I have been dealing with inconsistent extrusion that shows up on all layers not just the top. some regions have perfect extrusion where the lines seamlessly merge so that you can’t even see them, and when you shine a light at an angle, the glossiness is smooth as if there’s was no 3d printed texture. But then there’s parts where there’s under extrusion that manifests either as a visible crosshatching pattern, which are see-through shell layers beneath, or as visible gaps between lines that refract light and make the 3d printed pattern very visible. And lastly, there are sections where it seems like there’s over extrusion where the texture is visibly harsh and it looks like the nozzle scrapes the lines and leaves behind scars. It’s very inconsistent and i don’t know whether that’s caused by uneven bed levelling. It’s most noticeable when i print prints that cover a large area of the bed. This is a photo of one of my prints having visible under extrusion which i couldn’t fix by simply tuning the flow ratio. When i set it to something high, it doesn’t really fix the under extrusion and just creates over extrusion artifacts, like visible blobs on the top layer or the previously mentioned scars show up.
But once i changed the z offset from 0.01 to -0.01, it seemingly fixed this issue. And i thought that was the end of it until i printed a larger first layer. My best guess is that this is a combination of multiple factors because the first layer has some kind of observable pattern to it. When i print something that spans the entire bad, the upper-right and lower-left corners show visible under extrusion. But only those corners. It might either be bad z leveling or it might have something to do with accel-decel. When we look at the picture above we can actually see that the lines match up with areas where there’s constant speed, meaning no acceleration or deceleration. These areas show under extrusion, however areas that either accel or decel have perfect extrusion. These are the two patterns i noticed: possibly bad z leveling as lines farther away from the center of the bed have worse extrusion, or accel decel related issues. Another thing i observed is that changing z offset from 0.01 to -0.01 fixed some under extrusion on the first layer, but it also introduced over extrusion. I didn’t notice this at first but when i checked out the print again that supposedly got “fixed“ by the z offset change, had rough elevated spots where the nozzle goes back to fill in holes at last. But all of this is only is only first layer related.
On top layers, it feels like there are no patterns to pick up on at all. It feels very random and i don’t know what to make of it. Because it’s not guaranteed that a bad first layer will produce a good top layer. I noticed that some areas might start out with over or perfect extrusion, but end up with under extrusion on the top layer. This is by far my biggest project with the largest surface area.
The large A and D have perfect extrusion. But the smaller A, K and W show gaps
This is a close-up of A and W. The large A and D don’t have this under extrusion. But then the outlines of the letters have visible blobs.
This is an example of the scarring i mentioned before, here we can see two completely different qualities, the lines to the right show scars and have a much rougher surface while the lines more in the center are perfect.
I did a manual color swap because i don’t have the AMS. Here you can see the inconsistencies a lot better. I am aware that the wavy texture is due to the sparse infill. But that doesn’t explain the inconsistent extrusion.
This is the P2S, all filaments are from bambu. K factor here was 0.032. Which is also kind of weird that it’s this high but every calibration test has shown it to be the best value. tweaking flow ratio also hasn’t really made a difference, it just made the corners bulge more and it also introduced more over extrusion. sparse infill gyroid at 10%, outer/inner wall width 0.3mm and surface lines set to 0.36mm with the stock 0.4mm nozzle (I might be pushing the nozzle to its limit). nozzle temp 220 bed temp 55. Top shell layers 8. outer wall speed 45mm/s. top surface 150 mm/s
the walking dead logo.3mf (397.5 KB)
Here is the project file.