Getting started

This guide takes you from nothing to a printer that clears its own bed, one step at a time. It assumes you have a Klipper printer with Mainsail or Fluidd, and nothing else. Every step says what to do, how to check that it worked, and where to look if it did not.

New words are explained in the glossary. Quick answers are in the FAQ.

Contents

1. Check your bed
2. Print the blade
3. Mount the blade
4. Install the macros
5. Run the guided setup
6. Watch a test eject
7. Set up your slicer
8. Print in a row
9. Optional: the web page

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Before you start

You need:

• A printer running Klipper, with Mainsail or Fluidd in the browser.
• A build sheet that lets go of parts when it is cool, such as textured PEI or BIQU CryoGrip (step 1 checks this).
• Filament for the blade: PETG, ABS or ASA. PLA works for a first try, but it softens near a hot bed.
• Four M3 × 10 mm screws with nuts, and two screws that fit your toolhead (usually the screws of its front cover, a few millimetres longer).
• A cardboard box to catch the parts.
• Recommended: a probe (Voron Tap, BLTouch, an inductive probe…). With it, the printer checks that the bed is really empty before it starts the next print.

Everything you type into the printer goes into the console: in Mainsail it is on the Dashboard (or the Console page), in Fluidd on the Dashboard. Type a command and press Enter.

Caution

The printer will move on its own. Stay next to it until you have watched several ejects, and keep your hands out of the printer while it moves. The emergency stop button in Mainsail or Fluidd stops everything at once.

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1. Check your bed

The blade only pushes. If a part is still stuck to the bed, nothing will move it, so check this first.

1. Print something small, or take a part you printed earlier.
2. Let the bed cool to room temperature.
3. Push the part sideways with one finger.

It worked if the part slides off without bending the sheet. If not: auto-eject will not work on this sheet. Textured PEI, smooth PEI with a release agent and CryoGrip-type sheets work well (which surfaces).

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2. Print the blade

The blade is three printed parts held together with M3 screws. Every joint has slots, so the same parts fit most toolheads.

Download these files from hardware/stl/ and hardware/test/:

Print	File	Notes
1	blade_60mm.stl, blade_80mm.stl or blade_100mm.stl	Pick one at least as wide as your toolhead. 100 mm fits a Voron Stealthburner
1	arm.stl
1	mount_screws.stl	Fits toolhead screws 28–50 mm apart. No usable screws? Print mount_strap.stl instead and use cable ties
1	blade_gauge.stl	A 1.5 mm strip that sets the blade height in step 3
2–3	test_hollow_cube.stl	Light test parts for step 6. Print them later, in step 6

Settings: PETG, ABS or ASA, 4 walls, 40 % infill, 0.2 mm layers. The files are already turned the right way for printing and need no supports.

It worked if you have a blade, an arm, a mount and a gauge, and the M3 nuts press into the six-sided pockets on the back of the mount.

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3. Mount the blade

1. Turn the printer's heaters off and let the nozzle cool.
2. Press two M3 nuts into the pockets on the back of the mount.
3. Screw the mount to the front of the toolhead with the two toolhead screws.
4. Bolt the arm to the mount, and the blade under the arm, with the M3 screws. Leave all four loose for now, and slide the blade as high as the slots allow.

Why high? Some probes (Voron Tap) home on whatever touches the bed first. A blade that hangs below the nozzle would touch first and give a wrong height.

1. Home the printer: type G28 in the console.
2. Move the nozzle over an empty part of the bed and bring it down to 0.2 mm:

   G90
   G1 X100 Y100 Z5 F3000
   G1 Z0.2 F300
   

   (Use any X and Y where the bed is empty and the blade is over the bed too.)
3. Slide the gauge under the blade, let the blade drop onto the gauge, and tighten the arm screws. The blade's lower edge is now 1.5 mm above the nozzle tip.
4. Raise the nozzle again: G1 Z20 F600.

It worked if, looking from the side, the blade's lower edge is a little higher than the nozzle tip, and the blade's face is the part of the toolhead furthest forward in the direction you want to push.

More detail, other toolheads and making your own size: hardware.md.

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4. Install the macros

The macros are installed with one line on the printer's computer (the Raspberry Pi or similar that runs Klipper). You reach it over SSH, a text connection from your computer:

1. Find the printer's address: it is what you type in the browser to open Mainsail or Fluidd, for example 192.168.1.50 or mainsailos.local.
2. On your computer, open a terminal (Windows: Terminal or PowerShell; Mac: Terminal) and connect. The user name is the one you chose when you set up the SD card (often pi):

   ssh pi@192.168.1.50
   

3. Paste this line and press Enter:

   cd ~ && if [ -d klipper-auto-eject ]; then git -C klipper-auto-eject pull --ff-only; else git clone https://github.com/ahmedbebars/klipper-auto-eject.git; fi && ./klipper-auto-eject/install.sh
   

4. It shows what it can set up, on one screen of tick boxes: tick a line with Space, then press Enter. (Without that screen it asks the same things one at a time: press Enter to keep the suggested answer, the one in capitals.)

It asks	Say yes if
Will this printer push its prints off with the blade?	Yes, unless you only want the web page or the farm on this printer
Add the auto-eject page to Mainsail?	You want the bed map, the queue and the settings in the browser (recommended)
Watch and control the printer from your phone, from anywhere?	You want it outside your home or office. It needs a free Tailscale account (step 10)
Notifications on your phone?	You want a message when the printer needs you
More than one Klipper printer?	You want all your printers on one page (step 11)

It may ask for your password, for the web page only. 5. At the end it offers to restart Klipper: press Enter. It never restarts a printer that is printing.

The script links the macros into your config folder, creates auto_eject_settings.cfg, adds the [include] lines and the sections auto-eject needs ([exclude_object], [respond], [save_variables]) to printer.cfg, and adds the project to Moonraker's update manager so you get updates from the Mainsail/Fluidd update panel. It backs up every file it changes.

It worked if typing AUTO_EJECT_SETUP in the console opens a dialog that says Printer check: all OK. Keep it open for the next step.

If not: Unknown command "AUTO_EJECT_SETUP" means Klipper has not been restarted: type FIRMWARE_RESTART in the console (never while printing). Other ways to install: installation.md.

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5. Run the guided setup

The setup is five short dialogs. You press buttons; there is nothing to type or measure with a ruler.

Step	You do	The printer does
1	Choose the drop edge, the side the parts fall off, and put the box under it. CoreXY printers: usually the front. Bed slingers: left or right
2	Clear the bed and press Bed is clear - move	Homes and moves to the bed
	With Voron Tap or another probe that touches with the nozzle: press Measure	Measures the blade by touching a small printed block, in 2–3 minutes
	With other probes: follow the jog buttons	Shows each move
3	Press your blade's width
4	Take everything off the bed, press Bed is clear - move, and look from the side	Moves the blade to the drop edge so you can check it reaches past the edge of the sheet
5	Pick the temperature at which parts let go (32 °C for PLA is a good start), press Save, then Dry test	Saves everything, then traces the path 2 cm above the bed

With Voron Tap, print calibration_block.stl from hardware/test before the setup: 100 % infill, anywhere but the middle of the bed, and leave it on the bed while it is still warm. The setup finds it by itself. Details and a picture of every screen: setup-wizard.md.

It worked if the last screen says the settings are saved and the dry test moved over the bed without touching it.

If a screen says it could not measure, it names the reason. The usual ones are in troubleshooting.md.

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6. Watch a test eject

Now the real thing, with you watching.

1. Print two or three test_hollow_cube.stl (in the slicer, turn on Label objects, see step 7). Leave them on the bed when the print ends.
2. Put the box under the drop edge.
3. Type AUTO_EJECT in the console (or, after a restart, AUTO_EJECT HOME=1).

What you will see:

1. Cooling. The heaters turn off, the part fan turns on, and the toolhead circles over the parts. This takes the longest: 10–30 minutes, depending on the room.
2. Pushing. The blade comes down behind the parts and pushes them over the edge, slowly and with less motor force than usual. If a part is stuck, the motor skips instead of breaking something. That clicking sound is expected.
3. Checking. X and Y are homed again, and the probe touches the bed where each part was. The console says bed verified clear.

It worked if the parts are in the box and the console says bed verified clear.

If not: parts that stay on the edge of the bed, a blade that rides over the parts, or a part that is found still there each have a fix in troubleshooting.md. Repeat this step until it works every time.

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7. Set up your slicer

The slicer has to do two things: write down where each part is (object labels), and run AUTO_EJECT at the end of every print (end G-code).

The easy way: open the web page's Blade and setup tab, card In your slicer. It shows where each setting is in your slicer and the lines to paste, with your printer's own end macro already in them, and a Copy button. The same lines for each slicer:

OrcaSlicer

1. Process → Others → G-code output: turn on Label objects and Exclude objects.
2. Printer settings → Machine G-code → Machine end G-code: add this line below what is already there:

   AUTO_EJECT HEIGHT=[max_layer_z] HOME=1
   

PrusaSlicer / SuperSlicer: Print Settings → Output options → Label objects: Firmware-specific, and the same end G-code line. Cura: see slicer-setup.md.

HEIGHT=[max_layer_z] tells the printer how tall the print is, so flat prints like stencils, which the blade cannot catch, are left on the bed for you instead of being pushed.

Your end macro retracts the filament while the nozzle is hot. AUTO_EJECT lets the nozzle cool, so it must run after that, which is why it goes below it. HOME=1 homes the printer again around the parts if the end macro turned the motors off. More in integration.md.

It worked if the next print clears the bed by itself when it finishes.

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8. Print in a row

To print many jobs one after another, use Moonraker's job queue. Open moonraker.conf (next to printer.cfg) and add:

[job_queue]
load_on_startup: False
automatic_transition: True
job_transition_delay: 5

Save, and restart Moonraker from the power menu at the top of Mainsail or Fluidd. Then, in the G-code files list, right-click a file and choose Add to queue, as many times as you like.

When a print ends, the printer clears the bed and the queue starts the next job. If a part stays on the bed, the print ends with an error and the queue stops, so nothing is printed on top of it. Take the part off, run AUTO_EJECT_CLEAR, and start the queue again.

Tell it how many parts your box holds, so it warns you before the box overflows: in the web page's Settings, Parts box, set bin_capacity (for example 40). When the box is full, the next print waits until you empty it and press I emptied the box (the parts box).

Before you leave it alone, read safety.md.

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9. Optional: the web page

A page in Mainsail with a live map of the bed, the queue, a check for your G-code files and all the settings, in English or Arabic:

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

If you said yes to the web page in step 4, it is already there. It asks for your password once (for the web server). Then reload Mainsail and click Auto-eject in the sidebar. See web-page.md.

10. Optional: from your phone, anywhere

Watch the printer and control it from your phone when you are not home, without opening the printer to the internet. It uses Tailscale, a free private network between your devices:

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

It asks before every step and shows the address to open on your phone at the end. See remote-access.md.

To get a notification when the printer needs you (a part still on the bed, a print that finished), add --push, then turn notifications on in the app; see notifications.md.

11. Optional: more than one printer

Put every Klipper printer of your network on one page, with the ones that need you first. Run this on one printer only; the others need nothing installed:

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

Then open the page's Printer farm tab and press Search the network. See farm.md.

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What next?

I want to…	Read
Understand every setting	configuration.md
Know what happens after a power cut	recovery.md
Watch the printer from my phone, anywhere	remote-access.md
See all my printers on one page	farm.md
Use a BLTouch, an inductive or an eddy-current probe	probes.md
Fix an error message	troubleshooting.md
See every command	commands.md
Ask a question or share my setup	Discussions