Hi could you tell me what drill bit to use to drill large hole in aluminium gate post opposite to where the bolt will go into a timber wall, would like to make it look like a professional job with the plastic lug to then cover this external hole. Ie I want the bolt to be up against internal side of post, not through the double thickness of aluminium and potentially dent the post.
Welcome to the Bunnings Workshop community @VBlake. It's brilliant to have you join us, and many thanks for your question about drilling holes in aluminium.
Standard steel drill bits (HSS) will work with aluminium. I'd recommend you use a stepped drill bit as I presume you want to drill quite a large hole to fit the socket through to tighten the nut. The bit will drill up to 32mm holes. The beauty of them is that they have quite close increments in step sizes, so you can select a size slightly bigger than your socket.