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Calibrate Extruder — K2 Plus

Extruder calibration (also called e-step calibration) ensures the printer extrudes exactly the amount of filament requested. This improves dimensional accuracy and reduces under/over-extrusion.

When to Calibrate

Calibrate your extruder when:

  • Installing a new extruder or drive gear
  • Changing filament diameter significantly
  • Noticing consistent under or over-extrusion that is not resolved by slicer flow rate adjustments
  • After any extruder hardware modification

The K2 Plus uses a direct drive extruder. The stock rotation_distance in printer.cfg is 6.9 — this is a good starting point but may need fine-tuning for your specific hardware.

Method 1 — Mark and Measure (Cold)

This is the most accurate method.

  1. Remove the bowden tube from the extruder or work with filament loaded.

  2. Mark the filament 120mm from the extruder entry point with a marker.

  3. From the Fluidd console, command the extruder to move 100mm:

    M83          ; relative extrusion
G1 E100 F100 ; extrude 100mm slowly

  4. Measure the distance from the extruder entry to your mark. If the printer extruded exactly 100mm, the distance should now be 20mm.

  5. Calculate the actual distance extruded: 

    actual_extruded = 120 - remaining_distance

  6. Calculate the new rotation_distance: 

    new_rotation_distance = current_rotation_distance × (100 / actual_extruded)

  7. Update rotation_distance in the [extruder] section of /mnt/UDISK/printer_data/config/printer.cfg and run FIRMWARE_RESTART.

After setting a baseline rotation_distance, fine-tune flow with a calibration cube:

  1. Print a single-wall calibration cube (20×20×20mm, 1 perimeter, 0% infill).
  2. Measure wall thickness with calipers.
  3. Expected thickness = nozzle diameter (0.4mm).
  4. Adjust flow in OrcaSlicer or via M221 S[value] until walls measure correctly.
  5. Once happy, bake the flow rate into your filament profile rather than changing rotation_distance further.

K2 Plus Extruder Notes

The K2 Plus uses a high-torque dual-drive extruder. Key values in stock printer.cfg:

[extruder]
rotation_distance: 6.9
microsteps: 16
max_extrude_only_distance: 1000.0
pressure_advance: 0.038
pressure_advance_smooth_time: 0.038

After calibrating rotation_distance, also consider tuning Pressure Advance for better corner quality. Run:

SET_PRESSURE_ADVANCE ADVANCE=0.04

and adjust while printing until corners are sharp without bulging. Save the final value in printer.cfg.