Calibrating your extruder is one of the most critical steps in achieving high-quality 3D prints. In Klipper firmware, the traditional "steps per mm" has been replaced by a more intuitive concept: Rotation Distance. Use this calculator to fine-tune your extruder or axis movement with precision.
Update your printer.cfg with this value under the relevant section (e.g., [extruder]).
Understanding Rotation Distance in Klipper
If you are coming from Marlin, you are likely used to M92 steps per mm. Klipper approaches this differently by focusing on how far the axis moves in one full rotation of the motor. This makes it easier to calculate values based on hardware specs like gear teeth and belt pitch.
The Basic Formula
The logic behind the calculator above is straightforward:
New Value = Old Value * (Actual Distance / Requested Distance)
This formula ensures that if your printer is under-extruding (extruding less than requested), the rotation distance decreases, effectively telling the motor to turn more to cover the same distance.
How to Calibrate Your Extruder
To get the most out of the Klipper rotation distance calculator, follow these steps:
- Preheat: Ensure your nozzle is at the operating temperature for the filament you are using.
- Mark the Filament: Use a caliper or ruler to mark your filament at 120mm from the intake of your extruder.
- Extrude: Use your printer's interface (Mainsail, Fluidd, or Octoprint) to extrude 100mm of filament at a slow speed (e.g., 1mm/s to 5mm/s).
- Measure: Measure the distance from the extruder intake to your mark. If the mark is 22mm away, your actual extruded distance was 98mm (120 - 22 = 98).
- Calculate: Enter your current
rotation_distance, the 100mm requested, and the 98mm measured into the calculator above.
Why Precision Matters
Even a 2% error in rotation distance can lead to significant print issues. Under-extrusion causes weak parts and gaps between lines, while over-extrusion leads to blobby surfaces, poor tolerances, and stringing. By using a PhD-level approach to your calibration, you ensure that every layer is exactly the thickness the slicer expects.
Common Starting Values
If you are building a new printer and don't know where to start, here are some common rotation distance values for popular extruders:
- Creality Stock/MK8: ~34.406
- BMG Extruder (3:1 Gear Ratio): ~7.711
- Titan Extruder (3:1 Gear Ratio): ~7.630
- Voron Stealthburner (Clockwork 2): ~22.678
Remember that these are just starting points. Due to variations in manufacturing, gear wear, and filament grip, you should always perform a manual calibration to find your specific machine's optimal value.