topic Re: Cut specific internal parts from STL in Fusion Design, Validate & Document Forum

Cut specific internal parts from STL

Anonymous — Sat, 11 Apr 2020 19:10:33 GMT

Hi, this is my first post but I did look for this topic prior to posting and I couldn't find anything specifically about what I need but I apologise if this is a duplicate post.

Now for what I'm trying to do. I am editing an Stl model of a formula 1 car in fusion 360 to print it in sections at 3/4 scale to the original to make a mould for a body I'm making out of fibreglass (basically an oversized go kart/ f1 car replica). The problem is that the model is quite detailed and I only need the basic body shape, completely hollowed to avoid wasting material when printing. I cannot simply hollow the model in mesh mixer because some parts are already hollow. I have attached images of the nose, which should be completely empty however has a "block" occupying a majority of the space. It would be a lot simpler if I had a solid model to begin with but unfortunately I don't so here I am. 😂

Re: Cut specific internal parts from STL

laughingcreek — Sat, 11 Apr 2020 20:57:51 GMT

what I would NOT do is convert the mesh to a brep.

one possibility is to use the mesh as a visual reference, and model a solid in the shape and locationof the void that you want. convert the solid that is shaped like the required void to a mesh.

there are some options from there-

-sometimes you can flip all the normals of the void shape to be facing out. export everything to mesh mixer and "combine". the will usually be interpreted by 3d printing software as a hollow object.

-sometimes after flipping the normals and combine, the "make solid option" will work.

-sometimes a Boolean subtract will work.

Re: Cut specific internal parts from STL

Anonymous — Sat, 11 Apr 2020 21:04:08 GMT

Thank you. Is it possible to 3d model the shape I want the hollow to be
like you said, save it as an STL then import that STL over the car mesh
model and use a cutting operation to treat the 2nd stl as a cut? I know
this is possible with normal bodies in fusion 360, where you can extrude to
cut etc and move objects where they overlap to perform a cutting operation.
Is this possible with mesh files or is the option not displayed? Thanks.

Re: Cut specific internal parts from STL

laughingcreek — Sat, 11 Apr 2020 21:18:53 GMT

@Anonymous wrote:
Thank you. Is it possible to 3d model the shape I want the hollow to be
like you said, save it as an STL then import that STL over the car mesh
model and use a cutting operation to treat the 2nd stl as a cut? ....

That's essentially the third suggested option (boolean subtract). But you can't do it in fusion. you have to do it in mesh mixer. fusion isn't particularly good at doing anything with meshes. you can export the bodies out separately, and then import into mesh mixer. they will come in at the same relative positions as they were in fusion. you don't actually have to do the convert to mesh part first if you do it that way. just export as an stl. If you do convert everything to a mesh first, then you can "combine" them, export it out, then just import once in mesh mixer and run a separate shells operation. I usually keep things separate.

Re: Cut specific internal parts from STL

Anonymous — Sat, 11 Apr 2020 21:23:08 GMT

Thanks, sorry I'm not familiar with some of the terminology (eg boolean
subtract) but I can Google that😂
Thanks for your help, I will try that idea tomorrow.