Meanwhile, over in the idiot corner...
I'm trying to drill through concrete (concrete ceiling), so I bought an absurdly expensive drill bit that says it's designed for concrete (but it is not suitable for aggregate).
Well, by a process of elimination I guess I'm trying to drill through aggregate because I was only able to make three 2cm holes before the bit was chipped to shit and not making any headway.
I'm just trying to fit a new light fixture to the ceiling. Any tips?