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problem with sliding 3D assemblies

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I made an assembly forom three parts. for processing in cura I made a part of the assembly and than a STL file.


If I slide the parts seperately cura slides well (see attached JPG's)


Wen I sliude them together there iare a lot surfaces missing (see attached JPG).


Any idee what I am doing wrong ?

profiel part 1.JPG

profiel part 2.JPG

profiel part 3.JPG

profile complete.JPG

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First of all - all that red in cura xray view is a problem.


Is it possible for you to merge all your parts into one large part?  if you have two separate solids touching each other then you have a shared wall.  Cura does not like this.


The STL file is a list of unordered triangles.  Cura intersects planes with the triangles (slices it).  Each slice generates a bunch of *unordered* line segments.  The key here is that they are unordered.  Cura then tries to link these lines into loops.  Because of floating point errors when two lines are supposed to be connected at a point, sometimes the X,Y values of that point aren't quite the same so Cura has to fudge a bit and sometimes chooses the wrong line!


Because of this - having two solids touching each other that have a shared wall can be a problem.


I skipped a few steps here in the explanation.  Let me know if I need to clarify this.

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