Extruder Calibration

Also known as “e-steps”, or extruder “rotation distance” or “steps per mm”.

:dizzy: This page is compatible with Klipper, Marlin, and RepRapFirmware.

Extruder calibration simply ensures that 100mm requested = 100mm extruded.

This simply guarantees that your extrusion multiplier will be the same across any (calibrated) printer, and will be comparable to others.

Hot or Cold?

You may choose to do the test cold (bypassing the hotend). This can ensure things like partial clogs don’t throw off your results.

  • With bowden, there’s no reason to do it hot. Disconnect the tube and do it cold.

  • With direct drive, however, this means taking the nozzle, hotend, or extruder off.

    • I find this to be a hassle, so I usually calibrate hot.

    • Just run the test a couple times to verify that you get exactly the same every time. I’ve never had an issue doing this.

Steps

  1. Klipper / RepRapFirmware:

    Klipper

    • Open your printer.cfg and find the [extruder] section.
      • Set max_extrude_only_distance to 101 or higher.
        • (+1 just helps avoid rounding error issues)
      • Set min_extrude_temp to 0 if doing the test cold.
    • Run RESTART.

    RepRapFirmware

    • If calibrating cold, run M302 P1 (allows cold extrusion)
  2. If calibrating hot, heat your hotend to printing temp.

    • If calibrating cold:

      • Bowden: Disconnect the bowden tube from your extruder.
      • Direct drive: Remove your nozzle, hotend, or extruder.

  3. Extrude a small amount to ensure that your extruder motor is on and holding.

    • You can usually do this in your printer’s web interface, if equipped.
    • G-codes:
      • M83 ; E relative
      • G1 E1 F60 ; Extrude 1mm at 1mm/s (60mm/min)

  4. Take a ruler and place a piece of tape at the 120mm mark.

    • You can use a marker too - I just find tape easier and a bit more precise.

    • Don’t worry if your ruler has extra length at the ends. We’re only taking a relative measurement.

  5. Where your filament enters your extruder, pull your filament as straight as you can against the ruler. Transfer the tape to mark 120mm.

  6. Extrude 100mm :warning: at 1mm/s. :warning:

    If doing this hot, watch to make sure the plastic isn’t shooting out to the side (partial clog) or showing signs of skipping.

    • You can usually do this in your printer’s web interface, if equipped.
    • G-codes:
      • M83 ; E relative
      • G1 E100 F60 ; Extrude 100mm at 1mm/s (60mm/min)

    • Only use the LCD to extrude if it allows you to choose a speed.

  7. Measure how much is left. Subtract it from 120 and note the value for later.

    • Example
      • I had 21mm left.
      • 120mm - 21mm = 99mm actual extrusion.

  8. Calculate your new rotation_distance / e-steps and activate it:

    Klipper

    • Find the [extruder] section in your printer.cfg. Note your current rotation_distance.
    • Calculate your new rotation_distance using this formula:
      • <new_rotation_distance> = <previous_rotation_distance> * ( <actual_extrude_distance> / 100 )
    • Temporarily set your new value with SET_EXTRUDER_ROTATION_DISTANCE.
      • Example: SET_EXTRUDER_ROTATION_DISTANCE EXTRUDER=extruder DISTANCE=34.99312407591

    Marlin

    • Run M503. In the output, find the M92 line and note your current E value.
    • Calculate your new e-steps using this formula:
      • <new_e-steps> = <current_e-steps> * ( 100 / <actual_extrude_distance> )
    • Temporarily set your new e-steps with M92.
      • Example: M92 E421.

    RepRapFirmware

    • Run M92. In the output, note the E value. (It will look similar to the screenshot for Marlin above)
    • Calculate your new e-steps using this formula:
      • <new_e-steps> = <current_e-steps> * ( 100 / <actual_extrude_distance> )
    • Temporarily set your new e-steps with M92.
      • Example: M92 E421.
  9. With your new value activated, mark and extrude again. It often takes a few iterations to dial in.

    • When using the formulas above, make sure you’re using your updated rotation_distance / e-steps value for the “current” value. Don’t keep using the original value.

    • :warning: If you get different lengths in back-to-back tests, you have an extruder issue
      (or, if printing hot, it could also be a hotend/nozzle obstruction.).

  10. Once you settle on a value, save it permanently:

    Klipper

    • Find the [extruder] section in your printer.cfg.
    • Update your rotation_distance and RESTART.

    Marlin

    • Set your new e-steps with M92.
      • Example: M92 E421.
    • Run M500 to save it to EEPROM.

    RepRapFirmware

    • Edit the M92 line in your config.g with the new value and reboot.
  11. Klipper only:
    • If you did the test cold, set your min_extrude_temp in your [extruder] section back to its previous value and RESTART.