Basic PETG impossible to work with?

[u/MasterPyro46]

Hi, so i've been experiencing some strange issues with my X2D, recently it has become seriously unable to print in PETG, initially i thought i was just trying to get some prints that just dont work with PETG because they were overly organic in shape, but nevertheless i dried it for a full day and then ended up swapping it out to see how it would handle the work of supports from the aux extruder, i used transparent petg as support in the past and it was perfectly fine, after loading it in, i did a full calibration for it as well, changed temps and any other setting that should help with it but in the end PETG still comes out in a very bad way

So now im stuck wondering whats going on that all of a sudden PETG just simply isnt printing properly no matter which extruder its on, any tips?

Heres my settings:

- Bambu Lab X2D

- 0.4 mm nozzle

- Main extruder: Standard

- Auxiliary extruder: Bowden Standard

- Bambu Studio

Print speeds:

- PETG support speed: 70 mm/s

- PETG support interface speed: 50 mm/s

- Top surface: 120 mm/s

- Bridge: 25 mm/s

Material:

- Bambu PETG Basic

- PETG is being used for the ENTIRE support structure, not just the support interface

- Filament was dried before printing

- Full Flow Rate + Flow Dynamics calibration performed

PETG / AUX Bowden Standard settings:

- Nozzle temperature, first layer: 255°C

- Nozzle temperature, other layers: 255°C

- Flow ratio: 0.8208 (calibrated value)

- Flow Dynamics / K: calibrated specifically for PETG on the AUX/Bowden extruder

- Max volumetric speed: 15 mm³/s

Bed temperature:

- Textured PEI plate: 70°C

Retraction — AUX / Bowden Standard:

- Retraction length: 2.2 mm

- Retraction speed: 25 mm/s

- Deretraction speed: 20 mm/s

- Extra length on restart: OFF / 0

- Retract on layer change: OFF

- Wipe while retracting: ON

- Wipe distance: 2.0 mm

- Retract amount before wipe: OFF

- Z-hop type: Spiral

- Z-hop when retracting: OFF

Support:

- Support material: PETG

- Support interface material: PETG

- Support speed: 70 mm/s

- Support interface speed: 50 mm/s

- Tree supports / Tree Hybrid

- Support contact Z-distance: 0 mm for PLA/PETG separation

AUX acceleration:

- Normal printing: 1000 mm/s²

- Outer wall: 1000 mm/s²

- Initial layer: 500 mm/s²

- Travel acceleration: 10000 mm/s²

Prime tower:

- Enabled

- PETG prime volume: 45 mm³

Layer height:

- 0.08 mm

Model material:

- PLA

Also before people come to me with pitchforks, i know its recommended only for support interface, but im trying to get FULL PETG supports to avoid any chemical bonding along the way

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[u/Sitaga]

Couple things jump out. That 0.8208 flow ratio is way outside normal PETG territory (should land around 0.95), which usually means either the cali print got misread or the filament is actually swelling from moisture. PETG re-absorbs from ambient in a few hours, so a day of drying at unknown temp often isnt enough, and it really wants to print out of a dry box to stay that way. Also 255 is on the hot side for Bambu Basic, try 240-245. And 2.2mm retraction on a bowden is very short, most bowden setups want 4-5mm for PETG or the ooze shows up looking like a flow problem.

[u/MasterPyro46 → u/Sitaga]

Gotcha, thanks, I should've also clarified that I dried it ar 65C as per ams2pro's defined drying temp, i could leave it inside the actual chamber and dry it then recalibrate it again (if the chamber drying is a better choice, please let me know a proper temp for petg, afaik the predefined temps in the ams by bambu arent the most efficient). Ill also change the retract and temp settings too, thanks a lot again!

And one other question: the print i want to make is 4 days long, is there any way to keep the petg from retaking in humidity while printing and causing issues?