PrusaSlicer 2.7 seam strangeness
 
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PrusaSlicer 2.7 seam strangeness  

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surfski
(@surfski)
Member
PrusaSlicer 2.7 seam strangeness

When I slice my part, the seam is shown in the desired location, with seam position set to Aligned.  But when I print the file, it's doing a strange start / stop in two other locations, leading to surface defects.  Previously I have incorrectly specified the seam position or part orientation, resulting in a similar defect, but only at one location.  Why would it start and stop at two, non-seam locations, instead of making a contiguous loop from and to the specified seam location?  Thanks for any insight.

Pics show both sides of the part, and preview with correct seam location.

Posted : 05/12/2023 12:51 am
Diem
 Diem
(@diem)
Illustrious Member
RE: PrusaSlicer 2.7 seam strangeness

It may correlate with the need to divert filament to internal structures, especially in thin sections.  If you would like us to look closer save your project as a .3mf file

Files > Save Project as

Zip the .3mf and post it here. It will contain both your part and your settings for us to diagnose.

Cheerio,

Posted : 05/12/2023 7:58 am
surfski
(@surfski)
Member
Topic starter answered:
RE: PrusaSlicer 2.7 seam strangeness

Thanks, there may be something to that.  But I just reverted to classic perimeter generator, and now it's printing correctly.  It seems like a problem with arachne.  

ps-arachne-seam-issue.3mf

Posted : 05/12/2023 5:46 pm
Diem
 Diem
(@diem)
Illustrious Member
RE: PrusaSlicer 2.7 seam strangeness

You have a slightly malformed .stl, notice the warning triangle next to the list entry.  It may pay to fix that first - this is a very technical part so the easy fixes in Blender might not be suitable, go back to the original CAD and make sure none of the structures have been included 'inside out'.

Cheerio,

Posted : 06/12/2023 11:54 am
surfski
(@surfski)
Member
Topic starter answered:
RE: PrusaSlicer 2.7 seam strangeness

Thanks, that's wild.  I did figure out that it's model specific.  I see the triangle next to the list entry, but no additional info about the issue - is there more?  A way to view the mesh or normals?  I've been printing these for many years, but slicing with Simplify3D (and use Rhino for CAD), but trying to switch to PS, and it's a challenge.  This model prints fine when sliced with S3D...

Posted : 06/12/2023 11:44 pm
Diem
 Diem
(@diem)
Illustrious Member

If you scroll down you will see that it has found 28 open edges - these are edges without any associated surface, a somewhat trancendental concept.  The usual reason but not the only one is that a part has been designed from geometric primitives but in pushing and pulling them into position some have been dragged inside-out - this may be a very thin part, imagine a sheet of paper turned inside out ...

PrusaSlicer can autofix some obvious examples and there are third party apps that will 'fix' everything - but the fix is always a guess and can easily make things worse.  With technical parts it is better to go back to the original cad.

Cheerio,

Posted : 07/12/2023 11:23 am
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