Nozzle Clog? Worn Extruder? Heat Creep?

Bambu Lab P Series Troubleshooting
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I have 1,500 hours on my P1S.
At least 200+ successful prints, almost all in PLA and PETG, a couple in ASA, and a few with Fiberon “PET-GF15”. This week, printing with Polymaker Fiberon PET-GF15, I have had 3 failed prints in a row. I have hardened extruder gears, and hardened nozzle. The filament is very dry.. (dried in ventilated lab oven at 100C for 6 hours, what does print with this filament looks super good.)

The print starts out great, gets to about layer 50-70 and then the extrusion is no longer occurring because the extruder gears wore a spot on the filament and are just sliding on it. I can unload the filament then cut the worn end of the filament off, and reload and the fresh filament going through the gears is able to purge the nozzle with no issues.

First print was with 0.4mm hardened nozzle, failed… Did two cold pulls and purged with a lot of PETG, examined retracted cold pool with magnification and it looked good, no evidence of a plug? Disassembled and cleaned the inside of the extruder (some dust and “lint” from the problem, but less than I thought would be there). Then reinstalled everything and tried again.

Second print failed in same manner. The tool head keeps moving all 6+ hours, and the printer says “Success!” but the print just stops after about layer 50-70, and the filament has a worn spot where the extruder gears were sliding.

I did the cold pull again, cleaned the extruder again, switched to a 0.6mm hardened steel nozzle.
Same problem. I cancelled print.

Am wondering if I need to replace the extruder gears?
I figured that since Polymaker recommends drying the filament at 100C that it should be fine to have the chamber be sealed up and have low –> zero fan for a large print with 120 sec + layers.
So I was letting the chamber heat soak up to about 47C and then letting it print at 47–> 50C chamber temp with no fans.
Polymaker also recommends 285 –> 315 nozzle temp. I printed at 300, with a 90C plate temp.

Should I buy new gears? increase cooling? do more cleaning of the nozzle and extruder?
Which is most likely?

2

This sounds very much like heat creep. With my H2, I do tend to run into heat creep issues with long prints and low flow.

If it wasn’t for the risk of warping/curling, I’d recommend increasing cooling and/or at least checking flow in the slicer preview. Unfortunately, I have not printed PET-GF and can only speculate at this point.

:four_leaf_clover: & :crossed_fingers:

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Thanks, I will try reducing the bed temp by 5 degrees, reducing the nozzle temp by 5 degrees and cracking the lid a little farther and turning on the toolhead fan to 20 percent so that it will draw air “down” through the toolhead. Will follow up if it works better.

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Yes, leaving the lid cracked open and adding 20% fans kept the chamber temps below 42C and the 7 hour print finished. So, it was either heat creep or this time I got lucky.

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