Not Ranked
Use a W shaped drill bit, they cut the outside diameter of the hole cleanly with no splintering before cutting the hole, not sure on what sizes are available, ive got one in 12mm, they are used for drilling holes in timber cleanly without splintering the grain so that a timber plug of the same wood can be plugged to cover the fixings on decorative finishes.
__________________
Nuts,,, Bolts,,, and 2 smoking barrels. 
|