How to Dry PETG HF on AMS2 Pro: Settings, Time, and What to Expect

What this covers: Drying PETG HF (High Flow) filament using the AMS 2 Pro’s built-in drying module before and during printing on Bambu Lab X1, P1, and A1 series printers.

Purpose: Eliminate moisture-caused defects — bubbles, stringing, uneven extrusion — that PETG HF is particularly susceptible to compared to standard PETG.

Prerequisites: An AMS 2 Pro unit connected to a compatible Bambu Lab printer. The AMS 1 (original) does not have a drying function — this workflow is AMS 2 Pro-specific. Standard spool, not a refill without a hub.

1. Why PETG HF Needs Drying (More Than Regular PETG)

PETG High Flow is engineered for speeds up to 400mm/s. The formulation that enables this speed is more hygroscopic than standard PETG — it pulls moisture from the air faster. Undried PETG HF produces visible bubbles and holes in extruded lines, audible popping during printing, and inconsistent layer bonding. Bambu Lab’s wiki specifically documents the defects from undried HF and provides a printing workaround for partially dried spools.

2. Set the Drying Parameters

In the AMS 2 Pro interface (or via the Bambu Lab app), set:

• Temperature: 65°C (the maximum the AMS 2 Pro can reach, and the correct target for PETG HF)
• Duration: 8 hours minimum

If your PETG HF roll has RFID, the AMS 2 Pro auto-configures both values when the spool is loaded — confirm the settings match before starting.

Temperature note: The 65°C maximum is only reliably achieved when ambient temperature is ≥ 25°C. In cooler environments, the unit may not reach full target temperature. Drying in a warmer room or enclosure improves results if your workshop is cold.

3. How the Drying Module Works

The AMS 2 Pro’s heater sits beneath the central frame. During drying, it opens an active air intake and exhaust vent to discharge moisture via external circulation — the damp air exits the unit rather than recirculating. This is more effective than passive desiccant drying because it removes extracted moisture rather than absorbing it.

You can dry filament while printing a different spool — the AMS 2 Pro manages drying independently for each slot. Start a drying cycle on a wet PETG HF spool while printing PLA from another slot.

4. The Trap: Printing Undried PETG HF

If you need to print before the 8-hour cycle completes, Bambu Lab’s wiki provides a partial-dry workaround: reduce print speed and increase extruder temperature slightly to compensate for residual moisture. This produces acceptable results for non-critical prints but doesn’t replace proper drying for functional or fine-detail work.

Don’t skip drying and assume the defects will be minor — PETG HF’s moisture sensitivity is pronounced enough that undried spools frequently cause print failures, not just surface artifacts.

5. Storage After Drying

Once dry, PETG HF reabsorbs moisture quickly in open air. If the spool won’t be used within a few hours of completing the cycle, remove it to a sealed bag with fresh silica gel or keep it loaded in the AMS 2 Pro with the drying circuit active between sessions. Target storage humidity: below 20%.

Cited References

• Filament drying guide for AMS 2 Pro and AMS HT — Bambu Lab Wiki
• Printing method when PETG HF is not completely dried — Bambu Lab Wiki
• Filament Drying Recommendations — Bambu Lab Wiki

Source: Bambu Lab Wiki

Content created with AI assistance and reviewed for accuracy.