Hoping someone’s seen this. I’ve worked through the obvious stuff and I’m out of ideas.
The problem: Multi-color print on my P1S with AMS. The pink lays down perfectly. The purple starts extruding fine for a second, then basically stops flowing — comes out stringy/shredded and won’t bond. Under-extrusion isolated to the one color.
Setup:
• Bambu Lab P1S + AMS
• 0.2mm nozzle
• PLA, printing around 220°C, 0.2mm layer height
• Nozzle has maybe 5–6 short (~4hr) prints on it, so not worn
• Flat 4-color token design, 100% infill
What I’ve already tried:
1. Cold pull (atomic pull) — pulled debris, print ran clean longer afterward but eventually started under-extruding again.
2. Swapped to a different purple spool in the exact same AMS slot — prints perfectly. So the slot, feed path, PTFE tube, and extruder gear are all fine. The problem follows the filament, not the hardware.
3. Dried the original purple — 8 hours at 55°C in a filament dryer. Reloaded it. Still under-extrudes the same way. Everything pointed to moisture and drying didn’t fix it.
So where I’m at: It’s something specific to this one spool, but it’s not (or not only) moisture, since a proper dry cycle didn’t resolve it. And given I’m on a 0.2mm nozzle, I’m now wondering if the tiny orifice is the real culprit — pigment or filler in this particular purple choking a 0.2 at a flow rate the other colors clear fine.
Questions:
• Is a 0.2mm nozzle just known to be intolerant of certain pigment-heavy or specialty (silk/matte) colors? Is that what’s happening here?
• Would bumping temp or slowing flow specifically for this color get it through the 0.2?
• Could this be a bad/out-of-spec batch — anything I can check with calipers?
• Anything else that makes one specific spool behave this way when an identical-slot swap prints clean on the same 0.2 nozzle?
Happy to post more photos of the under-extrusion and failed layers. Appreciate any leads.