Finally finished! This has been my biggest project yet and I hope to do more just like it. Anyway, after talking to a machinist, I found out the reason why the drill was not going through. It was due to the drill bit spinning too fast and this prevents the drill from catching onto the steel, causing the drill to slide around. This probably also was the reason why the drill slipped down the piece causing the wrong hole placement.
I then found 6 mm screws and slotted them through the holes allowing the door handle to…you guessed it! Fit to a door.
As I focus on traditional style blacksmithing I will use the least amount of machines possible. However sometimes, like in part 5 of the project, i have to use machines to progress as I did not have the tools required to punch and drift the holes and had no time to make any. In the meantime, I will build up my stock for a spring fare that I am hosting a stall for, while also building up a variety of new tools, like punches and drifts to decrease my machine use.