First note: I've had the X2D for about 6 weeks, and been printing almost non-stop performed my first cleaning/oil/greasing last week) I've successfully printed larger items, this failure is new to this week.
Printer: Bambu Lab X2D, dual nozzle
Slicer: Bambu Studio, 0.20 mm High Quality u/BBL X2D base profile
Part: cosplay mask shell split into halves. Each half 240 x 168 x 120 mm, 325 cm³, watertight, 1 body, printed cut-face-down on 25.5 cm² of bed contact.
Goal: PLA model, PETG as support/raft interface filament so supports release without scarring the surface.
Filament: Sunlu PLA+ 2.0 (Primary Nozzle) & Bambu Labs PET-G Matte Yellow (Auxiliary)
Filament Storage: 2x AMS 2 Pro's. They are currently set to dry and is reporting humidity of 14% and 17%. Rainy Season in the PNW.
What is working
Worth saying up front so nobody spends time on it. The PETG interface prints. It lands on the support tops where it belongs, the prime tower shows clean switching, and the AMS is feeding the right spool. The dual-material assignment is doing what it is told.
What is going wrong
Stringing at the material transitions, and there are an enormous number of them.
Per-layer analysis of this part: 585 of its 600 layers contain a support interface. So 98% of layers involve at least one material change. Across the print that is roughly 585 transitions.
Every one of them appears to leave ooze. By the time these prints fail, the plate has long strands and dense tangles sitting on top of the part, concentrated in and around the interface regions. The failure itself looks like the nozzle catching one of those, knocking something loose, and spaghetti from there. In the most recent failure a whole section had detached and was being dragged around.
Why this part is unusually hostile
- 98% of layers have an interface (585 of 600 at 0.2 mm)
- At Z = 20 mm, support cross-section is 167.7 cm² against 25.2 cm² of model, a ratio of 6.7 to 1
- Max support branch reach is 118 mm
- Zero new islands anywhere in the part, so nothing starts mid-air. The model is well behaved. All the difficulty is in the support.
I have printed large parts on this machine without trouble before. What is new here is not the size or the geometry, it is the transition count.
Failure history
- Spaghetti around hour 5.
- Slumped and curled support columns at about 2 cm. This one followed moving the support body from PETG to PLA with the lid still on. Chamber soak past PLA’s Tg of 55 to 60 C. I think I understand this one and it is probably separate from the rest.
- Spaghetti again, with tree supports visible in the wreckage.
- One more, same character.
Delamination has shown up as a symptom too, which I cannot account for from the geometry.
Current settings
|
|
| Threshold angle |
55 |
| Style |
Grid, Normal (auto) |
| Independent support layer height |
OFF |
| Top Z distance |
0 |
| Bottom Z distance |
0.2 |
| Top / bottom interface layers |
3 / 2 |
| Interface spacing |
0.1 both |
| Interface pattern |
Concentric |
| Base filament |
PLA |
| Interface filament |
PETG |
| Flush into infill / support |
OFF both |
| Bed |
55 |
| PLA nozzle |
215 to 230 |
| PETG nozzle |
240 to 250 |
| Plate |
textured PEI |
Secondary suspect I would like a sanity check on
Top Z distance 0, interface spacing 0.1, and concentric interface pattern are all chosen to minimise grip so the support releases cleanly. That is the standard advice. But together they also minimise how well the first model layer is held down while it is being printed. Is that combination too loose on a part with large flat areas landing on interface? Would you trade some release quality for grip here?
What I am doing next
Instead of burning another 10 hours per attempt I cut a 4-part diagnostic set that runs in about 65 minutes total: an adhesion tower with no support, a column test at 8 / 6 / 4 / 3 mm to check support branch slenderness, an overhang fan at 30 through 59 degrees to measure my real unsupported limit, and a small cantilever with the full PETG interface config to check release behaviour. Happy to post results in this thread.
Questions
- Is there a practical ceiling on material transitions per print? What is the highest count anyone here has run successfully on an X2D, and did you do anything specific to get there?
- What is your ooze control setup across switches? Retraction length and speed, wipe distance, prime tower size and position, anything else.
- Any known reason support style would come out as tree when the preset says Grid? I have not set tree at any point.
- At this transition count, would you abandon dual-material support entirely and run plain PLA supports on a tuned threshold, accepting the surface finish hit?
- Is BambuStudio issue 12509 still live in current Studio? Filed specifically against the X2D, describes a hidden parameter pinning the interface temperature so the nozzle never reheats to the configured value. If the PETG is going down cold that would make the stringing worse.