MMU2S Loading filament to extruder, but then the extruder rejects it....
Hi,
I got my MMU2S upgrade this june and it worked great for a little bit, but it's constantly having problems. Every time I fix it, I can generally get one or two prints out of it. One of the most reccuring problems is that the MMU starts to load the filament like normal, it gets to the extruder, waits a little bit, and then comes back out, unloading. It does this a few more times until either it says MMU load failed or it tries to print without filament. Ive been able to track this down a few times and fix it, but this time specifically I just can't seem to figure out why it is doing this. It goes in just fine, and I can see that the extruder bearings grab onto it, and they spin as if they are pulling it down towards the nozzle, but then they go the opposite way, unloading the filament. Is there something I should double check based on the description of my problem, or something new I should try?
Also:
-I've checked for jams, nothing is in there.
-the PTFE tube in the extruder is aligned correctly, I checked.
I would be very thankful for any help/advice as I am relatively new to the world of 3d printing, and need some help to finally fix my troublesome MMU2S
Thanks in advance!
RE: MMU2S Loading filament to extruder, but then the extruder rejects it....
I am having the exact same problem and have a post for this also in this forum. Most people say it is an IR sensor problem but I don't know. I have aligned the sensor multiple times and also printed out several different flag designed. Best of luck. If I find my issue I will post here but so far not luck. I had a string of successful prints and then had a really bad jam and it has not worked since.
RE: MMU2S Loading filament to extruder, but then the extruder rejects it....
Yeah, the comment you made about the IR sensor made me double check it, but no luck there...:( It's good to know though that I am not the only one with this issue. Hope you can find out your issue too! Ill make sure to update If i find something out.
Haha, I forgot that the website does the date by DD/MM/YY and not MM/DD/YY... I thought this was a post from the future for a second!
RE: MMU2S Loading filament to extruder, but then the extruder rejects it....
Definetly the IR sensor as the printer is not controlled by anything else in that moment. Another hint is continuing printing with no filament. Check the sensor read out in the settings menu. The IR sensor must read 1 all the time when the filament is in the extruder. It must not flicker. As I described in my recent (and first post here) the IR sensor does react on the position of the head as the PTFE tube bents the chimney a little bit. Check that as well. Calibrating the sensor in any other position does not always yield the result you want.
RE: MMU2S Loading filament to extruder, but then the extruder rejects it....
Unfortunately i too am suffering the same frustrations,my fix is reboot the mmu then power cycle the whole thing,to me it seems software related that the two stop talking to each other,you know how family gets, one sometimes just has to go against the grain,til dad steps in.
RE: MMU2S Loading filament to extruder, but then the extruder rejects it....
I am not too sure that there is much talking going on. And if it doesn't grind the minimal talking works perfectly fine. It just has the two sensors to negotiate between their actions. In your case what is exactly happening?
RE: MMU2S Loading filament to extruder, but then the extruder rejects it....
I Found one of my Problems. The set screw on the bondtech gears had loosened. I was not totally loose so it would print most times but every ones it a while I think it was slipping. Send thing I did was replace the extruder PTFE tube with a Carpicorn. It seems a little slicker than the regular PTFE tubing. I am not having failures with the MMU so I am printing out a new selector body with a magnet for the ball bearing. I had a few failed prints because it pulled the filament back to far.
RE: MMU2S Loading filament to extruder, but then the extruder rejects it....
I think I got the same problem...
I made a video:
But I have changed the filament sensor with my other Prusa, they work without problems.
Does anybody has an advise for me?
RE: MMU2S Loading filament to extruder, but then the extruder rejects it....
UPDATE: PROBLEM SOLVED
Ok so after a while I finally got on a live chat with prusa support. I originally thought that my screw with the spring on it, used to keep the idler door shut, was tight enough, but turns out it was just loose enough to be causing me problems, and was messing with the IR sensor. I turned it half a rotation tighter and now it's been doing everything independently for three prints straight and counting. Thanks to everyone who gave advice, even if I didn't end up using it. I hope this helps others with similar problems too. 😀
RE: MMU2S Loading filament to extruder, but then the extruder rejects it....
@owen
Thanks for the tip and it fixed my problem as same as yours.