topic Re: Can't cut rectangle with contour of a mesh object - DJI FPV in Fusion Design, Validate & Document Forum

Can't cut rectangle with contour of a mesh object - DJI FPV

kevin211096 — Sat, 07 Dec 2024 18:59:50 GMT

Hi all,

I'm trying to make a drone attachment that is supposed to attach to the bottom of my DJI FPV drone. I thought I would begin the project by creating a rectangle body that would be cut by the drone's contour, that way I wouldn't have to spend much time measuring and tediously fit my attachment to the shape of the drone. The thought was that I would import the 3D model of the drone (link below) as mesh, generate face groups and then convert from mesh to body, then tell fusion to use the body of the drone to cut the rectangle which is placed under the drone, and then get the countour of the drones bottom cut out from the rectangle.

However, when I convert the mesh to a body, I get the "Mesh is not closed" error (the same as this: https://www.autodesk.com/support/technical/article/caas/sfdcarticles/sfdcarticles/Mesh-is-not-closed-warning-message-in-Fusion-360.html).

I've tried to fix it by using the repair mesh tool with the close holes repair type, which works quite well.

When I go to convert the mesh to body after the mesh repair though, it's not the whole drone which is rendered as a body, only fragments of it is rendered, and I can't find a setting that will render the whole drone.

Attached is the file I've been working on for some time. There's not many steps in it because I keep deleting what doesn't work. The rectangled body called "attachment" is what I want to cut to the bottom shape of the drone.

Attached is a visual representation of what issue I'm facing as well.

Maybe an expert from the community can help me out? 🙂

DJI FPV STL file: https://www.printables.com/model/325800-dji-fpv-drone

Re: Can't cut rectangle with contour of a mesh object - DJI FPV

TimelesslyTiredYouth — Sat, 07 Dec 2024 20:11:45 GMT

Hi @kevin211096

Now, I've looked over the file and I can't lie, didn't see any noticable holes that need to be patched.

my advice to you is to use the inspect -> analyse mesh tool which will gighlight open edges where a hole can exist
however before that, try using the close gaps tool to see if this resolves the issue, this should work unless the hole is to big to fix or is a weird shape of sort

Re: Can't cut rectangle with contour of a mesh object - DJI FPV

kevin211096 — Sat, 07 Dec 2024 20:37:20 GMT

Hi Ricky,

Thanks for the reply.
The thing is that I don’t see any gaps either, that’s why this is so frustrating. 😄

I’ve already tried the close gaps/close holes (correct me if these 2 are not the same) option for mesh repair, and as I said in the original post, it works well it’s only the convert mesh to body function the deletes a lot of the drone (see screenshots in post).

Re: Can't cut rectangle with contour of a mesh object - DJI FPV

TimelesslyTiredYouth — Sat, 07 Dec 2024 20:54:35 GMT

Now, my last question before I give up is, is the triangle count below 10,000.

Otherwise this is the definition of misusing the @ command

@TrippyLighting can you come here please, I know your online.

Re: Can't cut rectangle with contour of a mesh object - DJI FPV

TimelesslyTiredYouth — Sat, 07 Dec 2024 20:56:40 GMT

Is it hollow or not the mesh (can mesh be solid?), is there any chance it could have any overly thin or overlapping walls

Re: Can't cut rectangle with contour of a mesh object - DJI FPV

kevin211096 — Sat, 07 Dec 2024 21:15:44 GMT

Triangle count is above 10.000.

Re: Can't cut rectangle with contour of a mesh object - DJI FPV

kevin211096 — Sat, 07 Dec 2024 21:19:43 GMT

The mesh is hollow at some places, and it does have very thin components in it. However, I thought that would be fixed using the repair mesh and then the close holes feature.

Re: Can't cut rectangle with contour of a mesh object - DJI FPV

TimelesslyTiredYouth — Sat, 07 Dec 2024 21:29:29 GMT

your right it should be fixed with that function, but then the fact that you got a "mesh is not closed" message doesn't back you up sorry...

Can you answer the question from before about is it less than 10,000 triangles and does it have any non-manifold geometry that doesn't include the fact that there may or may not be a hole in your design...
i also checked your design again and asked a friend to open it and zoom in on his widescrreen, we both found no holes so ...

@TrippyLighting , or another guru is my best advice, even if i get roasted for being wrong or saying something that is generic cuz i've said everything that I know now sorry, I'm young so I have quite limited knowledge...

Kind regards

Ricky

Re: Can't cut rectangle with contour of a mesh object - DJI FPV

TimelesslyTiredYouth — Sat, 07 Dec 2024 21:43:08 GMT

So sorrrrryyyyyy.....

Didn't realise you already stated triangle count, if so i mean it could be the fact that:

When the triangle count of a mesh exceeds 10,000 in Fusion 360, it can cause issues with mesh-to-body conversion due to the high complexity. Fusion 360 may attempt to simplify the mesh, leading to missing geometry or parts being deleted. This happens because Fusion 360's conversion process may remove smaller details or faces it deems unnecessary to manage the complexity and avoid overloading the system. To address this, you can reduce the triangle count using tools like Reduce Mesh
don't bother reading everything i wrote and just make a copy of your design and try using the reduce faces tool and then convert msh, see if this makes a different in how it converts and see if it gives any different warning instead this time

Re: Can't cut rectangle with contour of a mesh object - DJI FPV

TimelesslyTiredYouth — Sat, 07 Dec 2024 21:43:47 GMT

*reduce mesh sorry not reduce faces

Re: Can't cut rectangle with contour of a mesh object - DJI FPV

kevin211096 — Sat, 07 Dec 2024 22:24:56 GMT

I tried to reduce mesh and set it to 10, but it still have over 10.000 triangles.

It did make it more low-poly though so I gave it another shot with the mesh to body conversion, and I keep getting the same error "Cannot convert mesh..." and "Mesh to T-spline..." (see screenshot).

The mesh does have a lot of internal parts inside, so I guess these are what is causing the trouble here. Not sure how to patch those so the inside just become one solid mass.

Calling all experts!

Re: Can't cut rectangle with contour of a mesh object - DJI FPV

TrippyLighting — Sat, 07 Dec 2024 23:03:17 GMT

Do you want to 3D print that attachment?

If so, I'd suggest not converting the mesh into a solid body.

Converting that mesh into something usable with any method will likely not result in success!

Re: Can't cut rectangle with contour of a mesh object - DJI FPV

kevin211096 — Sat, 07 Dec 2024 23:16:26 GMT

Yes, that's correct. It's for 3d printing.

Do you have any suggestions on what I can do in order to make the drone mesh cut out a body?

Re: Can't cut rectangle with contour of a mesh object - DJI FPV

TrippyLighting — Sun, 08 Dec 2024 00:26:51 GMT

I would need more info on how that accessory will interact with the rest of the Drone.

I would model that accessory and tesselate it in the mesh workspace when done.

Then I'd combine-cut the freshly tessellated mesh with the part of the drone mesh.

Re: Can't cut rectangle with contour of a mesh object - DJI FPV

TimelesslyTiredYouth — Sun, 08 Dec 2024 07:25:04 GMT

Tesselate the drone?

won't problems occur with the fact that 10,000+ triangles and the fact that the inside is hollow with seperate sections...

just for learning sake

Kind regards

Ricky

Re: Can't cut rectangle with contour of a mesh object - DJI FPV

TrippyLighting — Sun, 08 Dec 2024 12:45:54 GMT

The drone is a triangulated mesh, so it was already tessellated when it was converted from a CAD model into a triangulated mesh.

IIRC, that 10k warning only appears when you try to convert a mesh directly into a solid body, which is not a good workflow!

It is just a warning, but you can still convert the mesh.

Re: Can't cut rectangle with contour of a mesh object - DJI FPV

TimelesslyTiredYouth — Sun, 08 Dec 2024 13:22:13 GMT

What steps should be followed for a good workflow when importing a mesh, and eventually converting it to a solid body that can be worked with?
is it not just, make body, make the triangle faces, group them?

sorry for asking begginer questions, just trying to learn

Kind regards

Ricky

Re: Can't cut rectangle with contour of a mesh object - DJI FPV

TrippyLighting — Sun, 08 Dec 2024 13:54:50 GMT

That depends on the mesh, even if we limit the conversation to triangulated meshes.

The geometry of the drone mesh, at least the body that interfaces with the attachment, is too complex to be converted into a "good" solid body.

The only way to convert it is the faceted version and I would advise against it.

Triangulated meshes are not native CAD geometry and are hard to impossible to model with in Fusion and many other CAD software.