Articles on: SimplyPrint features

Assigning filament spools to printers

Assigning filament spools to printers


Assigning a spool to a printer tells SimplyPrint which filament is currently loaded. This is the key step that enables automatic usage tracking, temperature settings, and low-filament warnings. Once you've added your spools to the Filament Manager, assigning them is how you unlock the full benefits of filament tracking.


Why assign spools?


When a spool is assigned to a printer, SimplyPrint knows exactly what material is loaded. This enables:


  • Automatic usage tracking - When you print, the estimated filament usage is deducted from the assigned spool
  • Temperature settings - SimplyPrint can automatically set nozzle and bed temperatures based on the spool's material profile
  • Low filament warnings - Get warned before starting a print if the assigned spool doesn't have enough filament
  • Queue matching - The print queue can match jobs to printers based on what material is loaded
  • Print history - See which specific spool was used for each print job
  • Cost calculation - Material costs are calculated using the assigned spool's purchase price


Without an assigned spool, SimplyPrint doesn't know what's in your printer - so none of these features can work.



Assigning from the Filament page


The Filament page in both the web panel and mobile app lets you click on any spool to assign it.


Assigning a spool from the Filament page


  1. Go to Filament in the menu
  2. Click on the spool you want to assign
  3. In the spool view popup, click Assign
  4. Select the printer from the list
  5. If the printer has multiple extruders, nozzles, or slots (like Bambu Lab AMS), choose which one to assign to


Pro tip: Double-click a printer in the list to assign immediately without clicking a confirm button!


The same workflow works in the mobile app - tap a spool, tap Assign, select the printer and slot.


Assigning from the mobile app



Assigning from the Printers page


You can also assign spools starting from the printer side. This is useful when you're looking at a specific printer and want to change what's loaded.


Assigning from the printer panel


  1. Go to Printers and select your printer
  2. Find the filament/material section - it shows currently assigned spools or empty slots
  3. Click on a slot (either an existing spool or an empty one)
  4. Click Pick new spool to open the spool selector
  5. Search or browse for the spool you want
  6. Click to select it


Pro tip: Double-click a spool in the list to assign it instantly!


Using scanning in the spool selector


When the spool selector is open, you can use any of SimplyPrint's scanning methods:


  • USB barcode/QR scanners - Scan a label and the spool is found instantly
  • NFC scanning - Tap an NFC tag to find the spool
  • Webcam scanning - Use your camera to scan a QR code


If the scan finds exactly one matching spool, it's selected and assigned automatically - no extra clicks needed.


See: Scanning filament label QR codes and barcodes



Quick assign by scanning


If you scan a QR code or tap an NFC tag that contains a SimplyPrint filament link (from our label generator), it opens the Spool view popup directly.


Spool view popup from scanning


From here you can:


  • See all the spool's details at a glance
  • Click Assign to assign it to any printer
  • Click Unassign if it's currently assigned elsewhere


This makes physical workflows fast - scan the spool you're loading, tap Assign, pick the printer, done.



Multi-extruder and AMS printers


For printers with multiple extruders or an Automatic Material System (AMS), you can assign different spools to each slot.


  • Multi-extruder printers - Assign a spool to each extruder (Extruder 1, Extruder 2, etc.)
  • Bambu Lab AMS - Assign spools to each AMS slot (Slot 1-4 per AMS unit)
  • Other material changers - SimplyPrint shows the available slots based on your printer configuration


Each slot tracks its assigned spool independently, so you can have different materials or colors loaded and ready to use.


When assigning, you'll see a dropdown or list of available slots - just pick the one you're loading the filament into.



Automatic assignment (Bambu Lab)


If you have a Bambu Lab printer with their branded spools, SimplyPrint can automatically assign spools when you load them into the AMS.


Bambu spools have NFC tags that the AMS reads. SimplyPrint matches the NFC tag UUID to your spool records and assigns automatically - no manual steps needed.


If SimplyPrint doesn't have a matching spool in your inventory, it can optionally create one automatically based on the NFC data.


Configure this in Settings > Printers > Material syncing.



What happens when you assign


When you assign a spool to a printer:


  1. The spool is marked as "in use" - It shows which printer it's assigned to
  2. Location updates - If you use filament locations, the spool is temporarily "checked out" of its storage location
  3. Printer shows the material - The printer's panel displays what's loaded
  4. Ready for tracking - Any prints started on that printer will use this spool for usage tracking



Changing filament during a print


SimplyPrint fully supports changing filament assignments while a print is running. This is useful when:


  • Running out of filament - Switch to a new spool mid-print
  • Color changes - Swap colors at a specific layer (M600 or manual pause)
  • Material changes - Some prints require different materials for different sections


To change the assignment during a print, simply assign a new spool to the printer using any of the methods above. The previous spool is automatically unassigned.


How usage tracking works with mid-print changes:


SimplyPrint tracks which spool was assigned at the end of the print. If you change spools during printing, the estimated usage for the entire print is deducted from the spool that's assigned when the print finishes.


For more precise tracking when changing filament mid-print, you can manually adjust the weight of the first spool after removing it to account for what was actually used.



Unassigning spools


To unassign a spool when you remove it from the printer:


  • From the spool view - Click Unassign
  • From the printer panel - Click the assigned spool and select Unassign or Remove


If you use filament locations, the spool automatically returns to its previous storage location when unassigned.


You don't have to unassign before assigning a different spool. If you assign a new spool to a slot that already has one assigned, the old spool is automatically unassigned first.



What if the wrong spool is assigned?


If you start a print with the wrong spool assigned (or no spool assigned):


  • Usage tracking is off - The filament used won't be deducted from the correct spool
  • Temps might be wrong - If SimplyPrint sets temperatures from the spool profile, they'll be based on whatever is assigned
  • History is inaccurate - The print job will show the wrong (or no) spool in its history


This isn't catastrophic - you can always manually adjust spool weights later. But for accurate tracking, try to keep assignments current with what's actually loaded.


You can fix this mid-print - see Changing filament during a print above.



Tips for smooth assignments


  • Scan when loading - If you use QR labels or NFC tags, scan the spool as you physically load it. This keeps assignments in sync with reality.
  • Double-click for speed - In both the printer and spool selectors, double-clicking skips the confirm step
  • Use the mobile app - The app makes it easy to scan and assign while you're at the printer
  • Check before printing - Glance at the assigned spool before starting a print to catch any mismatches
  • Let AMS do it - If you have Bambu Lab with branded spools, enable auto-assignment and let the system handle it





Updated on: 23/12/2025

Was this article helpful?

Share your feedback

Cancel

Thank you!