Better seams
I have been using a couple of methods to get seams that are (I think) much better than those that I get from slicers, including PrusaSlicer. I'm sure that they will be of interest to many 3D printers (the people, not the machines) and I'd like to see if it is worthwhile trying to get them incorporated into PrusaSlicer.
The photo shows a couple of examples. In the left photo a box 25mm square and 6mm tall was sliced in PrusaSlicer with 2 perimeters and no fill. The resulting gcode file was then added to with some custom gcode that makes a similar box (2 perimeters, no fill) but with what I call a scarf seam. In the right photo the object is a cylinder 12mm in diameter that was sliced in PrusaSlicer (6mm tall) and then extra gcode added that gives 6mm portions with the scarf seam (the middle 6mm) and a zipper seam at the top. Both prints were made on an MK4 with Prusament PLA, and the standard PrusaSlicer profiles for the printer (non-IS) and the filament at 0.2mm layer height. I have attached the gcode for the cylinder in case anyone wants to give it a go. You may need to replace the header portion which has MK4-specific instructions.
The scarf seam is like a woodworker's scarf joint, and is most easily described for the cylinder. The outer perimeter is printed first starting from the seam with extrusion that gradually increases in height from 0 to the full layer height. Once a full rotation is completed the nozzle steps over to do the inner perimeter and then steps back out to complete with outer perimeter with a ramp that goes from 0.2mm height down to 0 when the nozzle reaches the seam again. That means that there are three loops to complete the two perimeters. The results can be seen.
I'll write some more later, as my wife has called me to dinner!
RE: Better seams
If you want to suggest anything to the devs then feature requests (and bug reports etc) need to be made over on the Prusa Slicer github https://github.com/prusa3d/PrusaSlicer/issues
I do like the look of the scarf seam, looks very nice. Would be good to have that if it proves practical for geometry other than simple cylinders or cubes. Hate the look of the zipper one though. My normal PS seams aren't as pronounced as your pictured ones, but then again I calibrate for my individual filament and don't retract on layer change.
RE: Better seams
I agree, the scarf seams look nice! Put it on Github as a suggestion and give us the link so we can support it!
RE: Better seams
The scarf seams should be reasonably easily implemented for objects of any shape, but the benefit is most obvious where the seam has to occur in a smooth region like in my examples. It can be applied with any number of perimeters.
I seem to have mis-described the seam sequence in my original post. (Don't post things while hungry!) The scarf of the cylinder example extends all of the way around (although it doesn't have to do so) and it consists of first a taper that goes from zero layer height to 0.2mm layer height in one revolution, then from 0.2 back doewn to zero in a second revolution. The nozzle z-height is stationary during the second rotation. Then the nozzle moves inwards and the inner perimeter is done with a fixed 0.2mm layer height. When the nozzle moves outwards for the next outer perimeter it is effectively doing so with zero layer height, and that minimises any artefact at that time. The low angle scarf joint between the two outer perimeter tapers means that the end to end joint of a normal seam doesn't occur and so the total seam is pretty much invisible.
The scarf seam does have a couple of disadvantages that would probably be seen as fairly trivial in many circumstances. First, because the scarf joint requires two passes over the length of the joint it will be slower to print. For a large print with several perimeters and infill the additional time would be modest, but for the simple cylinder example the scarfed section requires one third longer to print than the plain seam because it needs three loops rather than two. The second possible disadvantage is that the scarfed region has uneven layer heights that can be visible if you look too closely. In the cylinder example the side opposite the start/end of the scarf has a layer height half of the nominal.
I will make a GitHub post in the PrusaSlicer repository once I have a chance to compose it carefully. I may also have a go at post-processing PrusaSlicer output gcode to insert the scarf seam, as success at that will prove that it can be incorporated into the slicer without too much trouble.
RE: Better seams
Submitted to GitHub here: https://github.com/prusa3d/PrusaSlicer/issues/11621
RE: Better seams
This method aims to create a smoother transition between layers and minimize the visibility of the seam.