Filament Stops Feeding
I've got a Dual Head XL, and I'm experiencing an issue with one of my Nextruders; it randomly stops feeding the filament.
It will stop on the second or third layer of a large (3+ hour) print. It seems okay if I do a smaller print, up to about 1.5 hours. Out of 12 attempts, one reached about 40% before it failed, and one was successful. All others failed within the first three layers. The 40% print and the successful print happened randomly during the 12 attempts.
The nozzle is not clogging. When I remove the filament, an area is worn away. It looks like the filament gets stuck, and the gear spins on the filament. But when I check the filament, before removing it, it moves freely. When I say it moves freely, I've checked this a couple of ways. First, I lightly pushed the filament into the guide tube and it started printing again. Second, when I open the filament drive gear door to clean it, I can pull the filament out freely if the nozzle is hot (well, with the expected amount of tension).
This happens with multiple files and different filament. If I print the same parts on the other head it works fine. I even used the same filament on the other head, so I know the filament is good.
Here's what I've tried, but the problem still exists.
- I cleaned and recalibrated everything.
- I reset the belt tension (unrelated to the filament but was part of my "recalibrating everything," and I had a different failure that prompted this).
- I cleaned the filament drive gear multiple times. (Is there a way to lube the filament drive gear, or is that unnecessary?)
- I changed the nozzles on both heads.
I was using the original 0.4 mm nozzles when the problem started. Now, I'm using the Nextruder V6 Nozzle Adapters (on both heads). - I tried both 0.4 mm to 0.6 mm brass nozzles with the adapter.
- I resliced the parts to get new .bgcode files (multiple times).
- I upgraded to the latest printer, Firmware v6.0.0.
- I tried different filament multiple times, even new filament right out of the bag.
- I tried black filament, thinking the blue color pigment could be causing an issue (I don't see how, but I was grasping).
- I adjusted the tension on the filament drive gear door, even though it's set at the factory and shouldn't need adjustment (both looser and tighter).
(I've got it set back to where it was now.)
I think I will swap the Nextruders at this point. That will eliminate the filament guide tube and the filament sensor.
I'm open to any help or suggestions.
Thanks in advance for all help!
RE: Filament Stops Feeding
First of all I would bypass the filament sensor on the side. You can turn it off pretty easily in the menu of the new firmware. Also please check if a little higher temperature might solve it.
Please also check if the bearings/drives in the nextruder that push the filament to the gear rotate freely.
This already happened to a lot of people me included, but for me the problem only happened with TPU of specific brand.
The long reverse bowden path is big problem actually.
RE:
Thanks,
I just swapped the Nexteuders, and did a factory reset. I’ve been getting multiple Red Screens since the firmware update. And, my Print Fans won’t pass the self test if I don’t take the air diverter off.
I’ll try your suggestions if it fails or on my next print whatever happens first.
RE: Filament Stops Feeding
@w sand - did you get to the bottom of the problem? I’m experiencing the same problem on tool 1. Extruded stops extruding part way through the second layer. Tool 2 has no issues printing the same file so in my head it’s a mechanical problem with tool 1 somewhere as environmental variables are equal for both prints…..
RE: Filament Stops Feeding
I think I might have it figured out, but the repairs are not complete yet.
I contacted support via chat on their website (these guys are great once you get through to them). They told me to clean the filament switches on the side of the machine. While doing so, I found the #1 Sensor was sticky. It turned out to be a parts manufacturing defect (the print had a burr inside where the ball moves). They are shipping me a replacement (it's currently in transit, so I should have it Monday). In the meantime, I removed the sensor block from the housing and turned off the sensors in the config. So, my side sensor assembly is just a guide at this point.
I also found that the block that pushes the filament against the gear is also defective. Prusa support sent me a link to print a new one ( https://www.printables.com/model/449554-xl-printable-parts/files ). I don't have it printed yet, but I should have that done in the next few days. This part is on my second head, but it was on my first head when this all started. I found this because if I get any drag on the filament, it will intermittently slip. For example, if the filament gets crossed up on the spool, so it's not coming off normally, or if my routing from my bottom spool to the sensor block gets slightly pinched or anything, the filament slips on the gear.
I also ordered some extra guide tubing and will use that to route my filament from my bottom spool to the sensor block. Pursa has the tubing for sale ( https://www.prusa3d.com/en/product/ptfe-tube-4x2-5x1275-mm/ ). I got mine from Amazon ( https://www.amazon.com/dp/B08Q813BQV ), so I didn't have to deal with the long shipping time since I'm in the US. Prusa's is cheaper, but Amazon's is faster. I figured I might as well make sure. It can't hurt.
When this all started, the two bad parts were on the same head.
So, I'm currently working on three fixes. Hopefully, with all of this, I'll get it fixed.
I'll keep you posted.
RE: Filament Stops Feeding
That sounds promising….. I did some experiments today to narrow down my problem and think I’ve ended up in a similar place….the filament sensor….
First I tried changing out the ptfe tube on tool head 1 with one with a wider inside diameter. Print got a bit further and then stopped extruding.
Secondly, Then I moved the print so that it was closer to the tool head. Nope…..stopped extruding.
I then took the filament sensor out of the picture by jamming a piece of filament in it and ran the spool on a low friction spool holder directly into the ptfe tube. I ran the print again and it printed successfully. Ran it again on a different position on the bed and success again….
So my thinking is that the drag caused by the sensor and / or the ptfe tube (leaning towards the sensor) is causing the extruder gear to slip which leads to the filament getting “stripped” and once that happens, extrusion stops.
Based on your experiences, I’ll pull the filament sensor apart next and see if there’s an issue in there.
Re the block that pushes the filament against the gear - was there a physical defect that you found or was it just the slipping filament that gave the clue?
Thanks for sharing ! It’s really helpful as I was getting frustrated with this problem……
RE:
This is the procedure they gave me to clean the side filament sensor.
https://help.prusa3d.com/guide/how-to-clean-the-side-filament-sensor-xl_547477
This is the procedure they gave me to clean the filament sensor on the head.
RE: Filament Stops Feeding
I then took the filament sensor out of the picture by jamming a piece of filament in it and ran the spool on a low friction spool holder directly into the ptfe tube. I ran the print again and it printed successfully.
@kevlad : You can also change the settings to turn off the filament sensors.
It's in Settings/Filament sensors. Then, find Side Filament Sensor 1 & Side Filament Sensor 2 and turn them both off. Then, you don't have to put filament into the sensors. You can even disconnect the connector, and everything will still work (this is how I'm running right now).
RE: Filament Stops Feeding
Thanks W-Sand. I took the filament sensor apart today and didnt see anything obvious wrong with it. The metal balls all seem to run smoothly in the channel. Decided just to bypass the side filament sensor in the short term and design something that lets me mount it somewhere else the allows for a straighter run through both the sensor and the ptfe tube.
RE:
I came across this today. It's a discussion and parts to remove the springs and use magnets to reduce drag caused by the filament sensors.
https://www.printables.com/model/700838-xl-side-filament-sensor-with-reduced-force-magneti
I'm gonna do this too.
Here's a link to the magnets I ordered from amazon. https://www.amazon.com/gp/product/B0CCXYF5TR
RE: Filament Stops Feeding
This just started happening to me a few weeks ago. Filament stripd at random times. Sometimes early, sometimes just a few layers from the end. Using Polymaker ASA. On inspection, it looks like the classic grind-up scenario that I'd thought was a thing of the past. Certainly not something I expected from a brand new, highly touted redesigned toolhead. At first I thought I had a clog, but it happens now on all toolheads and with new nozzles. I don't use the filament sensor, I don't even use the stock filament path; my path is much shorter, at least half the length of the original. And it's happening with filament right out of the bag and filament dried under vacuum. Slowing down isn't helping, disabling retraction isn't helping, tweaking flow isn't helping. Tweaking tension isn't helping. Point is, I've been printing for many years and it's been quite some time since I've come across a head scratcher as annoying as this one. Sorry for not having anything to contribute in the way of fixes. I'm in the process of trying out toolhead part mods myself. The XL is so weird. Flawless one moment, infuriating the next. What a mess.
RE: Filament Stops Feeding
Hi AMV,
I started another thread about underextrusion of filaments other than petg or pla (Linked post). Printing a new tension arm solved the problem for me. Doesn’t take long to print so might be worth a try?
good luck!
RE: Filament Stops Feeding
I haven't had the problem in a while now. My issue was not tension at all. And I do not think it had anything to do with the hardware or the printer's design. I had a friend suggest that maybe the temperature was too high. I have a third-party enclosure on my printer. I took the enclosed top off, and it stopped failing. Then I tried putting the top back on and opening the top door, and it still works great. I close the door, and it fails almost every time. All I can figure out is with the enclosure and the seasonal change, the temperature rose just enough to start melting the filament too far up, and it would start slipping.
I hope this helps someone.