====== Tuning Extruder Rotational Distance ======
{{tag> setup tuning}}

An accurate extruder rotational distance tuned for your specific extruder head is critical, if off so will all of [[Klipper]]s extrusion calculations. This should be done before other tuning and calibrations relating to extruding filament. 

The recommended method is known as "measure and trim". We have a current starting point from which to run our tests, the current value defined in the [extruder] stanza of printer.cfg, to use as an initial guess for the rotation distance so we don't need to obtain it from steps_per_mm or by inspecting the hardware. It's the same value you'll be changing after calibration. 

[[Klipper]] describes the the process in [[https://www.klipper3d.org/Rotation_Distance.html#calibrating-rotation_distance-on-extruders|this chapter of the documentation devoted to rotational distances]].

 <code>
Example rotational distance in printer.cfg, use as the starting 
point, then edit with calibrated value:

[extruder]
rotation_distance: 31.4
</code>
Example rotational distance in printer.cfg, use as the starting point, then edit with calibrated value:

[[Klipper]] describes the the process in [[https://www.klipper3d.org/Rotation_Distance.html#calibrating-rotation_distance-on-extruders|this chapter of the documentation devoted to rotational distances]].

Ellis's Tuning Guide provides a detailed explanation and covers the canonical process for tuning the value. See https://ellis3dp.com/Print-Tuning-Guide/articles/extruder_calibration.html

The best video resource for demonstrating this process is 00:02:22 into this [[https://youtu.be/mCcP8dffwLk?t=142|YouTube video]] by Wild Rose Builds.