Drilling an accurate hole through the center of your pen blank is easily done on a drill press. A pen drilling vise is needed to clamps the blank in vertical position directly under the drill’s spindle. Most pen vises have self-centering jaws to accommodate vary size blanks without changing the vise setup.
Alternately, drilling can also be done on the lathe using drill chuck in tail stock and jaws in the head stock.
A popular pen vise with many experienced pen turners is the PH Design pen vise designed and manufactured by machinist and fellow penturner Paul Huffman. This pen vise is only available from distributor Classic Nib. http://www.classicnib.com/ph-designs-vise-and-press.html