Adding tapped hole onto round surface

Add a plane normal to a point on the surface.

Yes, it is only done using a 3D sketch, but you should not have any problems, I have done it many times. I mainly have had circular parts but I just did an experiment with an ellipse and spline extrusion and had no problem either.

SA

yeah. using the 3d sketch it lets you relate the point. since you are not on a flat plane you need to tell the point where it needs to lie. i just use other surfaces or planes to fully define it. works perfectly. i have also used the plane normal to a point on the surface. also works great. just depends on what you are trying to accomplish