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# AMS auto-refill and filament tracking in SimplyPrint

SimplyPrint can track filament usage when your printer's AMS (Automatic Material System) switches to a backup spool mid-print.

||| SimplyPrint does not control AMS auto-refill. The auto-refill feature is handled entirely by your printer's firmware - SimplyPrint can only observe what the printer does and track usage accordingly.

---

## What SimplyPrint can and cannot do

| SimplyPrint can | SimplyPrint cannot |
| --------------- | ------------------ |
| Set filament color and type on your printer's screen | Trigger or control when auto-refill happens |
| Track which spool is being used | Decide which backup spool the printer picks |
| Calculate usage when the printer switches spools | Override your printer's auto-refill settings |

The auto-refill matching logic lives entirely in your printer's firmware. When your AMS decides to switch spools, SimplyPrint sees the tool change and updates its tracking - but the decision is made by the printer alone.

---

## How usage tracking works

| If auto-refill isn't working as expected, the issue is with how your printer matches spools - not with SimplyPrint.

When your printer switches spools mid-print, SimplyPrint detects the change and tracks usage based on print progress.

**Example:** If Spool A was used for 0-60% of the print and Spool B for 60-100%, SimplyPrint calculates usage proportionally for each spool.

The filament info SimplyPrint sends (color and type) is what the printer uses for matching.

---

## Setting up auto-refill on Bambu Lab printers

||| These steps are for reference only. Auto-refill configuration is handled by your printer firmware - consult Bambu Lab's official documentation for the most up-to-date instructions.

### Requirements

|| Bambu and third-party filaments are never considered "the same" - even if the color and type match. Bambu filament must be backed up with Bambu filament, and third-party with third-party.

The AMS will only auto-switch to a backup spool if it has **exactly matching properties**:

- Same brand (Bambu or third-party)
- Same material type (PLA, PETG, ABS, etc.)
- Same color
- Same nozzle temperature

### Enabling auto-refill

| For Bambu filament, RFID is read automatically. For third-party filament, manually set the type, color, and temperature to match.

1. Load your primary spool and backup spools with identical properties
2. Enable **"AMS Filament Backup"** in Bambu Studio or AMS settings on the printer
3. Verify all spools show correct filament information

### AMS 2 Pro note

On the X1E with AMS 2 Pro, backup spools must be in an AMS unit connected to the **same extruder** - left AMS units back up left, right backs up right.

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## Troubleshooting

| SimplyPrint only sets the color and type visible on your printer's screen. Make sure those values match between spools you want to use as backups - the rest is up to your printer's firmware.

If your printer doesn't auto-switch when a spool runs out, the problem is with the printer's matching logic - not SimplyPrint.

**Common causes:**

- **Properties don't match exactly** - even small temperature differences will prevent matching
- **Mixed brands** - Bambu and third-party filaments won't match each other
- **Filament info not configured** - third-party spools showing "?" need manual setup
- **Print was paused/unloaded** - this can disrupt the backup function

---

## Related articles

- [How does SimplyPrint track filament usage?](https://help.simplyprint.io/en/article/how-does-simplyprint-track-filament-usage-1rdwu3f/)
- [The Filament Manager feature](https://help.simplyprint.io/en/article/the-filament-manager-feature-track-organize-and-manage-your-filament-inventory-bpy529/)
- [Assigning filament spools to printers](https://help.simplyprint.io/en/article/assigning-filament-spools-to-printers-1r66t1p/)