Add an option for delta to home to the top

Marlin/Marlin_main.cpp

@@ -3438,7 +3438,7 @@ inline void gcode_G28() {
 
   endstops.not_homing();
 
-  #if ENABLED(DELTA)
+  #if ENABLED(DELTA) && ENABLED(DELTA_HOME_TO_SAFE_ZONE)
     // move to a height where we can use the full xy-area
     do_blocking_move_to_z(delta_clip_start_height);
   #endif

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

@@ -452,6 +452,9 @@
   // in ultralcd.cpp@lcd_delta_calibrate_menu()
   //#define DELTA_CALIBRATION_MENU
 
+  // After homing move down to a height where XY movement is unconstrained
+  #define DELTA_HOME_TO_SAFE_ZONE
+
   //#define DELTA_ENDSTOP_ADJ { 0, 0, 0 }
 
 #endif

Marlin/example_configurations/delta/generic/Configuration.h

@@ -452,6 +452,9 @@
   // in ultralcd.cpp@lcd_delta_calibrate_menu()
   //#define DELTA_CALIBRATION_MENU
 
+  // After homing move down to a height where XY movement is unconstrained
+  #define DELTA_HOME_TO_SAFE_ZONE
+
   //#define DELTA_ENDSTOP_ADJ { 0, 0, 0 }
 
 #endif

Marlin/example_configurations/delta/kossel_mini/Configuration.h

@@ -452,6 +452,9 @@
   // in ultralcd.cpp@lcd_delta_calibrate_menu()
   //#define DELTA_CALIBRATION_MENU
 
+  // After homing move down to a height where XY movement is unconstrained
+  #define DELTA_HOME_TO_SAFE_ZONE
+
   //#define DELTA_ENDSTOP_ADJ { 0, 0, 0 }
 
 #endif

Marlin/example_configurations/delta/kossel_pro/Configuration.h

@@ -22,8 +22,6 @@
 
 /**
  * Example configuration file for OpenBeam Kossel Pro
- * tested on 2015-05-19 by @Wackerbarth
- * using Arduino 1.6.5 (Mac)
  */
 
 /**
@@ -441,6 +439,9 @@
   // in ultralcd.cpp@lcd_delta_calibrate_menu()
   //#define DELTA_CALIBRATION_MENU
 
+  // After homing move down to a height where XY movement is unconstrained
+  #define DELTA_HOME_TO_SAFE_ZONE
+
   //#define DELTA_ENDSTOP_ADJ { 0, 0, 0 }
 
 #endif

Marlin/example_configurations/delta/kossel_xl/Configuration.h

@@ -450,6 +450,9 @@
   // in ultralcd.cpp@lcd_delta_calibrate_menu()
   //#define DELTA_CALIBRATION_MENU
 
+  // After homing move down to a height where XY movement is unconstrained
+  #define DELTA_HOME_TO_SAFE_ZONE
+
   //#define DELTA_ENDSTOP_ADJ { 0, 0, 0 }
 
 #endif