else
+            Z_AXIS
+          #endif
+        );
+      }
+    }
+
+  #endif // LEVELING_FADE_HEIGHT
 
   /**
    * Reset calibration results to zero.
@@ -6788,9 +6812,17 @@ void quickstop_stepper() {
 
 #if PLANNER_LEVELING
   /**
-   * M420: Enable/Disable Bed Leveling
+   * M420: Enable/Disable Bed Leveling and/or set the Z fade height.
+   *
+   *       S[bool]   Turns leveling on or off
+   *       Z[height] Sets the Z fade height (0 or none to disable)
    */
-  inline void gcode_M420() { if (code_seen('S')) set_bed_leveling_enabled(code_value_bool()); }
+  inline void gcode_M420() {
+    if (code_seen('S')) set_bed_leveling_enabled(code_value_bool());
+    #if ENABLED(ENABLE_LEVELING_FADE_HEIGHT)
+      if (code_seen('Z')) set_z_fade_height(code_value_linear_units());
+    #endif
+  }
 #endif
 
 #if ENABLED(MESH_BED_LEVELING)

Marlin/example_configurations/Cartesio/Configuration.h

@@ -745,6 +745,11 @@
     #define MBL_Z_STEP 0.025  // Step size while manually probing Z axis.
   #endif  // MANUAL_BED_LEVELING
 
+  // Gradually reduce leveling correction until a set height is reached,
+  // at which point movement will be level to the machine's XY plane.
+  // The height can be set with M420 Z<height>
+  #define ENABLE_LEVELING_FADE_HEIGHT
+
 #endif  // MESH_BED_LEVELING
 
 //===========================================================================
@@ -802,6 +807,13 @@
   // Probe along the Y axis, advancing X after each column
   //#define PROBE_Y_FIRST
 
+  #if ENABLED(AUTO_BED_LEVELING_BILINEAR)
+    // Gradually reduce leveling correction until a set height is reached,
+    // at which point movement will be level to the machine's XY plane.
+    // The height can be set with M420 Z<height>
+    #define ENABLE_LEVELING_FADE_HEIGHT
+  #endif
+
 #elif ENABLED(AUTO_BED_LEVELING_3POINT)
 
   // 3 arbitrary points to probe.

Marlin/example_configurations/Felix/Configuration.h

@@ -728,6 +728,11 @@
     #define MBL_Z_STEP 0.025  // Step size while manually probing Z axis.
   #endif  // MANUAL_BED_LEVELING
 
+  // Gradually reduce leveling correction until a set height is reached,
+  // at which point movement will be level to the machine's XY plane.
+  // The height can be set with M420 Z<height>
+  #define ENABLE_LEVELING_FADE_HEIGHT
+
 #endif  // MESH_BED_LEVELING
 
 //===========================================================================
@@ -785,6 +790,13 @@
   // Probe along the Y axis, advancing X after each column
   //#define PROBE_Y_FIRST
 
+  #if ENABLED(AUTO_BED_LEVELING_BILINEAR)
+    // Gradually reduce leveling correction until a set height is reached,
+    // at which point movement will be level to the machine's XY plane.
+    // The height can be set with M420 Z<height>
+    #define ENABLE_LEVELING_FADE_HEIGHT
+  #endif
+
 #elif ENABLED(AUTO_BED_LEVELING_3POINT)
 
   // 3 arbitrary points to probe.

Marlin/example_configurations/Felix/DUAL/Configuration.h

@@ -728,6 +728,11 @@
     #define MBL_Z_STEP 0.025  // Step size while manually probing Z axis.
   #endif  // MANUAL_BED_LEVELING
 
+  // Gradually reduce leveling correction until a set height is reached,
+  // at which point movement will be level to the machine's XY plane.
+  // The height can be set with M420 Z<height>
+  #define ENABLE_LEVELING_FADE_HEIGHT
+
 #endif  // MESH_BED_LEVELING
 
 //===========================================================================
@@ -785,6 +790,13 @@
   // Probe along the Y axis, advancing X after each column
   //#define PROBE_Y_FIRST
 
+  #if ENABLED(AUTO_BED_LEVELING_BILINEAR)
+    // Gradually reduce leveling correction until a set height is reached,
+    // at which point movement will be level to the machine's XY plane.
+    // The height can be set with M420 Z<height>
+    #define ENABLE_LEVELING_FADE_HEIGHT
+  #endif
+
 #elif ENABLED(AUTO_BED_LEVELING_3POINT)
 
   // 3 arbitrary points to probe.

Marlin/example_configurations/Hephestos/Configuration.h

@@ -737,6 +737,11 @@
     #define MBL_Z_STEP 0.025  // Step size while manually probing Z axis.
   #endif  // MANUAL_BED_LEVELING
 
+  // Gradually reduce leveling correction until a set height is reached,
+  // at which point movement will be level to the machine's XY plane.
+  // The height can be set with M420 Z<height>
+  #define ENABLE_LEVELING_FADE_HEIGHT
+
 #endif  // MESH_BED_LEVELING
 
 //===========================================================================
@@ -794,6 +799,13 @@
   // Probe along the Y axis, advancing X after each column
   //#define PROBE_Y_FIRST
 
+  #if ENABLED(AUTO_BED_LEVELING_BILINEAR)
+    // Gradually reduce leveling correction until a set height is reached,
+    // at which point movement will be level to the machine's XY plane.
+    // The height can be set with M420 Z<height>
+    #define ENABLE_LEVELING_FADE_HEIGHT
+  #endif
+
 #elif ENABLED(AUTO_BED_LEVELING_3POINT)
 
   // 3 arbitrary points to probe.

Marlin/example_configurations/Hephestos_2/Configuration.h

@@ -739,6 +739,11 @@
     #define MBL_Z_STEP 0.025  // Step size while manually probing Z axis.
   #endif  // MANUAL_BED_LEVELING
 
+  // Gradually reduce leveling correction until a set height is reached,
+  // at which point movement will be level to the machine's XY plane.
+  // The height can be set with M420 Z<height>
+  #define ENABLE_LEVELING_FADE_HEIGHT
+
 #endif  // MESH_BED_LEVELING
 
 //===========================================================================
@@ -796,6 +801,13 @@
   // Probe along the Y axis, advancing X after each column
   //#define PROBE_Y_FIRST
 
+  #if ENABLED(AUTO_BED_LEVELING_BILINEAR)
+    // Gradually reduce leveling correction until a set height is reached,
+    // at which point movement will be level to the machine's XY plane.
+    // The height can be set with M420 Z<height>
+    #define ENABLE_LEVELING_FADE_HEIGHT
+  #endif
+
 #elif ENABLED(AUTO_BED_LEVELING_3POINT)
 
   // 3 arbitrary points to probe.

Marlin/example_configurations/K8200/Configuration.h

@@ -774,6 +774,11 @@
     #define MBL_Z_STEP 0.025  // Step size while manually probing Z axis.
   #endif  // MANUAL_BED_LEVELING
 
+  // Gradually reduce leveling correction until a set height is reached,
+  // at which point movement will be level to the machine's XY plane.
+  // The height can be set with M420 Z<height>
+  #define ENABLE_LEVELING_FADE_HEIGHT
+
 #endif  // MESH_BED_LEVELING
 
 //===========================================================================
@@ -831,6 +836,13 @@
   // Probe along the Y axis, advancing X after each column
   //#define PROBE_Y_FIRST
 
+  #if ENABLED(AUTO_BED_LEVELING_BILINEAR)
+    // Gradually reduce leveling correction until a set height is reached,
+    // at which point movement will be level to the machine's XY plane.
+    // The height can be set with M420 Z<height>
+    #define ENABLE_LEVELING_FADE_HEIGHT
+  #endif
+
 #elif ENABLED(AUTO_BED_LEVELING_3POINT)
 
   // 3 arbitrary points to probe.

Marlin/example_configurations/K8400/Configuration.h

@@ -745,6 +745,11 @@
     #define MBL_Z_STEP 0.025  // Step size while manually probing Z axis.
   #endif  // MANUAL_BED_LEVELING
 
+  // Gradually reduce leveling correction until a set height is reached,
+  // at which point movement will be level to the machine's XY plane.
+  // The height can be set with M420 Z<height>
+  #define ENABLE_LEVELING_FADE_HEIGHT
+
 #endif  // MESH_BED_LEVELING
 
 //===========================================================================
@@ -802,6 +807,13 @@
   // Probe along the Y axis, advancing X after each column
   //#define PROBE_Y_FIRST
 
+  #if ENABLED(AUTO_BED_LEVELING_BILINEAR)
+    // Gradually reduce leveling correction until a set height is reached,
+    // at which point movement will be level to the machine's XY plane.
+    // The height can be set with M420 Z<height>
+    #define ENABLE_LEVELING_FADE_HEIGHT
+  #endif
+
 #elif ENABLED(AUTO_BED_LEVELING_3POINT)
 
   // 3 arbitrary points to probe.

Marlin/example_configurations/K8400/Dual-head/Configuration.h

@@ -745,6 +745,11 @@
     #define MBL_Z_STEP 0.025  // Step size while manually probing Z axis.
   #endif  // MANUAL_BED_LEVELING
 
+  // Gradually reduce leveling correction until a set height is reached,
+  // at which point movement will be level to the machine's XY plane.
+  // The height can be set with M420 Z<height>
+  #define ENABLE_LEVELING_FADE_HEIGHT
+
 #endif  // MESH_BED_LEVELING
 
 //===========================================================================
@@ -802,6 +807,13 @@
   // Probe along the Y axis, advancing X after each column
   //#define PROBE_Y_FIRST
 
+  #if ENABLED(AUTO_BED_LEVELING_BILINEAR)
+    // Gradually reduce leveling correction until a set height is reached,
+    // at which point movement will be level to the machine's XY plane.
+    // The height can be set with M420 Z<height>
+    #define ENABLE_LEVELING_FADE_HEIGHT
+  #endif
+
 #elif ENABLED(AUTO_BED_LEVELING_3POINT)
 
   // 3 arbitrary points to probe.

Marlin/example_configurations/RepRapWorld/Megatronics/Configuration.h

@@ -745,6 +745,11 @@
     #define MBL_Z_STEP 0.025  // Step size while manually probing Z axis.
   #endif  // MANUAL_BED_LEVELING
 
+  // Gradually reduce leveling correction until a set height is reached,
+  // at which point movement will be level to the machine's XY plane.
+  // The height can be set with M420 Z<height>
+  #define ENABLE_LEVELING_FADE_HEIGHT
+
 #endif  // MESH_BED_LEVELING
 
 //===========================================================================
@@ -802,6 +807,13 @@
   // Probe along the Y axis, advancing X after each column
   //#define PROBE_Y_FIRST
 
+  #if ENABLED(AUTO_BED_LEVELING_BILINEAR)
+    // Gradually reduce leveling correction until a set height is reached,
+    // at which point movement will be level to the machine's XY plane.
+    // The height can be set with M420 Z<height>
+    #define ENABLE_LEVELING_FADE_HEIGHT
+  #endif
+
 #elif ENABLED(AUTO_BED_LEVELING_3POINT)
 
   // 3 arbitrary points to probe.

Marlin/example_configurations/RigidBot/Configuration.h

@@ -743,6 +743,11 @@
     #define MBL_Z_STEP 0.025  // Step size while manually probing Z axis.
   #endif  // MANUAL_BED_LEVELING
 
+  // Gradually reduce leveling correction until a set height is reached,
+  // at which point movement will be level to the machine's XY plane.
+  // The height can be set with M420 Z<height>
+  #define ENABLE_LEVELING_FADE_HEIGHT
+
 #endif  // MESH_BED_LEVELING
 
 //===========================================================================
@@ -800,6 +805,13 @@
   // Probe along the Y axis, advancing X after each column
   //#define PROBE_Y_FIRST
 
+  #if ENABLED(AUTO_BED_LEVELING_BILINEAR)
+    // Gradually reduce leveling correction until a set height is reached,
+    // at which point movement will be level to the machine's XY plane.
+    // The height can be set with M420 Z<height>
+    #define ENABLE_LEVELING_FADE_HEIGHT
+  #endif
+
 #elif ENABLED(AUTO_BED_LEVELING_3POINT)
 
   // 3 arbitrary points to probe.

Marlin/example_configurations/SCARA/Configuration.h

@@ -760,6 +760,11 @@
     #define MBL_Z_STEP 0.025  // Step size while manually probing Z axis.
   #endif  // MANUAL_BED_LEVELING
 
+  // Gradually reduce leveling correction until a set height is reached,
+  // at which point movement will be level to the machine's XY plane.
+  // The height can be set with M420 Z<height>
+  #define ENABLE_LEVELING_FADE_HEIGHT
+
 #endif  // MESH_BED_LEVELING
 
 //===========================================================================
@@ -817,6 +822,13 @@
   // Probe along the Y axis, advancing X after each column
   //#define PROBE_Y_FIRST
 
+  #if ENABLED(AUTO_BED_LEVELING_BILINEAR)
+    // Gradually reduce leveling correction until a set height is reached,
+    // at which point movement will be level to the machine's XY plane.
+    // The height can be set with M420 Z<height>
+    #define ENABLE_LEVELING_FADE_HEIGHT
+  #endif
+
 #elif ENABLED(AUTO_BED_LEVELING_3POINT)
 
   // 3 arbitrary points to probe.

Marlin/example_configurations/TAZ4/Configuration.h

@@ -766,6 +766,11 @@
     #define MBL_Z_STEP 0.025  // Step size while manually probing Z axis.
   #endif  // MANUAL_BED_LEVELING
 
+  // Gradually reduce leveling correction until a set height is reached,
+  // at which point movement will be level to the machine's XY plane.
+  // The height can be set with M420 Z<height>
+  #define ENABLE_LEVELING_FADE_HEIGHT
+
 #endif  // MESH_BED_LEVELING
 
 //===========================================================================
@@ -823,6 +828,13 @@
   // Probe along the Y axis, advancing X after each column
   //#define PROBE_Y_FIRST
 
+  #if ENABLED(AUTO_BED_LEVELING_BILINEAR)
+    // Gradually reduce leveling correction until a set height is reached,
+    // at which point movement will be level to the machine's XY plane.
+    // The height can be set with M420 Z<height>
+    #define ENABLE_LEVELING_FADE_HEIGHT
+  #endif
+
 #elif ENABLED(AUTO_BED_LEVELING_3POINT)
 
   // 3 arbitrary points to probe.

Marlin/example_configurations/WITBOX/Configuration.h

@@ -737,6 +737,11 @@
     #define MBL_Z_STEP 0.025  // Step size while manually probing Z axis.
   #endif  // MANUAL_BED_LEVELING
 
+  // Gradually reduce leveling correction until a set height is reached,
+  // at which point movement will be level to the machine's XY plane.
+  // The height can be set with M420 Z<height>
+  #define ENABLE_LEVELING_FADE_HEIGHT
+
 #endif  // MESH_BED_LEVELING
 
 //===========================================================================
@@ -794,6 +799,13 @@
   // Probe along the Y axis, advancing X after each column
   //#define PROBE_Y_FIRST
 
+  #if ENABLED(AUTO_BED_LEVELING_BILINEAR)
+    // Gradually reduce leveling correction until a set height is reached,
+    // at which point movement will be level to the machine's XY plane.
+    // The height can be set with M420 Z<height>
+    #define ENABLE_LEVELING_FADE_HEIGHT
+  #endif
+
 #elif ENABLED(AUTO_BED_LEVELING_3POINT)
 
   // 3 arbitrary points to probe.

Marlin/example_configurations/adafruit/ST7565/Configuration.h

@@ -745,6 +745,11 @@
     #define MBL_Z_STEP 0.025  // Step size while manually probing Z axis.
   #endif  // MANUAL_BED_LEVELING
 
+  // Gradually reduce leveling correction until a set height is reached,
+  // at which point movement will be level to the machine's XY plane.
+  // The height can be set with M420 Z<height>
+  #define ENABLE_LEVELING_FADE_HEIGHT
+
 #endif  // MESH_BED_LEVELING
 
 //===========================================================================
@@ -802,6 +807,13 @@
   // Probe along the Y axis, advancing X after each column
   //#define PROBE_Y_FIRST
 
+  #if ENABLED(AUTO_BED_LEVELING_BILINEAR)
+    // Gradually reduce leveling correction until a set height is reached,
+    // at which point movement will be level to the machine's XY plane.
+    // The height can be set with M420 Z<height>
+    #define ENABLE_LEVELING_FADE_HEIGHT
+  #endif
+
 #elif ENABLED(AUTO_BED_LEVELING_3POINT)
 
   // 3 arbitrary points to probe.

Marlin/example_configurations/delta/biv2.5/Configuration.h

@@ -840,6 +840,11 @@
     #define MBL_Z_STEP 0.025  // Step size while manually probing Z axis.
   #endif  // MANUAL_BED_LEVELING
 
+  // Gradually reduce leveling correction until a set height is reached,
+  // at which point movement will be level to the machine's XY plane.
+  // The height can be set with M420 Z<height>
+  #define ENABLE_LEVELING_FADE_HEIGHT
+
 #endif  // MESH_BED_LEVELING
 
 //===========================================================================
@@ -899,6 +904,13 @@
   // Probe along the Y axis, advancing X after each column
   //#define PROBE_Y_FIRST
 
+  #if ENABLED(AUTO_BED_LEVELING_BILINEAR)
+    // Gradually reduce leveling correction until a set height is reached,
+    // at which point movement will be level to the machine's XY plane.
+    // The height can be set with M420 Z<height>
+    #define ENABLE_LEVELING_FADE_HEIGHT
+  #endif
+
 #elif ENABLED(AUTO_BED_LEVELING_3POINT)
 
   // 3 arbitrary points to probe.

Marlin/example_configurations/delta/generic/Configuration.h

@@ -834,6 +834,11 @@
     #define MBL_Z_STEP 0.025  // Step size while manually probing Z axis.
   #endif  // MANUAL_BED_LEVELING
 
+  // Gradually reduce leveling correction until a set height is reached,
+  // at which point movement will be level to the machine's XY plane.
+  // The height can be set with M420 Z<height>
+  #define ENABLE_LEVELING_FADE_HEIGHT
+
 #endif  // MESH_BED_LEVELING
 
 //===========================================================================
@@ -893,6 +898,13 @@
   // Probe along the Y axis, advancing X after each column
   //#define PROBE_Y_FIRST
 
+  #if ENABLED(AUTO_BED_LEVELING_BILINEAR)
+    // Gradually reduce leveling correction until a set height is reached,
+    // at which point movement will be level to the machine's XY plane.
+    // The height can be set with M420 Z<height>
+    #define ENABLE_LEVELING_FADE_HEIGHT
+  #endif
+
 #elif ENABLED(AUTO_BED_LEVELING_3POINT)
 
   // 3 arbitrary points to probe.

Marlin/example_configurations/delta/kossel_mini/Configuration.h

@@ -837,6 +837,11 @@
     #define MBL_Z_STEP 0.025  // Step size while manually probing Z axis.
   #endif  // MANUAL_BED_LEVELING
 
+  // Gradually reduce leveling correction until a set height is reached,
+  // at which point movement will be level to the machine's XY plane.
+  // The height can be set with M420 Z<height>
+  #define ENABLE_LEVELING_FADE_HEIGHT
+
 #endif  // MESH_BED_LEVELING
 
 //===========================================================================
@@ -896,6 +901,13 @@
   // Probe along the Y axis, advancing X after each column
   //#define PROBE_Y_FIRST
 
+  #if ENABLED(AUTO_BED_LEVELING_BILINEAR)
+    // Gradually reduce leveling correction until a set height is reached,
+    // at which point movement will be level to the machine's XY plane.
+    // The height can be set with M420 Z<height>
+    #define ENABLE_LEVELING_FADE_HEIGHT
+  #endif
+
 #elif ENABLED(AUTO_BED_LEVELING_3POINT)
 
   // 3 arbitrary points to probe.

Marlin/example_configurations/delta/kossel_pro/Configuration.h

@@ -836,6 +836,11 @@
     #define MBL_Z_STEP 0.025  // Step size while manually probing Z axis.
   #endif  // MANUAL_BED_LEVELING
 
+  // Gradually reduce leveling correction until a set height is reached,
+  // at which point movement will be level to the machine's XY plane.
+  // The height can be set with M420 Z<height>
+  #define ENABLE_LEVELING_FADE_HEIGHT
+
 #endif  // MESH_BED_LEVELING
 
 //===========================================================================
@@ -895,6 +900,13 @@
   // Probe along the Y axis, advancing X after each column
   //#define PROBE_Y_FIRST
 
+  #if ENABLED(AUTO_BED_LEVELING_BILINEAR)
+    // Gradually reduce leveling correction until a set height is reached,
+    // at which point movement will be level to the machine's XY plane.
+    // The height can be set with M420 Z<height>
+    #define ENABLE_LEVELING_FADE_HEIGHT
+  #endif
+
 #elif ENABLED(AUTO_BED_LEVELING_3POINT)
 
   // 3 arbitrary points to probe.

Marlin/example_configurations/delta/kossel_xl/Configuration.h

@@ -840,6 +840,11 @@
     #define MBL_Z_STEP 0.025  // Step size while manually probing Z axis.
   #endif  // MANUAL_BED_LEVELING
 
+  // Gradually reduce leveling correction until a set height is reached,
+  // at which point movement will be level to the machine's XY plane.
+  // The height can be set with M420 Z<height>
+  #define ENABLE_LEVELING_FADE_HEIGHT
+
 #endif  // MESH_BED_LEVELING
 
 //===========================================================================
@@ -899,6 +904,13 @@
   // Probe along the Y axis, advancing X after each column
   //#define PROBE_Y_FIRST
 
+  #if ENABLED(AUTO_BED_LEVELING_BILINEAR)
+    // Gradually reduce leveling correction until a set height is reached,
+    // at which point movement will be level to the machine's XY plane.
+    // The height can be set with M420 Z<height>
+    #define ENABLE_LEVELING_FADE_HEIGHT
+  #endif
+
 #elif ENABLED(AUTO_BED_LEVELING_3POINT)
 
   // 3 arbitrary points to probe.

Marlin/example_configurations/makibox/Configuration.h

@@ -748,6 +748,11 @@
     #define MBL_Z_STEP 0.025  // Step size while manually probing Z axis.
   #endif  // MANUAL_BED_LEVELING
 
+  // Gradually reduce leveling correction until a set height is reached,
+  // at which point movement will be level to the machine's XY plane.
+  // The height can be set with M420 Z<height>
+  #define ENABLE_LEVELING_FADE_HEIGHT
+
 #endif  // MESH_BED_LEVELING
 
 //===========================================================================
@@ -805,6 +810,13 @@
   // Probe along the Y axis, advancing X after each column
   //#define PROBE_Y_FIRST
 
+  #if ENABLED(AUTO_BED_LEVELING_BILINEAR)
+    // Gradually reduce leveling correction until a set height is reached,
+    // at which point movement will be level to the machine's XY plane.
+    // The height can be set with M420 Z<height>
+    #define ENABLE_LEVELING_FADE_HEIGHT
+  #endif
+
 #elif ENABLED(AUTO_BED_LEVELING_3POINT)
 
   // 3 arbitrary points to probe.

Marlin/example_configurations/tvrrug/Round2/Configuration.h

@@ -741,6 +741,11 @@
     #define MBL_Z_STEP 0.025  // Step size while manually probing Z axis.
   #endif  // MANUAL_BED_LEVELING
 
+  // Gradually reduce leveling correction until a set height is reached,
+  // at which point movement will be level to the machine's XY plane.
+  // The height can be set with M420 Z<height>
+  #define ENABLE_LEVELING_FADE_HEIGHT
+
 #endif  // MESH_BED_LEVELING
 
 //===========================================================================
@@ -798,6 +803,13 @@
   // Probe along the Y axis, advancing X after each column
   //#define PROBE_Y_FIRST
 
+  #if ENABLED(AUTO_BED_LEVELING_BILINEAR)
+    // Gradually reduce leveling correction until a set height is reached,
+    // at which point movement will be level to the machine's XY plane.
+    // The height can be set with M420 Z<height>
+    #define ENABLE_LEVELING_FADE_HEIGHT
+  #endif
+
 #elif ENABLED(AUTO_BED_LEVELING_3POINT)
 
   // 3 arbitrary points to probe.

Marlin/planner.cpp

@@ -104,6 +104,11 @@ float Planner::min_feedrate_mm_s,
   matrix_3x3 Planner::bed_level_matrix; // Transform to compensate for bed level
 #endif
 
+#if ENABLED(ENABLE_LEVELING_FADE_HEIGHT)
+  float Planner::z_fade_height = 0.0,
+        Planner::inverse_z_fade_height = 0.0;
+#endif
+
 #if ENABLED(AUTOTEMP)
   float Planner::autotemp_max = 250,
         Planner::autotemp_min = 210,
@@ -531,10 +536,24 @@ void Planner::check_axes_activity() {
       if (!abl_enabled) return;
     #endif
 
+    #if ENABLED(ENABLE_LEVELING_FADE_HEIGHT)
+      static float z_fade_factor = 1.0, last_raw_lz = -999.0;
+      if (z_fade_height) {
+        const float raw_lz = RAW_Z_POSITION(lz);
+        if (raw_lz >= z_fade_height) return;
+        if (last_raw_lz != raw_lz) {
+          last_raw_lz = raw_lz;
+          z_fade_factor = 1.0 - raw_lz * inverse_z_fade_height;
+        }
+      }
+      else
+        z_fade_factor = 1.0;
+    #endif
+
     #if ENABLED(MESH_BED_LEVELING)
 
       if (mbl.active())
-        lz += mbl.get_z(RAW_X_POSITION(lx), RAW_Y_POSITION(ly));
+        lz += mbl.get_z(RAW_X_POSITION(lx), RAW_Y_POSITION(ly)) * z_fade_factor;
 
     #elif ABL_PLANAR
 
@@ -551,7 +570,7 @@ void Planner::check_axes_activity() {
     #elif ENABLED(AUTO_BED_LEVELING_BILINEAR)
 
       float tmp[XYZ] = { lx, ly, 0 };
-      lz += bilinear_z_offset(tmp);
+      lz += bilinear_z_offset(tmp) * z_fade_factor;
 
     #endif
   }
@@ -562,10 +581,20 @@ void Planner::check_axes_activity() {
       if (!abl_enabled) return;
     #endif
 
+    #if ENABLED(ENABLE_LEVELING_FADE_HEIGHT)
+      if (z_fade_height && RAW_Z_POSITION(logical[Z_AXIS]) >= z_fade_height) return;
+    #endif
+
     #if ENABLED(MESH_BED_LEVELING)
 
-      if (mbl.active())
+      if (mbl.active()) {
+        #if ENABLED(ENABLE_LEVELING_FADE_HEIGHT)
+          const float c = mbl.get_z(RAW_X_POSITION(logical[X_AXIS]), RAW_Y_POSITION(logical[Y_AXIS]));
+          logical[Z_AXIS] = (z_fade_height * (RAW_Z_POSITION(logical[Z_AXIS]) - c)) / (z_fade_height - c);
+        #else
           logical[Z_AXIS] -= mbl.get_z(RAW_X_POSITION(logical[X_AXIS]), RAW_Y_POSITION(logical[Y_AXIS]));
+        #endif
+      }
 
     #elif ABL_PLANAR
 
@@ -583,7 +612,12 @@ void Planner::check_axes_activity() {
 
     #elif ENABLED(AUTO_BED_LEVELING_BILINEAR)
 
+      #if ENABLED(ENABLE_LEVELING_FADE_HEIGHT)
+        const float c = bilinear_z_offset(logical);
+        logical[Z_AXIS] = (z_fade_height * (RAW_Z_POSITION(logical[Z_AXIS]) - c)) / (z_fade_height - c);
+      #else
         logical[Z_AXIS] -= bilinear_z_offset(logical);
+      #endif
 
     #endif
   }

Marlin/planner.h

@@ -162,6 +162,10 @@ class Planner {
       static matrix_3x3 bed_level_matrix; // Transform to compensate for bed level
     #endif
 
+    #if ENABLED(ENABLE_LEVELING_FADE_HEIGHT)
+      static float z_fade_height, inverse_z_fade_height;
+    #endif
+
   private:
 
     /**