Travel moves unnecessarily crossing walls

[larsch]

Application version: 4.2.1

Printer Custom FDM

travel_moves.3mf.zip

Reproduction steps Set "Combing" to "Not in skin" or "Inside infill".

Actual results Cura generates travel moves with many jerks, crossing over skin instead of staying inside print when clearly possible.

Expected results Normal travel moves without jerks

Additional information Default slicing where "pointy" travel moves are visible everywhere:

Example: After printing outer wall, nozzle coasts a bit forward, then jerks outside print, crosses print to other hole in print, then jerks back to next outer wall being printing, even though the inside is fully connected.

[smartavionics]

Turn off the avoid printed parts when travelling setting.

[larsch]

Turning off Avoid Printed Parts does prevent the jerk travel moves. OK for this print.

[Ghostkeeper]

Yeah, looks buggy to me. I can see that it's combing correctly along the first inner wall, but when it needs to separate from that wall it decides to do a moveOutside which crosses the wall, and then makes a straight run for the moveOutside-location of the destination because it sees that it needs to cross the outer wall anyway (because it's now outside). It shouldn't do that moveOutside there.

It's probably doing that because it sees that the destination is already unreachable with combing. After all, combing is not allowed through skin as per the value of the Combing Mode setting.

[smartavionics]

Yes, it's because it can't comb within the skin. Notice that the spikes don't occur on the layers that don't have skin.

[smartavionics]

It would be better if it did a non-combed direct travel move with retraction (and, hopefully, z-hop to avoid wrecking the skin).

[Liger0]

I also have the nozzle going into empty areas going from start point to the ending one on a straight line instead of staying within the model on cura 4.3 beta, no matter if I use non in skin, in infill or all.

[smartavionics]

Please provide the .3mf file.

[Liger0]

Literally any model does it.

[smartavionics]

Unless you provide an example, I cannot help.

[Liger0]

Combing.zip

[smartavionics]

Thanks for the file. I have sliced it but can't see an obvious problem yet, please say what layer is causing the issue and maybe show an image of the problem. Thanks.

[Liger0]

I am not very good understanding everything combing does, but I think the travel on the top are not supposed to be there.

[smartavionics]

Ah, I see. Thing is, I don't get those travels when I slice with my cura. I think I fixed the bug that causes them a long time ago but the cura developers have not yet incorporated the fix. That was https://github.com/Ultimaker/CuraEngine/pull/973.