Beginner questions I'm afraid ...
I need to counterbore for an M4 cap-head screw (the head is about 8mm across). I don't have a M4 counterbore. I do have an 8mm end-mill and an
8mm slot-drill. Which of these is the better to use? Would the hole produced by a pukka M4 counterbore be noticeably better?I also need an accurate 8mm hole, so I've just got a shiny new 8mm reamer. How close to 8mm should I be before I start reaming away? I'm hoping I can just drill with a 7.9mm drill and then ream an accurate 8mm hole in one go.
Brendan