RE: Filament sensor triggering for no reason
Unfortunately it happened to me today again 😥 . This time with the hardened 0.4 nozzle and Prusament PETG Carbon Fibre. Pattern seems the be the same. I can see on the bed an under-extrusion shortly before and the filament in the extruder looks cut out by the gear. It looks like (base on the print quality on the print bed) the nozzle or heatsink temperature might go slowly down up to the point where the filament can not be pushed through anymore. The gear starts rubbing the filament until ist slips. I'm curious to understand how the XL measures the filament runout. If the sensor is located above the gear (as I guess) it actually could not trigger, because the filament there looks 100% normal. However if the XL also measures and consider the resistance of the transport gear it would make sense. As soon as it slips, there is basically a reduced resistance indicating there is no filament anymore. Of course just guessing here without technical specs, but it's also funny that it still goes for the unload process and can actually do it (see pic). From the logical point of view, going for the unload process makes only sense if the outside sensor has triggered, right. Btw, I continued the print, but saw basically on the last three objects (the three large ones on the left hand side) before it happened a missing layer effect on the next layer. By now I can not say whether the grub screw has loosen again. What I can say it that I did not see it on the print bed (yet) 😬 . I'll check it after the print. As you can see I also tried to take some temperatures. Bed is OK, gear I would say no problem, however the nozzle I couldn't get right. What ever I did (evens move the sock down) I could only get around 150C max, although the display said 265C.
I would really appreciate if Prusa takes it serious and look into this topic or at least opens the technical details in order to find the root cause. Looking also at @backroadman case and progress there must be something wrong, especially if it even re-occurs after the exchange of the tool head.
It's a quite expensive machine and it's still under warranty. And after 18 Monats waiting time I do not really want to become a public beta tester. Hope Prusa shares the same view. BTW, does anyone knows to address this issue official (I mean not chat) to Prusa. Is it sending an email? Thank you.
RE: Filament sensor triggering for no reason
Quick update. The rest of the 7 hours print finished without further problems. However at the end one can clearly see the "missing layer/filament" impact on the three objects before the filament sensor triggered for an "incorrect" reason. The close up is the one in the left back and effected first. Not sure what happened, but it seems to be a time frame of about 2-3 minutes where no filament comes through the nozzle, scratching it with the gear instead and finally ending with the filament change event. Looking closely to the print when it happened I could also see that the filament does not get the right temperature anymore, shortly before it finally stops extruding. Looks a like some drops and "dry". You can see this on my previous post with the gray Prusament PETG as well.
I guess it's also worth to mention that the nozzle was actually never clogged or blocked when loading the filament in again.
BTW, the grub screw for the heatsink was still at its place and tide.
I'm not an expert, but it seems to be related somehow with the temperature control of the nozzle.
Any ideas? Thank you.
RE: Filament sensor triggering for no reason
Wish Prusa would chime in on this issue. It seems like the Logic board timming of the filament release is off and as soon as the print head hits the sheet it triggers the filament sensor to call a filament change command. I really don't think it's a mechanical problem but PRUSA needs to own up to the problem not us.
RE: Filament sensor triggering for no reason
Having the same issue - now filament sensor hard fails the calibration. What is wrong with the XL's sensor?
RE: Filament sensor triggering for no reason
Just wanted to add I am also having the same issue. This started with problems on the side filament sensor which I was able to fix by disassembling it and lightly cleaning the parts. After that, I was able to print flawlessly for about a week. It has now evolved from the extruder sensor failing while swapping filaments mid-print to now completely not working and failing calibration.
RE: Filament sensor triggering for no reason
Just to close the loop Prusa support did send me a replacement side filament sensor which has resolved my issue. My side sensor values were barely changing based on whether the filament was inserted or not.
Prior to replacement, the sensor was. between 1300 with no filament to 1080 with filament installed. After replacement, the values are 1230 with no filament to 460 with filament installed.
RE: Filament sensor triggering for no reason
Having the same problem here now (XL filament sensor failing), I guess it's time to message support. I had similar problems with most of my old MK3's over time too (sensors just died over time), I wonder if they've just got a bad supplier or something.
RE: Filament sensor triggering for no reason
Although my sensor values looked in the monitor actually OK (basically the same range as after replacement), but after I got replacements for the side and head sensor from Prusa it never happened again, up to now. I suspect one of those sensors had sporadic stability issues. BTW, also the other print quality issues I experiened are all gone by now. However that could be caused by the recent firmware upgrades. For now I'm happy...
RE:
I have been doing a lot of experimenting with my enclosure the past few weeks. Between the long PTFE runs, temperature sensor, and higher temps there are issues.
The long runs of small ID PTFE of almost a meter and a half is a issue at higher temps. Between the difference in the expansion an contraction at mostly higher temps +45C printing ASA became a issue. I was getting filament binding at 3 key points. 1. Developed a kink at the wire ties behind the docking station. 2. Compression from the little black anti slide clamp on the PTFE tube. 3. Another kink where the PTFE enters the pneumatic connector on the Nextruder.
Between the small kinks, compression and the tension from the filament sensor. The filament would bind and stop feeding. The feed gear would just spin. At any temp under 45C I had no issues.
So to remedy this for now I switched the 1.9mm ID x 4mm OD PTFE tubing to a 3mm ID x 4mm OD PTFE tubing. I went to one wider wire tie in the back that is lightly tightened down. I also bypassed the filament sensor. Ever since I did the above I have had no issues.
Prusa should look into switching to larger ID PTFE tubing and putting a new modern filament sensor without the ball bearing. And maybe putting a spacer between the sensor and printer itself.
I would also think doing a top feed would be a good idea since it only require a few short runs of PTFE tubing.
You can check out my thread to see what I have done so far. I have over 300hrs of printing on my XL.
RE: Filament sensor triggering for no reason
Like ZeeKay mentioned when I started having this problem I took the side filament sensor apart and could see that the filament had cut the groove in the part deeper. I had ran a few rolls of glow in the dark filament and guess it's not really designed for abrasive filament. Seems like it would be an easy part to reprint, but I don't want to have to do that regularly.
My quick fix was to drill and tap M3 holes in the center of each slot and slightly round the end of some M3 bolts with a file. Seems to work for now but I've only done one small print.
RE: Filament sensor triggering for no reason
My XL has started to experience the same issue. This happens on long prints when I will need to add another spool of filament. It appears the machine will preform a few layers of very under extruder layers. Then it will stop and request for more filament. But at that point it’s too late. Nozzle is so far away from the print I have to start the whole print over again.