I'm somewhat puzzled which settings I need to look at in PrusaSlicer to solve those thin slits between perimeters. I've dialed in the flowrate optimally for dimensional correctness and 245°C (PETG) works really well for both flow and overhangs.
At first I thought of extrusion width, but that also increases the distance between each line. Raising the flowrate closes them, but also makes the printed parts grow in each dimension outside if the intended size.
Where am I missing something? Which settings do I need to adjust to not screw up everything else?
EDIT: It's not just corners!
It's not only on the first layer and also not only around corners (indeed the first layer is perfectly fine). The perspective is a little bit misleading, this is the third or fourth layer. Happens on all layers, it's just a little bit more common around corners and bends.
This comment is correct imo. Read / calibrate the pressure advance. I've had especially good luck with the adaptive pressure advance and highly recommend taking the time to calibrate it.
Its a little bit confusing to do, but once you get the hang of it and do a full calibration sweep it should fix all the 'corners have gaps' issues. (Also just any gap issues between line)
Pressure advance is going to impact any line where the head will be shortly changing directions. So though it typically is corners you can get it with any acceleration change of the print head.
Try decreasing the speed in corners and increase pressure advance a bit. There is a tuning print you can use.
It's not just in corners.
PA can impact more than just corners. It's when the print head is changing speed/direction
The issue is also present on long straight lines though.
Calibration of a printer is very much a cumulitive thing. Looking at your print I think your PA is off, but I would guess that it's a combination of multiple settings. When calibrating a filament, I usually do a sweep of calibrations, and then sometimes even come back to past steps to rerun since the values can impact eachother.
I.e. I typically do in this order per brand of filament type. Always starting with the closest preset I can find. Usually the generic version if there isn't the brands of exact filament as a preset in orca.
Temperatue
Max volumetric speed
Pressure advance
Flow
Retraction
Sometimes back to PA because flow can impact PA
VFA/input shaping (optional)
And then toss a tolerance calibration at it at the end, but I don't typically do this per filament, just do it per printer unless you're about to print some super tolerance intolerant parts
IMO your flow / pa are off and combined are causing this. But idk, if you've already done both those calibrations then I'm not experienced enough to be able to definitively say what the issue is.
Edit: OH, one thing to note, you can increase the flow rate, and then in tolerance you can adjust the shrinkage to get the tolerance correct. So in that scenario increase flowrate, and then jump to tolerance and adjust to get the correct dimensional accuracy. That will make orca slicer auto scale the part dynamically so your final dimensions are correct.
Extrusion width?