Netfabb modelling help

[Rjames112]

So I'm doing up my first model is Netfabb. I'm self taught so bear with me. I have drafted initially in Google Sketchup and converted the files to STL format and used the repair feature to clean them up. But to use the files at shapeways they need to be a single shell, and I am not sure how to combine shells in Netfabb.

If someone could help me out or point me to another printer that allows multiple shells.

 

[epilepticsquirl]

Care to post up some pictures?
From what it sounds like you have seperate surfaces that are not joined; thus the printer wouldn't know what to print. yea?

 

[darthviper107]

You don't have to combine objects into one to print it--as long as their intersecting a little bit they will be printed as one object.

 

[epilepticsquirl]

can you please post an example of a before and after of this occurring? I'm not sure I've ever heard of that before.

 

[Rjames112]

What caused the main problem seemed to be several of the face normals were facing the wrong direction. The normals direction indicates a surface at the starting point of the normal. So for example, you create a cube, flip the normal of 1 face. The cube is still manifold(watertight) but with that normal facing inward, Shapeways regards that faces surface to be inside the cube,not on the outer surface like the other 5, which face outward, so its rejected.
Yea its sorta picky, but makes sense when the model needs to be represented in real terms, not just a subject for a render.
Duplicated vertices can also cause numerous problems.

Just remember to check to see that the normals of a mesh are pointing in the direction that will designate a surface thoughout its design. Especially after any operation on the mesh(boolean, subdivision, mirroring,..,)

 

[darthviper107]

Yes, if a face of a cube were to be facing inward then the cube would no longer be solid---essentially that face would then be considered separate which would make a hole in the mesh.