axis_twist_compensation: Add X twist compensation module (#6149)
Implements AxisTwistCompensation, and Calibrater Supports calibration of z-offsets caused by x gantry twist Modify PrinterProbe._probe function to check if the probed z value should be adjusted based on axis_twist_compensation's configuration Add documentation for [axis_twist_compensation] module Signed-off-by: Jeremy Tan <jeremytkw98@gmail.com>
This commit is contained in:
Philippe Daouadi
GitHub
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# Axis Twist Compensation
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This document describes the [axis_twist_compensation] module.
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Some printers may have a small twist in their X rail which can skew the results
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of a probe attached to the X carriage.
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This is common in printers with designs like the Prusa MK3, Sovol SV06 etc and is
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further described under [probe location
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bias](Probe_Calibrate.md#location-bias-check). It may result in
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probe operations such as [Bed Mesh](Bed_Mesh.md),
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[Screws Tilt Adjust](G-Codes.md#screws_tilt_adjust),
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[Z Tilt Adjust](G-Codes.md#z_tilt_adjust) etc returning inaccurate
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representations of the bed.
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This module uses manual measurements by the user to correct the probe's results.
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Note that if your axis is significantly twisted it is strongly recommended to
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first use mechanical means to fix it prior to applying software corrections.
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**Warning**: This module is not compatible with dockable probes yet and will
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try to probe the bed without attaching the probe if you use it.
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## Overview of compensation usage
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> **Tip:** Make sure the [probe X and Y offsets](Config_Reference.md#probe) are
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> correctly set as they greatly influence calibration.
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1. After setting up the [axis_twist_compensation] module,
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perform `AXIS_TWIST_COMPENSATION_CALIBRATE`
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* The calibration wizard will prompt you to measure the probe Z offset at a few
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points along the bed
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* The calibration defaults to 3 points but you can use the option
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`SAMPLE_COUNT=` to use a different number.
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2. [Adjust your Z offset](Probe_Calibrate.md#calibrating-probe-z-offset)
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3. Perform automatic/probe-based bed tramming operations, such as
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[Screws Tilt Adjust](G-Codes.md#screws_tilt_adjust),
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[Z Tilt Adjust](G-Codes.md#z_tilt_adjust) etc
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4. Home all axis, then perform a [Bed Mesh](Bed_Mesh.md) if required
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5. Perform a test print, followed by any
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[fine-tuning](Axis_Twist_Compensation.md#fine-tuning) as desired
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> **Tip:** Bed temperature and nozzle temperature and size do not seem to have
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> an influence to the calibration process.
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## [axis_twist_compensation] setup and commands
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Configuration options for [axis_twist_compensation] can be found in the
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[Configuration Reference](Config_Reference.md#axis_twist_compensation).
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Commands for [axis_twist_compensation] can be found in the
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[G-Codes Reference](G-Codes.md#axis_twist_compensation)
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@ -1959,6 +1959,35 @@ z_offset:
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# See the "probe" section for more information on the parameters above.
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```
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### [axis_twist_compensation]
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A tool to compensate for inaccurate probe readings due to twist in X gantry. See
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the [Axis Twist Compensation Guide](Axis_Twist_Compensation.md) for more
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detailed information regarding symptoms, configuration and setup.
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```
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[axis_twist_compensation]
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#speed: 50
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# The speed (in mm/s) of non-probing moves during the calibration.
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# The default is 50.
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#horizontal_move_z: 5
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# The height (in mm) that the head should be commanded to move to
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# just prior to starting a probe operation. The default is 5.
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calibrate_start_x: 20
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# Defines the minimum X coordinate of the calibration
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# This should be the X coordinate that positions the nozzle at the starting
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# calibration position. This parameter must be provided.
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calibrate_end_x: 200
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# Defines the maximum X coordinate of the calibration
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# This should be the X coordinate that positions the nozzle at the ending
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# calibration position. This parameter must be provided.
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calibrate_y: 112.5
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# Defines the Y coordinate of the calibration
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# This should be the Y coordinate that positions the nozzle during the
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# calibration process. This parameter must be provided and is recommended to
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# be near the center of the bed
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```
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## Additional stepper motors and extruders
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### [stepper_z1]
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@ -1339,6 +1339,17 @@ print.
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#### SDCARD_RESET_FILE
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`SDCARD_RESET_FILE`: Unload file and clear SD state.
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### [axis_twist_compensation]
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The following commands are available when the
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[axis_twist_compensation config
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section](Config_Reference.md#axis_twist_compensation) is enabled.
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#### AXIS_TWIST_COMPENSATION_CALIBRATE
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`AXIS_TWIST_COMPENSATION_CALIBRATE [SAMPLE_COUNT=<value>]`: Initiates the X
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twist calibration wizard. `SAMPLE_COUNT` specifies the number of points along
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the X axis to calibrate at and defaults to 3.
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### [z_thermal_adjust]
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The following commands are available when the
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@ -35,6 +35,8 @@ communication with the Klipper developers.
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locations.
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- [Endstop phase](Endstop_Phase.md): Stepper assisted Z endstop
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positioning.
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- [Axis Twist Compensation](Axis_Twist_Compensation.md): A tool to compensate
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for inaccurate probe readings due to twist in X gantry.
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- [Resonance compensation](Resonance_Compensation.md): A tool to
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reduce ringing in prints.
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- [Measuring resonances](Measuring_Resonances.md): Information on
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@ -101,6 +101,7 @@ nav:
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- Manual_Level.md
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- Bed_Mesh.md
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- Endstop_Phase.md
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- Axis_Twist_Compensation.md
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- Resonance Compensation:
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- Resonance_Compensation.md
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- Measuring_Resonances.md
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@ -0,0 +1,258 @@
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# Axis Twist Compensation
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#
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# Copyright (C) 2022 Jeremy Tan <jeremytkw98@gmail.com>
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#
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# This file may be distributed under the terms of the GNU GPLv3 license.
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import math
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from . import manual_probe as ManualProbe, bed_mesh as BedMesh
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DEFAULT_SAMPLE_COUNT = 3
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DEFAULT_SPEED = 50.
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DEFAULT_HORIZONTAL_MOVE_Z = 5.
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class AxisTwistCompensation:
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def __init__(self, config):
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# get printer
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self.printer = config.get_printer()
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self.gcode = self.printer.lookup_object('gcode')
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# get values from [axis_twist_compensation] section in printer .cfg
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self.horizontal_move_z = config.getfloat('horizontal_move_z',
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DEFAULT_HORIZONTAL_MOVE_Z)
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self.speed = config.getfloat('speed', DEFAULT_SPEED)
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self.calibrate_start_x = config.getfloat('calibrate_start_x')
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self.calibrate_end_x = config.getfloat('calibrate_end_x')
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self.calibrate_y = config.getfloat('calibrate_y')
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self.z_compensations = config.getlists('z_compensations',
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default=[], parser=float)
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self.compensation_start_x = config.getfloat('compensation_start_x',
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default=None)
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self.compensation_end_x = config.getfloat('compensation_start_y',
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default=None)
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self.m = None
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self.b = None
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# setup calibrater
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self.calibrater = Calibrater(self, config)
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def get_z_compensation_value(self, pos):
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if not self.z_compensations:
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return 0
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x_coord = pos[0]
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z_compensations = self.z_compensations
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sample_count = len(z_compensations)
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spacing = ((self.calibrate_end_x - self.calibrate_start_x)
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/ (sample_count - 1))
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interpolate_t = (x_coord - self.calibrate_start_x) / spacing
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interpolate_i = int(math.floor(interpolate_t))
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interpolate_i = BedMesh.constrain(interpolate_i, 0, sample_count - 2)
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interpolate_t -= interpolate_i
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interpolated_z_compensation = BedMesh.lerp(
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interpolate_t, z_compensations[interpolate_i],
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z_compensations[interpolate_i + 1])
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return interpolated_z_compensation
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def clear_compensations(self):
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self.z_compensations = []
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self.m = None
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self.b = None
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class Calibrater:
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def __init__(self, compensation, config):
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# setup self attributes
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self.compensation = compensation
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self.printer = compensation.printer
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self.gcode = self.printer.lookup_object('gcode')
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self.probe = None
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# probe settings are set to none, until they are available
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self.lift_speed, self.probe_x_offset, self.probe_y_offset, _ = \
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None, None, None, None
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self.printer.register_event_handler("klippy:connect",
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self._handle_connect)
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self.speed = compensation.speed
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self.horizontal_move_z = compensation.horizontal_move_z
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self.start_point = (compensation.calibrate_start_x,
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compensation.calibrate_y)
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self.end_point = (compensation.calibrate_end_x,
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compensation.calibrate_y)
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self.results = None
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self.current_point_index = None
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self.gcmd = None
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self.configname = config.get_name()
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# register gcode handlers
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self._register_gcode_handlers()
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def _handle_connect(self):
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self.probe = self.printer.lookup_object('probe', None)
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if (self.probe is None):
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config = self.printer.lookup_object('configfile')
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raise config.error(
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"AXIS_TWIST_COMPENSATION requires [probe] to be defined")
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self.lift_speed = self.probe.get_lift_speed()
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self.probe_x_offset, self.probe_y_offset, _ = \
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self.probe.get_offsets()
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def _register_gcode_handlers(self):
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# register gcode handlers
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self.gcode = self.printer.lookup_object('gcode')
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self.gcode.register_command(
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'AXIS_TWIST_COMPENSATION_CALIBRATE',
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self.cmd_AXIS_TWIST_COMPENSATION_CALIBRATE,
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desc=self.cmd_AXIS_TWIST_COMPENSATION_CALIBRATE_help)
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cmd_AXIS_TWIST_COMPENSATION_CALIBRATE_help = """
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Performs the x twist calibration wizard
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Measure z probe offset at n points along the x axis,
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and calculate x twist compensation
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"""
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def cmd_AXIS_TWIST_COMPENSATION_CALIBRATE(self, gcmd):
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self.gcmd = gcmd
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sample_count = gcmd.get_int('SAMPLE_COUNT', DEFAULT_SAMPLE_COUNT)
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# check for valid sample_count
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if sample_count is None or sample_count < 2:
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raise self.gcmd.error(
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"SAMPLE_COUNT to probe must be at least 2")
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# clear the current config
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self.compensation.clear_compensations()
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# calculate some values
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x_range = self.end_point[0] - self.start_point[0]
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interval_dist = x_range / (sample_count - 1)
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nozzle_points = self._calculate_nozzle_points(sample_count,
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interval_dist)
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probe_points = self._calculate_probe_points(
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nozzle_points, self.probe_x_offset, self.probe_y_offset)
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# verify no other manual probe is in progress
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ManualProbe.verify_no_manual_probe(self.printer)
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# begin calibration
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self.current_point_index = 0
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self.results = []
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self._calibration(probe_points, nozzle_points, interval_dist)
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def _calculate_nozzle_points(self, sample_count, interval_dist):
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# calculate the points to put the probe at, returned as a list of tuples
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nozzle_points = []
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for i in range(sample_count):
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x = self.start_point[0] + i * interval_dist
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y = self.start_point[1]
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nozzle_points.append((x, y))
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return nozzle_points
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def _calculate_probe_points(self, nozzle_points,
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probe_x_offset, probe_y_offset):
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# calculate the points to put the nozzle at
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# returned as a list of tuples
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probe_points = []
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for point in nozzle_points:
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x = point[0] - probe_x_offset
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y = point[1] - probe_y_offset
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probe_points.append((x, y))
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return probe_points
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def _move_helper(self, target_coordinates, override_speed=None):
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# pad target coordinates
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target_coordinates = \
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(target_coordinates[0], target_coordinates[1], None) \
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if len(target_coordinates) == 2 else target_coordinates
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toolhead = self.printer.lookup_object('toolhead')
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speed = self.speed if target_coordinates[2] == None else self.lift_speed
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speed = override_speed if override_speed is not None else speed
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toolhead.manual_move(target_coordinates, speed)
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def _calibration(self, probe_points, nozzle_points, interval):
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# begin the calibration process
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self.gcmd.respond_info("AXIS_TWIST_COMPENSATION_CALIBRATE: "
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"Probing point %d of %d" % (
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self.current_point_index + 1,
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len(probe_points)))
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# horizontal_move_z (to prevent probe trigger or hitting bed)
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self._move_helper((None, None, self.horizontal_move_z))
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# move to point to probe
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self._move_helper((probe_points[self.current_point_index][0],
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probe_points[self.current_point_index][1], None))
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# probe the point
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self.current_measured_z = self.probe.run_probe(self.gcmd)[2]
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# horizontal_move_z (to prevent probe trigger or hitting bed)
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self._move_helper((None, None, self.horizontal_move_z))
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# move the nozzle over the probe point
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self._move_helper((nozzle_points[self.current_point_index]))
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# start the manual (nozzle) probe
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ManualProbe.ManualProbeHelper(
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self.printer, self.gcmd,
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self._manual_probe_callback_factory(
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probe_points, nozzle_points, interval))
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def _manual_probe_callback_factory(self, probe_points,
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nozzle_points, interval):
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# returns a callback function for the manual probe
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is_end = self.current_point_index == len(probe_points) - 1
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def callback(kin_pos):
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if kin_pos is None:
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# probe was cancelled
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self.gcmd.respond_info(
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"AXIS_TWIST_COMPENSATION_CALIBRATE: Probe cancelled, "
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"calibration aborted")
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return
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z_offset = self.current_measured_z - kin_pos[2]
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self.results.append(z_offset)
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if is_end:
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# end of calibration
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self._finalize_calibration()
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else:
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# move to next point
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self.current_point_index += 1
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self._calibration(probe_points, nozzle_points, interval)
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return callback
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def _finalize_calibration(self):
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# finalize the calibration process
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# calculate average of results
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avg = sum(self.results) / len(self.results)
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# subtract average from each result
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# so that they are independent of z_offset
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self.results = [avg - x for x in self.results]
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# save the config
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configfile = self.printer.lookup_object('configfile')
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values_as_str = ', '.join(["{:.6f}".format(x)
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for x in self.results])
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configfile.set(self.configname, 'z_compensations', values_as_str)
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configfile.set(self.configname, 'compensation_start_x',
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self.start_point[0])
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configfile.set(self.configname, 'compensation_end_x',
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self.end_point[0])
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self.compensation.z_compensations = self.results
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self.compensation.compensation_start_x = self.start_point[0]
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self.compensation.compensation_end_x = self.end_point[0]
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self.gcode.respond_info(
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"AXIS_TWIST_COMPENSATION state has been saved "
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"for the current session. The SAVE_CONFIG command will "
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"update the printer config file and restart the printer.")
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# output result
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self.gcmd.respond_info(
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"AXIS_TWIST_COMPENSATION_CALIBRATE: Calibration complete, "
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"offsets: %s, mean z_offset: %f"
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% (self.results, avg))
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# klipper's entry point using [axis_twist_compensation] section in printer.cfg
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def load_config(config):
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return AxisTwistCompensation(config)
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@ -127,6 +127,15 @@ class PrinterProbe:
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if "Timeout during endstop homing" in reason:
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reason += HINT_TIMEOUT
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raise self.printer.command_error(reason)
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# get z compensation from axis_twist_compensation
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axis_twist_compensation = self.printer.lookup_object(
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'axis_twist_compensation', None)
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z_compensation = 0
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if axis_twist_compensation is not None:
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z_compensation = (
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axis_twist_compensation.get_z_compensation_value(pos))
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# add z compensation to probe position
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epos[2] += z_compensation
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self.gcode.respond_info("probe at %.3f,%.3f is z=%.6f"
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% (epos[0], epos[1], epos[2]))
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return epos[:3]
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