Create MaxVolumetricSpeed.py

The script search for retractions and primes and changes the Max E Speed before and after.  The speeds of the retracts and primes are not affected.  The rest of the gcode will have a limit on the speed of the Extruder.

plugins/PostProcessingPlugin/scripts/MaxVolumetricSpeed.py

@@ -0,0 +1,98 @@
+# Written by GregValiant (Greg Foresi) November, 2024.
+#    Searches for retraction and prime lines and changes the printer max E speed to the user input of the Max Flow Rate
+# The result is that retractions will look something like this
+#    M203 E40.0
+#    G1 F2400 E659.39904
+#    M203 E6.24
+# This script is compatible with both Absolute and Relative Extrusion and/or Firmware Retraction and both 1.75 and 2.85 diameter filament.
+# Settings retreived from Cura are always for Extruder 1 (T0).
+
+import re
+from ..Script import Script
+from UM.Application import Application
+import math
+from UM.Message import Message
+
+class MaxVolumetricSpeed(Script):
+    """Performs a search-and-replace on the g-code.
+    """
+
+    def getSettingDataString(self):
+        return """{
+            "name": "Max E Speed by Flow Rate",
+            "key": "MaxVolumetricSpeed",
+            "metadata": {},
+            "version": 2,
+            "settings":
+            {
+                "enable_script":
+                {
+                    "label": "Enable post processor",
+                    "description": "Check the box to enable the script so it will run.",
+                    "type": "bool",
+                    "default_value": true
+                },
+                "max_E_flow_rate":
+                {
+                    "label": "Max E Flow Rate",
+                    "description": "The maximum flow rate that your printer works well at.  At every retraction or prime in the file the 'Max E Speed' will be adjusted upward for the retraction or prime and then back down for the printing extrusions.  The formula used is 'Max Flow Rate' divided by 'Filament Cross Section Area'.",
+                    "type": "float",
+                    "default_value": 12,
+                    "unit": "mm3 / sec",
+                    "enabled": "enable_script"
+                },
+                "use_units":
+                {
+                    "label": "The units to use in M203",
+                    "description": "Most firmwares (Ex: Marlin) use mm/second for the M203 Max Speeds.  RepRap might use mm/minute.",
+                    "type": "enum",
+                    "options": {
+                        "per_second": "mm / second",
+                        "per_minute": "mm / minute" },
+                    "default_value": "per_second",
+                    "enabled": "enable_script"
+                }
+            }
+        }"""
+
+    def execute(self, data):
+        # Exit if the script is not enabled
+        enable_script = self.getSettingValueByKey("enable_script")
+        if not enable_script:
+            Message(title = "[Set Max Volumetric E Speed]", text = "Is not enabled and will not run").show()
+            return data
+        # Get settings from Cura
+        curaApp = Application.getInstance().getGlobalContainerStack()
+        extruder = curaApp.extruderList
+        retract_enabled = bool(extruder[0].getProperty("retraction_enable", "value"))
+        cura_retract_speed = float(extruder[0].getProperty("retraction_retract_speed", "value"))
+        cura_prime_speed = float(extruder[0].getProperty("retraction_prime_speed", "value"))
+        # The reset_speed is used just for retractions and primes
+        if cura_retract_speed > cura_prime_speed:
+            speed_e_reset = cura_retract_speed
+        else:
+            speed_e_reset = cura_prime_speed
+        firmware_retraction = bool(curaApp.getProperty("machine_firmware_retract", "value"))
+        filament_dia = float(extruder[0].getProperty("material_diameter", "value"))
+        max_e_flow_rate = self.getSettingValueByKey("max_E_flow_rate")
+        # Adjust the search parameter depending on Firmware Retraction
+        if not firmware_retraction:
+            search_string = "G1 F(\d*\d.?) E(-?\d.*)"
+        else:
+            search_string = "G1[0-1]"
+        # Calculate the E Speed Maximum for the print
+        cross_sect = ((filament_dia/2)**2)*math.pi
+        speed_e_max = round(max_e_flow_rate / cross_sect, 2)
+        # RepRap firmware may require that the M203 units are mm/minute
+        if self.getSettingValueByKey("use_units") == "per_minute":
+            speed_e_max = round(speed_e_max * 60)
+            speed_e_reset = round(speed_e_reset * 60)
+        # Make the replacements
+        search_regex = re.compile(search_string)
+        for num in range(2, len(data) - 1):
+            lines = data[num].split("\n")
+            for index, line in enumerate(lines):
+                if re.search(search_regex, line) is not None:
+                    lines[index] = f"M203 E{speed_e_reset}\n" + line + f"\nM203 E{speed_e_max}"
+            data[num] = "\n".join(lines)
+        return data