Anet A8 - Gaps at circles

Hi

since a few weeks or month i have a problem with my Anet A8.
On the printed parts there are gaps at circles, these gaps sometimes go down to the bottom.
At the start of the problem the perimeters of the circles were completely loose.
By now i almost got rid of the gaps but they are still there. But i do not have ideas anymore.
It's mostly the two holes like on the picture. If they are hard to see i will take some more pictures tomorrow.

Maybe some one has an idea how i get rid of them so i can use the printer again.



Anet A8 with .4 mm nozzle, upgraded rods and bearings on the x and y axis (dold mechatronik), many printed upgrades.
Cura 3.4.1 (but the problem stays since a few versions before that)
Red PLA from DasFilament

Heattower printed
Filament measured

The first two images are the correct size for viewing, However could you please enlarge the last three with the Settings on them.

Sorry for that, i have enlarged the setting pictures.

I cant see any images..

Updated them in the first post.

I have the same exact problem. But anywhere with walls too. All my holes in every model.


I am using a Monoprice Maker Select Plus


I have been battling this for over a month now. Lots of research and experimenting and I just can't figure it out.


The pictures included are printed using Cura's default "draft quality profile" for PLA. One sample has wall thickness of 1.2 and the other is 2.4. So the issue is more obvious in the 2.4 mm wall thickness. So I conclude, the more walls, the more worse the problem. I've played around with the usual settings (temp, speed,..). Things that I have tried so far: Speeds from 15 to 60, Temps from 190 to 205 (surface quality begins to fade beyond 200), optimize wall printing order, skin overlap, changing nozzle + ptfe tube in case of clogs, taking apart hotend and cleaning, cleaning extruder gears, checking resistance from spool holder, using different filaments. The one setting that has made a difference so far is the "Flow Rate". At 110% Flow Rate, this issue disappears. Unfortunately, I've come to realize that this is not a proper fix. At this setting, my tolerances and precision is out of wack. And the top surface is becomes significantly uneven because of all the extra material extruded. I am very desperate for a solution as I have fought this for way too long.
Attachment 11935Attachment 11936

try switching off retractions between layers.
Actually making the retractions shorter and faster could help.

I've noticed on these i3 profiles that the retraction settings are really long. 3-6mm. And often done really slowly - like 30mm/s
For my delta (bowden) and my rep clones, direct drive - I only retrace about 2mm and do it as fast as I can - so 60-70mm/s.
It means there are potentially fewer places where the printhead has no filament to deposit.

Think the last setting I had for the ctc i3 prob. were 70mm/s speed and 3mm distance. It's not the best extruder so you do need a decent distance - as long as you do it fast enough it should work. Also for a wall like that - or any single model print, you don't need to retract between layers.

Thank you for the reply curious aardvark.
Retract at layer change is off by default.

At default it is at 6.5 for retraction. I have tried at 2.0 retraction on most of my profiles at 30 retraction speed. I will bump that up to 70 mm/s and start a test print. Will report back.

Results are back. Setting retraction speed at 70 mm/s has no effect. Also tested retraction completely off. Same results. My facebook group suggested an e step callibration, which I don't know how to do yet but I'll try. More ideas are welcome.

different filament ?
could be caused by inconsistent thickness in the filament I suppose.

You really don't see that very often these days - but it's possible.

Found out that the gaps only appear on the right of the circles and only at a height of up to 5mm. Otherwise they aren't a thing.

Quote:

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Originally Posted by curious aardvark

different filament ?
could be caused by inconsistent thickness in the filament I suppose.

You really don't see that very often these days - but it's possible.

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Yes, I've tried different filament. I did a E steps calibration. Although I could not get it to extrude 100 mm, Somehow it improved the undextrusion issue. Just printed a calibration cube with zero gaps. But now the cube is .5 mm off in the dimensions. I might have slight overextrusion now. But at least the gap/holes are gone!

But the problem isn't gone.

The holes problem is gone as far as I can tell. Despite the overextrusion, I am much happier about my prints.

I mean the problem i have with my prints.

I think it's a mechanical problem but i have no idea what it could be.

Maybe someone has an idea?

Looks like that at the moment.
Attachment 11954