Convert complex 3D terrain (.STL) to simplified Brep

[W.Alblas]

Hi!

I am trying to convert a complex 3D terrain (.stl) to T-splines (reduced) in Fusion in order to CNC mill the surface. The quad mesh to T-splines command gives me the Warning: This body contains a high percentage of triangles or n-sided polygons. It makes sense because the .stl is way too complex for fusion to convert. However, when I try to reduce it (using the reduce mesh command) I am not able to use the quad mesh to T-splines command anymore (even though I turned off the capture design history) (photo 1). Does anyone know why this is happening?

I also tried the 'convert mesh' command (2nd photo), but I have no idea how to transform it to a solid form that I can mill. Maybe anyone have any suggestions?

In general, my main goal is to figure out a workflow for CNC milling large 3D terrains based on a height map or a .stl. There are a lot of tutorials out there that I watched, but it seems that most people use other cam software like V-carve for carving large 3D terrains. Unfortunately, I am not able to spend 1500 euros for such software. Therefore, I'm looking for another workflow using Blender and Fusion. Because of the complex geometry I have still no idea how to fix it.

Thanks in advance!

Ward 

[HughesTooling]

Is there any reason you don't want to just machine using the mesh?

[W.Alblas]

Than you for answering! 

You mean use the mesh surface like the second photo?

[HughesTooling]

Not tried an open mesh but you can machine meshes without any conversion, needs to be triangulated not quad. Working directly from the mesh means you don't lose any detales. Have you tried going to the manufacture workspace and try creating a setup and some 3d toolpaths.

[TrippyLighting · Accepted solution]

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@W.Alblas wrote:

Hi!

It makes sense because the .stl is way too complex for fusion to convert.

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No, it isn't. It is simply NOT a quad mesh 😉

Fusion 360 has it's own tool to re-mesh triangulated meshes ( a .stl file is ALWAYS fully triangulated), but I've had very good success using InstantMeshes and created a tutorial a few years ago:

[W.Alblas]

I've watched so many different videos on this topic, but your tutorial is totally new for me! This is exactly what I was looking for, thank you so much!

[HughesTooling]

@W.Alblas Are you sure you really need to convert the mesh though? I just helped someone in this thread who had converted a mesh to a faceted brep. Machining directly from the mesh reduced the file size from 50mb down to 5mb. The memory use drops significantly and performance is a lot better. Note most of the CAM operations for something like this will need to convert the brep back to a mesh anyway so calculation time will be higher. 

I know @TrippyLighting 's conversion method will be more efficient than converting to a faceted brep but you'll still put a lot of effort into the conversion you might not need to do. The mesh in the link above was open and quite bad quality and the CAM had no problems machining from the mesh. Also you don't lose any detail if you use the mesh.

Mark