Hi all,
I’m seeing a sudden drop in print quality on my P1S and could use some help diagnosing the issue.
The outer surfaces look great, but the inner surfaces of my parts have lots of tiny blobs (photo attached). This only started happening last week. Up until then, print quality was acceptable.
Printer: P1S (185 hours total print time)
Filament: BBL PLA Matte
Slicer: Bambu Studio (standard profile, with reduced speed and acceleration to reduce noise!)
Nozzle: Stock 0.4mm
I’ve checked nozzle is clean (performed multiple cold pulls, and inserted pin). Filament is loaded in AMS fresh out of sealed packet from BBL.
What’s odd is that only inner surfaces are affected. Any ideas what might be causing this?
Seems to me if it was damp filament it would effect the entire model.
If your spool is damp throughout, and the toolhead is zipping around doing what looks to be a cylinder so making all these circular inner and outer walls, for example does the OD walls, then ID walls, then does infill, layer after layer.
Strange how the horizontal plane surfaces are so smooth and yet on very same level on vertical plane they look terrible.
Not quite.
The inside of a hole is printed as an outer wall with the inner wall lying in between. Going fast and with insufficient layer adhesion/ cooling time, the nozzle rips the freshly printed wall of its surface. The outsides is stabilized by the previously printed inner wall but the hole wall has no such stabilization.
So improved cooling behavior from dried filament (and maybe going a little bit slower) improved the holes wall while the outer wall has no such problem.
Thanks everyone for the replies! I’m still quite new to all this, if that wasn’t obvious already!
I hadn’t considered that Matte might be more moisture sensitive. I’ve not dried the filament, as I assumed it would be fine fresh out of the sealed packet, but it’s interesting to hear it could still be a factor. I’ve just bought a dryer to try PETG anyway, so I’ll see if it makes a difference.
I’ve included some better photos. The original was taken late at night with poor lighting. The part is a lamp base. Mostly cylindrical. Just to clarify, what looks like horizontal surfaces on the inside are actually 45° overhangs, and they come out looking smooth. Since these will have been printed at slower speed, that’s making me think it could be cooling related. Maybe the inner surface isn’t getting much airflow from the part cooling fan?
I’m using 3 walls with inner/outer/inner wall order. I’m printing at reduced speeds already, outer walls are at 60 mm/s. Do you think I should reduce speed even more?
Anyway, I will try drying the fillament first to see if that improves things.
Many thanks for your further insights. That helps a lot
Indeed it was not clear to me that the inside is an overhang, already printed slower. So slowing further is unlikely to give further improvements.
The main root cause still seems to me to be found in moisture though. Moist filament tends to retain for heat for longer, promoting overhang sagging. So going by my own experience, drying the Matte filament should really be enough.
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