Add bed size as a configuration option

Marlin/Conditionals_post.h

@@ -34,9 +34,28 @@
   #define X_MAX_LENGTH (X_MAX_POS - (X_MIN_POS))
   #define Y_MAX_LENGTH (Y_MAX_POS - (Y_MIN_POS))
   #define Z_MAX_LENGTH (Z_MAX_POS - (Z_MIN_POS))
-  #define X_CENTER float((X_MIN_POS + X_MAX_POS) * 0.5)
-  #define Y_CENTER float((Y_MIN_POS + Y_MAX_POS) * 0.5)
-  #define Z_CENTER float((Z_MIN_POS + Z_MAX_POS) * 0.5)
+
+  // Defined only if the sanity-check is bypassed
+  #ifndef X_BED_SIZE
+    #define X_BED_SIZE X_MAX_LENGTH
+  #endif
+  #ifndef Y_BED_SIZE
+    #define Y_BED_SIZE Y_MAX_LENGTH
+  #endif
+
+  #if ENABLED(BED_CENTER_AT_0_0)
+    #define X_CENTER 0
+    #define Y_CENTER 0
+  #else
+    #define X_CENTER ((X_BED_SIZE) / 2)
+    #define Y_CENTER ((Y_BED_SIZE) / 2)
+  #endif
+  #define Z_CENTER ((Z_MIN_POS + Z_MAX_POS) / 2)
+
+  #define X_MIN_BED (X_CENTER - (X_BED_SIZE) / 2)
+  #define X_MAX_BED (X_CENTER + (X_BED_SIZE) / 2)
+  #define Y_MIN_BED (Y_CENTER - (Y_BED_SIZE) / 2)
+  #define Y_MAX_BED (Y_CENTER + (Y_BED_SIZE) / 2)
 
   /**
    * CoreXY, CoreXZ, and CoreYZ - and their reverse
@@ -87,11 +106,11 @@
     #if ENABLED(DELTA)
       #define X_HOME_POS 0
     #else
-      #define X_HOME_POS ((X_MAX_LENGTH) * (X_HOME_DIR) * 0.5)
+      #define X_HOME_POS ((X_BED_SIZE) * (X_HOME_DIR) * 0.5)
     #endif
   #else
     #if ENABLED(DELTA)
-      #define X_HOME_POS (X_MIN_POS + (X_MAX_LENGTH) * 0.5)
+      #define X_HOME_POS (X_MIN_POS + (X_BED_SIZE) * 0.5)
     #else
       #define X_HOME_POS (X_HOME_DIR < 0 ? X_MIN_POS : X_MAX_POS)
     #endif
@@ -103,11 +122,11 @@
     #if ENABLED(DELTA)
       #define Y_HOME_POS 0
     #else
-      #define Y_HOME_POS ((Y_MAX_LENGTH) * (Y_HOME_DIR) * 0.5)
+      #define Y_HOME_POS ((Y_BED_SIZE) * (Y_HOME_DIR) * 0.5)
     #endif
   #else
     #if ENABLED(DELTA)
-      #define Y_HOME_POS (Y_MIN_POS + (Y_MAX_LENGTH) * 0.5)
+      #define Y_HOME_POS (Y_MIN_POS + (Y_BED_SIZE) * 0.5)
     #else
       #define Y_HOME_POS (Y_HOME_DIR < 0 ? Y_MIN_POS : Y_MAX_POS)
     #endif
@@ -151,10 +170,10 @@
    */
   #if ENABLED(Z_SAFE_HOMING)
     #ifndef Z_SAFE_HOMING_X_POINT
-      #define Z_SAFE_HOMING_X_POINT ((X_MIN_POS + X_MAX_POS) / 2)
+      #define Z_SAFE_HOMING_X_POINT X_CENTER
     #endif
     #ifndef Z_SAFE_HOMING_Y_POINT
-      #define Z_SAFE_HOMING_Y_POINT ((Y_MIN_POS + Y_MAX_POS) / 2)
+      #define Z_SAFE_HOMING_Y_POINT Y_CENTER
     #endif
     #define X_TILT_FULCRUM Z_SAFE_HOMING_X_POINT
     #define Y_TILT_FULCRUM Z_SAFE_HOMING_Y_POINT
@@ -792,25 +811,40 @@
     #define MANUAL_PROBE_HEIGHT Z_HOMING_HEIGHT
   #endif
 
+  /**
+   * Bed Probing rectangular bounds
+   * These can be further constrained in code for Delta and SCARA
+   */
   #if ENABLED(DELTA)
-    // These will be further constrained in code, but UBL_PROBE_PT values
-    // cannot be compile-time verified within the radius.
-    #define MIN_PROBE_X (-DELTA_PRINTABLE_RADIUS)
-    #define MAX_PROBE_X ( DELTA_PRINTABLE_RADIUS)
-    #define MIN_PROBE_Y (-DELTA_PRINTABLE_RADIUS)
-    #define MAX_PROBE_Y ( DELTA_PRINTABLE_RADIUS)
+    #ifndef DELTA_PROBEABLE_RADIUS
+      #define DELTA_PROBEABLE_RADIUS DELTA_PRINTABLE_RADIUS
+    #endif
+    // Probing points may be verified at compile time within the radius
+    // using static_assert(HYPOT2(X2-X1,Y2-Y1)<=sq(DELTA_PRINTABLE_RADIUS),"bad probe point!")
+    // so that may be added to SanityCheck.h in the future.
+    #define MIN_PROBE_X (X_CENTER - (DELTA_PROBEABLE_RADIUS))
+    #define MIN_PROBE_Y (Y_CENTER - (DELTA_PROBEABLE_RADIUS))
+    #define MAX_PROBE_X (X_CENTER +  DELTA_PROBEABLE_RADIUS)
+    #define MAX_PROBE_Y (Y_CENTER +  DELTA_PROBEABLE_RADIUS)
   #elif IS_SCARA
     #define SCARA_PRINTABLE_RADIUS (SCARA_LINKAGE_1 + SCARA_LINKAGE_2)
-    #define MIN_PROBE_X (-SCARA_PRINTABLE_RADIUS)
-    #define MAX_PROBE_X ( SCARA_PRINTABLE_RADIUS)
-    #define MIN_PROBE_Y (-SCARA_PRINTABLE_RADIUS)
-    #define MAX_PROBE_Y ( SCARA_PRINTABLE_RADIUS)
+    #define MIN_PROBE_X (X_CENTER - (SCARA_PRINTABLE_RADIUS))
+    #define MIN_PROBE_Y (Y_CENTER - (SCARA_PRINTABLE_RADIUS))
+    #define MAX_PROBE_X (X_CENTER +  SCARA_PRINTABLE_RADIUS)
+    #define MAX_PROBE_Y (Y_CENTER +  SCARA_PRINTABLE_RADIUS)
   #else
-    // Boundaries for probing based on set limits
-    #define MIN_PROBE_X (max(X_MIN_POS, X_MIN_POS + X_PROBE_OFFSET_FROM_EXTRUDER))
-    #define MAX_PROBE_X (min(X_MAX_POS, X_MAX_POS + X_PROBE_OFFSET_FROM_EXTRUDER))
-    #define MIN_PROBE_Y (max(Y_MIN_POS, Y_MIN_POS + Y_PROBE_OFFSET_FROM_EXTRUDER))
-    #define MAX_PROBE_Y (min(Y_MAX_POS, Y_MAX_POS + Y_PROBE_OFFSET_FROM_EXTRUDER))
+    // Boundaries for Cartesian probing based on set limits
+    #if ENABLED(BED_CENTER_AT_0_0)
+      #define MIN_PROBE_X (max(X_PROBE_OFFSET_FROM_EXTRUDER, 0) - (X_BED_SIZE) / 2)
+      #define MIN_PROBE_Y (max(Y_PROBE_OFFSET_FROM_EXTRUDER, 0) - (Y_BED_SIZE) / 2)
+      #define MAX_PROBE_X (min(X_BED_SIZE + X_PROBE_OFFSET_FROM_EXTRUDER, X_BED_SIZE) - (X_BED_SIZE) / 2)
+      #define MAX_PROBE_Y (min(Y_BED_SIZE + Y_PROBE_OFFSET_FROM_EXTRUDER, Y_BED_SIZE) - (Y_BED_SIZE) / 2)
+    #else
+      #define MIN_PROBE_X (max(X_MIN_POS + X_PROBE_OFFSET_FROM_EXTRUDER, 0))
+      #define MIN_PROBE_Y (max(Y_MIN_POS + Y_PROBE_OFFSET_FROM_EXTRUDER, 0))
+      #define MAX_PROBE_X (min(X_MAX_POS + X_PROBE_OFFSET_FROM_EXTRUDER, X_BED_SIZE))
+      #define MAX_PROBE_Y (min(Y_MAX_POS + Y_PROBE_OFFSET_FROM_EXTRUDER, Y_BED_SIZE))
+    #endif
   #endif
 
   // Stepper pulse duration, in cycles
@@ -835,7 +869,7 @@
   #endif
 
   /**
-   * DELTA_SEGMENT_MIN_LENGTH and DELTA_PROBEABLE_RADIUS for UBL_DELTA
+   * DELTA_SEGMENT_MIN_LENGTH for UBL_DELTA
    */
   #if UBL_DELTA
     #ifndef DELTA_SEGMENT_MIN_LENGTH
@@ -847,9 +881,6 @@
         #define DELTA_SEGMENT_MIN_LENGTH 1.00 // mm (similar to G2/G3 arc segmentation)
       #endif
     #endif
-    #ifndef DELTA_PROBEABLE_RADIUS
-      #define DELTA_PROBEABLE_RADIUS DELTA_PRINTABLE_RADIUS
-    #endif
   #endif
 
   // Shorthand

Marlin/Configuration.h

@@ -755,12 +755,16 @@
 
 // @section machine
 
-// Travel limits after homing (units are in mm)
+// The size of the print bed
+#define X_BED_SIZE 200
+#define Y_BED_SIZE 200
+
+// Travel limits (mm) after homing, corresponding to endstop positions.
 #define X_MIN_POS 0
 #define Y_MIN_POS 0
 #define Z_MIN_POS 0
-#define X_MAX_POS 200
-#define Y_MAX_POS 200
+#define X_MAX_POS X_BED_SIZE
+#define Y_MAX_POS Y_BED_SIZE
 #define Z_MAX_POS 200
 
 // If enabled, axes won't move below MIN_POS in response to movement commands.
@@ -968,8 +972,8 @@
 //#define Z_SAFE_HOMING
 
 #if ENABLED(Z_SAFE_HOMING)
-  #define Z_SAFE_HOMING_X_POINT ((X_MIN_POS + X_MAX_POS) / 2)    // X point for Z homing when homing all axis (G28).
-  #define Z_SAFE_HOMING_Y_POINT ((Y_MIN_POS + Y_MAX_POS) / 2)    // Y point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_X_POINT ((X_BED_SIZE) / 2)    // X point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_Y_POINT ((Y_BED_SIZE) / 2)    // Y point for Z homing when homing all axis (G28).
 #endif
 
 // Homing speeds (mm/m)

Marlin/Marlin_main.cpp

@@ -456,8 +456,8 @@ float filament_size[EXTRUDERS], volumetric_multiplier[EXTRUDERS];
 #if HAS_SOFTWARE_ENDSTOPS
   bool soft_endstops_enabled = true;
 #endif
-float soft_endstop_min[XYZ] = { X_MIN_POS, Y_MIN_POS, Z_MIN_POS },
-      soft_endstop_max[XYZ] = { X_MAX_POS, Y_MAX_POS, Z_MAX_POS };
+float soft_endstop_min[XYZ] = { X_MIN_BED, Y_MIN_BED, Z_MIN_POS },
+      soft_endstop_max[XYZ] = { X_MAX_BED, Y_MAX_BED, Z_MAX_POS };
 
 #if FAN_COUNT > 0
   int16_t fanSpeeds[FAN_COUNT] = { 0 };
@@ -6905,15 +6905,16 @@ inline void gcode_M42() {
 
     for (uint8_t n = 0; n < n_samples; n++) {
       if (n_legs) {
-        int dir = (random(0, 10) > 5.0) ? -1 : 1;  // clockwise or counter clockwise
-        float angle = random(0.0, 360.0),
-              radius = random(
-                #if ENABLED(DELTA)
-                  DELTA_PROBEABLE_RADIUS / 8, DELTA_PROBEABLE_RADIUS / 3
-                #else
-                  5, X_MAX_LENGTH / 8
-                #endif
-              );
+        const int dir = (random(0, 10) > 5.0) ? -1 : 1;  // clockwise or counter clockwise
+        float angle = random(0.0, 360.0);
+        const float radius = random(
+          #if ENABLED(DELTA)
+            0.1250000000 * (DELTA_PROBEABLE_RADIUS),
+            0.3333333333 * (DELTA_PROBEABLE_RADIUS)
+          #else
+            5.0, 0.125 * min(X_BED_SIZE, Y_BED_SIZE)
+          #endif
+        );
 
         if (verbose_level > 3) {
           SERIAL_ECHOPAIR("Starting radius: ", radius);

Marlin/SanityCheck.h

@@ -50,7 +50,9 @@
 /**
  * Warnings for old configurations
  */
-#if WATCH_TEMP_PERIOD > 500
+#if !defined(X_BED_SIZE) || !defined(Y_BED_SIZE)
+  #error "X_BED_SIZE and BED_Y_SIZE are now required! Please update your configuration."
+#elif WATCH_TEMP_PERIOD > 500
   #error "WATCH_TEMP_PERIOD now uses seconds instead of milliseconds."
 #elif DISABLED(THERMAL_PROTECTION_HOTENDS) && (defined(WATCH_TEMP_PERIOD) || defined(THERMAL_PROTECTION_PERIOD))
   #error "Thermal Runaway Protection for hotends is now enabled with THERMAL_PROTECTION_HOTENDS."

Marlin/example_configurations/AlephObjects/TAZ4/Configuration.h

@@ -770,12 +770,16 @@
 
 // @section machine
 
-// Travel limits after homing (units are in mm)
+// The size of the print bed
+#define X_BED_SIZE 298
+#define Y_BED_SIZE 275
+
+// Travel limits (mm) after homing, corresponding to endstop positions.
 #define X_MIN_POS 0
 #define Y_MIN_POS 0
 #define Z_MIN_POS 0
-#define X_MAX_POS 298
-#define Y_MAX_POS 275
+#define X_MAX_POS X_BED_SIZE
+#define Y_MAX_POS Y_BED_SIZE
 #define Z_MAX_POS 250
 
 // If enabled, axes won't move below MIN_POS in response to movement commands.
@@ -983,8 +987,8 @@
 //#define Z_SAFE_HOMING
 
 #if ENABLED(Z_SAFE_HOMING)
-  #define Z_SAFE_HOMING_X_POINT ((X_MIN_POS + X_MAX_POS) / 2)    // X point for Z homing when homing all axis (G28).
-  #define Z_SAFE_HOMING_Y_POINT ((Y_MIN_POS + Y_MAX_POS) / 2)    // Y point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_X_POINT ((X_BED_SIZE) / 2)    // X point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_Y_POINT ((Y_BED_SIZE) / 2)    // Y point for Z homing when homing all axis (G28).
 #endif
 
 // Homing speeds (mm/m)

Marlin/example_configurations/AliExpress/CL-260/Configuration.h

@@ -752,12 +752,16 @@
 
 // @section machine
 
-// Travel limits after homing (units are in mm)
+// The size of the print bed
+#define X_BED_SIZE 220
+#define Y_BED_SIZE 220
+
+// Travel limits (mm) after homing, corresponding to endstop positions.
 #define X_MIN_POS 0
 #define Y_MIN_POS 0
 #define Z_MIN_POS 0
-#define X_MAX_POS 220
-#define Y_MAX_POS 220
+#define X_MAX_POS X_BED_SIZE
+#define Y_MAX_POS Y_BED_SIZE
 #define Z_MAX_POS 260
 
 // If enabled, axes won't move below MIN_POS in response to movement commands.
@@ -965,8 +969,8 @@
 //#define Z_SAFE_HOMING
 
 #if ENABLED(Z_SAFE_HOMING)
-  #define Z_SAFE_HOMING_X_POINT ((X_MIN_POS + X_MAX_POS) / 2)    // X point for Z homing when homing all axis (G28).
-  #define Z_SAFE_HOMING_Y_POINT ((Y_MIN_POS + Y_MAX_POS) / 2)    // Y point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_X_POINT ((X_BED_SIZE) / 2)    // X point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_Y_POINT ((Y_BED_SIZE) / 2)    // Y point for Z homing when homing all axis (G28).
 #endif
 
 // Homing speeds (mm/m)

Marlin/example_configurations/Anet/A6/Configuration.h

@@ -839,47 +839,52 @@
 
 // @section machine
 
-// Travel limits after homing (units are in mm)
+// The size of the print bed
+//#define X_BED_SIZE 200
+//#define Y_BED_SIZE 200
+
+// Travel limits (mm) after homing, corresponding to endstop positions.
 //#define X_MIN_POS 0
 //#define Y_MIN_POS 0
+//#define X_MAX_POS X_BED_SIZE
+//#define Y_MAX_POS Y_BED_SIZE
 //#define Z_MIN_POS 0
-//#define X_MAX_POS 200
-//#define Y_MAX_POS 200
 //#define Z_MAX_POS 200
 
 // ANET A6 Firmware V2.0 defaults:
-//#define X_MIN_POS     0
-//#define Y_MIN_POS     0
-//#define Z_MIN_POS     0
-//#define X_MAX_POS     220
-//#define Y_MAX_POS     220
-//#define Z_MAX_POS     250
+//#define X_BED_SIZE 220
+//#define Y_BED_SIZE 220
+//#define X_MIN_POS 0
+//#define Y_MIN_POS 0
+//#define Z_MIN_POS 0
+//#define Z_MAX_POS 250
 
 // ANET A6, X0/Y0 0 front left bed edge :
-#define X_MIN_POS     -3
-#define Y_MIN_POS     -5
-#define Z_MIN_POS     0
-#define X_MAX_POS     222
-#define Y_MAX_POS     222
-#define Z_MAX_POS     230
+#define X_BED_SIZE 222
+#define Y_BED_SIZE 222
+#define X_MIN_POS -3
+#define Y_MIN_POS -5
+#define Z_MIN_POS 0
+#define Z_MAX_POS 230
 
 // ANET A6 with new X-Axis / modded Y-Axis:
-//#define X_MIN_POS     0
-//#define Y_MIN_POS     0
-//#define Z_MIN_POS     0
-//#define X_MAX_POS     235
-//#define Y_MAX_POS     230
-//#define Z_MAX_POS     230
+//#define X_BED_SIZE 235
+//#define Y_BED_SIZE 230
+//#define X_MIN_POS 0
+//#define Y_MIN_POS 0
+//#define Z_MIN_POS 0
+//#define Z_MAX_POS 230
 
 // ANET A6 with new X-Axis / modded Y-Axis, X0/Y0 0 front left bed edge :
-//#define X_MIN_POS     -8
-//#define Y_MIN_POS     -6
-//#define Z_MIN_POS     0
-//#define X_MAX_POS     227
-//#define Y_MAX_POS     224
-//#define Z_MAX_POS     230
-
+//#define X_BED_SIZE 227
+//#define Y_BED_SIZE 224
+//#define X_MIN_POS -8
+//#define Y_MIN_POS -6
+//#define Z_MIN_POS 0
+//#define Z_MAX_POS 230
 
+#define X_MAX_POS X_BED_SIZE
+#define Y_MAX_POS Y_BED_SIZE
 
 // If enabled, axes won't move below MIN_POS in response to movement commands.
 #define MIN_SOFTWARE_ENDSTOPS
@@ -1115,8 +1120,8 @@
 #define Z_SAFE_HOMING
 
 #if ENABLED(Z_SAFE_HOMING)
-  #define Z_SAFE_HOMING_X_POINT ((X_MIN_POS + X_MAX_POS) / 2)    // X point for Z homing when homing all axis (G28).
-  #define Z_SAFE_HOMING_Y_POINT ((Y_MIN_POS + Y_MAX_POS) / 2)    // Y point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_X_POINT ((X_BED_SIZE) / 2)    // X point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_Y_POINT ((Y_BED_SIZE) / 2)    // Y point for Z homing when homing all axis (G28).
 
   //Anet A6 with new X-Axis
   //#define Z_SAFE_HOMING_X_POINT 113    // X point for Z homing when homing all axis (G28).

Marlin/example_configurations/Anet/A8/Configuration.h

@@ -761,12 +761,16 @@
 
 // @section machine
 
-// Travel limits after homing (units are in mm)
+// The size of the print bed
+#define X_BED_SIZE 220
+#define Y_BED_SIZE 220
+
+// Travel limits (mm) after homing, corresponding to endstop positions.
 #define X_MIN_POS -33
 #define Y_MIN_POS -10
 #define Z_MIN_POS 0
-#define X_MAX_POS 220
-#define Y_MAX_POS 220
+#define X_MAX_POS X_BED_SIZE
+#define Y_MAX_POS Y_BED_SIZE
 #define Z_MAX_POS 240
 
 // If enabled, axes won't move below MIN_POS in response to movement commands.
@@ -974,8 +978,8 @@
 //#define Z_SAFE_HOMING
 
 #if ENABLED(Z_SAFE_HOMING)
-  #define Z_SAFE_HOMING_X_POINT ((X_MIN_POS + X_MAX_POS) / 2)    // X point for Z homing when homing all axis (G28).
-  #define Z_SAFE_HOMING_Y_POINT ((Y_MIN_POS + Y_MAX_POS) / 2)    // Y point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_X_POINT ((X_BED_SIZE) / 2)    // X point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_Y_POINT ((Y_BED_SIZE) / 2)    // Y point for Z homing when homing all axis (G28).
 #endif
 
 // Homing speeds (mm/m)

Marlin/example_configurations/BQ/Hephestos/Configuration.h

@@ -741,12 +741,16 @@
 
 // @section machine
 
-// Travel limits after homing (units are in mm)
+// The size of the print bed
+#define X_BED_SIZE 215
+#define Y_BED_SIZE 210
+
+// Travel limits (mm) after homing, corresponding to endstop positions.
 #define X_MIN_POS 0
 #define Y_MIN_POS 0
 #define Z_MIN_POS 0
-#define X_MAX_POS 215
-#define Y_MAX_POS 210
+#define X_MAX_POS X_BED_SIZE
+#define Y_MAX_POS Y_BED_SIZE
 #define Z_MAX_POS 180
 
 // If enabled, axes won't move below MIN_POS in response to movement commands.
@@ -954,8 +958,8 @@
 //#define Z_SAFE_HOMING
 
 #if ENABLED(Z_SAFE_HOMING)
-  #define Z_SAFE_HOMING_X_POINT ((X_MIN_POS + X_MAX_POS) / 2)    // X point for Z homing when homing all axis (G28).
-  #define Z_SAFE_HOMING_Y_POINT ((Y_MIN_POS + Y_MAX_POS) / 2)    // Y point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_X_POINT ((X_BED_SIZE) / 2)    // X point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_Y_POINT ((Y_BED_SIZE) / 2)    // Y point for Z homing when homing all axis (G28).
 #endif
 
 // Homing speeds (mm/m)

Marlin/example_configurations/BQ/Hephestos_2/Configuration.h

@@ -752,12 +752,16 @@
 
 // @section machine
 
-// Travel limits after homing (units are in mm)
+// The size of the print bed
+#define X_BED_SIZE 210
+#define Y_BED_SIZE 297
+
+// Travel limits (mm) after homing, corresponding to endstop positions.
 #define X_MIN_POS 0
 #define Y_MIN_POS 0
 #define Z_MIN_POS 0
-#define X_MAX_POS 210
-#define Y_MAX_POS 297
+#define X_MAX_POS X_BED_SIZE
+#define Y_MAX_POS Y_BED_SIZE
 #define Z_MAX_POS 210
 
 // If enabled, axes won't move below MIN_POS in response to movement commands.
@@ -965,8 +969,8 @@
 #define Z_SAFE_HOMING
 
 #if ENABLED(Z_SAFE_HOMING)
-  #define Z_SAFE_HOMING_X_POINT ((X_MIN_POS + X_MAX_POS) / 2)    // X point for Z homing when homing all axis (G28).
-  #define Z_SAFE_HOMING_Y_POINT ((Y_MIN_POS + Y_MAX_POS) / 2)    // Y point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_X_POINT ((X_BED_SIZE) / 2)    // X point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_Y_POINT ((Y_BED_SIZE) / 2)    // Y point for Z homing when homing all axis (G28).
 #endif
 
 // Homing speeds (mm/m)

Marlin/example_configurations/BQ/WITBOX/Configuration.h

@@ -741,12 +741,16 @@
 
 // @section machine
 
-// Travel limits after homing (units are in mm)
+// The size of the print bed
+#define X_BED_SIZE 297
+#define Y_BED_SIZE 210
+
+// Travel limits (mm) after homing, corresponding to endstop positions.
 #define X_MIN_POS 0
 #define Y_MIN_POS 0
 #define Z_MIN_POS 0
-#define X_MAX_POS 297
-#define Y_MAX_POS 210
+#define X_MAX_POS X_BED_SIZE
+#define Y_MAX_POS Y_BED_SIZE
 #define Z_MAX_POS 200
 
 // If enabled, axes won't move below MIN_POS in response to movement commands.
@@ -954,8 +958,8 @@
 //#define Z_SAFE_HOMING
 
 #if ENABLED(Z_SAFE_HOMING)
-  #define Z_SAFE_HOMING_X_POINT ((X_MIN_POS + X_MAX_POS) / 2)    // X point for Z homing when homing all axis (G28).
-  #define Z_SAFE_HOMING_Y_POINT ((Y_MIN_POS + Y_MAX_POS) / 2)    // Y point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_X_POINT ((X_BED_SIZE) / 2)    // X point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_Y_POINT ((Y_BED_SIZE) / 2)    // Y point for Z homing when homing all axis (G28).
 #endif
 
 // Homing speeds (mm/m)

Marlin/example_configurations/Cartesio/Configuration.h

@@ -749,12 +749,16 @@
 
 // @section machine
 
-// Travel limits after homing (units are in mm)
+// The size of the print bed
+#define X_BED_SIZE 435
+#define Y_BED_SIZE 270
+
+// Travel limits (mm) after homing, corresponding to endstop positions.
 #define X_MIN_POS 0
 #define Y_MIN_POS 0
 #define Z_MIN_POS 0
-#define X_MAX_POS 435
-#define Y_MAX_POS 270
+#define X_MAX_POS X_BED_SIZE
+#define Y_MAX_POS Y_BED_SIZE
 #define Z_MAX_POS 400
 
 // If enabled, axes won't move below MIN_POS in response to movement commands.
@@ -962,8 +966,8 @@
 //#define Z_SAFE_HOMING
 
 #if ENABLED(Z_SAFE_HOMING)
-  #define Z_SAFE_HOMING_X_POINT ((X_MIN_POS + X_MAX_POS) / 2)    // X point for Z homing when homing all axis (G28).
-  #define Z_SAFE_HOMING_Y_POINT ((Y_MIN_POS + Y_MAX_POS) / 2)    // Y point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_X_POINT ((X_BED_SIZE) / 2)    // X point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_Y_POINT ((Y_BED_SIZE) / 2)    // Y point for Z homing when homing all axis (G28).
 #endif
 
 // Homing speeds (mm/m)

Marlin/example_configurations/Creality/CR-10/Configuration.h

@@ -765,12 +765,16 @@
 
 // @section machine
 
-// Travel limits after homing (units are in mm)
+// The size of the print bed
+#define X_BED_SIZE 300
+#define Y_BED_SIZE 300
+
+// Travel limits (mm) after homing, corresponding to endstop positions.
 #define X_MIN_POS 0
 #define Y_MIN_POS 0
 #define Z_MIN_POS 0
-#define X_MAX_POS 300
-#define Y_MAX_POS 300
+#define X_MAX_POS X_BED_SIZE
+#define Y_MAX_POS Y_BED_SIZE
 #define Z_MAX_POS 400
 
 // If enabled, axes won't move below MIN_POS in response to movement commands.
@@ -977,8 +981,8 @@
 //#define Z_SAFE_HOMING
 
 #if ENABLED(Z_SAFE_HOMING)
-  #define Z_SAFE_HOMING_X_POINT ((X_MIN_POS + X_MAX_POS) / 2)    // X point for Z homing when homing all axis (G28).
-  #define Z_SAFE_HOMING_Y_POINT ((Y_MIN_POS + Y_MAX_POS) / 2)    // Y point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_X_POINT ((X_BED_SIZE) / 2)    // X point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_Y_POINT ((Y_BED_SIZE) / 2)    // Y point for Z homing when homing all axis (G28).
 #endif
 
 // Homing speeds (mm/m)

Marlin/example_configurations/Felix/Configuration.h

@@ -733,12 +733,16 @@
 
 // @section machine
 
-// Travel limits after homing (units are in mm)
+// The size of the print bed
+#define X_BED_SIZE 255
+#define Y_BED_SIZE 205
+
+// Travel limits (mm) after homing, corresponding to endstop positions.
 #define X_MIN_POS 0
 #define Y_MIN_POS 0
 #define Z_MIN_POS 0
-#define X_MAX_POS 255
-#define Y_MAX_POS 205
+#define X_MAX_POS X_BED_SIZE
+#define Y_MAX_POS Y_BED_SIZE
 #define Z_MAX_POS 235
 
 // If enabled, axes won't move below MIN_POS in response to movement commands.
@@ -946,8 +950,8 @@
 //#define Z_SAFE_HOMING
 
 #if ENABLED(Z_SAFE_HOMING)
-  #define Z_SAFE_HOMING_X_POINT ((X_MIN_POS + X_MAX_POS) / 2)    // X point for Z homing when homing all axis (G28).
-  #define Z_SAFE_HOMING_Y_POINT ((Y_MIN_POS + Y_MAX_POS) / 2)    // Y point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_X_POINT ((X_BED_SIZE) / 2)    // X point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_Y_POINT ((Y_BED_SIZE) / 2)    // Y point for Z homing when homing all axis (G28).
 #endif
 
 // Homing speeds (mm/m)

Marlin/example_configurations/Felix/DUAL/Configuration.h

@@ -733,12 +733,16 @@
 
 // @section machine
 
-// Travel limits after homing (units are in mm)
+// The size of the print bed
+#define X_BED_SIZE 255
+#define Y_BED_SIZE 205
+
+// Travel limits (mm) after homing, corresponding to endstop positions.
 #define X_MIN_POS 0
 #define Y_MIN_POS 0
 #define Z_MIN_POS 0
-#define X_MAX_POS 255
-#define Y_MAX_POS 205
+#define X_MAX_POS X_BED_SIZE
+#define Y_MAX_POS Y_BED_SIZE
 #define Z_MAX_POS 235
 
 // If enabled, axes won't move below MIN_POS in response to movement commands.
@@ -946,8 +950,8 @@
 //#define Z_SAFE_HOMING
 
 #if ENABLED(Z_SAFE_HOMING)
-  #define Z_SAFE_HOMING_X_POINT ((X_MIN_POS + X_MAX_POS) / 2)    // X point for Z homing when homing all axis (G28).
-  #define Z_SAFE_HOMING_Y_POINT ((Y_MIN_POS + Y_MAX_POS) / 2)    // Y point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_X_POINT ((X_BED_SIZE) / 2)    // X point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_Y_POINT ((Y_BED_SIZE) / 2)    // Y point for Z homing when homing all axis (G28).
 #endif
 
 // Homing speeds (mm/m)

Marlin/example_configurations/Folger Tech/i3-2020/Configuration.h

@@ -754,13 +754,18 @@
 
 // @section machine
 
-// Travel limits after homing (units are in mm)
+// The size of the print bed
+#define X_BED_SIZE 207
+#define Y_BED_SIZE 182
+
+// Travel limits (mm) after homing, corresponding to endstop positions.
 #define X_MIN_POS 6
 #define Y_MIN_POS 3
 #define Z_MIN_POS 0
-#define X_MAX_POS 207
-#define Y_MAX_POS 182
+#define X_MAX_POS X_BED_SIZE
+#define Y_MAX_POS Y_BED_SIZE
 #define Z_MAX_POS 175
+
 // If enabled, axes won't move below MIN_POS in response to movement commands.
 //#define MIN_SOFTWARE_ENDSTOPS
 // If enabled, axes won't move above MAX_POS in response to movement commands.
@@ -968,8 +973,8 @@
 #define Z_SAFE_HOMING
 
 #if ENABLED(Z_SAFE_HOMING)
-  #define Z_SAFE_HOMING_X_POINT ((X_MIN_POS + X_MAX_POS) / 2)    // X point for Z homing when homing all axis (G28).
-  #define Z_SAFE_HOMING_Y_POINT ((Y_MIN_POS + Y_MAX_POS) / 2)    // Y point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_X_POINT ((X_BED_SIZE) / 2)    // X point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_Y_POINT ((Y_BED_SIZE) / 2)    // Y point for Z homing when homing all axis (G28).
 #endif
 
 // Homing speeds (mm/m)

Marlin/example_configurations/Infitary/i3-M508/Configuration.h

@@ -759,12 +759,16 @@
 
 // @section machine
 
-// Travel limits after homing (units are in mm)
+// The size of the print bed
+#define X_BED_SIZE 205
+#define Y_BED_SIZE 205
+
+// Travel limits (mm) after homing, corresponding to endstop positions.
 #define X_MIN_POS 0
 #define Y_MIN_POS 0
 #define Z_MIN_POS 0
-#define X_MAX_POS 205
-#define Y_MAX_POS 205
+#define X_MAX_POS X_BED_SIZE
+#define Y_MAX_POS Y_BED_SIZE
 #define Z_MAX_POS 185
 
 // If enabled, axes won't move below MIN_POS in response to movement commands.
@@ -972,8 +976,8 @@
 //#define Z_SAFE_HOMING
 
 #if ENABLED(Z_SAFE_HOMING)
-  #define Z_SAFE_HOMING_X_POINT ((X_MIN_POS + X_MAX_POS) / 2)    // X point for Z homing when homing all axis (G28).
-  #define Z_SAFE_HOMING_Y_POINT ((Y_MIN_POS + Y_MAX_POS) / 2)    // Y point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_X_POINT ((X_BED_SIZE) / 2)    // X point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_Y_POINT ((Y_BED_SIZE) / 2)    // Y point for Z homing when homing all axis (G28).
 #endif
 
 // Homing speeds (mm/m)

Marlin/example_configurations/Malyan/M150/Configuration.h

@@ -774,12 +774,16 @@
 
 // @section machine
 
-// Travel limits after homing (units are in mm)
+// The size of the print bed
+#define X_BED_SIZE 200
+#define Y_BED_SIZE 200
+
+// Travel limits (mm) after homing, corresponding to endstop positions.
 #define X_MIN_POS 0
 #define Y_MIN_POS 0
 #define Z_MIN_POS 0
-#define X_MAX_POS 200
-#define Y_MAX_POS 200
+#define X_MAX_POS X_BED_SIZE
+#define Y_MAX_POS Y_BED_SIZE
 #define Z_MAX_POS 180
 
 // If enabled, axes won't move below MIN_POS in response to movement commands.
@@ -991,8 +995,8 @@
 //#define Z_SAFE_HOMING
 
 #if ENABLED(Z_SAFE_HOMING)
-  #define Z_SAFE_HOMING_X_POINT ((X_MIN_POS + X_MAX_POS) / 2)    // X point for Z homing when homing all axis (G28).
-  #define Z_SAFE_HOMING_Y_POINT ((Y_MIN_POS + Y_MAX_POS) / 2)    // Y point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_X_POINT ((X_BED_SIZE) / 2)    // X point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_Y_POINT ((Y_BED_SIZE) / 2)    // Y point for Z homing when homing all axis (G28).
 #endif
 
 // Homing speeds (mm/m)

Marlin/example_configurations/RepRapWorld/Megatronics/Configuration.h

@@ -751,12 +751,16 @@
 
 // @section machine
 
-// Travel limits after homing (units are in mm)
+// The size of the print bed
+#define X_BED_SIZE 200
+#define Y_BED_SIZE 200
+
+// Travel limits (mm) after homing, corresponding to endstop positions.
 #define X_MIN_POS 0
 #define Y_MIN_POS 0
 #define Z_MIN_POS 0
-#define X_MAX_POS 200
-#define Y_MAX_POS 200
+#define X_MAX_POS X_BED_SIZE
+#define Y_MAX_POS Y_BED_SIZE
 #define Z_MAX_POS 200
 
 // If enabled, axes won't move below MIN_POS in response to movement commands.
@@ -964,8 +968,8 @@
 //#define Z_SAFE_HOMING
 
 #if ENABLED(Z_SAFE_HOMING)
-  #define Z_SAFE_HOMING_X_POINT ((X_MIN_POS + X_MAX_POS) / 2)    // X point for Z homing when homing all axis (G28).
-  #define Z_SAFE_HOMING_Y_POINT ((Y_MIN_POS + Y_MAX_POS) / 2)    // Y point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_X_POINT ((X_BED_SIZE) / 2)    // X point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_Y_POINT ((Y_BED_SIZE) / 2)    // Y point for Z homing when homing all axis (G28).
 #endif
 
 // Homing speeds (mm/m)

Marlin/example_configurations/RigidBot/Configuration.h

@@ -749,12 +749,16 @@
 
 // @section machine
 
-// Travel limits after homing (units are in mm)
+// The size of the print bed
+#define X_BED_SIZE 254  // RigidBot regular is 254mm, RigitBot Big is 406mm
+#define Y_BED_SIZE 248  // RigidBot regular is 248mm, RigitBot Big is 304mm
+
+// Travel limits (mm) after homing, corresponding to endstop positions.
 #define X_MIN_POS 0
 #define Y_MIN_POS 0
 #define Z_MIN_POS 0
-#define X_MAX_POS 254  // RigidBot regular is 254mm, RigitBot Big is 406mm
-#define Y_MAX_POS 248  // RigidBot regular is 248mm, RigitBot Big is 304mm
+#define X_MAX_POS X_BED_SIZE
+#define Y_MAX_POS Y_BED_SIZE
 #define Z_MAX_POS 254  // RigidBot regular and Big are 254mm
 
 // If enabled, axes won't move below MIN_POS in response to movement commands.
@@ -962,8 +966,8 @@
 //#define Z_SAFE_HOMING
 
 #if ENABLED(Z_SAFE_HOMING)
-  #define Z_SAFE_HOMING_X_POINT ((X_MIN_POS + X_MAX_POS) / 2)    // X point for Z homing when homing all axis (G28).
-  #define Z_SAFE_HOMING_Y_POINT ((Y_MIN_POS + Y_MAX_POS) / 2)    // Y point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_X_POINT ((X_BED_SIZE) / 2)    // X point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_Y_POINT ((Y_BED_SIZE) / 2)    // Y point for Z homing when homing all axis (G28).
 #endif
 
 // Homing speeds (mm/m)

Marlin/example_configurations/SCARA/Configuration.h

@@ -763,12 +763,16 @@
 
 // @section machine
 
-// Travel limits after homing (units are in mm)
+// The size of the print bed
+#define X_BED_SIZE 200
+#define Y_BED_SIZE 200
+
+// Travel limits (mm) after homing, corresponding to endstop positions.
 #define X_MIN_POS 0
 #define Y_MIN_POS 0
 #define Z_MIN_POS MANUAL_Z_HOME_POS
-#define X_MAX_POS 200
-#define Y_MAX_POS 200
+#define X_MAX_POS X_BED_SIZE
+#define Y_MAX_POS Y_BED_SIZE
 #define Z_MAX_POS 225
 
 // If enabled, axes won't move below MIN_POS in response to movement commands.
@@ -976,8 +980,8 @@
 //#define Z_SAFE_HOMING
 
 #if ENABLED(Z_SAFE_HOMING)
-  #define Z_SAFE_HOMING_X_POINT ((X_MIN_POS + X_MAX_POS) / 2)    // X point for Z homing when homing all axis (G28).
-  #define Z_SAFE_HOMING_Y_POINT ((Y_MIN_POS + Y_MAX_POS) / 2)    // Y point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_X_POINT ((X_BED_SIZE) / 2)    // X point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_Y_POINT ((Y_BED_SIZE) / 2)    // Y point for Z homing when homing all axis (G28).
 #endif
 
 // Homing speeds (mm/m)

Marlin/example_configurations/TinyBoy2/Configuration.h

@@ -802,13 +802,17 @@
 
 // @section machine
 
-// Travel limits after homing (units are in mm)
+// The size of the print bed
+// Tinyboy2: 100mm are marketed, actual length between endstop and end of rail is 98mm
+#define X_BED_SIZE 98
+#define Y_BED_SIZE 98
+
+// Travel limits (mm) after homing, corresponding to endstop positions.
 #define X_MIN_POS 0
 #define Y_MIN_POS 0
 #define Z_MIN_POS 0
-// Tinyboy2: 100mm are marketed, actual length between endstop and end of rail is 98mm
-#define X_MAX_POS 98
-#define Y_MAX_POS 98
+#define X_MAX_POS X_BED_SIZE
+#define Y_MAX_POS Y_BED_SIZE
 #if ENABLED(TB2_L10)
   #define Z_MAX_POS 98
 #else
@@ -1020,8 +1024,8 @@
 //#define Z_SAFE_HOMING
 
 #if ENABLED(Z_SAFE_HOMING)
-  #define Z_SAFE_HOMING_X_POINT ((X_MIN_POS + X_MAX_POS) / 2)    // X point for Z homing when homing all axis (G28).
-  #define Z_SAFE_HOMING_Y_POINT ((Y_MIN_POS + Y_MAX_POS) / 2)    // Y point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_X_POINT ((X_BED_SIZE) / 2)    // X point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_Y_POINT ((Y_BED_SIZE) / 2)    // Y point for Z homing when homing all axis (G28).
 #endif
 
 // Homing speeds (mm/m)

Marlin/example_configurations/Velleman/K8200/Configuration.h

@@ -780,12 +780,16 @@
 
 // @section machine
 
-// Travel limits after homing (units are in mm)
+// The size of the print bed
+#define X_BED_SIZE 200
+#define Y_BED_SIZE 200
+
+// Travel limits (mm) after homing, corresponding to endstop positions.
 #define X_MIN_POS 0
 #define Y_MIN_POS 0
 #define Z_MIN_POS 0
-#define X_MAX_POS 200
-#define Y_MAX_POS 200
+#define X_MAX_POS X_BED_SIZE
+#define Y_MAX_POS Y_BED_SIZE
 #define Z_MAX_POS 200
 
 // If enabled, axes won't move below MIN_POS in response to movement commands.
@@ -993,8 +997,8 @@
 //#define Z_SAFE_HOMING
 
 #if ENABLED(Z_SAFE_HOMING)
-  #define Z_SAFE_HOMING_X_POINT ((X_MIN_POS + X_MAX_POS) / 2)    // X point for Z homing when homing all axis (G28).
-  #define Z_SAFE_HOMING_Y_POINT ((Y_MIN_POS + Y_MAX_POS) / 2)    // Y point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_X_POINT ((X_BED_SIZE) / 2)    // X point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_Y_POINT ((Y_BED_SIZE) / 2)    // Y point for Z homing when homing all axis (G28).
 #endif
 
 // Homing speeds (mm/m)

Marlin/example_configurations/Velleman/K8400/Configuration.h

@@ -751,12 +751,16 @@
 
 // @section machine
 
-// Travel limits after homing (units are in mm)
+// The size of the print bed
+#define X_BED_SIZE 200
+#define Y_BED_SIZE 200
+
+// Travel limits (mm) after homing, corresponding to endstop positions.
 #define X_MIN_POS 0
 #define Y_MIN_POS 20
 #define Z_MIN_POS 0
-#define X_MAX_POS 200
-#define Y_MAX_POS 200
+#define X_MAX_POS X_BED_SIZE
+#define Y_MAX_POS Y_BED_SIZE
 #define Z_MAX_POS 190
 
 // If enabled, axes won't move below MIN_POS in response to movement commands.
@@ -964,8 +968,8 @@
 //#define Z_SAFE_HOMING
 
 #if ENABLED(Z_SAFE_HOMING)
-  #define Z_SAFE_HOMING_X_POINT ((X_MIN_POS + X_MAX_POS) / 2)    // X point for Z homing when homing all axis (G28).
-  #define Z_SAFE_HOMING_Y_POINT ((Y_MIN_POS + Y_MAX_POS) / 2)    // Y point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_X_POINT ((X_BED_SIZE) / 2)    // X point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_Y_POINT ((Y_BED_SIZE) / 2)    // Y point for Z homing when homing all axis (G28).
 #endif
 
 // Homing speeds (mm/m)

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

@@ -751,12 +751,16 @@
 
 // @section machine
 
-// Travel limits after homing (units are in mm)
+// The size of the print bed
+#define X_BED_SIZE 200
+#define Y_BED_SIZE 200
+
+// Travel limits (mm) after homing, corresponding to endstop positions.
 #define X_MIN_POS 0
 #define Y_MIN_POS 20
 #define Z_MIN_POS 0
-#define X_MAX_POS 200
-#define Y_MAX_POS 200
+#define X_MAX_POS X_BED_SIZE
+#define Y_MAX_POS Y_BED_SIZE
 #define Z_MAX_POS 190
 
 // If enabled, axes won't move below MIN_POS in response to movement commands.
@@ -964,8 +968,8 @@
 //#define Z_SAFE_HOMING
 
 #if ENABLED(Z_SAFE_HOMING)
-  #define Z_SAFE_HOMING_X_POINT ((X_MIN_POS + X_MAX_POS) / 2)    // X point for Z homing when homing all axis (G28).
-  #define Z_SAFE_HOMING_Y_POINT ((Y_MIN_POS + Y_MAX_POS) / 2)    // Y point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_X_POINT ((X_BED_SIZE) / 2)    // X point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_Y_POINT ((Y_BED_SIZE) / 2)    // Y point for Z homing when homing all axis (G28).
 #endif
 
 // Homing speeds (mm/m)

Marlin/example_configurations/adafruit/ST7565/Configuration.h

@@ -751,12 +751,16 @@
 
 // @section machine
 
-// Travel limits after homing (units are in mm)
+// The size of the print bed
+#define X_BED_SIZE 200
+#define Y_BED_SIZE 200
+
+// Travel limits (mm) after homing, corresponding to endstop positions.
 #define X_MIN_POS 0
 #define Y_MIN_POS 0
 #define Z_MIN_POS 0
-#define X_MAX_POS 200
-#define Y_MAX_POS 200
+#define X_MAX_POS X_BED_SIZE
+#define Y_MAX_POS Y_BED_SIZE
 #define Z_MAX_POS 200
 
 // If enabled, axes won't move below MIN_POS in response to movement commands.
@@ -964,8 +968,8 @@
 //#define Z_SAFE_HOMING
 
 #if ENABLED(Z_SAFE_HOMING)
-  #define Z_SAFE_HOMING_X_POINT ((X_MIN_POS + X_MAX_POS) / 2)    // X point for Z homing when homing all axis (G28).
-  #define Z_SAFE_HOMING_Y_POINT ((Y_MIN_POS + Y_MAX_POS) / 2)    // Y point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_X_POINT ((X_BED_SIZE) / 2)    // X point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_Y_POINT ((Y_BED_SIZE) / 2)    // Y point for Z homing when homing all axis (G28).
 #endif
 
 // Homing speeds (mm/m)

Marlin/example_configurations/delta/FLSUN/auto_calibrate/Configuration.h

@@ -875,7 +875,11 @@
 
 // @section machine
 
-// Travel limits after homing (units are in mm)
+// The size of the print bed
+#define X_BED_SIZE ((DELTA_PRINTABLE_RADIUS) * 2)
+#define Y_BED_SIZE ((DELTA_PRINTABLE_RADIUS) * 2)
+
+// Travel limits (mm) after homing, corresponding to endstop positions.
 #define X_MIN_POS -(DELTA_PRINTABLE_RADIUS)
 #define Y_MIN_POS -(DELTA_PRINTABLE_RADIUS)
 #define Z_MIN_POS 0

Marlin/example_configurations/delta/FLSUN/kossel_mini/Configuration.h

@@ -875,7 +875,11 @@
 
 // @section machine
 
-// Travel limits after homing (units are in mm)
+// The size of the print bed
+#define X_BED_SIZE ((DELTA_PRINTABLE_RADIUS) * 2)
+#define Y_BED_SIZE ((DELTA_PRINTABLE_RADIUS) * 2)
+
+// Travel limits (mm) after homing, corresponding to endstop positions.
 #define X_MIN_POS -(DELTA_PRINTABLE_RADIUS)
 #define Y_MIN_POS -(DELTA_PRINTABLE_RADIUS)
 #define Z_MIN_POS 0

Marlin/example_configurations/delta/generic/Configuration.h

@@ -862,7 +862,11 @@
 
 // @section machine
 
-// Travel limits after homing (units are in mm)
+// The size of the print bed
+#define X_BED_SIZE ((DELTA_PRINTABLE_RADIUS) * 2)
+#define Y_BED_SIZE ((DELTA_PRINTABLE_RADIUS) * 2)
+
+// Travel limits (mm) after homing, corresponding to endstop positions.
 #define X_MIN_POS -(DELTA_PRINTABLE_RADIUS)
 #define Y_MIN_POS -(DELTA_PRINTABLE_RADIUS)
 #define Z_MIN_POS 0

Marlin/example_configurations/delta/kossel_mini/Configuration.h

@@ -860,7 +860,11 @@
 
 // @section machine
 
-// Travel limits after homing (units are in mm)
+// The size of the print bed
+#define X_BED_SIZE ((DELTA_PRINTABLE_RADIUS) * 2)
+#define Y_BED_SIZE ((DELTA_PRINTABLE_RADIUS) * 2)
+
+// Travel limits (mm) after homing, corresponding to endstop positions.
 #define X_MIN_POS -(DELTA_PRINTABLE_RADIUS)
 #define Y_MIN_POS -(DELTA_PRINTABLE_RADIUS)
 #define Z_MIN_POS 0

Marlin/example_configurations/delta/kossel_pro/Configuration.h

@@ -865,7 +865,11 @@
 
 // @section machine
 
-// Travel limits after homing (units are in mm)
+// The size of the print bed
+#define X_BED_SIZE ((DELTA_PRINTABLE_RADIUS) * 2)
+#define Y_BED_SIZE ((DELTA_PRINTABLE_RADIUS) * 2)
+
+// Travel limits (mm) after homing, corresponding to endstop positions.
 #define X_MIN_POS -(DELTA_PRINTABLE_RADIUS)
 #define Y_MIN_POS -(DELTA_PRINTABLE_RADIUS)
 #define Z_MIN_POS 0

Marlin/example_configurations/delta/kossel_xl/Configuration.h

@@ -928,7 +928,11 @@
 
 // @section machine
 
-// Travel limits after homing (units are in mm)
+// The size of the print bed
+#define X_BED_SIZE ((DELTA_PRINTABLE_RADIUS) * 2)
+#define Y_BED_SIZE ((DELTA_PRINTABLE_RADIUS) * 2)
+
+// Travel limits (mm) after homing, corresponding to endstop positions.
 #define X_MIN_POS -(DELTA_PRINTABLE_RADIUS)
 #define Y_MIN_POS -(DELTA_PRINTABLE_RADIUS)
 #define Z_MIN_POS 0

Marlin/example_configurations/gCreate/gMax1.5+/Configuration.h

@@ -766,13 +766,17 @@
 
 // @section machine
 
-// Travel limits after homing (units are in mm)
+// The size of the print bed
+#define X_BED_SIZE 420   // These numbers are not accurate for an unaltered gMax 1.5+ printer.  My print bed
+#define Y_BED_SIZE 420   // is inset a noticable amount from the edge of the bed.  Combined with the inset,
+                         // the nozzle can reach all cordinates of the mesh.
+
+// Travel limits (mm) after homing, corresponding to endstop positions.
 #define X_MIN_POS 0
 #define Y_MIN_POS 0
 #define Z_MIN_POS 0
-#define X_MAX_POS 420   // These numbers are not accurate for an unaltered gMax 1.5+ printer.  My print bed
-#define Y_MAX_POS 420   // is inset a noticable amount from the edge of the bed.  Combined with the inset,
-                        // the nozzle can reach all cordinates of the mesh.
+#define X_MAX_POS X_BED_SIZE
+#define Y_MAX_POS Y_BED_SIZE
 #define Z_MAX_POS 500
 
 // If enabled, axes won't move below MIN_POS in response to movement commands.

Marlin/example_configurations/makibox/Configuration.h

@@ -754,12 +754,16 @@
 
 // @section machine
 
-// Travel limits after homing (units are in mm)
+// The size of the print bed
+#define X_BED_SIZE 110
+#define Y_BED_SIZE 150
+
+// Travel limits (mm) after homing, corresponding to endstop positions.
 #define X_MIN_POS 0
 #define Y_MIN_POS 0
 #define Z_MIN_POS 0
-#define X_MAX_POS 110
-#define Y_MAX_POS 150
+#define X_MAX_POS X_BED_SIZE
+#define Y_MAX_POS Y_BED_SIZE
 #define Z_MAX_POS 86
 
 // If enabled, axes won't move below MIN_POS in response to movement commands.
@@ -967,8 +971,8 @@
 //#define Z_SAFE_HOMING
 
 #if ENABLED(Z_SAFE_HOMING)
-  #define Z_SAFE_HOMING_X_POINT ((X_MIN_POS + X_MAX_POS) / 2)    // X point for Z homing when homing all axis (G28).
-  #define Z_SAFE_HOMING_Y_POINT ((Y_MIN_POS + Y_MAX_POS) / 2)    // Y point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_X_POINT ((X_BED_SIZE) / 2)    // X point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_Y_POINT ((Y_BED_SIZE) / 2)    // Y point for Z homing when homing all axis (G28).
 #endif
 
 // Homing speeds (mm/m)

Marlin/example_configurations/tvrrug/Round2/Configuration.h

@@ -746,12 +746,16 @@
 
 // @section machine
 
-// Travel limits after homing (units are in mm)
+// The size of the print bed
+#define X_BED_SIZE 205
+#define Y_BED_SIZE 205
+
+// Travel limits (mm) after homing, corresponding to endstop positions.
 #define X_MIN_POS 0
 #define Y_MIN_POS 0
 #define Z_MIN_POS 0
-#define X_MAX_POS 205
-#define Y_MAX_POS 205
+#define X_MAX_POS X_BED_SIZE
+#define Y_MAX_POS Y_BED_SIZE
 #define Z_MAX_POS 120
 
 // If enabled, axes won't move below MIN_POS in response to movement commands.
@@ -959,8 +963,8 @@
 //#define Z_SAFE_HOMING
 
 #if ENABLED(Z_SAFE_HOMING)
-  #define Z_SAFE_HOMING_X_POINT ((X_MIN_POS + X_MAX_POS) / 2)    // X point for Z homing when homing all axis (G28).
-  #define Z_SAFE_HOMING_Y_POINT ((Y_MIN_POS + Y_MAX_POS) / 2)    // Y point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_X_POINT ((X_BED_SIZE) / 2)    // X point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_Y_POINT ((Y_BED_SIZE) / 2)    // Y point for Z homing when homing all axis (G28).
 #endif
 
 // Homing speeds (mm/m)

Marlin/example_configurations/wt150/Configuration.h

@@ -757,12 +757,16 @@
 
 // @section machine
 
-// Travel limits after homing (units are in mm)
+// The size of the print bed
+#define X_BED_SIZE 150
+#define Y_BED_SIZE 150
+
+// Travel limits (mm) after homing, corresponding to endstop positions.
 #define X_MIN_POS 0
 #define Y_MIN_POS 0
 #define Z_MIN_POS 0
-#define X_MAX_POS 150
-#define Y_MAX_POS 150
+#define X_MAX_POS X_BED_SIZE
+#define Y_MAX_POS Y_BED_SIZE
 #define Z_MAX_POS 143.0
 
 // If enabled, axes won't move below MIN_POS in response to movement commands.
@@ -970,8 +974,8 @@
 //#define Z_SAFE_HOMING
 
 #if ENABLED(Z_SAFE_HOMING)
-  #define Z_SAFE_HOMING_X_POINT ((X_MIN_POS + X_MAX_POS) / 2)    // X point for Z homing when homing all axis (G28).
-  #define Z_SAFE_HOMING_Y_POINT ((Y_MIN_POS + Y_MAX_POS) / 2)    // Y point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_X_POINT ((X_BED_SIZE) / 2)    // X point for Z homing when homing all axis (G28).
+  #define Z_SAFE_HOMING_Y_POINT ((Y_BED_SIZE) / 2)    // Y point for Z homing when homing all axis (G28).
 #endif
 
 // Homing speeds (mm/m)

Marlin/ubl_G29.cpp

@@ -467,8 +467,8 @@
                 g29_x_pos = X_HOME_POS;
                 g29_y_pos = Y_HOME_POS;
               #else // cartesian
-                g29_x_pos = X_PROBE_OFFSET_FROM_EXTRUDER > 0 ? X_MAX_POS : X_MIN_POS;
-                g29_y_pos = Y_PROBE_OFFSET_FROM_EXTRUDER < 0 ? Y_MAX_POS : Y_MIN_POS;
+                g29_x_pos = X_PROBE_OFFSET_FROM_EXTRUDER > 0 ? X_BED_SIZE : 0;
+                g29_y_pos = Y_PROBE_OFFSET_FROM_EXTRUDER < 0 ? Y_BED_SIZE : 0;
               #endif
             }
 
@@ -1132,12 +1132,12 @@
       SERIAL_PROTOCOLLNPGM("Both X & Y locations must be specified.\n");
       err_flag = true;
     }
-    if (!WITHIN(RAW_X_POSITION(g29_x_pos), X_MIN_POS, X_MAX_POS)) {
+    if (!WITHIN(RAW_X_POSITION(g29_x_pos), X_MIN_BED, X_MAX_BED)) {
       SERIAL_PROTOCOLLNPGM("Invalid X location specified.\n");
       err_flag = true;
     }
 
-    if (!WITHIN(RAW_Y_POSITION(g29_y_pos), Y_MIN_POS, Y_MAX_POS)) {
+    if (!WITHIN(RAW_Y_POSITION(g29_y_pos), Y_MIN_BED, Y_MAX_BED)) {
       SERIAL_PROTOCOLLNPGM("Invalid Y location specified.\n");
       err_flag = true;
     }