3D Printing Issue

[FlyingFishKeeper]

Hi, so I know that this is rather off topic for a forum about aquatics, however I know that there are a lot of people on here who also have experience 3D printing so I thought I could ask.

I've been printing these parts of an airplane wing using a stock Ender 3, Cura, and PLA, and seem to have these almost "indents" around the areas where the printer puts down a new layer, but only when the hot end is at a certain position on the vertical axis. I'm not entirely sure how to describe it, so I've taken photos to try to help. (For background, the parts are printed vertically on the build plate, and are 1 wall thick, with no slicer generated supports (there are supports designed into the wing however))

(The photo above is a picture with the flat side of the wing facing down. On the wings on the left and right the "indenting" is on the left side of each print, then seems to fade going right. There also appears to be a pattern where the issue happens only at certain areas on the vertical axis even on prints that were made at separate times?)

(This picture shows the curved side facing upwards, as well as the seam where the outer shell starts and ends for the wing in the center. The indenting on the other two wings seems to have faded significantly on this side? By the time the nozzle makes a lap around the center wing it looks like the indenting has evened out as well.)

Each of these was printed on their own (no other parts on the build plate). I'm guessing this is a hardware issue given that a .gcode file with similar settings failed, even after I had gotten good results from the same file awhile ago, although I could definitely be wrong. 

So far I've tried retightening the belts, going around and tightening fasteners, and trying to print at a slower speed (with no luck). The wings in the picture are sliced from the same .stl file, and use roughly similar settings (I changed the speed between them I believe, and possibly other settings)

Thank you for reading! I'd be more than happy to share anymore of my settings from Cura, or details about the printer, thanks! (I can't however share the .stl/.gcode files as they are not of my own design, and are to the best of my knowledge copyrighted. 

[colo3000]

You may find more help in a 3D printing forum or subreddit if you haven't posted there already. It seems like the printer is either under-extruding at those specific heights or a slight "layer-shift" is occurring. Past that I don't have much advice to give.

[TheDukeAnumber1]

@FlyingFishKeeper

Trying to figure how to best troubeshoot. Correct me if I'm wrong but are you saying you've printed these gcode files before without issues?

[eatyourpeas]

I wonder if the thermistor may be having issues...

[FlyingFishKeeper]

On 3/31/2022 at 12:10 PM, TheDukeAnumber1 said:

Trying to figure how to best troubeshoot. Correct me if I'm wrong but are you saying you've printed these gcode files before without issues?

Not the ones in the image itself, however a different gcode file (that is essentially just a mirror of the parts in the pictures) came out quite well 

[TheDukeAnumber1]

On 4/1/2022 at 9:20 PM, FlyingFishKeeper said:

Not the ones in the image itself, however a different gcode file (that is essentially just a mirror of the parts in the pictures) came out quite well 

Sry for the slow response, been a busy week & weekend. If I am reading your notes correctly it looks just like a Z seam issue, which there can be a few causes and a few solutions. I believe Cura has options for z seam alignment, I would try "sharpest corner" but the "random" setting may work too. I've never messed with retraction settings but I understand that to help solve z seam issues. Also overly hydrated filament can cause a little over extrusion too.

[FlyingFishKeeper]

Thank you! I've been rather busy myself with school, and test prints. I've made SOME progress I believe (I printed an unrelated part with very little issue), however I'm starting to think that perhaps enough filament is oozing out of the nozzle/stringing during travels that there's less plastic in the hot end then the printer thinks, so it ends up under extruding until it evens out? I've been tinkering with retraction settings so far with moderate success (I got the aforementioned part working at close to perfect quality)