Duplicate center perimeter generated for 3 perimeter wall

[kaetemi]

Version

Version 2.4.0+win64

Operating system type + version

Windows 10

3D printer brand / version + firmware version (if known)

Ender 3 Pro

Behavior

Model with wall thickness 1.26 (3 perimeter wall)
Slicer with the default Ender 3 profile, and 0.24mm layer height DRAFT preset

The center perimeter of the walls will be generated twice, once for the outside and once for the inside wall. The resulting print is a horrible mess of blobs everywhere.

Project File (.3MF) where problem occurs

cdrack v29.zip

[kaetemi]

(Works fine in SuperSlicer, though!)

[foreachthing]

The center perimeter of the walls will be generated twice, once for the outside and once for the inside wall. The resulting print is a horrible mess of blobs everywhere.

How could I reproduce it and where would I have to look for duplicate lines?

[kaetemi]

How could I reproduce it and where would I have to look for duplicate lines?

Just slice with the default Ender 3 profile, and 0.24mm layer height DRAFT preset.
ALL the center perimeters are printed over twice.

[kaetemi]

See the yellow line? It's putting down the exact same yellow line in the exact same spot a second time.

[foreachthing]

Jup, it does it with your settings, not with mine, though... that's odd. I am using an Ultimaker 2.
But I can't see anything standing out that could cause the issue.

[Jebtrix]

Doubling of perimeter kind of like #7762

As @bubnikv stated in other issue Thin Wall Detection works in this particular scenario. It's definite a narly bug since its hard to even see in preview with certain objects. The other issue was a single perimeter, this is 3. Wonder if its an odd number of perimeters issue.

[NGC869]

I described the same faulty slicing logic here:
#7973

I found also that the "Thin wall detection" feature does not work very well: it lead to a very slowly (or crashing) slicing, also introducing bad printing strategies.

Thank you.

[stepikovo]

We released PrusaSlicer 2.5.0-alpha2 today with the Arachne perimeter generator, it should fix the issue, can you please confirm?