Ive seen this topic discussed before but I am still having issues. Maybe because this is 2021 sketchup. Anyway, I am trying to put an angled hole through my post. And potentially into a second beam. I have been trying to make a cylinder of the size of the hole I want and then intersect faces and then delete the tails and the face. Be left with a hole. The intersect faces function is giving me a lot of problems. See the photo below and attached file.
see file here Siprelle__Library-Kitchen - connection details.skp (316.0 KB)
I expect your problem comes from the nesting of the components. If you want to use Intersect Faces to put the holes in the components, cut the drill component to the clipboard. Then open the King Post_ Outer component for editing and use Paste in place to paste the drill inside that component. Explode the drill component, use Intersect Faces and erase the ends of the drill and the faces skinning the hole. Then open the Top Chord component and do the same thing again with Paste in place, Intersect Faces and erase everything that isn’t the Top Chord with a hole in it.
By the way, you are using tags incorrectly. Untagged should always be active and ALL geometry should be created and remain untagged.
Once the geometry is fixed and you move the drill in away from the face of the kingpost, you could use Trim and Subtract from Eneroth Solid Tools to drill the holes. Here I used keyboard shortcuts for Cut and Paste in place.