PVA extrusion fails after an hour or two (from flow sensor)

[philippe44 0]

Hi - I did a few prints using PVA on my S3 and they worked fairly well. I have been away for a few months and now I'm trying to print a large object with a fair bit of support (more than previously) and all attempts failed. After a few hours, prints pause because the S3 thinks there is no more filament in BB core. Indeed, the PVA extrusion begins well and after a while, it starts to under-extrude to a point that nothing comes out. Removing filament shows signs of grinding, but not awful though. I don't think it's the flow sensor being faulty otherwise flow would not stop. I've tried various adjustments in the feeder tension, no change. The PVA is a *new* roll that was sealed with desiccant and I've even tried to cure that roll with a special heating system and full of desiccant, no change. I've cleaned the bowden tube and the core multiple times and the hot & cold pull come back clean so I'm running out if ideas and getting frustrated to see my 12 hours print failing after 2-3 hours all the time. Could not find anything Googl'ing so here I am on the forum : Any further hints?

[philippe44 0]

Just to check, I've replaced the BB core by an AA and printed the same part with same support but using that other AA core with PLA. The idea is to make sure there is no issue with the feeder. So far it has been printing with no problem.

[tomnagel 126]

Have you installed latest firmware (7.1.0)? If you can reproduce the situation again, please save the logfiles to USB disk within an hour after the error, and post the ZIP file here, I will have a look

 

[philippe44 0]

I did install 7.1.0 and I'll update the log