klipper-macros/macros/purge_until_empty.cfg

#####################################################################
# PURGE_UNTIL_EMPTY - purge a broken filament out through the nozzle
#
# When the filament snaps inside the PTFE tube, the piece below the break
# is still in the extruder. This macro repeats the Blobifier purge and
# measures each one with bd_pressure (load-check firmware). It stops after
# the first purge without sustained nozzle pressure: the extruder no longer
# has filament to push.
#
# What stays behind: the extruder can only push filament its gears still
# grip. Once the tail has passed the gears, the last bit between the gears
# and the nozzle stays in the hotend. The next normal load pushes it out.
#
# The AFC lane is unsynced first (UNSET_LANE_LOADED). Otherwise AFC keeps
# feeding the lane together with the extruder, the spool side of the break
# can catch up and the purge never ends. Afterwards AFC sees no lane loaded:
# eject or reload the lane as usual.
#
# bdwidth sits at the start of the tube, so after the break it sees no
# filament while the extruder keeps pushing. Its runout response (motion or
# width) would pause the printer mid-purge, so it is switched off during the
# purges (SET_FILAMENT_SENSOR) and restored afterwards. bdwidth is not used
# to decide when to stop: only the nozzle pressure can see the last piece.
#
# Needs: bdpressure_check.py + [bdpressure_check] (see purge_check.cfg)
#        Blobifier, homed printer, hot nozzle (the macro heats if needed)
#
# Usage (printer idle or paused, not while printing):
#   PURGE_UNTIL_EMPTY                     defaults below
#   PURGE_UNTIL_EMPTY TEMP=240 MAX=10     filament temperature, purge limit
#   PURGE_UNTIL_EMPTY LENGTH=100          mm per purge (default: Blobifier's)
#   PURGE_UNTIL_EMPTY UNSYNC=0            keep the AFC lane synced
#
# Each purge prints one line; the end result says whether the nozzle ran
# empty or MAX purges were reached (lane still feeding, or nozzle blocked).
#####################################################################

[gcode_macro PURGE_UNTIL_EMPTY]
description: Repeat the Blobifier purge until bd_pressure measures no more filament
variable_max_purges: 15        # safety limit: ~1.2 m of bowden is ~8 purges of 150 mm
variable_empty_ms: 5000        # longest pressure below this = no filament (good purge ~17 s, empty ~30 ms)
variable_done: 0
variable_count: 0
gcode:
    {% set cfg = printer["gcode_macro PURGE_UNTIL_EMPTY"] %}
    {% set max_purges = params.MAX|default(cfg.max_purges)|int %}
    {% set length = params.LENGTH|default(0)|float %}
    {% set unsync = params.UNSYNC|default(1)|int %}
    {% set min_temp = printer.configfile.settings.extruder.min_extrude_temp|float %}
    {% set temp = params.TEMP|default([printer.extruder.target, 0]|max)|float %}
    {% if 'bdpressure_check' not in printer %}
        {action_raise_error("PURGE_UNTIL_EMPTY: needs bdpressure_check.py and [bdpressure_check]")}
    {% elif printer.print_stats.state == "printing" %}
        {action_raise_error("PURGE_UNTIL_EMPTY: printer is printing, pause the print first")}
    {% elif "xyz" not in printer.toolhead.homed_axes %}
        {action_raise_error("PURGE_UNTIL_EMPTY: home the printer first")}
    {% elif temp < min_temp %}
        {action_raise_error("PURGE_UNTIL_EMPTY: give the filament temperature, e.g. PURGE_UNTIL_EMPTY TEMP=240")}
    {% else %}
        BDP_CHECK_QUERY
        _PURGE_UNTIL_EMPTY_RUN MAX={max_purges} LENGTH={length} UNSYNC={unsync} TEMP={temp}
    {% endif %}

# Rendered after BDP_CHECK_QUERY, so 'available' is current.
[gcode_macro _PURGE_UNTIL_EMPTY_RUN]
gcode:
    {% if not printer.bdpressure_check.available %}
        {action_raise_error("PURGE_UNTIL_EMPTY: bd_pressure load-check firmware not found")}
    {% endif %}
    SET_GCODE_VARIABLE MACRO=PURGE_UNTIL_EMPTY VARIABLE=done VALUE=0
    SET_GCODE_VARIABLE MACRO=PURGE_UNTIL_EMPTY VARIABLE=count VALUE=0
    {% if params.UNSYNC|int and printer.AFC.current_load %}
        RESPOND MSG="PURGE_UNTIL_EMPTY: unsyncing {printer.AFC.current_load} from the extruder (UNSET_LANE_LOADED)"
        UNSET_LANE_LOADED
    {% endif %}
    {% set bdw = printer.bdwidth_status.name if 'bdwidth_status' in printer else '' %}
    {% set runout_was = 1 if bdw and printer.bdwidth_status.enabled else 0 %}
    {% if runout_was %}
        RESPOND MSG="PURGE_UNTIL_EMPTY: bdwidth runout response off during the purges"
        SET_FILAMENT_SENSOR SENSOR={bdw} ENABLE=0
    {% endif %}
    M109 S{params.TEMP}
    {% for i in range(params.MAX|int) %}
        _PURGE_UNTIL_EMPTY_STEP LENGTH={params.LENGTH}
    {% endfor %}
    _PURGE_UNTIL_EMPTY_RESULT MAX={params.MAX} BDW={bdw if runout_was else '-'}

# Rendered when it runs, so it sees the result of the previous purge.
[gcode_macro _PURGE_UNTIL_EMPTY_STEP]
gcode:
    {% if not printer["gcode_macro PURGE_UNTIL_EMPTY"].done %}
        {% set length = params.LENGTH|default(0)|float %}
        M400
        G4 P500
        BDP_CHECK_START
        BLOBIFIER {'PURGE_LENGTH=%.1f' % length if length > 0 else ''}
        M400
        BDP_CHECK_STOP
        _PURGE_UNTIL_EMPTY_EVAL
    {% endif %}

[gcode_macro _PURGE_UNTIL_EMPTY_EVAL]
gcode:
    {% set cfg = printer["gcode_macro PURGE_UNTIL_EMPTY"] %}
    {% set p = printer.bdpressure_check %}
    {% set n = cfg.count + 1 %}
    {% if not p.available %}
        {action_raise_error("PURGE_UNTIL_EMPTY: lost the bd_pressure load-check reading, stopped. bdwidth runout response may still be off: SET_FILAMENT_SENSOR SENSOR=<bdwidth name> ENABLE=1")}
    {% endif %}
    {% set empty = p.longest_ms < cfg.empty_ms %}
    SET_GCODE_VARIABLE MACRO=PURGE_UNTIL_EMPTY VARIABLE=count VALUE={n}
    RESPOND MSG="PURGE_UNTIL_EMPTY purge {n}: pressure longest {p.longest_ms} ms, total {p.above_ms} ms, peak {p.peak} -> {'empty' if empty else 'filament'}"
    {% if empty %}
        SET_GCODE_VARIABLE MACRO=PURGE_UNTIL_EMPTY VARIABLE=done VALUE=1
    {% endif %}

[gcode_macro _PURGE_UNTIL_EMPTY_RESULT]
gcode:
    {% set cfg = printer["gcode_macro PURGE_UNTIL_EMPTY"] %}
    {% if params.BDW|default('-') != '-' %}
        SET_FILAMENT_SENSOR SENSOR={params.BDW} ENABLE=1
    {% endif %}
    {% if cfg.done %}
        RESPOND MSG="PURGE_UNTIL_EMPTY: no more filament after {cfg.count} purge{'s' if cfg.count != 1 else ''}. The last bit between the extruder gears and the nozzle is pushed out by the next load."
    {% else %}
        RESPOND TYPE=error MSG="PURGE_UNTIL_EMPTY: still pressure after {params.MAX} purges. The lane may still be feeding, or the nozzle is blocked - check before running it again."
    {% endif %}