Layers loosing adhesion?

[tidal garnet]

Printer: Anycubic Kobra 2
Settings: I tried many, there is no reasonable difference between them with this issue. Pictures on my fast profile
Material: PETG (Devil design)

My issue is that very often 2-3 hours into print, the filament suddenly behaves like if it was moist. I keep my filament dryer on 24/7 with current spool. This is fresh spool, unpacked +- 24h before start of print, baked for 24h before use (and baking during print).

It messes up adhesion to previous layer, but often recovers, leaving ugly very weak spots (I print only functional things, so cosmetically I dont care that much, but the weak spot is really bothersome).

It allways starts the same, prints well, than some minor stringing happenes, than it gets messed up, and if I leave it running, it recovers. It dosen't nesseserly affect entire layers of prints, rather it often happenes in same are of print (so on other side of print it often is OK). I don't see that's happening always on same side, seems at random.

I am honestly at loss what it could be.

More pictures in next message, but I can't give great pictures as it's still printing and even semi-failed, I want that print for test fits, will be trashed anyway.

Settings:
Temps: head 235C , bed 70, first layer bed 80
Layer height 0.32, width 0.4
Speeds: see screenshot

The picture with the "+" in the middle is not sharp, apologies, but I wanted to show that the infil of it printed well, and around it it's generally good (enough), and it was hard to get sharp picture of it moving without disturbing print head

[topaz elbow]

105 mm/s is very fast for petg on that printer. Does the problem appear at like 60 mm/s too?

There is also the possibility of heatcreep

[tidal garnet]

Let me check my "slow" profile, 1 second

Okay, I didn't go down to 60mm/s

What's reasonable balanced speed for PETG for my printer? I care more about the structural integrity of print than speed, but I also love printing as it allows me to reasonably quickly iterate over designs.

[topaz elbow]

Id say 60 to 70 mm/s there is also the ptfe tube issue

I dont think the printer has an allmetal heatbreak

So overtime the ptfe lining breaks down .. and these fumes are not really healthy

[tidal garnet]

🤔 I will give it a shot on slower speeds. Im unsure what to do with the ptfe tube, but I dont think it should cause this issue? Although I will bear in mind

[topaz elbow]

It breaks down overtime resulting in a gap inside the heatblock that can cause a lot of issues

Other tip the fan looks quite dirty maybe clean it 😄

[tidal garnet]

Does this look reasonable?

Somehow with these speeds it only bumped from 8h45m to 9h01m. For slashing speeds by almost 2? 🤔

[topaz elbow]

Id say so

That means you were already hitting hardware limits in acceleration or so

Or software depending on how they are set

[tidal garnet]

Printer theoretically has limit of 300mm/s

Enough printed so I can check the fit, so I will try with these speeds in few minutes and will see. Fingies crossed.

[topaz elbow]

300mm/s advertised printing speed is usally a lie. That across the complete print area at max acceleration and then usally the meltrate of the hotend isnt enough

The ender 3v3 is advertised with 38mm³/s for example

With its .4 nozzle and .2 mm layerheight it would need 48 mm³/s

To reach the 500mm/s

[tidal garnet]

About the nozzles, I have offtopic question. I don't really want to spend on new printer (dont have space for second one too), and this all in all was nice printer for utter noobie like me. But I wonder if it's worthwhile to buy other hotend to be able to plug in volcano nozzles. And since you mentioned the tube issue, would this help or hurt the situation of it? 🤔

And I want volcano nozzles (this one has slightly different nozzles, no aftermarket at all) to be able to plug in .6 or .8 nozzles for sketches printing speed

[topaz elbow]

Im not sure. I thought the printer you have has some special crap so it can onlytake anycubic nozzles

And with an increase of diameter and layerheight you increase your mm³/s so you could hit the meltrate even sooner

[tidal garnet]

Ye, it has special hotend that accepts only their own nozzles. But I san swap the hotend to another one (from viper I believe should be compatible) to plug in "normal" nozzles. Im not sure how to bench the meltrate without buying it.

Also I figured out why speed bump was by 15 minutes 🤦‍♂️ I reset my infil to profile default and got it smaller. With correct infill its up by 1h, still not as much as I expected.

[topaz elbow]

you can try that but i cant tell you if it fits

[tidal garnet]

Yeah, sure, i will do my own research which one fits. But assuming it fits, i wonder if it may help or hurt with the ptfe tube.
Also.
Its been running 1h 50m and first small strings aprared, but so far printed beautyfully, and it just printed over these strings without failing the print. Will update if it actually fails or suceeds.
I cant help but notice that the surface looks marketably better, so absolutely slowing it down was improvement.

[topaz elbow]

i guess you didnt melt the material good enough with the speed you had.

unfortunaly there are many lies about 3d printer specs

[tidal garnet]

Hmm. Oke, im specsheet loving kind of guy, any pointers how to read it cutting through BS?

[topaz elbow]

https://youtu.be/80pUYf-7otw?si=i-ZJRRJZ1wjWSGJE shameless pug 😄

[tidal garnet]

Thanks

From bad news, it completely failed

At same height as previous one

[topaz elbow]

at the same place again?

would you share the gcode you use?

[tidal garnet]

Sure

1 second

First one that I orginally tried to print, and second one. The second one has slower speeds and lower infill % to cut down some of the time.

I have custom suffix at the end so that it moves build plate towards me

29,18mm height of second failed print. Hard to say if its layer 29.00 or 29.32

[topaz elbow]

there are quite a lot of rettractions in a short time

30 roughly but its odd that it starts to fail a specifitc height

[tidal garnet]

🤔 Im parse what that means but it dosen't translate to anything what that means if that makes sense

[topaz elbow]

have you tired a different sd card?

[tidal garnet]

🤔 I don't think I have another one, will need to look for another one

[topaz elbow]

too many retractions in a short time = half clogged or clogged hotend

[tidal garnet]

I dont have any other sd card at hand but I have one somewhere

[topaz elbow]

you can try formating it

you also print with 5 walls

that could cause back pressure into the hothend

because the material cant go anywere

oh 4 walls soory

[tidal garnet]

You mean thickness of walls before it goes to for infill?

[topaz elbow]

shells or wall thickness yes

( i wish slicers would use the same words)

[tidal garnet]

Im using super slicer, so most keywords from prusa slicer works

I wonder if there is more a way to calibrate that instead of shrinking the walls, the print will be used to carry gas bottles so it needs to have some extra structure integrity

[topaz elbow]

well okay next thing to try would be formating the sd card and try printing slow and maybe without arachne as slicerengrine

[tidal garnet]

Any reason why not arachne?

[topaz elbow]

because arachne sucks hard XD

it causes variations in line width

this results in speed temp flow changes

soo basickly everything you dont really want if possible

[tidal garnet]

Huuh, okay, I will bear that in mind. Oddly I selected it as I had the best results with it (in my subjective opinion)

[topaz elbow]

ist line widht variation by design=

i say its arachne. you go from .12 to 2mm linewiidht in your gcode

thats either massive underextruding or massive overextrusion depeding on the nozzle size

[tidal garnet]

Nozzle is the only stuff avail for the printer, 0.4 if matters

[topaz elbow]

yeah so max line withd for .4 is .44 to .5 mm if you are lucky

soo i guess thats your issue

[tidal garnet]

Oke. So will try same print, with classic engine instead of archane, on fresh formatted card.

[topaz elbow]

https://tenor.com/view/team-cheer-penguin-good-luck-you-got-this-gif-9806304395254740889

[tidal garnet]

I have also set max width in some places for .45

I have no idea how I came up with these settings, I put some time into going through builtin super slicer's calibration and it might come from there, but it was some months ago.

Just don't remember 😅

[topaz elbow]

eh happens

sometimes i also feel people putt fake profiles online

[tidal garnet]

Well, I didn't download any profile :)

Should I upload new gcode or straight onto pritnter?

[topaz elbow]

im here so you can

[topaz elbow]

looks better but my prusaslicer still shows 2 mm line width that sood

[tidal garnet]

🤔

TBH I dont know what sood means 😅

[topaz elbow]

its a mystery or a typo

cura says its okay

id try it

[tidal garnet]

Oke, thanks. This will take significantly more time, so tommorow I will know if it suceeded run out of current spool and need bake other one (or today if failed 🙈)

[topaz elbow]

i hope it works for you

[tidal garnet]

Same

Thanks for help, will circle back if it works or not

[topaz elbow]

hope it works now 😄

[tidal garnet]

Aaah I see what happened

[tidal garnet]

Yep, new print immidetely failed due to clogged nozzle. Easy to fix luckly

[topaz elbow]

and it clogged due a gap in the heatblock or what do you think?

[tidal garnet]

Hm, IDK why it clogged, but you mentioned too many retraction cycles in period of time

So I assume thats what happened

Just stick needle into nozzle and will be fine™️

[topaz elbow]

whats your retraction distance

[tidal garnet]

2mm

This is rare clog that I cant defeat with needle nor cold plug. Well, I will disassemble the head to unclog it

[topaz elbow]

hmmm

there is a chance that the hotend wasnt assebmeld correctly

aka at a temp above your print temperatuire

[tidal garnet]

If thats the case I must have screwed it up before

[topaz elbow]

They often are already by factory

Many even have in their guides to change at 190c or so when print temp is 220 or so

[tidal garnet]

I have no idea. I will disassemble it and reassemble without any filament thats left inside. How do I know when it's assembled OK and when not?

[topaz elbow]

You hot tighten it at max temp

Soo preassembly at 220c and then you heat it up to max temp and tighten it down

[tidal garnet]

Eh I have clog in heatbreak, I need to figure something out with that... I unscrew nozzle and its solid plastic in that I cant figure out how to get rid of. Well I wanted to upgrade that so I can get standard volcano nozzles anyway, so if I break it will figure smh out.

[tidal garnet]

It just finished. It aint perfect but im happy with thilat.

Ive removed heatbreak from block to unclog it, and reassembled. Also figured out that this means nozzle compatibility mod should be simple.

Thanks a lot.
Now that printing takes so long, any tips how to optimize print time from this profile?

[rugged geode]

@tidal garnet As for optimizing print time, there are a few things you can try. You could increase the printing speed, but be careful not to go too fast or you might sacrifice print quality. You could also try using a smaller layer height, which will result in a higher print resolution, but it will take longer to print.

[tidal garnet]

Yeah with this print I slowed it down significantly as it was braking. I wonder if there is some known things I could follow/know to get there more efficiently

[rugged geode]

slowing down the print speed can definitely help with print quality, but it can be a bit of a tradeoff in terms of efficiency. That said, there are some common best practices that can help improve your printing efficiency. For example, making sure your first layer is well-calibrated and adhered to the bed, reducing retraction distance and speed, reducing travel speed, and using minimum layer time settings. Do you know how to adjust these settings in your slicer?

[topaz elbow]

You can try .24mm layerheight

I still wonder where the underextrusion comes from

[tidal garnet]

My first layers are okay (somewhat, a little bit of bedwrap, it's perfect in center, closer to edges it puts out slightly too much)
I know how to reduce retraction distance and speed, IIRC I followed with super slicer calibration for this.

[topaz elbow]

Maybe increase extruder tension if thats possible

[tidal garnet]

Right now Im happy with the quality, part is strong (maybe cosmetically not perfect, but I dont care much), but I effectively went from 8.5h to 11.25h for this print, and while awesome that it worked I wonder can I cut that down for faster iterations.

for layer height I have it set to .32

[tidal garnet]

Im not entirely sure what do you mean?

Do you mean like going really hard for tightening nozzle or heatbreak?

Oh also I figured out how to upgrade to normal volcano nozzles. I can buy other heatbreak and it will make the nozzles fit :)

[topaz elbow]

The extruder is usally spring loaded

This can change overtime

https://www.anycubic.com/blogs/3d-printing-guides/calibrate-extruder-tension

[tidal garnet]

🤔 I've disassembled it one time entirely, this time I just took the cover off and removed block with heatbrak with radiator and nozzle

[topaz elbow]

It might be wrong from factory :> well calibrated machine cost at least 10 times more 😉

[tidal garnet]

Yeah, it's saving some $$ and comes with some 🤔 downsides, Im more than aware

With that tension I see in their doc that you linked that it might be too high given once what they mentioned happened from too high tension

Once I had annoying "clog" where filament got broken in the extruder and I had no way to pull it out and had to disassemble the thing

[topaz elbow]

Too much and too less cause the same issue

[tidal garnet]

Hm I don't see how I could follow their guide

I dont have any regulation thing here

[topaz elbow]

you are showing the filament runout sensor and back of your extruder

the sprinttension screw is usally some whre on the side of the print head

[tidal garnet]

Oh yeah its there

[topaz elbow]

https://tenor.com/view/yay-couple-swing-spin-spinning-gif-23487968

[tidal garnet]

This should be fine?