More on the ongoing stuck filament issue.
Prusa MK4S - built from kit in April ‘25
Nozzle 0.4mm Hiigh-flow
Firmware 6.4.0
After 8 months of ownership and printing ,according the the printer stats, 2.5Km of filament, mainly PLA with some PETG and a little ASA, I have finally encountered the stuck filament issue.
Yesterday I was printing a large PETG object taking a little over 11 hours when I saw the problem; it first started around 50 minutes into the print and recurred at intervals of between 3 and 20 minutes. Each time I followed the on-screen prompts to unload and reload the filament and each time the print continued after extruding some filament, albeit with a surface imperfection visible at that point.
Eventually, against my better judgement, I disabled the stuck filament sensor and set it running again. The resulting print was flawless until, within an hour of the end, I heard something; a new sound which I haven’t heard or seen reported before...
When the nozzle was in one particular region there was a rasping or rubbing noise. The print didn’t stop so I continued to watch it to the end and after the print ended I inspected it and found that, confined to the region where the printer had been making this noise, the surface had a distinct roughness unlike the flawless surface formed after I disabled the stuck filament sensor. The rough area is close to and on one side of a seam which may be relevant?
I’m writing this in the hope that someone smarter than me can explain why the machine printed apparently flawlessly between disabling the stuck filament sensor and the sudden appearance of the odd noise and rough print.
I should add the this is with a new (less than 10 hours use) nozzle.
B
RE: More on the ongoing stuck filament issue.
My guess is that if you look at the region where you heard the rasping or rubbing noise, you’ll find that the bottom surface was curling upwards as it slowly released from the bed due to poor adhesion. As it curls up, the top surface also rises slightly but just enough to where the nozzle is now dragging through previously deposited layers. The extruder has to work harder to push out the filament, and that triggers the “stuck filament” error. Turning off the detection allowed it to run but didn’t fix the root problem of poor adhesion.
MK4S/MMU3
RE: More on the ongoing stuck filament issue.
I don't believe this is a 'curling up' issue as the region is on a vertical surface high on the print [1] .However your comment that the extruder is working harder for some reason is probably right, maybe somehow the extruder is trying to push more filament than is needed? I shall try printing the top of the model again; first with the stuck filament sensing off to see if the problem can be reproduced and, if so, I'll enable the sensing to see if the same region triggers stuck filament alerts.
[1] x between 200 and 210, y between 75 and 125, z between 80 and 115 (mm)
I didn't describe the problem fully for which I apologise. The attached image might help.
My guess is that if you look at the region where you heard the rasping or rubbing noise, you’ll find that the bottom surface was curling upwards as it slowly released from the bed due to poor adhesion. As it curls up, the top surface also rises slightly but just enough to where the nozzle is now dragging through previously deposited layers. The extruder has to work harder to push out the filament, and that triggers the “stuck filament” error. Turning off the detection allowed it to run but didn’t fix the root problem of poor adhesion.
RE: More on the ongoing stuck filament issue.
A picture is worth 1000 words! I think there may be two different things going on, probably unrelated.
You may have a partial clog in your HF nozzle. Have you tried doing a cold pull?
As for the odd noises, I don’t know. Maybe just harmonics?
Best of luck! Every day is a new adventure in 3D printing!
MK4S/MMU3
Please show us the underside of that failed print.
Cheerio,