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 Artifacts Worsen or Blur After Enabling Input Shaper

Symptoms: After configuring [input_shaper], surface ringing (ghosting/ripples) on printed parts becomes more obvious than when disabled, or details become blurred, 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 type (e.g., using 2hump_ei on a high-rigidity machine causing excessive smoothing).
• Mechanical structure has looseness (loose belts, large slider gaps, un-tightened screws), which resonance compensation cannot fix.
• Pressure Advance was not re-calibrated after enabling Input Shaper, resulting in extrusion anomalies from their combination.

Solutions:

1. First rule out mechanical issues: Check belt tension, slider/rail gaps, and frame screw tightness with power off.

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

   TEST_RESONANCES AXIS=X
   TEST_RESONANCES AXIS=Y

3. Choose the 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%	Medium
   ei	Bed-slinger / high vibration machines	±20%	Medium-High
   2hump_ei	Multiple resonance frequencies present	±45%	High
   3hump_ei	Complex resonance patterns	±60%	Highest

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

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

5. If blurring is severe, try decreasing 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 out of print bounds
• Invalid accel_chip / cannot find specified chip name

Common Causes:

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

Solutions:

1. Ensure the configuration section names match:

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

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

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

4. In multi-chip scenarios, you can specify accel_chip_x and accel_chip_y for different axes.

Hardware Communication Errors: For errors like ACCELEROMETER_QUERY returning timeout or ID errors, please refer to the common problem handling in Accelerometer Testing and Calibration.

Failed to configure shaper(s)

Error Messages: configparser.Error: Failed to configure shaper(s) shaper_x with given parameters, Failed to configure shaper(s) shaper_z with given parameters.

Common Causes:

• shaper_freq_x or shaper_freq_y is outside the usable frequency range of the selected shaper_type. For example, mzv may have no valid solution at higher frequencies.
• damping_ratio is set incorrectly (too small or too large), preventing the shaper from generating valid parameters.
• Manually entered parameter combinations that were not validated by SHAPER_CALIBRATE.

Solutions:

1. Re-run SHAPER_CALIBRATE and use the automatically recommended shaper_type and shaper_freq.
2. If adjusting manually, try lowering shaper_freq or switching to a more tolerant shaper type (e.g., ei or 2hump_ei).
3. Ensure damping_ratio is within a reasonable range (default 0.1, common range 0.05–0.2).
4. If you only want to disable the shaper for a specific axis, set shaper_freq_x: 0 instead of entering an invalid value.

shaper_freq Too High Causing Motor Noise or Skipping

Symptoms: After enabling Input Shaper, the motor emits high-frequency whining, printed parts show regular striping, or steps are lost during high-speed moves.

Common Causes:

• shaper_freq value is set significantly higher than the actual resonance frequency (e.g., filling in 80 Hz when actual is 40 Hz).
• Misinterpretation 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 manually reading the resonance graph, choose 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 lose steps (recommended to start from 3000 and gradually increase):

   [printer]
   max_accel: 3000

4. If the motor continues to make unusual noises, temporarily disable Input Shaper to confirm if it's a configuration issue:

   SET_INPUT_SHAPER SHAPER_FREQ_X=0 SHAPER_FREQ_Y=0

Corner Blobs or Gaps After Enabling Pressure Advance

Symptoms: After enabling pressure_advance, printed corners show material buildup (blobs) or a section before the corner is under-extruded/thinner.

Common Causes:

• PA value too low: Residual nozzle pressure during deceleration is not fully compensated → corner blobs.
• PA value too high: Excessive retraction during acceleration → under-extrusion before corners, thin lines.
• Slicer has Coasting or Extra restart distance enabled, conflicting with PA compensation.
• Extruder rotation_distance is not calibrated, leading to 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 remote Bowden.

4. Choose the layer with the clearest corners and most even lines corresponding to the height, and 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 beyond 1.0, the issue is not related to PA.

Related configuration reference: Klipper Pressure Advance Official Documentation.

PA Value Too High Causing Extruder Skipping

Symptoms: After using a relatively high pressure_advance value (e.g., >0.2), the extruder makes clicking sounds during acceleration/deceleration phases, or printed parts show broken lines.

Common Causes:

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

Solutions:

1. Reduce max_accel to decrease the instantaneous extrusion amount from PA compensation.
2. Appropriately lower the PA value to balance corner quality and extrusion reliability.
3. Check if the extruder current setting (TMC driver run_current) is sufficient.
4. Ensure the filament is not slipping (check extruder gear wear, spring tension).

Note

The PA system does not change the print time or total extrusion amount; it only redistributes extrusion movement during acceleration and deceleration phases. Extremely high PA values will result in very large instantaneous extruder movements, and there is no configuration option to limit the amplitude of this movement.

Improper Setting of pressure_advance_smooth_time

Symptoms: Periodic ripples on the print surface, unsmooth extrusion speed, or unnatural corner transitions.

Common Causes:

• pressure_advance_smooth_time is set too large (>0.1s), causing a sluggish PA compensation response.
• Set too small (<0.01s), causing aggressive PA compensation leading to extrusion jitter.
• Older configurations used the deprecated standalone [pressure_advance] section.

Solutions:

1. The default value 0.040 is suitable for most scenarios and generally requires no modification.

2. The configuration should be written inside the [extruder] section:

   [extruder]
   pressure_advance: 0.05
   pressure_advance_smooth_time: 0.040

3. Do not use the standalone [pressure_advance] configuration section (deprecated).

4. If using a long Bowden tube, you can increase it to 0.060–0.080.

Slicer Settings Conflict with Klipper Extrusion Control

Symptoms: Print quality worsens after configuring PA, with increased stringing, abnormal corners, or extrusion blobs.

Common Causes:

• Slicer has Coasting enabled, which stacks with PA deceleration compensation.
• Simplify3D's Extra restart distance causes drastic extrusion speed changes.
• KISSlicer's PreloadVE duplicates PA functionality.
• Slicer's "Dynamic Acceleration Control" or "Scarf joint" interferes with testing.

Solutions:

1. Disable the following functions in the slicer:
   • Coasting
   • Extra restart distance
   • PreloadVE (KISSlicer)
   • Dynamic Acceleration Control / Dynamic Pressure Control
   • Scarf joint seam (when calibrating PA)
2. Keep normal retraction settings (recommended 0.5–1.0 mm) and "wipe on retract".
3. Disable the slicer's "Z-lift on retract", let Klipper macros handle it.

Tip

During PA calibration testing, it is recommended to set the slicer speed to 100 mm/s, layer height to about 75% of the nozzle diameter, infill 0%, and disable dynamic acceleration control to fully expose the PA effect.

Resonance Compensation Configuration Changes After Upgrading Klipper

Symptoms: After upgrading Klipper, SHAPER_CALIBRATE behavior changes, resonance test results differ from before, or configuration 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 has been replaced by minimum_cruise_ratio.
• Accelerometer sampling logic or filter algorithms were updated.

Solutions:

1. After upgrading, check the Klipper Config Changes documentation to see if there are items affecting resonance compensation.

2. If you need to restore the old testing behavior, explicitly add in [resonance_tester]:

   [resonance_tester]
   sweeping_period: 0
   accel_per_hz: 75

3. After upgrading, it is recommended to re-run SHAPER_CALIBRATE and not reuse old frequency values.

4. If max_accel_to_decel reports a deprecation error, switch to:

   [printer]
   minimum_cruise_ratio: 0.5

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