1.4 Meet the AMS
Module 1 · Part 1: Understand the machines · Lesson 4 of 14 · about 4 min
None of the makerspace's older printers had anything like this, so read this section even if you have printed before.
AMS stands for Automatic Material System. On a basic printer you hang a spool on a holder and feed the filament into the extruder by hand, and that is the only material until you change it yourself. The AMS, in contrast, is a closed box that grips and feeds the filament with motors. That lets the printer load, unload and change material without you being there.
The two kinds in this room
Open Bambu Lab AMS 2 Pro with one orange filament spool and four feeder assemblies visible
An AMS HT beside an X2D. Left: lid open, showing the empty single-spool bay and rollers. Right: lid closed, with the front display showing humidity, temperature and drying time
AMS 2 Pro: holds four spools. Each slot has its own feeder, so the printer can switch between four spools by itself. Every X2D has one, feeding the left nozzle. Each H2S has one too, feeding its only nozzle. On the X2D rack, an upper-row printer's AMS 2 Pro sits on top of the rack, above that printer. The lower row's sit on a slide-out platform at the bottom.
AMS HT: holds one spool. Every X2D has one to its right, feeding the right nozzle.
With Module 1, you load one spool into the AMS 2 Pro. The AMS HT, and printing with more than one spool, are Module 2.
It keeps the filament sealed in
Most filament takes up water from the air, and wet filament prints badly. The water turns to steam in the hotend, so the plastic bubbles and spits and the printer can't control how much comes out. The AMS is sealed, so the filament in it takes up much less moisture, and it has a humidity sensor you can check on the screen. That is why you must close and latch the lid: an open AMS lets damp room air in.
The AMS can also dry filament while you print (Module 2 covers that), but you can't use it for drying when you are not printing.
How the filament gets to the nozzle
Each slot's feeder pushes filament into a white PTFE tube. Inside the unit the paths join, and a single tube carries the chosen filament to the printer. On an X2D it passes through a filament buffer, which takes up slack, and then into the extruder. That is a long, closed path with motors at one end and a hot nozzle at the other, and you do not touch any of it.
The filament buffer at the back of an X2D, with the PTFE tubes for the left and right nozzles pushed into its couplers
✅ Hard rule. Filament always reaches the printer the way the room has set it up: from the AMS, through the tubes as they are connected. Apart from pushing the loose end into the AMS when you load a spool, filament only moves under the machine's control, either by the AMS itself or by Load and Unload on the screen.
⛔ Hard rule. Never reroute a tube, bypass the AMS, feed from an external spool holder or a spool on the table, or add a splitter to switch between feed sources. Never push or pull filament through the tubes by hand, except when an official Bambu Lab guide tells you to (see below).
Every printer here is set up the same way, and that is why they all behave the same. A filament forced through by hand is the easiest way to jam a printer for the next person. Many online guides show people feeding filament from an external spool holder, especially for flexible filament. That is normal on other people's printers, but not allowed here.
Fixing a fault is different. If an official Bambu Lab troubleshooting guide tells you to take a PTFE tube off, for example to pull out a piece of broken filament, you may do that. Put the tube back exactly as it was, pushed all the way in (1.13 Faults, fire, and who to tell).
What happens when the filament changes
A handful of purge squiggles in black, white and grey: the plastic pushed out when the printer changes filament
When the printer switches filament, for example between colours, it:
Cuts the filament with a small cutter just above the hotend.
Pulls the cut end back into the AMS.
Pushes the new filament forward into the hotend.
Purges: pushes plastic out of the nozzle until only the new material comes out. The waste goes out the back through the purge chute and down the purge chute system into a collection box.
Wipes the nozzle, primes it on the prime tower next to your part, and carries on printing.
That is where the little plastic squiggles in the collection boxes come from. It is also why a four-colour print wastes a surprising amount of plastic. Module 2 shows you how to waste less.
With Module 1 you print with one spool, so your own prints never change filament. Printing in several colours or materials is Module 2.
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