Adding cut feature to object

[knightersunit345]

Hello, I am trying to remake an .stl model in fusion and so far I've been using sketches to trace the model as close as possible.

In the screenshot, I have circled a feature on the stl model that I have not figured out how to replicate. Use section analysis to see the entire feature on the stl model.

Could someone show me how replicate this feature? I have a sketch outline in Sketch2 that I tried to use a rail on but it did not work. 

Also, do anyone know a better way to replicate this stl file in fusion 360? I've seen the "Fit Curves To Mesh Section" tool but I can't figure out how to use it.

Thanks!

 

[TheCADWhisperer]

Is there a logical reason that you are not fully defining  your sketches?

I would do this sketch as an Ellipse...

Shown overtop of your complex Spline.

[knightersunit345]

I just forgot to define all the lines.

Could you describe what you have done here? I do not understand any of your screenshots or the directions you have given.

[etfrench · Accepted solution]

Use the Create Mesh Section Sketch to get the profile.

Then Fit Curves to Mesh Section