How to dry filament in the Bambu Lab AMS 2 Pro: settings, power and limits

Why I care about this one

My Bambu Lab P2S Combo came with the AMS 2 Pro, which sits on top of the printer. I bought it at Best Buy Canada and have run about 25 prints in a month, mostly Bambu PLA and wood-fill PLA, with some Bambu PETG. My longest job was a 16-hour white PETG mask printed from a spool I hadn't dried. It came out with fine strings across the eye and mouth openings. They pulled off by hand, but it was exactly the kind of flaw the AMS 2 Pro's built-in dryer is meant to prevent.

I haven't reprinted that mask with dried filament yet. So this guide is built on Bambu Lab's own documentation and on reports from owners on the Bambu Lab community forum, not a before-and-after of my own. For my general impressions of the printer, see the hands-on review at Bambu Lab P2S Combo (AMS 2 Pro) review.

What the AMS 2 Pro dryer can and can't do

Bambu's spec sheet gives the AMS 2 Pro a maximum drying temperature of 65 °C. An electromagnetic vent opens to release moisture while drying and closes again to keep storage airtight. During drying the spools can turn automatically for more even heat. For Bambu's own filaments, the RFID tag fills in the temperature and time for you.

There is one catch that matters in Canada. Bambu says the 65 °C maximum is only reached when the room is above 25 °C. In a cooler room, heat loss means the actual drying temperature may fall short. A printer in a cool basement or a cold spare room in winter may therefore dry more slowly than the screen suggests.

The 65 °C ceiling suits the common materials. Bambu's wiki says filaments that need hotter drying may not dry fully in the AMS 2 Pro and points owners to the AMS HT or the printer's heated bed instead. ABS, ASA, PC and nylon are all marked as not compatible with AMS 2 Pro drying in Bambu's table.

Bambu's recommended settings

These are the AMS 2 Pro figures from Bambu's filament drying table:

PLA Basic, PLA Matte, PLA Silk, PLA Wood and PLA-CF: 45 °C for 12 hours. Bambu marks drying as required for PLA Wood, so dry wood-fill before you use it.

Support for PLA, and Support for PLA/PETG: 60 °C for 12 hours.

PETG and PETG-CF: 65 °C for 12 hours.

TPU 85A, TPU 90A, TPU 95A HF and TPU for AMS: 65 °C for 12 hours. Bambu warns that the AMS 2 Pro may not fully dry TPU and suggests the heated bed or AMS HT instead.

Twelve hours is a long cycle. If you plan to print PETG first thing in the morning, start drying the evening before.

Power: the P2S has a specific limitation

This is the part that catches owners out. Bambu's FAQ says the H2 series, P2S and X2D can power one AMS 2 Pro for drying straight from the printer. On a P2S, though, while the printer is powering the dryer, it can't heat or move. In practice, drying and printing take turns. Adding Bambu's AMS 2 Pro Switching Adapter lets the P2S start a print while drying continues. The FAQ lists P2S firmware 01.02.00.00 or later for printing and drying at the same time.

Older X1 and P1 printers can't power the dryer at all, so every AMS 2 Pro used for drying on those machines needs its own adapter. If you run more than one AMS 2 Pro on any printer, each extra unit drying at the same time also needs one. Bambu says the adapter is rated 24 V 4 A and warns that third-party adapters may damage the unit and affect warranty coverage.

Even with an adapter, the AMS 2 Pro can't dry on its own. Bambu says it must stay connected to a powered-on printer through the 6-pin bus cable.

Rotation mode vs static mode

The AMS 2 Pro has two drying modes, and choosing the wrong one can damage soft filaments.

Rotation mode turns the spools. To use it, Bambu says to pull the filament out of the feeder inlet and tuck the end against the side of the spool. Owners on the Bambu forum found the same thing: if filament stays in the feeders, the spools don't turn. Some also reported that removing filament before opening the drying menu could make the AMS treat that slot as empty.

Static mode leaves the filament loaded but doesn't rotate the spools. Bambu says static mode isn't suitable for PLA, PVA, Support for PLA/PETG or TPU. These soften at low temperatures, and the layers on a stationary spool can stick together or deform. That makes rotation mode the right choice for PLA, which is most of what many people print.

Step by step on a P2S

1. Update the printer and AMS firmware and Bambu Studio, since drying features have changed through updates.

2. Check that the desiccant is fresh and the vents underneath the AMS are clear. Bambu says moisture leaves through vents at the bottom.

3. For PLA, PETG or TPU, unload the filament and tuck each end against its spool so rotation mode can work.

4. Don't mix temperatures. Bambu warns that drying a hotter material with PLA still inside can deform the PLA. Take out any lower-temperature spools first.

5. Close the lid, choose the filament type (Bambu spools fill this in through RFID), confirm the time and start. Bambu's FAQ says drying can now also be started from the Devices page in Bambu Studio. That's newer than some forum complaints about it being screen-only.

6. When the cycle ends, let the unit cool for 5 to 10 minutes, as Bambu suggests. Check the filament for flattening or gear marks, then reload it and print, or seal it with desiccant.

What owners report

Owner feedback on the Bambu forum is mixed. Owners point out that Bambu filament makes setup simple, because the RFID tag fills in the temperature and time. Several threads complain about the restrictions: rotation drying needs filament pulled from the feeders, cycles are long, and one owner reported that drying doesn't resume after a power cut. Some owners say they prefer a standalone dryer because it works independently of the printer.

Printing while drying is supported now, but with limits. Bambu says the drying temperature automatically drops once a print starts, to 45 °C for PLA and 55 °C for PETG, so filament doesn't soften in the AMS feed path. On the forum, one H2D owner whose AMS 2 Pro shut off while drying at 65 °C during a hot-chamber print was told the likely causes were heat or power. Another owner on an X2D hit a software glitch when starting a print mid-cycle. Neither problem is confirmed as a general fault. Both are good reasons to let a cycle finish before a long print.

From a tech standpoint

Use Bambu's table: 45 °C for PLA, 65 °C for PETG, both for 12 hours, in rotation mode with the filament unloaded. On a P2S without the Switching Adapter, plan drying and printing as separate steps. In a room below 25 °C, expect drying to fall short of the 65 °C maximum. Look elsewhere for ABS, ASA, nylon or demanding TPU drying.