firmware_retract: Remove z_hop support

The current z_hop support did not work correctly with common slicers
that change Z height between retract and unretract, and it did not
work correctly with slicers that issue a retract at the end of a print
and then at the beginning of the next print.

The z_hop support is therefore being removed until these issues can be
fixed.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

config/example-extras.cfg

@@ -1664,9 +1664,6 @@
 #   The length (in mm) of *additional* filament to add when unretracting.
 #unretract_speed: 10
 #   The speed of unretraction, in mm/s. The default is 10 mm/s.
-#z_hop: 0
-#   The amount of lift applied to the Z axis (in mm) on retract and
-#   restored on unretract. The default is 0 mm.
 
 
 # Include file support. One may include additional config file from

docs/Config_Changes.md

@@ -6,6 +6,10 @@ All dates in this document are approximate.
 
 # Changes
 
+20190710: The z_hop option was removed from the [firmware_retract]
+config section. The z_hop support was incomplete and could cause
+incorrect behavior with several common slicers.
+
 20190710: The optional parameters of the PROBE_ACCURACY command have
 changed. It may be necessary to update any macros or scripts that use
 that command.

docs/G-Codes.md

@@ -457,18 +457,15 @@ stringing during non-extrusion moves from one part of the print to
 another.  Appropriately configuring pressure advance reduces the length
 of retraction required.
  - `SET_RETRACTION [RETRACT_LENGTH=<mm>] [RETRACT_SPEED=<mm/s>]
-   [UNRETRACT_EXTRA_LENGTH=<mm>] [UNRETRACT_SPEED=<mm/s>] [Z_HOP=<mm>]`:
-   Adjust the parameters used by firmware retraction.  RETRACT_LENGTH
-   determines the length of filament to retract and unretract.  The
-   speed of retraction is adjusted via RETRACT_SPEED, and is typically
-   set relatively high.  The speed of unretraction is adjusted via
+   [UNRETRACT_EXTRA_LENGTH=<mm>] [UNRETRACT_SPEED=<mm/s>]`: Adjust the
+   parameters used by firmware retraction. RETRACT_LENGTH determines
+   the length of filament to retract and unretract. The speed of
+   retraction is adjusted via RETRACT_SPEED, and is typically set
+   relatively high. The speed of unretraction is adjusted via
    UNRETRACT_SPEED, and is not particularly critical, although often
    lower than RETRACT_SPEED. In some cases it is useful to add a small
    amount of additional length on unretraction, and this is set via
-   UNRETRACT_EXTRA_LENGTH.  It is possible to lift the Z axis by a small
-   amount when in retracted state by setting Z_HOP, although this is
-   more commonly used for printers where fast Z movements are supported,
-   such as delta printers. SET_RETRACTION is commonly set as part of
+   UNRETRACT_EXTRA_LENGTH. SET_RETRACTION is commonly set as part of
    slicer per-filament configuration, as different filaments require
    different parameter settings.
  - `GET_RETRACTION`: Queries the current parameters used by firmware

klippy/extras/firmware_retraction.py

@@ -12,7 +12,6 @@ class FirmwareRetraction:
         self.unretract_extra_length = config.getfloat(
             'unretract_extra_length', 0., minval=0.)
         self.unretract_speed = config.getfloat('unretract_speed', 10., minval=1)
-        self.z_hop = config.getfloat('z_hop', 0., minval=0.)
         self.unretract_length = (self.retract_length
                                  + self.unretract_extra_length)
         self.is_retracted = False
@@ -28,7 +27,6 @@ class FirmwareRetraction:
             "retract_speed": self.retract_speed,
             "unretract_extra_length": self.unretract_extra_length,
             "unretract_speed": self.unretract_speed,
-            "z_hop": self.z_hop
         }
 
     def cmd_SET_RETRACTION(self, params):
@@ -44,9 +42,6 @@ class FirmwareRetraction:
         self.unretract_speed = self.gcode.get_float(
             'UNRETRACT_SPEED',
             params, self.unretract_speed, minval=1)
-        self.z_hop = self.gcode.get_float(
-            'Z_HOP',
-            params, self.z_hop, minval=0.)
         self.unretract_length = (self.retract_length
                                  + self.unretract_extra_length)
         self.is_retracted = False
@@ -54,36 +49,29 @@ class FirmwareRetraction:
     def cmd_GET_RETRACTION(self, params):
         msg = ("RETRACT_LENGTH=%.5f RETRACT_SPEED=%.5f "
                "UNRETRACT_EXTRA_LENGTH=%.5f UNRETRACT_SPEED=%.5f"
-               "Z_HOP=%.5f"
                % (self.retract_length, self.retract_speed,
-                  self.unretract_extra_length, self.unretract_speed,
-                  self.z_hop))
+                  self.unretract_extra_length, self.unretract_speed))
         self.gcode.respond_info(msg)
 
     def cmd_G10(self, params):
         if not self.is_retracted:
             self.gcode.run_script_from_command(
                 "SAVE_GCODE_STATE NAME=_retract_state\n"
-                "G92 E0\n"
                 "G91\n"
                 "G1 E-%.5f F%d\n"
-                "G1 Z%.5f\n"
                 "RESTORE_GCODE_STATE NAME=_retract_state"
-                % (self.retract_length, self.retract_speed*60, self.z_hop))
+                % (self.retract_length, self.retract_speed*60))
             self.is_retracted = True
 
     def cmd_G11(self, params):
         if self.is_retracted:
             self.gcode.run_script_from_command(
                 "SAVE_GCODE_STATE NAME=_retract_state\n"
-                "G92 E0\n"
                 "G91\n"
                 "G1 E%.5f F%d\n"
-                "G1 Z-%.5f\n"
                 "RESTORE_GCODE_STATE NAME=_retract_state"
-                % (self.unretract_length, self.unretract_speed*60, self.z_hop))
+                % (self.unretract_length, self.unretract_speed*60))
             self.is_retracted = False
 
-
 def load_config(config):
     return FirmwareRetraction(config)