[3.6.0-beta.1] Inconsistent underextrusion at start of new layer
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This is a bit of a weird one as I have not been able to isolate if this is related to the updated input shaper motion pipeline, or a pressure advance oddity. I have attached some pictures which shows the magnitude of the under extrusion, as it only seems to appear when the layer change is in an alternative direction to the layer behind, or when placed near/on a curve.
The under extrusion also appears slightly after text, similar to what @Exerqtor witnessed in the early Alpha firmware's with a growing amount of under extrusion after/during text.
Currently this behaviour is consistent between multiple extruder & nozzle combinations, (15mm, 25mm, 45mm melt chamber lengths), and thankfully the under extrusion is mitigated by reducing the amount of pressure advance, however this does come at the expected cost of more bulging on the corners of the rest of the print.
.....side note: reducing any wipe distance in the slicer has also helped mitigate, but this is a band aid, not solving the problem.The thing that makes this surprisingly difficult to track is that the seam/layer change on certain models is completely fine, but moving the seam to another location on the model can suddenly cause the under extrusion.
One thing that does play in the back of my mind, is I remember reading about someone's tool changer being unable to successfully dock as some of the move commands were being merged with the ones directly before/after. I wonder if what could be happening is if the immediate movements after the layer change are being executed at the same time the filament is being de-retracted causing a momentary amount of under extrusion.
Alternatively, this only slightly explains the under extrusion which occurs after after text is printed, as the constant ramping of speeds could cause an error amount to build up as consecutive letters are printed, resulting in an under extrusion artefact
I am still gathering data for this, but I thought it best to start a new post thread just incase others have experienced this as well.