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Cura thinks file is not watertight


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Posted · Cura thinks file is not watertight

Hi Guys,

I have no idea why cura keeps telling me the file is not watertight. 

When I go to slice the file it creates a top and bottom where there is none and infills it, this happens no matter what orientation the part is and depending on orientation is different.


If anyone has any ideas where Im going wrong that would be greatly appreciated

Screen Shot 2021-09-14 at 9.21.12 am.png

Screen Shot 2021-09-14 at 9.29.11 am.png

Screen Shot 2021-09-14 at 9.29.36 am.png

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    Posted · Cura thinks file is not watertight

    You could post the STL file so I could have a look at it.  You probably have the normals backwards in many parts of the file.  An stl file has an unordered list of triangles in 3d space.  The normals tell cura which side of each triangle faces in or out.  You can fix the normals with cura or in cad.  normals are very easy to fix either way.  For example in sketchup or blender it's super easy to fix them all.


    If this model is from blender google about the "remesh modifier".  And also about "normals" in blender.
    More here: https://www.sculpteo.com/en/tutorial/prepare-your-model-3d-printing-blender/

    If this model is from sketchup read this:



    Cura has an amazing plugin to test your model to see if something is wrong with it and can repair a very few of the many potential problems:
    In the upper right corner of Cura click "marketplace" and make sure you are on the "plugins" tab and install "Mesh Tools".  Then restart Cura.  Now right click on your model, choose "mesh tools" and first choose
    "check mesh", then "fix model normals"


    Also in cura "mesh fixes" make sure "remove all holes" is unchecked.

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    Posted · Cura thinks file is not watertight

    The normals are not takes into account when checking the water-tightness of a model. This article from the SettingsGuide plugin explains what manifold or watertight is: https://github.com/Ghostkeeper/SettingsGuide/blob/master/resources/articles/troubleshooting/missing_parts.md#non-manifold-meshes

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