Incomplete lines and first layer issues (A1)

[Chris_Je]

Hello everyone,

first of all, this is my first post on here and I am still rather new here - but from what I have seen so far as a silent observator, I am more than confident that the community can help with this issue (or at least hint me towards the right direction).

So, I got my Bambu A1 roughly two weeks ago and used it relatively often - I have to say, this is my first printer, so experience was very limited, but prints came out SO good at almost 100% success rate, that even as a total beginner it was possible to run overnight prints etc. - it was really great.

Then, all of a sudden, some issues arose - it started with single walls on the first layer being pulled away (despite other identical structures sticking nicely) and that became more and more frequent. Also, over time, other issues such as infill scratching happened as well. I got rid of the scratching by adding Z-hops, using gyroid infill and various other settings - that solved it pretty much for good (though I have to say I am a bit clueless as to why that became an issue all of a sudden since it hasn’t been one in the first place).

I was somehow able to get most prints done from that point, but the first layer (which was 100% perfect out of the box) never was that great again and basically every print from that point on required babysitting and hoping for a lucky first layer - afterwards, it usually goes rather well.

Now, to get a bit more specific about my problem:
I am currently printing a gridfinity system, and since I started this, everything went downhill even more - but I think I can more or less pinpoint the issue.

I am printing rather large baseplate and ensure bed adhesion, I am using 5mm brims both on the inside, as well as the outside:

However, it just won’t work properly, the first layer fails almost everytime.
Before I put down the brims, I put down a skirtline as well - in the beginning, this always worked perfectly fine and gave a nice, closed structure, but lately, it will have a gap at the start - this gap seems to happen, because the material does not make contact early enough, the line makes contact 2 mm later than it should but is thicker at the start (not really a blob, more like folded filament), I made a picture of that as well:

Well - one might think this is only the skirtline that is not part of the print anyways, but actually it also happens inside the actual print - in this picture, you can see the the effect in the top right rectangle (still brim, but is also happens in the actual bottom layer walls as well - it is not on the picture, since I stopped the print before it printed the walls, since so much issues already happened at that stage that I did not want to waste the time and filament to finish it - I finished comparable prints which partially actually finished, but had significant holes at the bottom afterwards).

This is the picture that shows the issue:

This one has worse image quality but shows the “folding” at the beginning much better (two different prints, same issue):

It is driving me crazy, since:

a) that start of the line that won’t stick to the bed (I cannot really tell if it gets printed in midair or touches the bed at the right time but gets dragged away) is leaving an empty space that will late be visible as a hole

AND

b) the “lump” it produces sometimes gets in the way of the nozzle for other lines on the same or the next few layers, causing these to get weird as well.

It also does this on prints that worked perfectly fine in the past - starting with incomplete skirtlines and sometimes sloppy starts of wall lines. However, I have the impression that it gets worse the further the distance between two objects are - a small object where the beginning of the next line is very close to the ending of the previous one works better, maybe there is less travel time in which the filement in the nozzle loses temperature - but still, this cannot be the whole reason, since EVERY time the skirtline fails at the start with some kind of “blob” - no matter if the object is small or big, while in the past, it just didn’t.

This happens with four different filaments from different manufacturers (2x PETG, 2 x PLA). I currently do not have the possibility to properly dry my filament, but I keep if in airtight vacuum packs whenever it is not used - also, two of these came straight from the package (I know, there is no guarantee that they are dry from the factory) - but let’s be realistic, four filaments having exactly the same issue all of a sudden - all in the same places without any crackling noises or blobs during long lines, ONLY at the start would be a huge coincidence I guess. I WILL get a filament dryer rather soon and of course try that as well, but I doubt this is the issue.

I have been spending MUCH time, trying to trouble shoot this myself, also checking for similar issues here, but I did not find anything really identical.

So, what I already did:

• I tried four different filaments, 2x PETG, 2x PLA - exactly same issue in the same places.
• I calibrated the printer several times, also did a factory reset and new calibration afterwards → NO change
• I changed the nozzle → NO change
• I disassembled the extruder as far as the “deep cleaning” instruction in the wiki describes to check for any debris → absolutely NO debris found, after reassambly, the result was identical to before the assembly.
• I also fastened the three screws on the hotend and before I did it, I removed them to fasten the four screws on the backside, since this seems to have caused some issues for some users) → no effect, unfortunately
• I did a full flow rate and pressure advance calibration for the filament I use → no improvement as well
• I tried the other side of the plate that was completely new → same issue…
• I also gave the plate a proper washing with dish soap and water to remove ANY traces of lipids or whatever (no effect, also, I wipe the plate with 99% IPA before every print anyways, so I assume the plate is clean)

One idea: I cannot really say when the problems started and when I updated the firmware for the first time - in the beginning I definitely used the firmware that it was delivered with, though I updated at some point to the current version.

I read that some people had issues with version 01.03.02.00, these also related to Z-behaviour being odd and first layer adhesion problems, but since this is a common topic and can have many causes, I am not sure if this relates to my problem as well. Also, I don’t know if the issues some users experienced have been fixed with later versions than 01.03.02.00.

I already downgraded to 01.03.01.00 - no change yet, but I have to say I did not do a new full printer calibration after the downgrade (it finished roughly at midnight, so I cannot do that before tomorrow morning due to noise ).

Not sure that will help, but maybe other users who had problems with the firmware upgrade as well could confirm whether the issues were the same as described - that would be helpful.

Things I will do in the next couple of days:

• Rerun full calibration
• If this wont help: Another factory reset (staying on the old firmware) + new calibration again
• Manual bed tramming

However, to me, it looks like an extruder issue - the impression I get is that the extruder will start too late and then catch up by pushing all the missing material out as once - like the initial acceleration of the wheel could be too late, since once it extrudes, the lines are very good - as soon as infill starts with a non-stop line, it is actually very precise and good (which is why I do not think the geometry of my A1 is shifted).

So - sorry for the HUGE post, it became much longer than I thought it would, but I hope the information is useful.

I really hope someone can find out what the issue is, so I can get the A1 back to what it was in the beginning. It is just over two weeks old and has less than 100 operating hours - so far, the “just works” feeling really hit rock-bottom, but hey, on the plus side - I probably learned more about the printer than I would have in two years if this would not have happened, so maybe this also brings some benefits .

MANY thanks in advance,
Chris

[Ruby_in_Wyoming]

I have an A1 and do not see those problems. So it might not be the firmware causing them. After you downgrade or upgrade the firmware, “reboot” the printer with the switch at the back, then run the calibrations. Double check that both the bed and the hotend are heating to the correct temp for the filament that you are using. (If not, open a ticket as this is a potential hardware error)

If you open a ticket use small sentences, as everything you write will probably be going through translation software. State everything that you have already done and upload the log files. (These will take hours to upload so be patient) Take pictures of any error messages, and include the pictures that you provided in the forums. This will make things go a little smoother with support. Also, be aware that they are backlogged so it may take a while for them to even get to your ticket, but when I did mine, they got back to me almost immediately.

I had a bad bed on mine, I went through the wiki for all of the steps before I contacted support, did all of the things that I recommend that you do, and I had a new one sent out the next day.

[Chris_Je]

Hey, thanks for the answer .

Yes, I am aware that I will need to shorten that quite a bit for a ticket.

Probably it is a good idea to start one asap to get it going again, if it is indeed some hardware error I will probably just lose more time.

[Lenyo]

It’s simple to say the PETG likely needs drying, it’s pretty common for me. But that may not be the only issue or it may not even be an issue. Plus it doesn’t excuse the PLA which is generally more forgiving.

What I’m focusing on is that you had good luck for a while and now you are not . So the first thing that presents to me is a possible dirty build plate. Are you cleaning it often and well with HOT water and anti-grease dish soap?

If that doesn’t completely resolve the issue I would then likely raise bed temp by 5 - 10C and try again. But realize that moist filament will contribute to issues (by extruding more filament than required due to the moisture escape expanding the filament).

[Chris_Je]

Hello,

many thanks for your reply.

Actually, I do not think the filament is the issue - sure, drying filament is certainly never a bad idea, but in this case, I really doubt it is the cause, since it happened with four different filaments (2x PLA, from which one was directly from the factory packaging and 2x PETG with one of the rolls also coming directly from the factory package).

Before the issues started I printed without ANY problems with PETG that was opened and mostly unprotected from moisture for a week - then, once the issues started, I have them on that filament (which would not be a surprise if this caused a steadily worsening result) but also on other, partially completely new rolls, even with PLA. Also, as I understand, wet filament would cause a more chaotic / less reproducable result with all sorts of errors, but I cannot hear any bubbles burst, nor do I have any issues with adhesion and or line widths - once the new line has began, the lines are very even and extrusion is nice and steady, no blobs or anything inbetween. At the start of the line, however, it is almost 100% reproducable - as soon as I have a dryer, I will of course do a test as well, but I would be very surprised.

Regarding the plate: Yes, it was washed with hot water, lots of dish soap and proper drying - this was directly before the picture with the folded line .

I usually clean the plate with highly pure IPA before each print as well - I had some issues where prints would get loose at one certain spot when I touched the plate with my fingers and thought I might get away with NOT cleaning - but this is not the issue, I am completely where those issues came from. Here it is different - adhesion itself is almost perfect, except for the first 2 mm of the skirtline and frequently after travaling when a new line is started (inner brims or walls of the structure), so it is not a general adhesion problem, adhesion itself is fine.

Also, I tried the flipside of the plate to ensure it was not the buildplate itself - unfortunately, to no avail - it was the same result (plate was clean and has never had a print on it - the start of the line was once again terrible, afterwards, it became usual again).

Going by this experience, I really doubt it is an issue with the filament or plate, because it it was I would expect more errors that pop up more randomly in different places.

I also tried setting my initial layer temps for the nozzle higher - recommended range of Elegoo PLA, which I used for this test, is max. 220°C - I had the effect both with 210°C and 215°C which I used before. I know some data on the filament packages do not really fit modern high speed printers and slightly exceeding them is worth a try, but at 225°C, it already started oozing and stringing, while the start of the first line was still being slightly folded:

Also, I ran full printer calibration with the firmware downgrade I did yesterday - no change, sadly, neither at the previously used 215°C, not at 225°C, so I guess it is not a firmware issue either.

While I wait for an official answer for the ticket I started yesterday, I will probably also try downgrading further, but I do not expect much from it.

I am starting to believe it is an extruder issue with the extruder not being able to start early enough but quickly finding the right flow afterwards.

I will also try cleaning the PTFE tube - MAYBE the extruder has a minimal delay on feeding new filament if friction in the tube is too high. This might also explain why the issue only happens when extrusion starts and stops as soon as it is in motion, because static friction is usually higher than dynamic friction - but this is a wild guess (and probably a result of me running out of further ideas).

Oh, and one thing I forgot to mention, here is a picture of the disassebled extruder - I cannot see anything weird going on, but maybe someone else will:

Also, I made a test print with a smaller object where line end and line start of the next layer are together so close there is barely any interruption - the result is way better, but as you can see there is still the faulty skirtline as well as an error on the inner wall of the first layer. If the infill get printed so fine, I really doubt something major is off with the axxis:

Also found another picture of my PETG-test - as you can see, the folded start of the skirt is the same as PLA:

Maybe someone can make some sense of this, I really hope so .

[Lenyo]

Try a simple test for moisture. If you manually heat up the hot end to 220C and then extrude the filament in question a bunch, does it come straight out and down the nozzle? No curling? Hopefully not it doesn’t seem like a partial clog issue but:

Now manually clip the filament off quickly after extruding with tweezers or such… Now does the filament continue to creep out?

If so it kind of makes sense based on your description of large item being a problem (especially skirt - or anytime the nozzle is not printing for a while) versus smaller item looking good.

So I’m thinking maybe you get some creep due to moisture and that is causing an issue when it first starts to extrude.

[Chris_Je]

I am going to try that, but from what I observed from watching the flow dynamics calibration at the start of the print, it came out very straight and in constant strength - also, I tried different nozzles, which all led to the same results - does not seem clogged .

I am currently doing a test run, when it is finished, I will try cutting it quickly to see if it keeps oozing / stringing. When changing filaments, I observed it kind of does - but the algorithm of the A1 heats up to 250°C when loading, so I am not surprised it keeps leaking since this is way too hot for the PLA I use.

I would be VERY happy if it was just a filament issue - but in that case, would it not get better at lower temperatures that cause less ooze creeping out? However, at low temps it is the same, the folded part is just more solid.

Also, it does not really explain why I all of a sudden got this on all filament (including new ones) when before this did not even happen with unprotected PETG (especially the skirt line).

Will give it a try later - maybe the open filaments caught moisture and BOTH the new ones were not properly factory dried. That would be quite an insane coincidence, but hey - you never know .

I will update once I tried, also hoping this helps others who are facing the same issue (saw thread on reddit etc. of people also having comparable issues that never got resolved).

Also: I manually adjusted Z-Offset from 0.02 to 0.03, so far it looks A BIT better, but may be coincidence.

UPDATE: The print with 0.3 mm Z-Offset actually went way better, though there are still pieces of debris, but no holes in the bottom layer - maybe that might have something to do with the issue?

Also did the extrusion test - it comes out in a very solid line, but after cutting or pulling, it oozes a lot at 220°C. I tested at lower temps and the temperature it finally stopped oozing after the extruder stopped was at 185°C.

What is still not explained by this: Oozing filament would explain extra material applied that does not belong - kind of like a blob at the start. However, this should be impacted by lower temperatures. In my case, it does not put a blob at the start putting MORE material than required - instead, it puts the right amount of material on the plate but folded / extruded at the wrong time, which leads to blank spots, followed by folded material.

UPDATE 2: This may have solved the issue!

So, running out of ideas, I switched back to the 0.4 mm nozzle and (even though I don’t want to jinx it…) the first test with the very same “maybe wet” filament turned out SO MUCH better. Skirtline closed nicely, also, no debrist / not completely molten filement in the wall lines etc.

There ARE still some very minor blobs at the start of some of the lines, especially when the travel distance between two squares is rather high, but I can definitely see that this may just be from the slightly prolonged time the filament stays in the nozzle and gets a bit softer than it would - this is probably just physics in the end and this is the part of the problem that made sense to me in the first place. Things that did not make sense like the shortened lines with shortened filament (after long travel with longer time inside the heated nozzle, the opposite should be the case - as it is now!) are currently gone.

So, what happened (probably)? I think I changed too many parameters at the same time.
I started to see issues with the first layer, so I initially thought the nozzle / hotend was jammed, so I switched to a 0.6 nozzle (the spare 0.4 nozzle is ordered but due to the holidays, it is taking a bit longer than usual). If a jam would have been the cause, that would certainly have made a difference, however, it didn’t.

After that, I tightened all the 7 screws (3 front + 4 back) on the pressure block - one of the 4 screws on the back was indeed slightly loose, maybe half a turn from sitting snug, honestly, I cannot say how big the effect of that was.

From that point on, I did not change anything regarding the nozzle (except for deep cleaning the whole extruder) but I got the issues described above.

Since nothing else helped, I wanted to try the 0.4 nozzle again and switched + recalibrated and tried the same model again (same filament, same setting) - and so far it looks near perfect.

As mentioned, there are some slightly bigger starts of the line after travel, but no material is missing → This is fine for me since it makes sense. Also, these mini blobs get covered perfectly by the next layers. There are some TINY pieces of debris / blobs that happen in seemingly random places (almost unnoticeable), but this is something that I can ABSOLUTELY attribute to filament that is not dried perfectly → also explainable.

However, I checked what other users experienced with the 0.6 nozzle profile - and indeed they had some problems (retraction settings etc.).

So, what I think has happened:
→ Issues with 0.4 nozzle (probably loose screw) → change to 0.6 nozzle, even worse (same problems + new ones apparently specific to 0.6 nozzle) → screws tightened (maybe improved things, but the 0.6 specific issues remained and I was focused on them) → (many other tests) → change back to 0.4 nozzle → Everything is fine, since the 0.6 specific issues to not apply and I probably fixed the initial problem by tightening the screws.

That screw issue also explains why it got worse over time without changing any parameters - and the 0.6 specific setting problems explain why the actual fix did not show any effect (if I had started with a 0.6 nozzle right out of the box when everything was still tight, it probably would not have worked as well). I guess it is always bad if you get two rather similar problems from different sources at the same time and start focussing on the wrong one.

This is the first print after changing back:

Now, I will keep my fingers crossed that it stays this way .

THANK you to anyone who tried to help me with this (and bothered to reach this “novel” )! It was a bumpy start with the printer, but I guess it helped me a lot with further understanding and troubleshooting, so I try to see the upsides.

I will set this to “solved” for now but keep posting updates if something should change again.