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Frequently asked questions

Contents: Before you start · Using it · When something goes wrong · Updates and removal

Before you start

Will it work on my printer? On almost any Klipper printer with a rectangular bed: CoreXY (Voron, RatRig, Sovol SV08…), Cartesian and bed slingers (Ender 3 on Klipper…). Not on delta printers, and not on Marlin, Bambu Lab or stock Prusa firmware. See Compatibility.

Do I need a probe? No, but it is strongly recommended. Without one the printer pushes the parts but cannot check that the bed is empty, so a stuck part could be printed over. Contact probes (Voron Tap, BLTouch, Klicky) can check; eddy-current probes need their touch mode (probes.md).

Which bed sheet do I need? One that lets go of parts when it is cool: textured PEI, smooth PEI with a release agent, or CryoGrip-type sheets. Test it first: a cooled part should slide off with a finger push.

Which parts work well? Parts at least 2 mm tall with a flat bottom: boxes, brackets, cookie cutters, figures on a base. Very flat parts (stencils, signs) are left on the bed on purpose. Tall, narrow parts can tip over: push lower and slower (troubleshooting).

Can I use PLA for the blade? For a first try, yes. PETG, ABS or ASA last longer, because PLA softens near a warm bed.

Will the blade scratch my bed? No. The blade's lower edge sits about 1.5 mm above the nozzle tip, and the nozzle stays above the bed while pushing (push_z). Nothing touches the sheet except the parts.

Do I have to edit config files? Only to add three short sections to printer.cfg once (getting started, step 4). Everything else is set with the guided setup or the web page.

Using it

How long does one eject take? Mostly cooling: 10–30 minutes, depending on the room and the bed. Pushing and checking take a minute or two. A warmer cool_temp is faster, but parts must still let go at that temperature.

My room is warm and the bed never gets down to cool_temp. After cool_timeout (30 minutes) the parts are pushed anyway, with a warning. To wait less, set cool_temp a few degrees higher (for example 35 °C) if your parts still let go there.

What happens to flat prints like stencils? Prints lower than 2 mm (min_part_height) are left on the bed, the queue pauses, and a dialog asks you to take them off. Click Bed is clear - continue the queue when you have.

Can I print some files without ejecting? Yes: keep a second printer profile in the slicer without the AUTO_EJECT line in the end G-code.

What if the power goes out or the printer restarts? The outlines of the parts on the bed are saved while printing. After the restart, run AUTO_EJECT HOME=1: it homes on an empty spot, never on a part, then clears the bed. With AUTO_EJECT_GUARD in the start G-code, a new print never starts on top of old parts (recovery.md).

Do I have to tell the printer the bed is clear before every print? No. After a normal eject the probe checks the bed, and once it is clear the printer forgets the parts by itself. When you take the parts off (after cancelling a print, after a print without AUTO_EJECT, or after a thin print it left for you), you don't have to tell it either: with AUTO_EJECT_GUARD in the start G-code, the next print first probes where the parts were and starts if the bed is clear (recovery.md). A dialog also offers Bed is clear right after such a print, or click I took the parts off on the web page (AUTO_EJECT_CLEAR). Without a probe that can touch plastic, the guard stops the print until you do.

Can I watch it from my phone when I'm not home? Yes. install.sh --remote sets up Tailscale, a free private network between your devices, so Mainsail and the auto-eject page open from your phone anywhere, without opening the printer to the internet (remote-access.md).

Can it tell me when something goes wrong? Yes. With install.sh --push, the auto-eject app on your phone gets a notification, even while it is closed, when a part is still on the bed, a print was too thin to push, or the next print did not start; and, if you like, when every print is done. install.sh --notify does the same through the free ntfy app, Telegram or Discord (notifications.md).

How do I stop it? The emergency stop button in Mainsail or Fluidd stops everything at once. Afterwards, clear the bed by hand and run AUTO_EJECT_CLEAR.

Does it work with Fluidd? Yes, the setup dialogs work in both. The web page works too; Fluidd just has no sidebar link for it, so bookmark http://<printer>/auto-eject/.

Does it work with my print start/end macros (DEMON, Klippain, RatOS…)? Yes. Put AUTO_EJECT HEIGHT=[max_layer_z] HOME=1 in the slicer's end G-code after your end macro, which retracts the filament while the nozzle is still hot. With DEMON, AUTO_EJECT_GUARD does not go in the slicer's start G-code but in DEMON's _CUSTOM_PRE_START hook, which install.sh sets up (install.sh --demon on a printer that has auto-eject already): DEMON stops the printer when something runs before DEMON_START for more than a few seconds. Details in integration.md.

When something goes wrong

A part was not pushed off. The probe finds it, the blade pushes it again, lower and harder. If it still does not move, the print ends with an error and the queue stops. Take it off, run AUTO_EJECT_CLEAR, and start the queue again.

The parts end up on the edge of the bed instead of falling off. The blade does not reach past the edge of the sheet. Check it with step 4 of the guided setup (troubleshooting).

I got an error message. Most errors say what to do. The full list is in troubleshooting.md.

Where can I ask for help? Open an issue with your auto_eject_settings.cfg, the console output and a photo of the blade, or ask in the discussions.

Updates and removal

How do I update? Click Update next to klipper-auto-eject in the Mainsail/Fluidd update panel, then FIRMWARE_RESTART (not while printing). Your settings are never overwritten.

What does the installer change on my printer? It adds two [include] lines to printer.cfg and one section to moonraker.conf, after making a backup of each. With --web it also adds a small web server file and a sidebar link (web-page.md).

How do I remove it? ~/klipper-auto-eject/install.sh --uninstall takes everything back out (removing it, step by step).