diff --git a/cnc/config.py b/cnc/config.py
index c54a9bc..15668a5 100644
--- a/cnc/config.py
+++ b/cnc/config.py
@@ -28,7 +28,7 @@ STEPPER_INVERTED_E = True
 # means zero position.
 ENDSTOP_INVERTED_X = True
 ENDSTOP_INVERTED_Y = True
-ENDSTOP_INVERTED_Z = True
+ENDSTOP_INVERTED_Z = False  # Auto leveler
 
 # Workplace physical size.
 TABLE_SIZE_X_MM = 200
@@ -42,12 +42,12 @@ SPINDLE_MAX_RPM = 10000
 EXTRUDER_MAX_TEMPERATURE = 250
 BED_MAX_TEMPERATURE = 100
 MIN_TEMPERATURE = 40
-EXTRUDER_PID = {"P": 0.0993079964195,
-                "I": 0.00267775053311,
-                "D": 0.267775053311}
-BED_PID = {"P": 5.06820175723,
-           "I": 0.0476413193519,
-           "D": 4.76413193519}
+EXTRUDER_PID = {"P": 0.059161177519,
+                "I": 0.00206217171374,
+                "D": 0.206217171374}
+BED_PID = {"P": 0.226740848076,
+           "I": 0.00323956215053,
+           "D": 0.323956215053}
 
 # -----------------------------------------------------------------------------
 # Pins configuration.
diff --git a/cnc/gmachine.py b/cnc/gmachine.py
index 6403ced..2fc37b2 100644
--- a/cnc/gmachine.py
+++ b/cnc/gmachine.py
@@ -37,12 +37,12 @@ class GMachine(object):
         hal.init()
 
     def release(self):
-        """ Return machine to original position and free all resources.
+        """ Free all resources.
         """
-        self.safe_zero()
         self._spindle(0)
         for h in self._heaters:
             self._heaters[h].stop()
+        self._fan(False)
         hal.deinit()
 
     def reset(self):
@@ -183,7 +183,7 @@ class GMachine(object):
             pq = q
         return ea, eb
 
-    def _circular(self, delta, radius, velocity, direction):
+    def _move_circular(self, delta, radius, velocity, direction):
         delta = delta.round(1.0 / STEPPER_PULSES_PER_MM_X,
                             1.0 / STEPPER_PULSES_PER_MM_Y,
                             1.0 / STEPPER_PULSES_PER_MM_Z,
@@ -360,9 +360,9 @@ class GMachine(object):
         elif c == 'G1':  # linear interpolation
             self._move_linear(delta, velocity)
         elif c == 'G2':  # circular interpolation, clockwise
-            self._circular(delta, radius, velocity, CW)
+            self._move_circular(delta, radius, velocity, CW)
         elif c == 'G3':  # circular interpolation, counterclockwise
-            self._circular(delta, radius, velocity, CCW)
+            self._move_circular(delta, radius, velocity, CCW)
         elif c == 'G4':  # delay in s
             if not gcode.has('P'):
                 raise GMachineException("P is not specified")