I am trying to drill and/or bore a 20.58 hole radially on a live tooling lathe into 4140 prehard 32-40 Rc. Its a tight size tolerance of ±0.015mm with a micro of 1.6Ra. So far drill , reaming, or single point boring has failed. Anyone have a solution for this Micro other than second operation grinding? This is a high production job running from bar stock and the radial hole is through the part 64mm in diameter.
Help PLEASE!!!!!