negative mold from STL file

[mogey336]

Can i make a negative mold from stl file?
I made an two part mold before but i can't make it from stl file since i can't align or subtract it from a body or a components. 

[I_Forge_KC]

You will need to either convert to STL to Brep geometry (e.g. TSplines or faceted) or you will need to use a tool like Meshmixer that can handle mesh boolean operations.

[TrippyLighting]

No that cannot be done without prior conversion as @I_Forge_KC has already explained. Boolean operations in any CAD software I know are based on Solid Geometry otherwise known as BRep.

A .stl file only contains a triangle mesh which is a degraded form of geometry as far as CAD is concerned.

Whether that conversion can be done in Fusion 360 depends on how many triangles it is comprised of. Meshes with more than 10k or so triangles cannot be converted for performance reasons.

[laughingcreek]

Your question suggest you're new to solid modeling and mesh modeling.  Fusion is really bad at dealing with mesh models.  Also, the approaches used for dealing with meshes are entirely different than those used with solid models.  I suggest getting mesh mixer and learning how to use it to manipulate meshes, if your going to be dealing with stl's very much.  There are a ton of youtube video's on using mesh mixer.  The things you learn about mesh files will be relevant even if you later choose to use a different mesh editing software. 

That said, you can do what your asking in fusion (though it works better with mesh mixer, which has more tools).  The trick is to reverse the normal direction of the faces on your model, and then place it inside of a mesh shape that will be your mold.  here's a screen cast (the last step would be to run "make closed mesh" on each half of the result.  not always necessary)

[TrippyLighting]

@laughingcreek very cool. I was not aware of this! I do agree that Meshmixer is a tool better suited for work with triangulated meshes. 

[laughingcreek]

@TrippyLighting, there's other mesh Boolean voodoo that can be done using the "merge-make closed meshed workflow".  like making a hole.  Of course you lose a little bit of detail in your model each time you do this.  I can only imagine that AD bought mesh mixer for it's re-meshing algorithm (For FEA analysis),  B/C they totally miffed implementing mesh editing.

[TrippyLighting]

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@laughingcreek wrote:

B/C they totally miffed implementing mesh editing.

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I am assuming you are referencing Fusion 360, not Meshmixer ?

[Anonymous]

@I_Forge_KC is there a meshmixer forum I am trying to do the exact same thing and create a vacuum forming mold.

the video below does have some good tips.

https://youtu.be/7tqy-PJq6Ds 

[I_Forge_KC]

Yep:

https://forums.autodesk.com/t5/netfabb/ct-p/980

[I_Forge_KC]

Here is the reference I mentioned: https://help.autodesk.com/view/MSHMXR/2019/ENU/