I need to make a hole that is 11.5mm wide at the bottom, 12.2mm wide at the top and 34mm deep into a metal cylinder. The dimensions may vary. I have a lathe.
I was thinking of getting a 11.5mm drill bit and drilling 34mm deep, then getting a 13.2mm bit and drilling 1-2mm deep and then use a fine round file on the lathe and try to make the transition as smooth as possible per hand.
