Integration

Where AUTO_EJECT goes depends on one thing your end macro almost certainly does: it retracts the filament (G1 E-2 or similar). AUTO_EJECT turns the hotend off and cools the bed for several minutes, and Klipper refuses to move the filament once the nozzle is below min_extrude_temp ("Extrude below minimum temp"). An end macro that runs after AUTO_EJECT would stop there: the print ends with an error and the job queue stops.

So run AUTO_EJECT after the retract. There are two ways:

Where	Use it when
After your end macro, with HOME=1	You don't want to change your macros (DEMON, Klippain, RatOS, stock Voron). Z must home with the probe
Inside your own end macro, after the retract	You write your own PRINT_END, or Z homes with a switch

Never home Z on a part: the probe would measure the part, not the bed, and the next push would hit the bed. AUTO_EJECT refuses to run on an unhomed printer, and HOME=1 homes Z on a free spot inside the bed mesh, away from every part.

After the end macro (recommended)

Slicer end G-code:

PRINT_END
AUTO_EJECT HEIGHT=[max_layer_z] HOME=1

Use your end macro's name (DEMON_END, END_PRINT, …). The end macro retracts while the nozzle is hot, parks, turns the heaters off and usually the motors too. Then AUTO_EJECT HOME=1:

1. homes X and Y, and homes Z with the probe on a free spot inside the [bed_mesh] area, on the print sheet;
2. with a nozzle probe (Voron Tap), first waits for the nozzle to cool to nozzle_probe_max_temp (150 °C), so it does not mark the sheet;
3. cools the bed, pushes the parts off and checks the bed, as always.

Needs Z to home with the probe (endstop_pin: probe:z_virtual_endstop) and [force_move] with enable_force_move: True. If Z homes with a switch that sits off the bed, set home_method: "g28". If the switch is on the bed, use the next method instead.

You can keep a second printer profile in the slicer without the AUTO_EJECT line for prints you want to remove by hand.

Inside your own PRINT_END

Add AUTO_EJECT after the retract and before the heaters and motors are turned off:

[gcode_macro PRINT_END]
gcode:
    G91
    G1 E-2 F2700          ; retract while the nozzle is hot
    G1 Z5 F600            ; lift off the part
    G90
    {% if params.EJECT|default(0)|int == 1 %}
      AUTO_EJECT {% if params.HEIGHT is defined %}HEIGHT={params.HEIGHT}{% endif %}
    {% endif %}
    TURN_OFF_HEATERS
    M107
    M84

Slicer end G-code: PRINT_END EJECT=1 HEIGHT=[max_layer_z]. Leave EJECT out on prints you want to remove by hand. The printer is still homed, so no HOME=1 is needed.

DEMON Klipper Essentials

End G-code. DEMON_END retracts at its start (also after its _CUSTOM_PRE_END hook), so a hook that runs AUTO_EJECT hits the cold-nozzle error. Put AUTO_EJECT in the slicer end G-code, after DEMON's line:

DEMON_END
AUTO_EJECT HEIGHT=[max_layer_z] HOME=1

DEMON_END turns the motors off (M84) and clears the bed mesh, so HOME=1 is needed. Z must home with the probe (home_method "auto" or "probe", never "g28"): DEMON's own Z homing probes the middle of the bed, where a part may be. Finding Z brings the gantry down to the bed over its whole width, so prints taller than max_part_height are left on the bed instead, without homing.

Start G-code. Keep DEMON's start lines exactly as DEMON gives them (its DEMON_START line carries a version that DEMON checks), and do not put AUTO_EJECT_GUARD above them. DEMON stops the printer (an emergency stop: DKEU detected your DEMON Machine Start Gcode is not functional) when DEMON_START has not come a few seconds into a print, and when parts from the last print are still known, the guard checks the bed with the probe for longer than that. The guard runs from DEMON's first hook instead, inside DEMON_START, before heating and homing.

install.sh sets this up by itself when it finds DEMON's Demon_User_Files. On a printer that has auto-eject already, run once:

~/klipper-auto-eject/install.sh --demon

It saves a copy of demon_custom_expansion_v2.0.0.cfg, turns on variable_ceal_master_enable and variable_pre_start in _CUSTOM_EXPANSION_ACTIVE_LIST, puts the line first in the section that is already there, keeping what you have in it, and restarts Klipper unless it is printing (in a terminal it asks first):

[gcode_macro _CUSTOM_PRE_START] # Very first action after you hit print!
gcode:
  AUTO_EJECT_GUARD FROM=DEMON

By hand, make the same three changes, then FIRMWARE_RESTART. FROM=DEMON tells the guard it runs inside DEMON_START. An AUTO_EJECT_GUARD left in the slicer's start G-code then does nothing and says so: DEMON's hook checks the bed a moment later. Without the hook, the guard before DEMON_START stops the print itself with a message that says so, before DEMON would stop the printer. The web page's In your slicer card shows whether the hook is set up. A new version of DEMON's expansion file may come without the line: run install.sh --demon again.

Auto power-off. With DEMON's PRINTER_AUTO_OFF switch on, DEMON_END switches the printer off 5 seconds later. Klipper runs that timer even while AUTO_EJECT pushes, so the power would go off in the middle of a push. AUTO_EJECT holds DEMON's power-off while it clears the bed, and two minutes after, lets DEMON switch the printer off, unless the job queue has started the next print by then. Keep Moonraker's job_transition_delay under two minutes, or turn PRINTER_AUTO_OFF off while you print a queue. When a part is left on the bed, the eject stops with an error and the printer stays on.

The variables file. DEMON keeps its values in ~/demon_vars.cfg, the file of [save_variables], and auto-eject keeps its own there too (the stored parts, the blade measurement, the values saved from the web page). Keep the one [save_variables] section DEMON set up: a second one would move DEMON's values to another file. Running DEMON's installer again downloads a fresh demon_vars.cfg: take the parts off the bed before, and run the guided setup again after.

Purge. For EJECT_PURGE, turn DEMON's purge lines off with variable_purge_lines: False in demon_user_settings (PURGE_LINE_TOGGLE only lasts until the next restart), and call EJECT_PURGE from DEMON's _CUSTOM_PRE_PRINT hook, with ceal_master_enable and pre_print set to True in _CUSTOM_EXPANSION_ACTIVE_LIST.

Heat soak. The bed cools to cool_temp before each push, so DEMON heat-soaks the bed again before every queued job. That is time, not a fault.

Klippain, RatOS and other macro sets

The same: put AUTO_EJECT HEIGHT=[max_layer_z] HOME=1 in the slicer end G-code after the end macro. The web page's Check a file warns when a file runs AUTO_EJECT before another macro.

No end macro

If the slicer's end G-code is a list of plain commands, AUTO_EJECT goes last, below the retract:

G91
G1 E-2 F2700
G90
M104 S0
M140 S0
M84
AUTO_EJECT HEIGHT=[max_layer_z] HOME=1

Cura has no [max_layer_z]: write AUTO_EJECT HOME=1, and the printer uses the height it tracked while printing.

Moonraker job queue

sequenceDiagram
    autonumber
    participant Q as Moonraker job queue
    participant K as Klipper
    participant B as Bed
    Q->>K: start job 1
    K->>B: print
    K->>K: AUTO_EJECT: cool down
    K->>B: sweep parts off the edge
    K->>K: home X and Y again
    K->>B: probe old part positions
    opt a part is still there
        K->>B: push it again, lower and harder, then probe again
    end
    alt bed is clear
        K-->>Q: job complete
        Q->>K: start job 2
    else a part is still there
        K-->>Q: error
        Note over Q: queue pauses until you clear the bed
    end

# moonraker.conf
[job_queue]
load_on_startup: False
automatic_transition: True
job_transition_delay: 5

• Queue jobs from Mainsail/Fluidd (Add to queue) or from OrcaSlicer (Upload and queue).
• When a print ends normally, Moonraker starts the next queued job after job_transition_delay.
• When AUTO_EJECT raises an error, the print ends in the error state and the queue pauses. Fix the problem, clear the bed, home, and resume the queue.

Slicer settings

Copy-paste start and end G-code for OrcaSlicer, PrusaSlicer, SuperSlicer and Cura, plus how to turn on object labels in each, are in slicer-setup.md.

EJECT_PURGE instead of a purge line

EJECT_PURGE extrudes while raising the nozzle, building a pellet several millimetres tall. It places the pellet in front of the nearest part, centred on the parts' span, so the columns sweep pushes it off with everything else.

Call it in your print start, after heating, instead of the purge line:

EJECT_PURGE

or at a fixed spot: EJECT_PURGE X=200 Y=60.

• KAMP: replace the LINE_PURGE call in your print start with EJECT_PURGE.
• DEMON: see DEMON Klipper Essentials (purge lines off, EJECT_PURGE in _CUSTOM_PRE_PRINT).
• [extruder] max_extrude_cross_section must allow the pellet. The macro tells you the value it needs.