How do I make one object contour another (complex) object?

[Anonymous]

So I have this geometric shape and I want the bottom face to contour a mask shape. I have tried extruding the geometric shape face and cutting the excess using the mask face as the cutting tool but this didn't work. I was able to get one part to contour the mask by extruding the geometric shape to a face (the mask), but this only worked with one part. Maybe there is a way to simplify the mask contour that I'm not aware of?

I've attached the .f3d file along with a couple screenshots to get a better idea of what I'm talking about.

Here is a google drive link to the .f3d file: https://drive.google.com/file/d/1UyqcwVyqmM8chqPj8jBlktnN359jWEY6/view?usp=sharing

Thanks for any help. I've been struggling with this for a while now

[jhackney1972]

Forum users are usually very hesitant downloading a model from an external source.  If you want the forum users to take a look at your model, you should attach it to your forum post like everyone else.  If you do not know how to attach your Fusion 360 follow these easy steps. Open the model in Fusion 360, select the File menu, then Export and save to your hard drive. Then use the Attachments section of a forum post to attach it.

[Anonymous]

Updated it to have the .f3d file attached to the post. 

[jean.flower · Accepted solution]

Hi  tw78952, I took a look at your f3d, thanks for attaching.

You begin with these two meshes.  I see you used the mesh-to-brep command to make a brep (lots of triangular faces). 

In contrast, on these meshes, I would take a different approach to creating brep geometry, using a mix of forms and prismatic geometry.  I'll outline my steps below.

First, look at the head-shaped part.  Here it looks like we want a smooth shape, so I would use the Form workspace, make a rectangular form shape, adjust its shape and use the "Pull" command on selected vertices to bring the Form vertices close to the imported mesh shape.  You can choose how carefully you want to match the original shape.

I made sure my form sheet was wide enough to act as a base to trim the upper geometry.

For the prismatic-shaped part, instead of using  the triangles, I would build four parts in sequence.  Here's one of the four parts - project six points down onto a sketch and draw sketch lines for form a close polygon.

Extrude the polygon into a solid and use the "Extent Type" as "To Object", selecting the sheet we made from a form.

The extrusion sticks up too far - make three construction planes matching the original mesh and split the solid so the top shape is right.

Finally, the mesh shape had a hollowed inside, so we can use the shell command to hollow out our solid.

The reasons I chose to model from scratch is that
(i) we won't get a smooth shape from mesh-to-brep and
(ii) the prismatic part of the mesh appears to have internal triangles which get in the way when performing downstream operations like split, so modeling from scratch creates a clean geometry without unwanted internal faces

I chose to model the prismatic part in four steps because the four parts join in a single edge - where multiple faces from different parts of the solid align on a single shared edge. Best to make four simple solids without this "non-manifold" edge, then think about how you want to combine them at the end.  An edge like this, as it stands, won't make the design viable for manufacture.

Hope that helps!

[Anonymous]

This is perfect, thank you so much! I haven't done a lot of modeling so I very much appreciate the detailed step-by-step instructions. oh, and sorry if my file was messy. I'm still working on getting my workflow cleaned up.