Safety

klipper-auto-eject moves the printer on its own, without anyone watching, and can start the next print. Read this page before relying on it.

Built-in protections

Risk	What the macros do
Homing with parts on the bed (wrong Z, then the blade hits the bed)	AUTO_EJECT refuses to run unhomed. AUTO_EJECT HOME=1 homes X/Y normally and measures Z with the probe on the spot furthest from every stored part
Parts taller than the gap under the gantry: the beam the toolhead runs on, or the toolhead, hits them while the blade pushes or while the probe finds the bed	Prints taller than max_part_height are left on the bed with nothing moving, not even homing; the queue waits and the next print does not start until they are taken off (tall parts)
Printing on top of parts left by an interrupted print	Part outlines are saved while printing. AUTO_EJECT_GUARD in the start G-code stops the print, or ejects first
A part that will not move	Motor current on the push steppers drops to push_current, so the motor skips instead of breaking the blade, the part or the belt
Fast, violent moves	Pushing runs at push_speed and push_accel. The previous acceleration and currents are restored afterwards
The blade landing on a part	Each push starts rear_clearance behind the parts. Starts that cannot get behind a part (too close to the far edge) are refused. objects checks the landing zone before anything moves
A part left on the bed, then printed over	The probe checks the old positions. Anything found raises an error, so the job queue does not continue
Pushing hot, soft parts	Heaters off, part fan on, wait for cool_temp
A misconfigured setting	Unknown strategy or direction names stop with an error before any movement

What you still need to do

• Watch it. Do several DRY=1 runs and several real ejects while standing next to the printer before leaving it unattended.
• Thermal runaway protection must be active (verify_heater is on by default in Klipper). Do not run unattended print farms without it, or without a smoke detector near the printers.
• Keep the drop zone clear, and make sure the box cannot overflow back onto the bed.
• Check the blade after crashes. A bent blade changes its height and offset.
• Re-measure after toolhead changes: a new nozzle, hotend or probe changes the geometry.
• Set max_part_height for your printer (AUTO_EJECT_SETUP asks for it), and keep HEIGHT=[max_layer_z] in the end G-code: without the print height, a tall print is pushed.
• Eddy-current probes cannot see plastic. Without a contact/touch command in verify_probe_gcode, the bed is not verified (probes.md).
• Verification has limits. Three outline points can miss a part that was pushed partly off and rotated, and center mode cannot see hollow parts. Thin, flat leftovers (under verify_threshold) are not detected.
• Purge lines and skirts are too thin to be swept and will build up. Use EJECT_PURGE.

Emergency stop

M112 (or the emergency stop button in Mainsail/Fluidd) stops everything immediately. After an emergency stop, clear the bed by hand before homing.