Failing prints when extruding small amounts - help needed
Firstly I'd just like to say after years and years of telling myself "I won't use it enough to justify it"; since I built my Core One I've been printing so much more than I ever imagined I would and I've been having a fantastic time with it.
Now I've been having a problem with some prints which dates back to probably the first weekend I had the printer up and running. It doesn't happen on every print but if you find a print where it does occur it will repeat the issue quite reliably. In fact, I have isolated a few scenarios and cropped the prints down to just the areas that cause this issue sort of as a benchmark to see if I could resolve the problem by changing variables such as print speed, door open, door closed, etc. However so far I've not had any luck which is why I'm here asking for help.
I have two videos demonstrating the issue along with a Prusa slicer screenshot of the area in question so you can see what's being printed.
Example One
0.15mm layer height; Prusament PLA (Galaxy Black and Prusa Orange).
This is a little character I was printing for my partner to show demonstrate the printer. It was unfortunately the first print I ever had fail.
So as you can see it cannot deal with the ears. The full model has failed like this 4 times. After cropping down to just the the ears I can get a failure after just a few millimetres of print height.
Example Two
0.2mm layer height; Prusament PLA (Galaxy Black).
This is more recent one I've recreated. I noticed in one of my real prints that while trying to use organic supports to support an overhang that was only about 1.6mm off the print bed. It caused the organic supports to be plentiful but tiny (presumably because of the lack of height) and that seemed to also cause the issue.
My Observations/Things I've Tried
- Once the head of the printer starts making that clicking noise it won't recover on it's own; even if it gets to a part of the print which requires heavy extrusion (you can see this when it starts to do the infill in the second example video).
- If you pause the print and do a filament change and just reload the filament it'll print again for a short period.
- I have recreated this with the door open, door closed. Door open and the window to the room open with the cold winter air flowing in the room.
- Heatbreak temperature being maintained below 32 degrees, still occurs.
- I have noticed there could be a correlation that the print cooling fan is at 100% when this failure occurs (because the layer takes less than 8 seconds to print).
- I have ran at a slower speed for these difficult areas, still occurs.
- I've done cold pulls until I get the 3 small filaments at the end nice and clean.
I'm hoping someone can help me work this out as I feel like I've run out of ideas.
Thanks for taking the time to read this far!
Adam
RE: Failing prints when extruding small amounts - help needed
Clicking is not normal and I'm wondering if your problem is related to the nearby post from @jbpr on underextrusion. Can you zip and post your two 3mf files. I want to run them and see what happens. In the moderate amount of printing I've done, I don't think I've heard the head click once.
RE: Failing prints when extruding small amounts - help needed
Also throw in the STL files or a link to the models. Thanks!
RE: Failing prints when extruding small amounts - help needed
Hi Conrad, thanks for your reply I really appreciate it.
You can find the 3MF files for both the failing tests I showed video for here. I've included the STL for the model I created to quickly cause the problem too. I've not included the STL for the bunny because it's not mine, I just cut the ears off in Prusa Slicer for this test. The original model was this one...it actually seems to have been removed from Printables. I'd love to hear how your printing goes with those.
I really hope my problems aren't the same as @jbpr in the other thread as it sounds like he's been through a lot trying to find the cause. However, as a lot of suggestions seem to suggest a heat issue I thought I'd conduct a stress test and I printed the 15m Benchy from the USB stick, door closed, vent closed, chamber fans off, the absolute worst case scenario. Heatbreak got all the way up to 40 degrees, the Benchy is indistinguishable from my other two and the no sign of the issue I'm encountering.
I am currently printing a Benchy that I have sliced myself from Printables; to see if it's possibly a Prusa Slicer issue? I am literally reaching for anything at this point.
The only other thing that crossed my mind is if when I was installing the hot end assembly I could have done the two thumb screws up too tightly? The directions said 'firmly' and I wonder if that should have been more like 'just snug'. But I'm not sure why that would only manifest as an issue in situations where it's not depositing a lot of material.
It's almost like a clog is occurring and the extruder can't feed material through but I'm just not sure how that's happening.
RE: Failing prints when extruding small amounts - help needed
I see that you have the printer profile set for a 0.4mm HF nozzle. Do you actually have a high flow nozzle installed? You also have it set for PLA. Are you sure it's PLA and not PETG?
With regard to it potentionaly being a PrusaSlicer issue I would say: no, it's most likely user error in this case (selecting the wrong profiles) or something mechanical.
If you've hand-tightened the thumb screws then they are not too tight. You want it firm enough that the nozzle and heatblock assembly doesn't rotate or drop down.
RE: Failing prints when extruding small amounts - help needed
Thanks for your reply hyiger.
I believe the Core One ships with a high flow nozzle. Also when I've done cold pulls I've seen those 3 separate filaments coming out which I believe is due to how the high flow nozzle is made? I would have to say yes, I have a 0.4 high flow nozzle but I couldn't be 100% without taking it back out the printer and reading the tube. I am relatively sure I'm printing PLA; with the caveat if there were PETG on a PLA labelled roll I don't have any experience of PETG to know the difference. I've printed with two different rolls and both smelled the same though, I imagine PETG might smell different to PLA.
I am all for being told it's user error, I just don't know what would be causing it.
Yep they were hand tightened only, I guess I'm just worried I have a strong finger and thumb and looking for a possible cause. The hot end assembly does not twist or drop, it's definitely secure.
The Prusa Slicer Benchy printed fine; in fact, better quality than the 15m Benchy as it did take 40 minutes. Does make me wonder what tricks they perform to print Benchy in 15 minutes; it's quite impressive!
RE: Failing prints when extruding small amounts - help needed
Bit of a weird one..like @hyiger said it's very likely to be mechanical.
You've ruled out the obvious like correct filament and nozzle selected?
How is your filament being fed? Is your filament roll on the hanger on the side of Core One? Are u sure there's not resistance where the extruder is pulling the filament from the roll? Ive had it before where a (badly wound) roll of filament had basically got stuck and it lead to very similar clicking from the extruder.
One other thing to check is to open the idler door, (the latch above the fan...) look in there from the left hand side (shine a torch for a better view)...does it look clean? any filament debris on the gear?
RE: Failing prints when extruding small amounts - help needed
I ran the ears, making no changes to your 3mf file. Pretty much perfect with Buddy 3D PLA and a 0.4 mm hf nozzle. I'll put up a photo after trying the second print. I've had the same worry about the thumb screws, but you have to remember that the head is moving rapidly and suddenly, so they need to be reasonably tight, lest the nozzle shift. If you grab the sock and gently twist, the heat block shouldn't move, but it shouldn't be much tighter than that. As @hyiger asks, are you positive it's PLA?
RE:
Here's a couple photos. The disk has so much support they're impossible to remove, but I suppose that's the idea. At any rate, I don't think all PLA is the same, but a simple one with no sparkles or blend seems to work fine. The clicking still bothers me. Did you remove the tube from the Nextruder and pull on the filament from that end? It should take very little to draw it out and rotate the spool on the side of the machine. Anything that makes it harder for you makes it harder for the Nextruder. A badly cut end or burr or misalignment might be a problem. Or, I'm flumexed again.
RE: Failing prints when extruding small amounts - help needed
RE: Failing prints when extruding small amounts - help needed
One more thing to check! I read about somebody having a problem with the ID of a tubing fitting being too small. Low odds, but take the tubing fitting right out of the Nextruder, put it back on the tube, and do the pull test.
RE:
Hi there
While your the printer in the video sounds exactly like mine sounds, the files provided in the thread here just came out fine (apart from some very, very fine strings between the two ears). No clicking, no underextrusion.
My last tests that I made for my other thread this morning looked like this though:
Since you mentioned the 15min benchy prints fine, it is not the same behavior as with my printer. My benchys used to look like this:
Now they look like this:
I really hope you figure out what is going on with your printer. I cannot figure out what is wrong with mine...
RE: Failing prints when extruding small amounts - help needed
Good afternoon everyone and a good afternoon it most definitely is!
gb160 thank you for your reply and Conrad, thank you for taking the time to print those tests out for me and confirm it wasn't anything to do with the files. I hope the disc wasn't too much hassle to get off the print sheet!
So after reading your posts that came in while my previous one was waiting for moderation (how many posts do I need before that stops happening?) it spurred me to investigate filament feed. It's not an area I've experimented with because the printer feeds absolutely fine when it's printing at speed, it's just smaller extrusions it's having an issue with which made me think the filament feed was fine.
I removed the filament and undid the bowden tube fitting from the print head. I tested how it felt pulling the filament through with the fitting still in place and it felt easy enough but I also have no reference. However, pushing it back in to the tube was significantly more difficult. I decided to see how the printer would perform if I eliminated the bowden tube altogether so I fed filament straight in from over the side.
Obviously this would be a nightmare in a real world scenario but these prints are so small I just stuck around and made sure there was always ample filament available so it wasn't doing any work except shoving it through the hot end.
Now would you look at that! So at this point I realised I've actually made two changes because I'd also removed the top so there was loads of room for hot air to escape so I wanted to do a few more tests to make sure I'd definitely identified the issue. So I did a few more prints:
- Bowden tube on, acrylic off - failure.
- Bowden tube off, acrylic on (with a screwdriver propping it up to allow the filament in) - success.
I checked over the feed tube assembly and the filament sensor near the filament holder adds a bit of resistance but it's nothing compared to what happens when you add this to the bowden tube...
I've just done both tests again with the whole printer back together, minus that part. Both successful.
Obviously I know that part is there for a reason but at least now I know it's resistance in the feed tube, be it from a single thing or the accumulation of resistance from everything.
Thank you all so much for your help and suggestions. I've been fighting with this on and off since the start of February and not once did I consider looking at the bowden tube as it seemed like it was all in order.
jbpr, I know your symptoms are quite different from mine (other than the extruder click) but have you tried omitting the bowden tube and feeding filament straight in to the print head? If you haven't it might be worth it if only to eliminate that as a problem area.
RE:
That's fantastic that something finally affected it! Now the question is, what's wrong with the part? Mine and most seem to work fine, but there has to be something different with that one or in the immediate vicinity that interacts with it.
BTW, this is similar to the problems I had feeding very soft TPE-83A filament. It actually fed through the tube OK at speed, probably because it was being vibrated or wiggled through. But, there was no way to overcome the friction and pull it through at low speed.
RE:
Good to hear it works for you that way. As @conrad wrote...the question is what is wrong with the part?!
I did try feeding filament exactly the same way. Unfortunately, it did not make any difference for me.
RE: Failing prints when extruding small amounts - help needed
@jbpr, did you unscrew and remove the fitting for the test?
RE:
@jbpr, did you unscrew and remove the fitting for the test?
Yes, it looked the same as in this post https://forum.prusa3d.com/forum/postid/786637/
RE: Failing prints when extruding small amounts - help needed
So I have an update. After gaining confidence with the idea of the resistance in the bowden tube causing my failures it turns out all those tests were just leading me up the garden path. I had a print fail without that black plastic curve at the end of the bowden tube above the head. I repeated the print but with filament feeding straight in to the head again which also failed. So seemingly back to square one.
I decided to take a good look at the extruder gear; didn't seem to be anything of note in there after the the filament was removed and the tensioner open. There was maybe a small amount of dust or lint built up in there. I manually rotated the extruder while I used a small clean paintbrush to brush over the teeth. I then repeated the process but with the paintbrush dipped in isopropyl alcohol. My thought process being here that the extruder gear is slipping after all so it can't hurt to try.
So the printer is configured as it's meant to be with regards to the bowden tube and the top window is in place. I've done several of my tests with the door closed, I've also printed 3 complete Miffy models (the full model that those ears belong to) without any problems. I'm reluctant to say that the issue is solved but the situation definitely seems improved at the moment. I'm starting to wonder if I put too much grease in the extruder gearbox and somehow it's getting out and on to the outside of the gear where it contacts the filament? I'm going to see how long it is before I experience another print failure and when that occurs I might consider removing the gearbox, cleaning it out and being a bit more conservative with the grease on reassembly.
Just an aside, when removing the PTFE tube from that fitting on the print head; is there a way to release it? As it seems no matter what I do the only way it's letting go is if I pull on the tube very hard. Pressing the black ring in, or pulling it out appears to have no effect.
RE:
Pressing the black ring is the release mechanism, but it can be a bit finicky and it needs to be evenly pressed all the way. Those fittings are fairly common in the pneumatic world and for some liquids, so they have to grip well.
This sort of problem seems to have shown up for people after printing fine for some amount of time. The grease theory fits because it would take some time for the grease to work its way to where it could cause trouble. More time will tell!
RE: Failing prints when extruding small amounts - help needed
I use the multi-wrench on the bowden tube release ring to press the ring down. One of the openings is just the right size to span the diameter of the tube.