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sveneb

Support inside the printed element

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Posted · Support inside the printed element

Hi Cura.

I have been using Cura slicing software for a couple of years now are very satisfied with the results. 

However yesterday i tried to printing a auger with two different increases, and half of it looked fine but the other half was very fragile.
When i looked at the layers inside the slicer i spotted that on some layers the support was inside the printed element.

Can somebody tell me what I have configured wrong in my configuration to end up with this result?
Thanks in advance
 

PrintedElementWithoutSupport.png

SupportInsidePrintedElement.png

FTFT5_Snegl.3mf

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Posted · Support inside the printed element

The model has all sorts of STL errors. Basically, it is not watertight. Here is a pic of the STL Check I ran in 3DS MAX. What this does is prevent the slicer from detecting a true inside and outside, therefore putting support everywhere. I am going out on a limb and guessing this is another Sketchup file.

 

STLErrors.thumb.jpg.76de6087a178b1d190af81443719a002.jpg

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Posted · Support inside the printed element

Thanks for the feedback.
I am not using Sketchup, but I am using freecad to make the 3D models in. 
But now I at least know where the root cause of the problem is.
Can any of you recommend a tool to validate the stl files with?
Thanks in advance

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Posted · Support inside the printed element

I think this is the leading STL checker online: https://service.netfabb.com/login.php

 

I thought freecad had a better reputation than this seems to present.

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Posted · Support inside the printed element

I haven't used FreeCAD for STL-export, so I can't comment on this specific issue.

 

But in general my experience with complex shapes like this is that if you need to combine things (="union" function), make them *overlap* each other first. If the edges just touch each other, the software is more likely to have difficulties sorting out where the edges belong. Probably due to rounding errors? DesignSpark Mechanical usually gives an error-message that it can't do the combine, so it refuses, but it has never created invalid models. However, early versions of other commercial programs I tried, did sometimes create invalid models. And SketchUp nearly always creates invalid models, since it wasn't ment for 3D-printing anyway, but that is another topic...

 

Did you make this screw by combining a rod and a spiral? If so, try again with a royal overlap?

 

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Posted · Support inside the printed element

@geert_2
Thanks for the suggestion on let the parts overlap when making a union. 
Yes the part is made by a union of a rod and a spiral, and in fact i had some problems in making a union of them in the beginning, and I solved it by let them overlap as you suggested. After that i could make a union of them without any errors, and then I thought the problem was solved.
But apparently it was not :-/


@kmanstudios
Thanks for the link to the validating tool, I will use this tool to try to find the reason for the error that I am seeing.
I think that I am doing something wrong, rather then there are an error in freecad. 

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Posted · Support inside the printed element

Another thing that just comes to my mind: did you export it to STL as a solid, or as a bunch of separate surfaces? I don't know what the mathematical difference is, but in DesignSpark Mechanical there is such an option: "Connected Mesh" vs. "Simple Mesh". Maybe in FreeCAD too?

 

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Posted · Support inside the printed element

i'm using freecad, yes try to male "part union" before stl export, often you get a different (normally better) result.

i made in this way: save project, make union, make stl export, close without save project

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