Hi! Looking for some advice here from friendly local experts.
I've printed this with Elegoo Neptune 3 Pro, 0.4 nozzle, Elegoo PETG filament, no enclosure. Using PrusaSlicer.
This print is basically all walls - the hex grid is thin. It's 2mm thick and each segment is 1.5mm wide. I set 3 layers for walls in slicer. It was printed vertically, just as seen on picture.
The solid part of the print (back wall) came out just fine, but the hex grid part came... dirty. On the picture, there are a few hex segments that just broke off during the print at the base of vertical segments. And the rest of them have small loops of filament that stick outside of the intended surface, to the sides.
My suspicion is the print temperature is too low. I'm printing at 230, which is the low end of 230-260 range of the filament. But in my previous tests I noticed stringing that starts around 240, so I did a few other prints that were just fine at 230, and I made it my default temp for this spool.
Or is it just too fine detail for my printer with PETG? Or something else that I am missing?
My guess is mechanical stress during the print.
Think of your print object as a lever. The attachment to the print bed is the fulcrum. The taller the object gets, the longer the lever arm and the more potential for movement, especially while the plastic is still warm and soft.
On the other end of the lever is the nozzle spitting out melted plastic. The melted plastic is sticky (PETG in particular is kind of like chewing gum at print temperature). As the nozzle moves across the printed surface, the sticky plastic pulls on the previous layer, exerting a lateral force (you can watch this happen during the print, it's most obvious with tall thin parts). If there isn't enough contact area between the topmost layer and the one below it (which in your case it appears those parts of the hexagons have very little contact with the layer below) then the top layer can be ripped off.
Basically the individual limbs of the hexagons are too thin, and the angles are too steep. As the print gets taller the whole thing will flex more, making failures more likely near the top.
That also makes sense. I imagine if there is a way to increase adhesion between layers that would help with such problem