Hi, I’ve had a P1S for about a year and a half (got it summer 2024), and it was pretty great for the first year, but then I started to have some issues. Rounded prints started having this weird line of small holes. I’ve tried a lot of different settings and got a 0.2mm nozzle, which was slightly better, but didn’t solve it. I’ve also played around with the settings, but don’t really think that it’s a settings issue because the prints were coming out perfect before with the same settings. I’ve tried tightening the belts, cleaning and regreasing the Z-screws, and cleaning the carbon rod, but nothing made a difference.
I used Bambu PLA filament for all of these prints (except for the shiny one, that was generic PLA). I have desiccant in the AMS and a humidity meter that usually reads around 10%.
I’ve looked all over for a solution but haven’t found anything helpful. Any suggestions would be greatly appreciated. Thanks!
I’d start by going through the remaining steps of the Bambu Lab P1 series printer Maintenance Recommendation | Bambu Lab Wiki. I do not think that this will solve the issue, but after all this time it is certainly advisable 
Bambu Lab P1 series printer Maintenance Recommendation | Bambu Lab Wiki
Next, I’d take a close look at the nozzle (clogged, worn, bent?, Nozzle/Hotend Unclogging Procedure for X1/P1 | Bambu Lab Wiki), the extruder gears (How to Fix Extruder Clog in Bambu Lab X1C | Bambu Lab Wiki) and the PTFE tubes from the AMS to the print head (Replacing the Bambu PTFE Tube - X1 Series/P1 Series/AMS | Bambu Lab Wiki).
There are of course further possible root causes, but let’s hope it is not something as serious as the extruder motor. Hopefully just something more benign like worn PTFE’s or couplers or a dirty and/or worn extruder.
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I’ve seen a video that had very similar artifacts occur in their prints, and they fixed it by messing around with the retraction settings. They ended up doubling the retraction length and it was solved for them, but your scenario might be different. It might not at all be related to retraction length and could be something actually worn out that needs replacement.
All of your examples show ragged extrusion following an extreme overhang. If desired, you can confirm this in the slicer by slicing to that layer, and scrubbing thru the timeline on the bottom to confirm the nozzle direction is moving from overhang → area that is ragged. You might also want to check the visualizer to see what happens to flow/speed in these areas, settings dependant.
Calibrate your pressure advance and flow rates [per filament], adjust your overhang speeds, or try replacing the nozzle/cold pulling it till its clean enough to go in the CERN [actually idk if this impacts P series, no eddy current sensor?]. Supports also are the tool that can help limit exactly how much is able to be air-extruded, so it can make those defects only occur on one or two layers instead of many.
That’s some pretty severe underextrusion in those sections. I just fixed a similar issue with mine, but here’s what I’d recommend to test it.
Cold pull the nozzle to eliminate the possibility of partial clogs.
Run a test print and watch the temps to see if they’re changing more than 1-2C during the print. If yes, I’d swap out the heating element and thermistor and use new thermal paste. I’d probably also swap the silicone sock if it’s looking chewed up.
If it’s still messing up, crack open the extruder and clean it out fully. Look for any damage on the spring arm piece, and feel if it spins freely. I had a lot of damage to a third party hardened gear set of extruder gears and it was binding in the extruder. If you find a lot of magnetic black dust in there, something is grinding the hardened gears which will cause skipping.
Thanks so much for your responses! Here’s what I’ve done:
- cleaned and lubricated the Y and Z-axis linear rods
- 3 cold pulls
- tested, no difference
- doubled the retraction length
- tested again, no difference
- calibrated filament
- halved the overhang speeds and most other speed settings
- no difference
- completely took the extruder off
- disassembled
- did not find any obvious damage or magnetic dust, but did find a small hair and dust ball
- thoroughly cleaned everything
- relubricated the gears
- reassembled
- tested, still bad
I did a final test where I slowed the acceleration down a ton more. This was the first thing to actually make a difference. It still wasn’t perfect, but it was a lot better. However, this isn’t super sustainable because the print times are super long now. And I keep remembering how the prints were coming out perfect when I first got the printer, so it was never a settings problem originally. Not sure what to do next.
