diff --git a/Marlin/planner.cpp b/Marlin/planner.cpp
index b4271bab35e36e03f36a3a3e50542b2ce6369bd5..888fe45c8fd066efe919041b0c9e92bd53ed00b5 100644
--- a/Marlin/planner.cpp
+++ b/Marlin/planner.cpp
@@ -65,6 +65,7 @@
 #include "temperature.h"
 #include "ultralcd.h"
 
+//public variables
 unsigned long minsegmenttime;
 float max_feedrate[4]; // set the max speeds
 float axis_steps_per_unit[4];
@@ -76,14 +77,16 @@ float max_xy_jerk; //speed than can be stopped at once, if i understand correctl
 float max_z_jerk;
 float mintravelfeedrate;
 unsigned long axis_steps_per_sqr_second[NUM_AXIS];
-// Manage heater variables.
+long position[4];   //rescaled from extern when axis_steps_per_unit are changed by gcode
 
+
+//private variables
 static block_t block_buffer[BLOCK_BUFFER_SIZE];            // A ring buffer for motion instfructions
 static volatile unsigned char block_buffer_head;           // Index of the next block to be pushed
 static volatile unsigned char block_buffer_tail;           // Index of the block to process now
 
 // The current position of the tool in absolute steps
-long position[4];   
+
 
 #define ONE_MINUTE_OF_MICROSECONDS 60000000.0
 
diff --git a/Marlin/temperature.cpp b/Marlin/temperature.cpp
index c25b9c31204825dca05eddfb8edc22c235b80690..1121c654eecfc921a21c449aed8100072bee9a85 100644
--- a/Marlin/temperature.cpp
+++ b/Marlin/temperature.cpp
@@ -42,25 +42,29 @@
 int target_raw[3] = {0, 0, 0};
 int current_raw[3] = {0, 0, 0};
 
-bool temp_meas_ready = false;
+static bool temp_meas_ready = false;
 
-unsigned long previous_millis_heater, previous_millis_bed_heater;
+static unsigned long previous_millis_heater, previous_millis_bed_heater;
 
 #ifdef PIDTEMP
-  float temp_iState = 0;
-  float temp_dState = 0;
-  float pTerm;
-  float iTerm;
-  float dTerm;
+  //static cannot be external:
+  static float temp_iState = 0;
+  static float temp_dState = 0;
+  static float pTerm;
+  static float iTerm;
+  static float dTerm;
       //int output;
-  float pid_error;
-  float temp_iState_min;
-  float temp_iState_max;
-  float pid_setpoint = 0.0;
-  float pid_input;
-  float pid_output;
-  bool pid_reset;
+  static float pid_error;
+  static float temp_iState_min;
+  static float temp_iState_max;
+  static float pid_input;
+  static float pid_output;
+  static bool pid_reset;
+  
+  // probably used external
   float HeaterPower;
+  float pid_setpoint = 0.0;
+
   
   float Kp=DEFAULT_Kp;
   float Ki=DEFAULT_Ki;
@@ -69,29 +73,29 @@ unsigned long previous_millis_heater, previous_millis_bed_heater;
 #endif //PIDTEMP
   
 #ifdef WATCHPERIOD
-  int watch_raw[3] = {-1000,-1000,-1000};
-  unsigned long watchmillis = 0;
+  static int watch_raw[3] = {-1000,-1000,-1000};
+  static unsigned long watchmillis = 0;
 #endif //WATCHPERIOD
 
 #ifdef HEATER_0_MINTEMP
-  int minttemp_0 = temp2analog(HEATER_0_MINTEMP);
+  static int minttemp_0 = temp2analog(HEATER_0_MINTEMP);
 #endif //MINTEMP
 #ifdef HEATER_0_MAXTEMP
-  int maxttemp_0 = temp2analog(HEATER_0_MAXTEMP);
+  static int maxttemp_0 = temp2analog(HEATER_0_MAXTEMP);
 #endif //MAXTEMP
 
 #ifdef HEATER_1_MINTEMP
-  int minttemp_1 = temp2analog(HEATER_1_MINTEMP);
+  static int minttemp_1 = temp2analog(HEATER_1_MINTEMP);
 #endif //MINTEMP
 #ifdef HEATER_1_MAXTEMP
-  int maxttemp_1 = temp2analog(HEATER_1_MAXTEMP);
+  static int maxttemp_1 = temp2analog(HEATER_1_MAXTEMP);
 #endif //MAXTEMP
 
 #ifdef BED_MINTEMP
-  int bed_minttemp = temp2analog(BED_MINTEMP);
+  static int bed_minttemp = temp2analog(BED_MINTEMP);
 #endif //BED_MINTEMP
 #ifdef BED_MAXTEMP
-  int bed_maxttemp = temp2analog(BED_MAXTEMP);
+  static int bed_maxttemp = temp2analog(BED_MAXTEMP);
 #endif //BED_MAXTEMP
 
 void manage_heater()
diff --git a/Marlin/ultralcd.pde b/Marlin/ultralcd.pde
index a45b3683e7cf91c688934e408a13212924d4c665..a0c56e926af4f1420cbbd2724a0148f50c67a580 100644
--- a/Marlin/ultralcd.pde
+++ b/Marlin/ultralcd.pde
@@ -3,14 +3,17 @@
 
 
 extern volatile int feedmultiply;
+extern volatile bool feedmultiplychanged;
+
 extern long position[4];   
 
-char messagetext[LCD_WIDTH]="";
+static char messagetext[LCD_WIDTH]="";
 
 #include <LiquidCrystal.h>
 LiquidCrystal lcd(LCD_PINS_RS, LCD_PINS_ENABLE, LCD_PINS_D4, LCD_PINS_D5,LCD_PINS_D6,LCD_PINS_D7);  //RS,Enable,D4,D5,D6,D7 
 
-unsigned long previous_millis_lcd=0;
+static unsigned long previous_millis_lcd=0;
+static long previous_millis_buttons=0;
 
 inline int intround(const float &x){return int(0.5+x);}
 
@@ -18,9 +21,9 @@ volatile char buttons=0;  //the last checked buttons in a bit array.
 int encoderpos=0;
 short lastenc=0;
 #ifdef NEWPANEL
- long blocking=0;
+ static long blocking=0;
 #else
- long blocking[8]={0,0,0,0,0,0,0,0};
+ static long blocking[8]={0,0,0,0,0,0,0,0};
 #endif
 MainMenu menu;
 
@@ -31,10 +34,9 @@ void lcd_status(const char* message)
 
 inline void clear()
 {
-  
   lcd.clear();
 }
-long previous_millis_buttons=0;
+
 
 void lcd_init()
 {
@@ -228,7 +230,6 @@ MainMenu::MainMenu()
   linechanging=false;
 }
 
-extern volatile bool feedmultiplychanged;
 
 void MainMenu::showStatus()
 {