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hartparr

Cura STL Expectations

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Howdy folks.

I'm trying to export an STL file out of Siemens NX (formally UGS) 3D cad software. After following some other 3D print software instructions on the settings to use for triangle and adjacent tolerances, the STL file never loads into Cura. I have also tried loading it into Netfabb to which I get an error "Invalid STL file".

Any pro tips to make this work?

 

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download meshlab. It's free.

Just loading into meshlab and resaving the STL can fix most problems.

How many faces do you have? Meshlab tells you at the bottom of the main window.

If it's more than say 1 million or even 100K it's worthwhile to reduce this with meshlab. Google something like "meshlab reduce number of faces" or "triangles" or something similar as the feature is well hidden.

 

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Can you send me an example stl file? (to d.braam@ultimaker.com) just a cube or something. Maybe the CAD software is doing something odd in the file and I can catch and fix the problem in the stl loader.

(Note that Cura also supports obj, maybe that export works)

 

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Thanks for the responses.

I have installed MeshLab and when I try to load the STL files, nothing happens. I see "Current Mesh:" is my file name, but vertices and faces remain 0.

I can't send these specific STLs due to ITAR, but will try to find a different part I can send assuming I have the same problem with it.

The STL files, depending on tolerance and what all I have loaded are anywhere from 80 to 340 MB.

 

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STL is really stupidly simple, so that Cura cannot read the export tells me something is odd in the export. I'm not asking for the specific STL (actually, if they are weapon bits, I rather not have them anyway, doesn't reflect good on Ultimaker right now with all the silly 3D printed weapon stuff)

Negative coordinates shouldn't be an issue in STL.

 

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The STL format is defined nicely here:

http://en.wikipedia.org/wiki/STL_%28file_format%29

It shows examples. Note that there are binary and text versions. Most readers can handle either format. I'm 90% sure Cura can handle either.

 

Actually, Cura can handle more then the wiki page shows. As some packages violate the standard. (Ascii files should be detectable by starting with "solid", but some binary files also start with "solid". I think FreeCAD does this)

Maybe this is a case of the reverse, making an ascii file without starting with solid (I won't detect that case right now)

 

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I got some more figured out yesterday. These parts in NX are very complicated. I had been trying to export full assemblies with a part count close to 1000 to STL. I tried a single part from an assembly and it worked like a champ straight to Cura.

I'm not a heavy NX user, so I'm not sure how, but it seems to me that if I could take an assembly and just export the outer most dimensions as a single part "skin" that it would go straight into cura without an issue.

In the meantime, I have a much more sloppy process of exporting to a .WRL file, importing that into Meshlab, exporting as STL then taking that STL file into NetFabb for a lot of repair work then into Cura works ok.

Does anyone know how to export a skin from an NX assembly?

 

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I got some more figured out yesterday. These parts in NX are very complicated. I had been trying to export full assemblies with a part count close to 1000 to STL. I tried a single part from an assembly and it worked like a champ straight to Cura.

I'm not a heavy NX user, so I'm not sure how, but it seems to me that if I could take an assembly and just export the outer most dimensions as a single part "skin" that it would go straight into cura without an issue.

In the meantime, I have a much more sloppy process of exporting to a .WRL file, importing that into Meshlab, exporting as STL then taking that STL file into NetFabb for a lot of repair work then into Cura works ok.

Does anyone know how to export a skin from an NX assembly?

 

You can try (from the menu) assemblies>advanced>simplify assembly

You can select all components which you want to have in 1 solid body.

 

One other thing...When I export from NX I get "Negative Coordinates Found in Output File". Does this affect how Cura or Meshlab loads an STL?

 

I have this almost every time, it doesn't seem to be a problem.

If your part is not classified or anything I can try it for you.

 

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