start_end: Speed up START_PRINT

* Skip parking, etc. when heaters are already at target.
* Added parameter to skip Z rehoming when bed hits temp.

globals.cfg

@@ -61,6 +61,8 @@ variable_start_bed_heat_delay: 2000
 variable_start_bed_heat_overshoot: 2.0
 # Set to level bed in PRINT_START after stabilizing at temp; set 0 to disable.
 variable_start_level_bed_at_temp: True
+# Set to rehome the Z in PRINT_START after the bed temperature stabilizes.
+variable_start_home_z_at_temp: True
 # Set to clear adjustments (e.g. feedrate, extrusion, heater) at end of print.
 variable_start_clear_adjustments_at_end: True
 # Length of filament (in millimeters) to purge at print start.

start_end.cfg

@@ -20,7 +20,9 @@ gcode:
   {% set NOZZLE_SIZE = params.NOZZLE_SIZE|default(settings.NOZZLE_SIZE)|
          default(printer.configfile.settings.extruder.nozzle_diameter)|float %}
   {% set km = printer["gcode_macro _km_globals"] %}
-  {% set bed_overshoot = (BED + (km.start_bed_heat_overshoot if BED else 0.0),
+  {% set bed_at_target = (BED - printer.heater_bed.temperature)|abs < 0.3 %}
+  {% set bed_overshoot = (BED + (km.start_bed_heat_overshoot if
+             (BED and not bed_at_target) else 0.0),
            printer.configfile.settings.heater_bed.max_temp ) | min %}
 
   INIT_LAYER_GCODE LAYERS="{LAYERS}"
@@ -39,25 +41,30 @@ gcode:
   # home all axes
   G28
   G90
-  PARK
-  {% if BED > 0.0 %}
+  # Skip this if the bed was already at target when START_PRINT was called.
+  {% if BED > 0.0 and not bed_at_target %}
+    PARK
     # Overshoot the target a bit.
     M190 S{bed_overshoot}
     G4 P{km.start_bed_heat_delay / 2}
     M190 R{BED} # Settle down after the overshoot.
     G4 P{km.start_bed_heat_delay / 2}
   {% endif %}
   {% if CHAMBER > 0.0 %}
+    _KM_PARK_IF_NEEDED HEATER="chamber" RANGE=ABOVE
     M191 S{CHAMBER}
   {% endif %}
   {% if km.start_level_bed_at_temp %}
     M104 S{EXTRUDER} # set the final extruder target temperature
-    G28 Z # Re-home only the Z axis now that the bed has stabilized.
+    {% if km.start_home_z_at_temp and not bed_at_target %}
+      G28 Z # Re-home only the Z axis now that the bed has stabilized.
+    {% endif %}
     BED_MESH_CALIBRATE_FAST{% if MESH_MIN %} MESH_MIN={MESH_MIN}{% endif
                          %}{% if MESH_MAX %} MESH_MAX={MESH_MAX}{% endif %}
-    PARK
+    G4
   {% endif %}
   # Wait for extruder to reach temperature
+  _KM_PARK_IF_NEEDED HEATER={printer.toolhead.extruder} RANGE=ABOVE
   M109 S{EXTRUDER}
   # apply Z offset for bed surface (just in case it was reset).
   _APPLY_BED_SURFACE_OFFSET
@@ -67,6 +74,30 @@ gcode:
                     %}{% if MESH_MAX %} PRINT_MAX={MESH_MAX}{% endif %}
   {% endif %}
 
+[gcode_macro _km_park_if_needed]
+description: Parks the extruder if the current temperature of the supplied
+  heater is not within the specified target range.
+  Usage: _KM_PARK_IF_NEEDED HEATER=<heater> RANGE=[<percentage>|ABOVE|BELOW]
+gcode:
+  # This needs to get called as its own macro to get the current temp evaluated.
+  {% set HEATER = params.HEATER %}
+  {% set RANGE = (params.RANGE|default(1))|string|upper %}
+
+  {% if printer[HEATER].target %}
+    {% if RANGE == "ABOVE" %}
+      {% if printer[HEATER].temperature < printer[HEATER].target %}
+        PARK
+      {% endif %}
+    {% elif RANGE == "BELOW" %}
+      {% if printer[HEATER].temperature > printer[HEATER].target %}
+        PARK
+      {% endif %}
+    {% elif (printer[HEATER].temperature - printer[HEATER].target)|abs >
+             (printer[HEATER].target * RANGE|float * 0.01)|abs %}
+      PARK
+    {% endif %}
+  {% endif %}
+
 [gcode_macro print_start_set]
 description: Inserted by slicer to set values used by PRINT_START.
   Usage: PRINT_START_SET <VARIABLE>=<value>