Random stringing, blobs, bad layers amongst batches

[rwbotx]

Never run into this issue before so hoping someone here has.

-Started getting blobs, bad layers, with varying severity amongst the objects (ex front left almost perfect while the one right behind it looks catastrophic). Also stringing, sometimes minimal, sometimes it looks like the extruder was used to collect cotton candy.

-Yes, all spools get dried at 70C for 24hrs before being moved to AMS. And it will still happen even if I print with the spool left in the drier at 70C afterwards.

-The batch right before this came out perfect and both batches were from the same spool of BBL PETG-HF.

-Print file is an export from Orca that’s been saved on the SD card since December, and that same file is printed daily. Until February, every batch was printed perfectly.

-Started few weeks ago, with occasionally one bad object in the batch. Isn’t consistent as I can get a perfect batches and the next has a few with defects and the next has a few less then perfect again. But the extent has gotten worse over time and this was the first time almost the entire batch has defects.

-Tried different spools and colors of BBL PETG-HF. Tried different brands of PETG-HF with varying results. replaced the hot end, ran every calibration and even factory reset. Problem persists.

-Printer is an X1C, almost two years old. Bought in June 2023. Ballscrews are cleaned and lubed monthly.

Any ideas?

[EnoTheThracian]

Tricky to guess. Pic’s could perhaps give some indications.

I expect you being quite thorough in your maintenance and since you already replaced the hot end and the issues you mentioned are stringing, blobbing and layer separation, I’d probably have a look at the extruder gears. With heavy use over the years, they may be worn.

If you are printing from an AMS, I am rather thorough in checking my PTFE paths outsides the AMS but I admit I try to avoid opening the AMS to check those PTFE’s and the internal filament switch. Unlikely though considering the failure type.

I hope it is not something more troubling like the TH board and its connectors starting to give in or a need to replace XY-belts or even the the entire XY assembly.

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