topic Re: How to subtract / cut from a mesh? in Fusion Support Forum

How to subtract / cut from a mesh?

SimonPlatten — Wed, 03 Jan 2018 15:45:21 GMT

I have a mesh, I would like to subtract / cut an object from the mesh, but how?

Re: How to subtract / cut from a mesh?

paul.clauss — Wed, 03 Jan 2018 17:12:12 GMT

Thanks for posting and welcome to the Fusion 360 community! To subtract or cut away from a mesh, you can use either the "Plane Cut" or "Separate" tools in the Mesh workspace. I have shown a brief example of this in the screencast below.

You could always convert the mesh to a solid body and then use the split bodies tool to edit the model as well - if your desired final format is a mesh, you could convert the mesh to a solid, make the desired model changes, and then save the edited body as an STL.

Hopefully this helps! Please let me know if you have any questions.

Re: How to subtract / cut from a mesh?

SimonPlatten — Wed, 03 Jan 2018 17:17:01 GMT

Thank you, I tried converting the mesh to an object, but it failed Triangles = 42735.

Re: How to subtract / cut from a mesh?

paul.clauss — Wed, 03 Jan 2018 17:22:39 GMT

Hi @SimonPlatten

Thanks for the response! You will need to Reduce the mesh to convert it, as shown briefly in my video. There is a limit to how many triangles can be converted from a mesh to solid.

Re: How to subtract / cut from a mesh?

SimonPlatten — Wed, 03 Jan 2018 17:27:24 GMT

I've tried to do this and I get an error, which isn't very helpful because it simply says "Reduce failed due to invalid input"

The settings in the dialog are:

Mesh Faces / Body: 1 Selected

Reduce Type: Adaptive

Reduce Target: Density

I've tried various options but all result in the same.

Re: How to subtract / cut from a mesh?

paul.clauss — Wed, 03 Jan 2018 17:29:12 GMT

Hi @SimonPlatten

Thanks. Would you mind sharing the mesh file you are working with me? I'm happy to have a look.

Re: How to subtract / cut from a mesh?

SimonPlatten — Wed, 03 Jan 2018 17:33:59 GMT

No problem, only problem is I have no idea where on my iMAC the project files are located, if you can tell me I will attach the model.

The original model is not my work, I download the STL file and imported into Fusion 360, then split the mesh into multiple parts for printing.

Re: How to subtract / cut from a mesh?

paul.clauss — Wed, 03 Jan 2018 17:35:58 GMT

Sharing a Fusion 360 design - or feel free to attach the downloaded STL file to your next post.

Re: How to subtract / cut from a mesh?

SimonPlatten — Wed, 03 Jan 2018 17:45:05 GMT

Ok, thank you, that doesn't really help though because although I've created the archive, I still have no idea where to find it.

Re: How to subtract / cut from a mesh?

SimonPlatten — Wed, 03 Jan 2018 17:47:41 GMT

Sorry for double post, I got an error when trying to post the initial reply.

Re: How to subtract / cut from a mesh?

paul.clauss — Wed, 03 Jan 2018 17:58:30 GMT

Hi @SimonPlatten

When you create the export, the dialogue box shows a flag to "Save to my computer," and then the filepath the local copy will be saved at. You can change this location by clicking the ellipses in the box to the right of the filepath.

Re: How to subtract / cut from a mesh?

SimonPlatten — Wed, 03 Jan 2018 18:04:20 GMT

Its so frustrating, the file dialog only shows the end folder called "files", but I have no idea where it is in my profile.

Re: How to subtract / cut from a mesh?

paul.clauss — Wed, 03 Jan 2018 18:06:53 GMT

Hi @SimonPlatten

Thanks. Clicking the ellipse should take you to the folder the file was exported to in Windows File Explorer/ Mac Finder. You also always export another copy to any location by clicking the ellipses to change the output location.

Re: How to subtract / cut from a mesh?

SimonPlatten — Wed, 03 Jan 2018 18:37:48 GMT

I think I have it....Attached is the project.

Re: How to subtract / cut from a mesh?

paul.clauss — Wed, 03 Jan 2018 19:46:53 GMT

Hi @SimonPlatten

Thanks for attaching the file. I think the issue with being unable to reduce the mesh was due to a small hole somewhere - I was able to reduce after making a closed mesh. I have shown this in the screencast below.

It does look like you were able to split the mesh into four parts successfully, so you may be able to keep more detail in the model by converting the four sections of the model individually. Depending on what you are trying to do with this model, you may not even need to convert it. If you just want to remove areas, I would recommend keeping a mesh this large in mesh form and then using the methods described in my previous screencast - my recommendation would be to split off the base, as it would be easy to recreate as a much simpler solid body. This would be easy to do with a plane cut, as shown in the GIF below:

I also found that the mesh contains some internal geometry - deleting this geometry (as it is not visible from the exterior), may also help keep the detail in this design while reducing it.

Hopefully this helps!

Re: How to subtract / cut from a mesh?

SimonPlatten — Wed, 03 Jan 2018 20:03:15 GMT

Thank you, I'm very new to Fusion 360, I have a lot to learn.

Re: How to subtract / cut from a mesh?

SimonPlatten — Wed, 03 Jan 2018 20:14:46 GMT

Out of the meshes, I can't reduce these:

FrontRightTop

FrontRightBottom

FrontLeftTop

All the others have been successfully reduced, how do I go about finding the problem?

Edit....actually I think I've found the solution, Select problem mesh, Make Closed Mesh, then reduce and this works.

Thanks again!

Re: How to subtract / cut from a mesh?

autodesk5K59U — Wed, 22 Jan 2025 01:01:08 GMT

Paul - 7 years later and you helped me today! The video is still helpful despite the UI changes... I wish all product support teams were this helpful. Thanks!