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Extruder Calibration

On an extruder, the rotation_distance is the amount of distance the filament travels for one full rotation of the stepper motor. The best way to get an accurate value for this setting is to use a "measure and trim" procedure.

Procedure

  • Remove PTFE tube from the Extruder for the measure.

  • Heat the Hotend to an appropriate temperature and insert filament in it.

  • Use a marker to place a mark on the filament 120 mm from the inlet of the extruder.

  • Then use a digital caliper to measure the actual distance from that mark as accurately as possible.

    Note this value of 120 mm as the <initial_mark_distance>.

  • Open Console on your Web interface:

    • On Mainsail Web Interface go to CONSOLE tab on the left side.
    • On Fluidd Web Interface go to Console icon on the left side.

  • Extrude 100mm of filament with the following command sequence:

    Console
    G91
    Console
    G1 E100 F100

    Note this value of 100 mm as the <requested_extrude_distance>.

  • Wait for extruder to complete the movement (this will take several seconds). It's important to use a slow extrusion speed for this test, as a faster speed can cause high pressure in the extruder which will skew the results. So don't use the EXTRUDE button from Mainsail/Fluidd or from the screen for this test as they extrude at a fast rate.

  • Then use a digital caliper to measure the new distance from the inlet of the extruder to the mark on the filament.

    Note this value as <measured_distance>.

  • Then calculate:

    <initial_mark_distance> <measured_distance> <extrusion_distance>

  • Then retrieve the current rotation_distance value from the printer.cfg file at the rotation_distance: line of the [extruder] section:

    printer.cfg
    [extruder]
step_pin: PE0
dir_pin: !PB9
enable_pin: !PE4
microsteps: 16
rotation_distance: 4.5

    Note this value as <current_rotation_distance>.

  • Calculate the rotation_distance as follows:

    <current_rotation_distance> <extrusion_distance> <requested_extrude_distance> <rotation_distance>

  • Then replace the new value in the printer.cfg file by rounding the new rotation_distance to three decimal places.

  • You can now retract filament and replace your PTFE tube in its place, your extruder is calibrated.

Example

  • After extruding 100mm, I measure a distance of 18 mm between the inlet of my extruder and the mark on the filament.

  • So I have :

    • My <initial_mark_distance> value of 120 mm.
    • My <requested_extrude_distance> value of 100 mm.
    • My <measured_distance> value of 18 mm.

  • So I calculate my current <extrusion_distance> for 100 mm requested:

    <initial_mark_distance> <measured_distance> <extrusion_distance>

    120 mm 18 mm 102 mm

  • I get the <current_rotation_distance> value from the printer.cfg file which is 4.5.

  • So I then calculate my new <rotation_distance> value:

    <current_rotation_distance> <extrusion_distance> <requested_extrude_distance> <rotation_distance>

    4.5 102 mm 100 mm 4.59

  • I replace the rotation_distance: 4.5 line in the printer.cfg file with:
    rotation_distance: 4.59

    printer.cfg
    [extruder]
step_pin: PE0
dir_pin: !PB9
enable_pin: !PE4
microsteps: 16
rotation_distance: 4.59

  • Once done, click on SAVE & RESTART button at the top right to save the file.


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