purge_arc.cfg

[gcode_macro PURGE_ARC]
variable_direction: 'CW'            # purge clockwise or counterclockwise (either 'CW' or 'CCW')
variable_start_angle: 180.0         # angle in Degree of start point (0 is at Y_MAX)
variable_end_angle: 0.0             # angle in Degree of end point (0 is at Y_MAX)
variable_edge_offset: 5.0           # offset in mm from edge of bed defined in printer.cfg
variable_purge_speed: 25.0          # purge line printing speed in mm/s
variable_purge_line_height: 0.2     # height of purge line in mm
variable_purge_line_width: 0.6      # width of purge line in mm
variable_z_travel_height: 5.0       # z height for travel moves in mm
variable_travel_speed: 50.0         # travel speed in mm/s
variable_retract_after_purge: 0.25  # retraction in mm after purge line has been printed
variable_z_height_after_purge: 5.0  # retraction in mm after purge line has been printed
variable_retract_speed: 30.0        # retraction speed in mm/s
gcode:
  {% set radius = printer.configfile.settings.printer.delta_radius - edge_offset | float %} 
  {% set start_angle_rads = ((start_angle * 6.283185) / 360) | float %}
  {% set end_angle_rads = ((end_angle * 6.283185) / 360) | float %}

  {% if start_angle < 0 or start_angle > 360 or end_angle < 0 or end_angle > 360 %}
    { action_raise_error("ERROR: Angles in [gcode_macro PURGE_ARC] must be between 0 and 360 !!!") }
  {% endif %}

  # calculate start coordinates
  {% set sin0 = (start_angle_rads) %}
  {% set sin1 = ((start_angle_rads ** 3) / 6) | float %}
  {% set sin2 = ((start_angle_rads ** 5) / 120) | float %}
  {% set sin3 = ((start_angle_rads ** 7) / 5040) | float %}
  {% set sin4 = ((start_angle_rads ** 9) / 362880) | float %}
  {% set sin5 = ((start_angle_rads ** 11) / 39916800) | float %}
  {% set sin6 = ((start_angle_rads ** 13) / 6227020800) | float %}
  {% set sin7 = ((start_angle_rads ** 15) / 1307674368000) | float %}
  {% set sin = (-(sin0 - sin1 + sin2 - sin3 + sin4 - sin5 + sin6 - sin7)) | float %}

  {% set cos0 = (1) | float %}
  {% set cos1 = ((start_angle_rads ** 2) / 2) | float %}
  {% set cos2 = ((start_angle_rads ** 4) / 24) | float %}
  {% set cos3 = ((start_angle_rads ** 6) / 720) | float %}
  {% set cos4 = ((start_angle_rads ** 8) / 40320) | float %}
  {% set cos5 = ((start_angle_rads ** 10) / 3628800) | float %}
  {% set cos6 = ((start_angle_rads ** 12) / 479001600) | float %}
  {% set cos7 = ((start_angle_rads ** 14) / 87178291200) | float %}
  {% set cos = (-(cos0 - cos1 + cos2 - cos3 + cos4 - cos5 + cos6 - cos7)) | float %}
  {% set start_x = (radius * sin * -1) |round(4) | float %}
  {% set start_y = (radius * cos * -1) |round(4) | float %}

  # calculate end coordinates
  {% set sin0 = (end_angle_rads) %}
  {% set sin1 = ((end_angle_rads ** 3) / 6) | float %}
  {% set sin2 = ((end_angle_rads ** 5) / 120) | float %}
  {% set sin3 = ((end_angle_rads ** 7) / 5040) | float %}
  {% set sin4 = ((end_angle_rads ** 9) / 362880) | float %}
  {% set sin5 = ((end_angle_rads ** 11) / 39916800) | float %}
  {% set sin6 = ((end_angle_rads ** 13) / 6227020800) | float %}
  {% set sin7 = ((end_angle_rads ** 15) / 1307674368000) | float %}
  {% set sin = (-(sin0 - sin1 + sin2 - sin3 + sin4 - sin5 + sin6 - sin7)) | float %}

  {% set cos0 = (1) | float %}
  {% set cos1 = ((end_angle_rads ** 2) / 2) | float %}
  {% set cos2 = ((end_angle_rads ** 4) / 24) | float %}
  {% set cos3 = ((end_angle_rads ** 6) / 720) | float %}
  {% set cos4 = ((end_angle_rads ** 8) / 40320) | float %}
  {% set cos5 = ((end_angle_rads ** 10) / 3628800) | float %}
  {% set cos6 = ((end_angle_rads ** 12) / 479001600) | float %}
  {% set cos7 = ((end_angle_rads ** 14) / 87178291200) | float %}
  {% set cos = (-(cos0 - cos1 + cos2 - cos3 + cos4 - cos5 + cos6 - cos7)) | float %}
  {% set end_x = (radius * sin * -1) |round(4) | float %}
  {% set end_y = (radius * cos * -1) |round(4) | float %}

  # calculate extrusion amount
  {% if clockwise|upper == 'CW' %}
    {% set diff_rads = start_angle_rads - end_angle_rads %}
  {% else %}
    {% set diff_rads = start_angle_rads - end_angle_rads %}
  {% endif %}
  {% if diff_rads < 0 %} {% set diff_rads = diff_rads + 6.283185 %} {% endif %}
  {% if diff_rads > 6.283185 %} {% set diff_rads = diff_rads - 6.283185 %} {% endif %}
  {% set purge_line_len = diff_rads * radius %}
  {% set purge_line_volume = purge_line_len * purge_line_height * purge_line_width %}
  {% set filament_cross_section = printer.configfile.settings.extruder.filament_diameter * printer.configfile.settings.extruder.filament_diameter / 4 %}
  {% set extrude_length = purge_line_volume / 3.14 / filament_cross_section %}

  # print the pruge line 
  G0 Z{z_travel_height} F{travel_speed * 60}                # lift z to travel height
  G0 X{start_x} Y{start_y} F{travel_speed * 60}             # move to start of purge line
  G0 Z{purge_line_height} F{travel_speed * 60}              # lover Z to purge line height
  G92 E0                                                    # reset extruder
  {% if clockwise|upper == 'CW' %}
    G2 X{end_x} Y{end_y} I{start_x * -1} J{start_y * -1} E{extrude_length} F{purge_speed * 60} # purge
  {% else %}
    G3 X{end_x} Y{end_y} I{start_x * -1} J{start_y * -1} E{extrude_length} F{purge_speed * 60} # purge
  {% endif %}
  G92 E0                                                    # reset extruder
  G1 E{retract_after_purge * -1} F{retract_speed * 60}      # retract to prevent oozing
  G1 Z1 F{travel_speed * 60}                                # lift Z