Feeding issue
Yesterday, the printer developed a very persistent issue feeding the filament during a print. I've done a bunch of researching these forums and the broader web, and done tons of experimentation late into last night and most of today. No fixes I've tried have worked for long.
The problem:
Upon starting a new print, everything is fine for a little while, but then the extruder starts making a clicking noise (usually during the first layer), and the filament either stops, or comes out very slowly. When the problem first started, it would only happen for a bit (50mm of travel or so), and then the filament would start flowing normally again for a while. As I've been troubleshooting, though, it's only gotten worse and now, once it stops flowing, it doesn't start again.
Relevant details:
- The printer is in the Prusa enclosure.
- Before the issue started, I'd been running multiple back to back prints that use the whole bed, but are very short (gridfinity base pates).
- The problem happens across three different spools of two different types of filament (PLA & PETG).
- I replaced the hot end with a new one, which maybe helped briefly, but the problem quickly returned.
- I've cleared several clogs in the nozzle during my troubleshooting, but I feel like they've been symptoms of the problem, and not the cause.
My research led me to two possible issues.
- Some people have reported issues with the enclosure getting too hot and some of the plastic parts getting soft and deforming. Of particular note was the idler lever.
- Someone recently on this page helping another person with a similar issue mentioned "heat creep."
Both of those still seem like possible culprits, however..
- The first print I tried this morning exhibited the same problem immediately, after the printer had been sitting idle and cooling off all night. Standing there with the doors wide open doesn't stop the problem from happening.
- The printer very briefly started working again today, as if by magic, managing to squeak out parts A and B for a new idler lever before failing again. I took out the old lever, intending to replace it with the new one, but when comparing the two, they're an exact match. Even comparing them under a magnifying glass shows absolutely no difference in any dimensions to suggest any deforming or warping of the original.
I think I've now managed to narrow things down to quickly reproduce the problem without having to wait for the printer to do all of it's homing and leveling at the beginning of a print. My steps are as follows.
- Start the process of loading filament in to the extruder.
- If the extruder fails to purge any filament, skip strait to step 5.
- Otherwise, once it's done purging, when the printer asks if the color is correct, tell the printer to "Purge more."
- Repeat step 3 until the extruder starts clicking and the filament stops purging.
- At this point, I can release the idler lever, tell the printer to "Purge more" and manually push filament into the top of the extruder and it will ooze out the other end as if it's extruding under it's own power. (This rules out a "clog" in my opinion).
- Now, I can re-clamp the idler lever, tell the printer to "Purge more", and IT WILL... for a while, maybe one or two whole purge cycles, but by the third cycle (usually the first or second), it will always start clicking again, and the filament stops feeding.
- Return to step 5.
Any suggestions on how to proceed would be greatly appreciated.
RE: Feeding issue
Update
After leaving the printer sitting with the enclosure doors open for 16 hours, it immediately failed to purge, and I can alternate between steps 5 & 6 above and it starts clicking and stops purging within seconds on each attempt at step 6.
RE: Feeding issue
Current state of the idler adjustment, since I expect that'll be a question.
RE:
This is so absolutely frustrating.
This post has been up for over two weeks with not so much as a "Hmmm, that's odd" from anybody at Prusa.
I've since bought the MK4S upgrade kit and installed that hoping that would fix things if the problem was due to heat warping the plastic parts. That's installed and I also removed the printer from the enclosure. This seemed to improve for a couple of test prints, but then immediately devolved back to the same problem. So, I think that rules out overheating.
The only thing left that I could think of was replacing the gear assembly in the extruder. So, I ordered a replacement, installed it, ran the allignment/calibration for it, and everything worked great for .... a couple of test prints. Then it, again, devolved back to the same problem.
So, the point I'm at now is right where I was. The printer won't even get through the first layer of a small print before the filament (Prusament PLA) stops feeding. Frequently this is correlated with a clicking or grinding noise, but not always. Manually purging after freshly loading filament is the same. It might purge for a bit, but always quits in the first, second, or at most, third purge cycle.
I've lost track of how many tens of hours I've spent fiddling with this. I used to calibrate and repair medical equipment used in operating rooms and emergency rooms, and I've never ever had this much difficulty with a piece of equipment. I was very seriously eyeing the XL as a holiday gift for myself this winter, but now I'm on the verge of throwing this thing out and swearing off Prusa forever.
RE:
Have you tried cleaning filament? Have you tried a high temp filament purge? Have you tried adjusting the idler tension screws?
Also, there is such a thing as bad filament, especially since you've been through different extruders. Some filaments go bad, crystallization sets in and you get hard chunks showing up in the filament. A chunk larger than say 0.4mm and you get a clogged nozzle. Eventually the filament becomes so brittle it will break all by itself sitting in a vacuum bag.
As for complaining you're not getting a response here, this is a free user to user forum, no one is paid to help anyone. And honestly, sometimes it is better to not get a response than have to read some of the hairbrained ideas a lot of people have about how to fix this or that. Add the fact you posted a printing question in the hardware section.
RE: Feeding issue
Have you tried cleaning filament?
No, never heard of it. I'll look into it, thanks.
Have you tried a high temp filament purge? Have you tried adjusting the idler tension screws?
Yes, and yes. Multiple times for both.
Also, there is such a thing as bad filament, especially since you've been through different extruders. Some filaments go bad, crystallization sets in and you get hard chunks showing up in the filament. A chunk larger than say 0.4mm and you get a clogged nozzle. Eventually the filament becomes so brittle it will break all by itself sitting in a vacuum bag.
The filaments I'm having problems with are brand new and different brands (Prusa and Sainsmart). The problem started part way into a new spool of Sainsmart filament, so suspecting that might be the issue, I broke open the Prusa filament and tried it. There's no apparent difference between the two.
As for complaining you're not getting a response here, this is a free user to user forum, no one is paid to help anyone. And honestly, sometimes it is better to not get a response than have to read some of the hairbrained ideas a lot of people have about how to fix this or that. Add the fact you posted a printing question in the hardware section.
Understood, and that comment wasn't at all meant to be addressed at other users. Considering this isn't just some random forum on the internet, and instead the official "Forum" linked directly to from the official website and hosted on the company domain, I don't think it's unreasonable to expect that the company pays someone to monitor what gets posted here and therefore should be paying someone who knows what they're talking about to answer questions. If it were my company, I sure as heck wouldn't be hosting a support forum on the company website without making sure it was presenting a positive image of the company. Maybe I'm weird that way.
Anyway, I'll look into that cleaning filament you mentioned, although I'm not optimistic at this point.
RE: Feeding issue
An example (I haven't used this brand) https://www.matterhackers.com/store/l/cleaning-filament-1.75mm/sk/M8M6988V
But I find raising the nozzle to 280c and pumping through a meter of fresh PLA almost as effective.
And to be 100% clear, you have changed the extruder, right? The heater block, nozzle, thermistor. And you are now at the 4s model stage with the Nextruder?
Have you closely watched the nozzle temperature while this is happening? Broken wires in the bundle from the extruder to the control board are pretty common and can cause what you are seeing, too. The only sign is the nozzle starts cooling down.
Regarding this website: Prusa has a chat window to help customers having problems.
RE: Feeding issue
An example (I haven't used this brand) https://www.matterhackers.com/store/l/cleaning-filament-1.75mm/sk/M8M6988V
But I find raising the nozzle to 280c and pumping through a meter of fresh PLA almost as effective.
Sweet. Thanks.
And to be 100% clear, you have changed the extruder, right? The heater block, nozzle, thermistor. And you are now at the 4s model stage with the Nextruder?
Yes. First thing I did was change out the whole hot end when I thought the problem was a clog that wouldn't clear.
Have you closely watched the nozzle temperature while this is happening? Broken wires in the bundle from the extruder to the control board are pretty common and can cause what you are seeing, too. The only sign is the nozzle starts cooling down.
No, good idea. I'm usually paying more attention to the temps when I'm waiting for them to get up to temperature but after that not so much. Next test I'll see what happens there. Thanks!
Regarding this website: Prusa has a chat window to help customers having problems.
Heh. Didn't see that. (sigh) Thanks.
RE: Feeding issue
You need to be on the store side of the site to see the chat option, rather than forums.
RE:
Did you perform a cold pull after the problems started and before you replaced the hotend ?.
I expect you replaced also the nozzle when you installed the new hotend ?.
I ask this because these symptoms are typical of a partial clog. Not easy to diagnose in a nextruder because nozzle and heatbreak are a single part.
If you perfomed one or more cold pulls, did they look like the image below, showing a neat tip at at the end of the conical shape ? ( I hope you're not using those troublesome HF nozzles, because then cold pulls would be meaningless ).
