Resonance Compensation and Pressure Advance Configuration Issues

This page compiles configuration errors and tuning anomalies related to Input Shaper (resonance compensation) and Pressure Advance. For accelerometer hardware connection and communication errors, please refer to Accelerometer Testing and Calibration.

Print Quality Worsens or Becomes Blurry After Enabling Input Shaper

Symptom: After configuring [input_shaper], surface ringing (ghosting/ripples) on the printed part becomes more noticeable than when disabled, or details become blurry and corners become rounded.

Common Causes:

• shaper_freq_x / shaper_freq_y deviates significantly from the actual resonance frequency.
• shaper_type is unsuitable for the current machine model (e.g., using 2hump_ei on a high-rigidity machine causes excessive smoothing).
• Loose mechanical components (loose belts, large slop in linear guides/rails, un-tightened screws) that resonance compensation cannot fix.
• Pressure Advance was not re-calibrated after enabling Input Shaper, leading to extrusion irregularities from the interaction of both features.

Solutions:

1. First, eliminate mechanical issues: Check belt tension, guide/rail clearance, and frame screw tightness after powering off.

2. Re-perform resonance measurement to obtain accurate frequencies:

   TEST_RESONANCES AXIS=X
   TEST_RESONANCES AXIS=Y

3. Choose an appropriate shaper type based on the resonance graph:

   Shaper	Application Scenario	Frequency Tolerance	Smoothness Impact
   zv	High-rigidity, low-vibration machines	±5%	Lowest
   mzv	Most desktop machines (recommended first choice)	±10%	Moderate
   ei	Bed-slinger / higher vibration	±20%	Medium-High
   2hump_ei	Multiple resonance frequencies present	±45%	High
   3hump_ei	Complex resonance patterns	±60%	Highest

4. After enabling Input Shaper, you must re-calibrate Pressure Advance:

   SET_PRESSURE_ADVANCE ADVANCE=0
   TUNING_TOWER COMMAND=SET_PRESSURE_ADVANCE PARAMETER=ADVANCE START=0 FACTOR=.005

5. If blurriness is severe, try reducing shaper_freq by about 5–10% or switching to a shaper type with lower tolerance.

Related configuration reference: Klipper Resonance Compensation Official Documentation.

TEST_RESONANCES / SHAPER_CALIBRATE Configuration Errors

Error Messages:

• accel_chip not configured / No accelerometer configured
• probe_points must be specified or coordinates are out of the print area
• Invalid accel_chip / Could not find specified chip name

Common Causes:

• accel_chip is not configured in [resonance_tester], or its name does not match the section name in [adxl345] / [mpu9250] / [lis2dw].
• probe_points coordinates exceed the position_max range defined in [stepper_x] / [stepper_y].
• Incorrect capitalization or prefix for accel_chip in multi-accelerometer configurations.

Solutions:

1. Ensure the configuration section names are consistent:

   [adxl345]
   cs_pin: SHT36:gpio12
   spi_bus:spi0_gpio4_gpio3_gpio2
   
   [resonance_tester]
   accel_chip: adxl345
   probe_points:
       150, 150, 20

2. The X and Y coordinates of probe_points must be within the print area. The Z coordinate is the nozzle height during testing (recommended 20 mm).

3. If using an accelerometer on a toolboard, the accel_chip name must exactly match the configuration section name (case-sensitive).

4. In multi-chip scenarios, accel_chip_x and accel_chip_y can be specified for different axes.

Hardware Communication Errors: If ACCELEROMETER_QUERY returns a timeout or ID error, please refer to the common issues section in Accelerometer Testing and Calibration.

High shaper_freq Causes Motor Noise or Skipping Steps

Symptom: After enabling Input Shaper, the motor emits a high-frequency whine, the print shows regular striping, or steps are lost during high-speed moves.

Common Causes:

• The shaper_freq value is set much higher than the actual resonance frequency (e.g., setting 80 Hz when the actual frequency is 40 Hz).
• Incorrect interpretation of the resonance graph, mistaking a noise peak for the resonance frequency.
• max_accel is set too high, exceeding the motor's torque capability.

Solutions:

1. Re-run SHAPER_CALIBRATE and use the automatically recommended frequency and shaper type.

2. When interpreting the resonance graph manually, select the frequency corresponding to the highest and sharpest peak, ignoring low, broad noise.

3. Reduce max_accel to a range where the motor does not skip steps (suggest starting at 3000 and increasing gradually):

   [printer]
   max_accel: 3000

4. If the motor continues to make unusual noise, temporarily disable Input Shaper to confirm if the configuration is the cause:

   SET_INPUT_SHAPER SHAPER_FREQ_X=0 SHAPER_FREQ_Y=0

Corner Blobs or Gaps After Enabling Pressure Advance

Symptom: After enabling pressure_advance, printed corners show material buildup (blobs) or a section just before the corner is underextruded/thinner.

Common Causes:

• PA value too low: Residual nozzle pressure during deceleration is not sufficiently compensated -> corner blobs.
• PA value too high: Excessive retraction during acceleration -> underextrusion/thin lines before corners.
• Slicer has Coasting or Extra restart distance enabled, conflicting with PA compensation.
• Extruder rotation_distance is not calibrated, resulting in inaccurate base extrusion.

Solutions:

1. Disable Coasting, Extra restart distance, and dynamic acceleration control in the slicer.

2. Calibrate the extruder rotation_distance first, then calibrate PA.

3. Print a test tower using TUNING_TOWER:

   SET_VELOCITY_LIMIT SQUARE_CORNER_VELOCITY=1 ACCEL=500
   TUNING_TOWER COMMAND=SET_PRESSURE_ADVANCE PARAMETER=ADVANCE START=0 FACTOR=.005

   Use FACTOR=.005 for direct drive extruders, FACTOR=.020 for Bowden setups.

4. Select the layer height where corners are sharpest and lines are most uniform, then calculate the PA value:

   pressure_advance = START + Height × FACTOR

5. Typical value ranges: Direct drive 0.02–0.15, Bowden 0.1–1.0. If there is no improvement even with values exceeding 1.0, the issue is likely not related to PA.

Related configuration reference: Klipper Pressure Advance Official Documentation.

High PA Value Causes Extruder Skipping

Symptom: When using a high pressure_advance value (e.g., >0.2), the extruder makes clicking sounds during acceleration/deceleration phases, or the print has gaps/under-extrusion.

Common Causes:

• PA compensation generates significant additional extrusion/retraction movement during acceleration/deceleration, exceeding the extruder's torque capability.
• Acceleration is set too high, causing the instantaneous PA compensation amount to be too large.
• Insufficient extruder motor current or filament slipping.

Solutions:

1. Lower max_accel to reduce the instantaneous extrusion amount from PA compensation.
2. Appropriately reduce the PA value to balance corner quality and extrusion reliability.
3. Check extruder motor current settings (TMC driver run_current) to ensure it is sufficient.
4. Verify the filament is not slipping (check extruder gear wear, spring tension).

Note

The PA system does not change the total print time or total extrusion amount; it only redistributes extrusion movement during acceleration and deceleration phases. An extremely high PA value can lead to very large instantaneous extruder movements, and there is no configuration option to limit this movement amplitude.

Improper Setting of pressure_advance_smooth_time

Symptom: The printed surface shows periodic ripples, uneven extrusion speed, or unnatural corner transitions.

Common Causes:

• pressure_advance_smooth_time is set too large (>0.1s), causing slow PA compensation response.
• Set too small (<0.01s), causing aggressive PA compensation leading to extrusion jitter.
• An old configuration uses the deprecated standalone [pressure_advance] section.

Solutions:

1. The default value of 0.040 works for most scenarios and generally doesn't need modification.

2. The configuration should be placed within the [extruder] section:

   [extruder]
   pressure_advance: 0.05
   pressure_advance_smooth_time: 0.040

3. Do not use a separate [pressure_advance] configuration section (deprecated).

4. If using a long Bowden tube, it can be increased slightly to 0.060–0.080.

Slicer Settings Conflict with Klipper Extrusion Control

Symptom: Print quality decreases after configuring PA, showing increased stringing, abnormal corners, or extrusion blobs.

Common Causes:

• Coasting enabled in the slicer, which overlaps with PA's deceleration compensation.
• Simplify3D's Extra restart distance causes drastic extrusion speed changes.
• KISSlicer's PreloadVE duplicates the PA function.
• Slicer's "dynamic acceleration control" or "Scarf joint" interferes with testing.

Solutions:

1. Disable the following features in the slicer:
   • Coasting
   • Extra restart distance
   • PreloadVE (KISSlicer)
   • Dynamic acceleration control / Dynamic pressure control
   • Scarf joint seams (when calibrating PA)
2. Keep normal retraction settings (suggest 0.5–1.0 mm) and "wipe while retracting".
3. Disable the slicer's "Z-lift on retract", let Klipper macros handle it.

Tip

For PA calibration testing, it is recommended to use a slicer speed of 100 mm/s, layer height approximately 75% of the nozzle diameter, 0% infill, and disable dynamic acceleration control to fully expose the effects of PA.

Configuration Changes Related to Resonance Compensation After Klipper Update

Symptom: The behavior of SHAPER_CALIBRATE changes after a Klipper update, resonance test results differ from before, or deprecation warnings appear.

Common Causes:

• Klipper updated default parameters for [resonance_tester] (e.g., sweeping_period, accel_per_hz).
• The old max_accel_to_decel parameter has been replaced by minimum_cruise_ratio.
• Accelerometer sampling logic or filtering algorithms have been updated.

Solutions:

1. After the update, check the Klipper Configuration Changes to see if any items affect resonance compensation.

2. If restoring the old test behavior is desired, explicitly add to [resonance_tester]:

   [resonance_tester]
   sweeping_period: 0
   accel_per_hz: 75

3. It is recommended to re-run SHAPER_CALIBRATE after the update rather than reusing old frequency values.

4. If max_accel_to_decel reports deprecation, use instead:

   [printer]
   minimum_cruise_ratio: 0.5

Configuration Migration: For more configuration migration issues after updates, please refer to the relevant sections in Configuration Errors.