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What is causing this pattern in the first layer?
(lemmy.world)
Flashforge creator pro 2 with PLA, standard quality preset, textured removable magnetic bed on the build plate.
The first lines are straight, but as it makes more parallel lines to build the layer, it starts to develop a scalloped pattern. This creates issues with smoothness when it fills back to join it from the other side later. I've leveled the build plate, although I suspect it's not perfectly flat and maybe slightly higher in the middle. Is this my problem? It appears to have the pattern even away from the middle if that makes sense.
Might be too close to the bed
To elaborate a bit, it looks like over extrusion. Do you have a first layer calibration procedure you've used?
This is my attempt at calibrating the first layer. I don't know if there's some other process I should be using (while I'm fairly technical, I'm new to 3D printing)
If you look around you can find some pretty good tests to characterize all the different features that contribute to good performance. Usually they include using a feeler gauge at several points, and printing certain test shapes in different areas. I don't have one at hand, since I'm on mobile. Can you describe how you leveled it already? If you're looking for something to try immediately, I'd try printing at 10 and 20% less flow in the first layer and see how it behaves. Based on that, you can adjust the offset if necessary.
I think this could be the case but I just calibrated it twice and it still does it.
In the case that is an uneven bed, where the middle is slightly high/convex, how do people fix that?
You could fix that by shimming the print surface with paper. I don't recommend that. You could also get a mesh leveling sensor. It's technically a workaround, but it works. But it is very hard to believe that your bed is this heavily warped. It looks like the nozzle is generally too close to the bed and the squeeze out accumulates. I've had this problem before. I would recommend releveling the bed.
Would you mind also saying what printer you are using?
This is a flashforge creator pro 2 (in original comment). I'm not sure how to characterize the distortion, but the standard leveling routine puts the extruder in 3 locations near the screw adjustment. After adjusting spacing with a sheet of paper (included, calibrated thickness), it puts the extruder down on the center. The center is always higher than the 3 calibration points, often significantly.
Well then I have bad news. You will have to get your bed straight, be it by replacing or some sanding on a flat quartz block. Maybe you could even mill it. One last test I would run is trying to print without the bed heater just to see if the warping gets any better.
A hackier solution is mesh leveling, but in your case it will still produce parts that aren't flat.
Also back the nozzle off from the bed by about 0.05-0.1mm in the meantime to get some semi usable results.