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Broken .stl files


BenG

Question

I have no idea if this is a VW problem or not, but it is certainly related.

 

My current business is designing plastic motorized microscope stages (XYZ).  I design the parts in VW, convert the files to .stl files, read them into a “Slicer” program, which exports the gcode necessary to run the 3D printer.

 

Occasionally, the Slicer program produces a garbled result, so the gcode is garbage.  The .stl object looks OK when imported into the Slicer pgm, but slicing shows numerous errors and  problems.

 

I have not suspected VW in the past, but recent events make me wonder.  First is the bloated file size of VW.  We are told to Convert to a Generic Solid, which does reduce file size dramatically.  VW should have an optional automatic command to do this as we draw.  I understand this means the internal surface joints (from adds, subtracts, P/P…) are not properly executed, leaving internal code conflicts which are not visible to the designer.  Generic Solids is supposed to help this situation, but there are no details as to what this means.  Sometimes VW says it cannot do the Generic conversion and spews out the famous “fix the file and try again” as if that means anything.

 

Recently, I got a significant failure of the Slicer to properly render a VW file.  I went back to the .wvx file and did my best to clean it up.   I looked at the wireframe view to see if there were any hidden lines indicating edges, surfaces, etc. that shouldn't be there.  After numerous cycles of fixing, exporting .stl, and Slicing failures, I posted my problem on the 3D printer forum and was asked to post the .stl file for someone to examine.  Remember, this file comes directly from VW.  I hasn't gone to the Slicer yet. The reviewer's comments are below: 

---------------------------------

Wow, that's quite possibly the most broken stl file I have come across.  Imported it into Blender and it was obvious that its broken as I'd say about 50% of the faces are missing and you can see through large parts of it.  If you run the 3d print tool on it it reports the following

44604 Non Manifold Edges
1357 Non Contiguous Edges
18832 Intersecting Faces
976 Zero Faces
188 Thin Faces

---------------------------------

I then went back to the previous copy of the file (several days before), which sliced OK (but citing numerous internal errors).  

 

All I can say is VW doesn’t seem to have a robust way of getting rid of internal conflicts.  I have had numerous problems with ordinary commands such as P/P, Add, Subtract, fillet, chamfer, etc. not working properly - as mentioned in many posts elsewhere.  Now I can add creating .stl files to the list.

 

Is there any information about detecting and fixing the internal errors VW seems to create?

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