Spoolman: does the spool finish the queue?

A queue that runs through the night is of little use if the spool runs out halfway through a job. Spoolman knows what is left on each of your spools. With it, auto-eject checks the queue against the spool on the printer and stops the queue before a job the spool cannot finish.

There is nothing to turn on in auto-eject: when Moonraker is linked to Spoolman, the page and the service find it. Without Spoolman, nothing changes.

Where	What you get
Print queue	A Spool card: the spool on the printer, what is left on it, and whether the queue fits. Each job shows the grams it needs, and the one the spool cannot finish is marked Spool runs out. Change the spool picks another of your spools.
Overview	A Spool chip with the grams left, and a message when the print running may run out or the queue stopped for the spool.
Starting the queue	When the spool cannot finish the next job, Start the queue asks first.
The service	With the page closed, it stops the queue before a job the spool cannot finish and sends a notification. It needs the klipper-auto-eject service (install.sh --push).

How the pieces fit

Spoolman is a small program of its own, with a web page, that keeps the list of your spools. It is not part of Klipper or of auto-eject. Each printer's Moonraker tells it how much filament the printer used, so Spoolman always knows what is left on each spool. Before each job, auto-eject asks it, through Moonraker, what is left on the spool on that printer.

flowchart LR
    S["Spoolman<br/>one, for all your printers<br/>on a computer that is always on"]
    A["Printer 1<br/>Moonraker + auto-eject"] -- "filament used" --> S
    B["Printer 2<br/>Moonraker + auto-eject"] -- "filament used" --> S
    S -- "grams left on its spool" --> A
    S -- "grams left on its spool" --> B

Where to run Spoolman

One Spoolman for all your printers, on a computer that is on whenever a printer prints.

Where
A computer that is always on: Home Assistant, a NAS, a Raspberry Pi, a mini PC	Best, above all with several printers: switching a printer off changes nothing for the others
One of the printers	Fine, with no extra hardware: Spoolman is small. Pick the printer that is never switched off
A copy on every printer	No: each keeps its own list, and a spool moved to another printer is not followed
A server on the internet	No: Spoolman has no password, so anyone who reaches it can change your spools. To reach it from outside, use Tailscale (remote-access.md)

While Spoolman is off, a printer keeps what it used and sends it once Spoolman is back (it is lost if Moonraker restarts in the meantime), and the queue is not checked: the Spool card says Moonraker cannot reach Spoolman.

Setting it up

1. Install Spoolman, once, on the computer you chose: with Docker (Spoolman's own advice), with its install script on any Linux computer such as a Raspberry Pi, or as a Home Assistant add-on. See Spoolman's installation guide. Its page opens at http://<that computer>:7912.
2. Add your spools in Spoolman's page. Give each filament its weight, and each spool what is on it: without a weight, Spoolman cannot say what is left.
3. Link each printer to it. The installer does it: on each printer, over SSH,

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

It looks for Spoolman on its own port (7912) on the printer and on your network, and asks whether to use the one it found. Elsewhere (another port, another network), it asks for the address as in your browser, for example 192.168.1.50:7912. It checks that Spoolman answers, adds the section and restarts Moonraker when the printer is idle. By hand, it is the same address in each printer's moonraker.conf:

[spoolman]
server: http://192.168.1.50:7912

then restart Moonraker (from the power menu of Mainsail or Fluidd, not while printing). 4. Say which spool is on each printer: in the Spool card of the print queue, or in Mainsail or Fluidd. Say it again each time you change the spool.

For the queue to stop by itself while the page is closed, the klipper-auto-eject service must run on the printer: install.sh --push, or --farm (notifications.md).

How it counts

• What a job needs: the filament weight the slicer writes in the file (OrcaSlicer, PrusaSlicer, SuperSlicer and Cura write it). A file that gives only a length is weighed with the density and diameter Spoolman has for the spool's filament.
• What is left: Spoolman's remaining weight for the spool, less what Moonraker has not reported to it yet.
• The print running: only the part not printed yet.
• The reserve: slicer weights are estimates, so spool_reserve grams (10 by default) are kept back. A job that would leave less on the spool counts as one it cannot finish.
• Not checked: a file without a weight, and a file that prints more than one filament (multi-material or colour changes), since one spool says nothing about it. The jobs after it are not checked either, and the card says so.

Settings

Setting	Default	What it does
spool_low_action	"stop"	Before a job the spool cannot finish: "stop" stops the job queue before it and sends a message (needs the service), "notify" only sends the message, "off" does not check
spool_reserve	10.0	Grams to keep on the spool, since slicer weights are estimates

Change them in the Settings tab (The spool (Spoolman)), in auto_eject_settings.cfg, or with AUTO_EJECT_SET (configuration.md).

When the queue stops

You get a notification that names the job, what it needs and what is left. Put on another spool, choose it (the Spool card, Mainsail, Fluidd or Spoolman), then start the queue.

If you start the queue again with the same spool, it is not stopped again for the same job: you have decided.

A print that has started is never stopped. If the spool may run out during it, you get a message to keep another spool ready. Stopping a print when the filament ends is the job of a filament runout sensor.