Working with STL files

[Anonymous]

Many useful items that I would like to modify for my own needs are available only as STL format files.  When I import STL files into Fusion 360 I'm presented with a blue solid that can be moved and rotated but does not allow me to sketch or make holes in the model mode. 

I've read a lot on this and some people say to convert to another file format such as STEP or IGES but I cannot find a clean way to do this.  I've tried MeshMixer, NetFabb and 123D all with no success.

What am I doing wrong?

Thanks!

[TheCADWhisperer]

Can you attach the original *.stl file here?

[Anonymous]

Yes ... this is one example. But I've had the same results with several different STL files.

[cekuhnen]

@Anonymous

Well you load a triangulated mesh model into a CAD system that prefers to work with NURBS.

So you cannot modify the STL import with SOLID tools.

You can however use the MESH 2 BREP command.

With the timeline active you have to import the STL mesh then make a base feature and in the base feature call the MESH 2 BREP command.

When you are in Direct Modeling you can just go to SOLID and then call the command after you imported the mesh.

This command will make a NURBS face for each polygon triangle. The result will be as choppy as the STL import.

So I would suggest to mesh fine the STL model or best import it, convert, but then use it to measure and rebuild a new clean solid.

[Anonymous]

I had to do some reading to properly interpret your reply because at this point I'm still using F3D as a blunt instrument to make regular shapes and extrude and modify as required.  I'm afraid I only have a rudimentary appreciations of meshes and splines. I haven't required that knowledge to this point. 

I used the Mesh 2 BRep command on the imported STL file and it became semi-solid, but still left a lot of triangular sections that can be individual highlighted and I was unable to join. 

Is there a utility that can convert an STL into a completely solid body that I can used sketch, extrude and modify to make the features I require?