Convert fan speed to servo movement (post processing script)

[troyproffitt 0]

I am attempting to use a CPAP fan as a parts cooler for my 3d printer.  Since it needs a controller to function (ESC), on my Duet WIFI 2, I cannot just plug it into the fan0 port on the controller board.  Good news is that I was able to re-purpose one of the heater pins to behave like a servo and then I can use an M42 command to turn on / off the CPAP fan and increase / decrease the fan speed.  For example

CPAP fan at 0%

M42  P8 S0.4

CPAP fan at 100%

M42  P8 S0.7

 

What I am hoping to accomplish is to re-use the post processing script InsertAtLayerChange to convert the fan_speed value from the M106 (or possibly reference the CURA keyword cool_fan_speed) to an M42 command.  Here is my math to get the appropriate range:

 

M42 P8 S({cool_fan_speed}/250)+.4)

 

I'd like this to be evaluated at every layer.  I am not familiar with the Python syntax, but I was hoping someone could help me figure out how to modify the current Insert at Layer Change script to add in this additional functionality.

 

Here is the original script:

# Copyright (c) 2020 Ultimaker B.V.
# Cura is released under the terms of the LGPLv3 or higher.
# Created by Wayne Porter

from ..Script import Script

class InsertAtLayerChange(Script):
    def __init__(self):
        super().__init__()

    def getSettingDataString(self):
        return """{
            "name": "Insert at layer change",
            "key": "InsertAtLayerChange",
            "metadata": {},
            "version": 2,
            "settings":
            {
                "insert_location":
                {
                    "label": "When to insert",
                    "description": "Whether to insert code before or after layer change.",
                    "type": "enum",
                    "options": {"before": "Before", "after": "After"},
                    "default_value": "before"
                },
                "gcode_to_add":
                {
                    "label": "G-code to insert.",
                    "description": "G-code to add before or after layer change.",
                    "type": "str",
                    "default_value": ""
                }
            }
        }"""

    def execute(self, data):
        gcode_to_add = self.getSettingValueByKey("gcode_to_add") + "\n"
        for layer in data:
            # Check that a layer is being printed
            lines = layer.split("\n")
            for line in lines:
                if ";LAYER:" in line:
                    index = data.index(layer)
                    check_fan_speed = data.index(cool_fan_speed)
                    if self.getSettingValueByKey("insert_location") == "before":
                        layer = gcode_to_add + layer
                    else:
                        layer = layer + gcode_to_add 

                    data[index] = layer
                    break
        return data

 

Thanks for your help,

-Troy

[troyproffitt 0]

So if I was able to use the S value off the M106, the formula would be something like this:

(<fan_value>/850)+.4

So if M106 S255 , I'd like to add a row that said

M42 P8 S((255/850)+.4) 

 

Edited January 20, 2021 by troyproffitt

[troyproffitt 0]

I ended up figuring out how to create the script on my own.  I also added some additional functionality by providing parameters for min / max servo range values and also letting the user provide the pin value on the M42 command.

Hope this helps others that are trying to use a berdair or other servo type air source:

 

# Copyright (c) 2020 Ultimaker B.V.
# Cura is released under the terms of the LGPLv3 or higher.
# Created by Wayne Porter

from ..Script import Script

class convertFantoServo(Script):
    def __init__(self):
        super().__init__()

    def getSettingDataString(self):
        return """{
            "name": "Convert Fan to Servo",
            "key": "convertFantoServo",
            "metadata": {},
            "version": 2,
            "settings":
            {
               "minServo":
                {
                    "label": "Servo Min Travel Value.",
                    "description": "Servo Min Travel Value.",
                    "type": "str",
                    "default_value": ".4"
                },
                "maxServo":
                {
                    "label": "Servo Max Travel Value.",
                    "description": "Servo Max Travel Value.",
                    "type": "str",
                    "default_value": ".7"
                },
                "servoPin":
                {
                    "label": "Servo pin assigned in M42.",
                    "description": "What pin on the controller board your servo is connected to.",
                    "type": "str",
                    "default_value": "8"
                }
            }
        }"""

    def execute(self, data):
        minServo = float(self.getSettingValueByKey("minServo"))
        maxServo = float(self.getSettingValueByKey("maxServo"))
        servoPin = self.getSettingValueByKey("servoPin")
        servoRange = maxServo - minServo
        conversionVal = 255 / round(servoRange, 3)
        for layer in data:
            # Check that a layer is being printed
            lines = layer.split("\n")
            for line in lines:
                if "M106" in line:
                    index = data.index(layer)
                    getFanval = line.replace("M106 S", "")
                    check_fan_speed = (float(getFanval) / conversionVal) + minServo
                    layer = "M42 P" + servoPin + " S" + str(round(check_fan_speed, 3)) + "\n" + layer
                    data[index] = layer
                    break
        return data

 

Edited January 23, 2021 by troyproffitt