Fuzzy Skin on TOP LAYER idea.

[jefftopp1984]

Why don't you vary the extrusion rate of the top layer and make the Z do small 0.2-0.3mm "hops" when the extrusion rate is high? Sure, I understand that would take some time to process, but so does the extrusion variation in the walls. On steeply sloped top surfaces such as a low wide arch where the entire line of a perimeter or more is the top surface, apply both the X/Y diversion and the Z diversion to the outer perimeter and then the top surface logic to the exposed areas of the perimeter and top solid infill. That way the entire model can have the same finish. By default the top lines would have to be limited to 10mm/s since that is what most printers are. I'm sure some can go faster than that, but most printers are 10mm/s on the Z axis.

But a big issue with this is the slicer NOT recognizing the inner wall of an internal overhang and applying overhang rules to it. It doesn't print the correct bridge layers below it nor does it slow down for steep internal overhangs. It treats them as normal walls. This is especially bad when the printer prints inner to outer with the perimeters. The inner wall is printed at FULL SPEED, which is sometimes 250mm/s or higher, with NOTHING TO SUPPORT IT OR IT TO GRIP because it hasn't even printed the other perimeter layers for it to grab something on the side! It has maybe a few lines of sparse infill to grab and that's it. To change your perspective on things, internal sparse infill is nothing more than SUPPORT MATERIAL for the TOP LAYERS of the model. If you'd support it and put a support interface under it externally, the SAME RULES should be applied INTERNALLY. So, you do an interface layer to assist the bridge layer. then a bridge layer (or possibly just 2 bridge layers like you already have with extra bridge layers), and then lay the perimeter or internal solid infill on that. But it does NONE of this. It acts like it's a normal straight up perimeter wall and there's nothing weird about it. This is for things with like a 15-30 degree angle. It never recovers and snowballs up through NINE layers of top solid infill because of how much wasn't supported. This issue MUST be fixed before the fuzzy skin idea will work. Even extra bridge layers turned on and filter out small internal bridges set to No Filtering, it still will not apply the correct rules to steep internal overhangs.

[pi-squared-studio]

https://www.youtube.com/watch?v=85FJl5P0AoU

[jefftopp1984]

@SoftFever Please review the second paragraph of this. I have been attempting to contact you about this for 2 months now. I have sent messages on Facebook messenger, added it to the bug reports, and added it to feature requests, but it has not even gotten your attention. Prusa does the SAME THING, so it's coming from the core coding. It simply does not recognize steep internal overhangs as overhangs and therefore does not apply the correct rules. The results are this:

It fdo

It prints that line at full speed with no cooling when there is nothing other than sparse infill to support it. And since it's printing inner to outer, there isn't even a perimeter line to grab. It snowballs and even after 9 more layers are printed on top of it, the top surface is still broken.