Unexpected behavior using the suggested thin wall thickness
 
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Gohancz
(@gohancz)
New Member
Unexpected behavior using the suggested thin wall thickness

Hello, according to the slicer, suggested thin wall thickness for 3 lines is 1.32mm and for 2 lines 0.9mm.

https://imgur.com/wPEvmj1

Therefore I modeled with these values in mind:

https://imgur.com/M2dfaHO

When sliced however, instead of 3 lines i get 2 and a gap fill.

https://imgur.com/2X9ST2t

The 0.9 walls work as expected with 2 perimeters.

There is also a secondary thin gap fill, that I have no idea how it got there as per the sketch there is no space between the 0.9 and 1.32 walls.

 

Why is it behaving in this way? Thank you

 

 

Posted : 06/12/2020 2:00 pm
Neophyl
(@neophyl)
Illustrious Member
RE: Unexpected behavior using the suggested thin wall thickness

Because your walls wont actually be that thick all the way around.  Not on a circular piece anyway.  When exported to a stl file the model is converted to a bunch of triangles.  Where those triangles meet the wall is now no longer your perfect modeled thickness.  Any time there is a join of two triangles the model may no longer be what you made it as.  All it takes is for it to drop to 0.8999999999 and its no longer 0.9

Its why you often see short lengths of perimeters interspersed with gapfill on slices.  Where the maths is right on the edge between one or the other.  Its better at least where it picks either another perimeter or gapfill all the way around at least like on your example. 

Posted : 06/12/2020 2:53 pm
Gohancz
(@gohancz)
New Member
Topic starter answered:
RE: Unexpected behavior using the suggested thin wall thickness

But the 0.9mm walls work as expected. And so did 4 perimeter walls when tested.

3 perimeter walls are the problem.

 

What you are describing makes it look like the problem should be with all of them.

Posted : 06/12/2020 4:56 pm
Neophyl
(@neophyl)
Illustrious Member
RE: Unexpected behavior using the suggested thin wall thickness

There have been so many posts about this on here and github.  If its working for some of your thicknesses then good.  You got lucky.  Try looking through the threads or go add your bit to one of the open issues on github.

https://github.com/prusa3d/PrusaSlicer/issues/3025

or https://github.com/prusa3d/PrusaSlicer/issues/1405

or https://github.com/prusa3d/PrusaSlicer/issues/3822

Posted : 06/12/2020 7:08 pm
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