exactly ... you couldn't have ever said it betterWhat are we doing here?
cut a face before drilling, so to make sure that the drill is starting on a surface that is perpendicular on it's axis, and also to minimize the start cutting load, since material crust, in most cases, is harder then the coreHow do we solve this issue?
through coolant
rigid fixture & tool clamping
aligned tool & machine
use load monitor ( and/or listen carefully ), to detect load peeks; they should occur as depth increases, and, if so, manage them by pecking/full retraction
a 3D drill should be enough, as most tool sizes are allready standard : flute length ~24, active length ~17
in order to improve hole cylindricity near the end (+ extend tool life), it may be required to reduce feed right before the tool is piercing out
kindly yet again, what are we doing here ?