Strange Slicing Issue With Inner Perimiters in Corners
I want to preface this by saying i am using an Ender 3 Neo with a brass 0.6mm nozzle, every parameter i know of (e-steps, k-factor, flow rate, etc.) is well calibrated and all the parts pictured are within ~0.05mm of the original model. (Mainly under by 0.05mm with the largest oversize being just 0.1mm over)
It is exceedingly unlikely that this is an issue with the printer calibration, although I have more tests I'm going to run.
I designed and printed off a simple dry box today that had 2mm thick wall and i ran it at the 0.44 *speed* preset for the Ender 3 Neo.
The problem was that *all four* corners looked like this.
After this i started looking for causes and found that instead of a complete ring around the perimeter the slicer was placing a small amount of plastic on each corner, then the external perimeters, and finishing by connecting each of the corners with a single internal perimeter line.
Screenshot for clarity
I currently do not know if it is because the high layer height or if an 0.6 nozzle is too large for such small details, but the result is that the extrusions would come out bulbous and irregular and interfere with the following perimeters basically stacking up the error each layer.
I printed the second part with external perimeters first and it helped a fair amount but the corners were still out of spec similar to how they would look without linear advance enabled. At this point i decided to make some tests to better understand what was happening and it appears that this issue is occurring because the slicer does not think that a single internal perimeter would fully fill the space between the external walls and so splits it up like this.
The tests suggest that this is all to so with extrusion width and the combination of the Creality 0.44mm layer with 0.6mm nozzle preset and the 2mm walls creates this circumstance.
The following screenshots are of the preset extrusion width settings followed by the same 2mm walled test cube with 0.6mm 0.8mm and 1mm in all fields.
Link to the 3mf on Printables
All these cubes were sliced at the same time and printed sequentially resulting in these prints with the top left being the 0.6mm width, then the Creality preset with the bulged corners, then the 0.8 with the single internal wall, and finally the 1mm with just 2 external walls.
I am going to continue my own testing with different nozzle sizes and layer height, but would be interested to see if this issue in present on other (better) printers so feel free to post you own results, or if anyone knows an easier way to avoid this without manually checking the tool paths and making edits until its gone. Though it does seem to only present itself under very specific circumstances.