I want to make a flap by making extruded bodies cut by the Right Horizontal Stabilizer and Flap Edge. I don't get why this error occurs. I could just use patch -> split face -> extrude, but this way I get to lose some details.
I will attach my f3d file.
P.S. there is a tiny gap between the upside loft and the downside loft, so you should include this in the splitting tool in order to cut the bodies.
I'm not 100% sure what result you are trying to achieve, but the error is coming from the fact that you have a surface body and a solid body with overlapping faces. What I suspect you were doing was choosing the surface body AND the solid body as splitting tools, so the error is exactly accurate - you are choosing two splitting tools that intersect. If I turn off the surface body, and pick the two faces of the solid, you can split successfully:
like this? If this is not what you are looking for, can you record a screencast showing what you are trying?
sorry, @Anonymous - I probably was in a hurry, and did not explain what is going on there. I'll try to do so here.
For the splitting tool in Split body, you can select a few different types of things:
If you select a face, the default setting is to extend the face so that it intersects with the body. If you do that with this model, you get this:
turning off a few of the bodies, you can see that this extension causes the cutting tool to self-intersect:
while, selecting the body, either through the browser, or via Select Other (click and hold the left mouse button), selects the entire body, and does not extend it, and that is why you don't get that error message.
@Anonymous - you have to use Remove, not Delete. For an in-depth discussion of why, see: what-is-the-difference-between-delete-and-remove-a-component-or-body . The confusion here is especially high with Split Body, unfortunately.
