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Adds a toggle to enable or disable flow compensation based on the filament width sensor readings without disabling the sensor entirely. Useful on printers where the hall effect sensor is too inaccurate to helpfully adjust the extrusion multiplier, but is good enough to act as a filament runout sensor. The new setting defaults to true to preserve the existing sensor behavior. Existing width sensor G-Code commands are updated to optionally enable and disable flow compensation and to show the state of the sensor and command outputs are normalized. Also includes updates to the relevant doc pages. Signed-off-by: Ben Lye ben@lye.co.nz
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Hall filament width sensor
This document describes Filament Width Sensor host module. Hardware used for developing this host module is based on two Hall linear sensors (ss49e for example). Sensors in the body are located on opposite sides. Principle of operation: two hall sensors work in differential mode, temperature drift same for sensor. Special temperature compensation not needed.
You can find designs at Thingiverse, an assembly video is also available on Youtube
To use Hall filament width sensor, read Config Reference and G-Code documentation.
How does it work?
Sensor generates two analog output based on calculated filament width. Sum of output voltage always equals to detected filament width. Host module monitors voltage changes and adjusts extrusion multiplier. I use the aux2 connector on a ramps-like board with the analog11 and analog12 pins. You can use different pins and different boards.
Template for menu variables
[menu __main __filament __width_current]
type: command
enable: {'hall_filament_width_sensor' in printer}
name: Dia: {'%.2F' % printer.hall_filament_width_sensor.Diameter}
index: 0
[menu __main __filament __raw_width_current]
type: command
enable: {'hall_filament_width_sensor' in printer}
name: Raw: {'%4.0F' % printer.hall_filament_width_sensor.Raw}
index: 1
Calibration procedure
To get raw sensor value you can use menu item or QUERY_RAW_FILAMENT_WIDTH command in terminal.
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Insert first calibration rod (1.5 mm size) get first raw sensor value
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Insert second calibration rod (2.0 mm size) get second raw sensor value
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Save raw sensor values in config parameter
Raw_dia1andRaw_dia2
How to enable sensor
By default, the sensor is disabled at power-on.
To enable the sensor, issue ENABLE_FILAMENT_WIDTH_SENSOR command or
set the enable parameter to true.
Use as a runout switch only
By default, the sensor measures filament diameter and adjusts the extrusion multiplier to compensate for variations.
If you want to use the sensor as a runout switch only, set the enable_flow_compensation
config parameter to false. In this mode, the sensor will only trigger runout
events when filament is not detected, it will not modify the extrusion multiplier.
This is useful for printers where the filament sensor is not accurate enough for flow compensation but can reliably detect filament runout, or when printing with flexible filaments which have unstable diameter characteristics.
Issue ENABLE_FILAMENT_WIDTH_SENSOR FLOW_COMPENSATION=1 to enable flow compensation or ENABLE_FILAMENT_WIDTH_SENSOR FLOW_COMPENSATION=0 to disable it.
Note that disabling filament width compensation automatically resets the extrusion multiplier to 100%.
QUERY_FILAMENT_WIDTH includes the current state of flow compensation in its output.
Logging
By default, diameter logging is disabled at power-on.
Issue ENABLE_FILAMENT_WIDTH_LOG command to start logging and issue
DISABLE_FILAMENT_WIDTH_LOG command to stop logging. To enable logging
at power-on, set the logging parameter to true.
Filament diameter is logged on every measurement interval (10 mm by default).