▁or ▁gr inding . ▁ ▁Deep ▁hole ▁dr illing ▁▁ ▁Deep ▁hole ▁dr illing ▁is ▁defined ▁as ▁dr illing ▁a ▁hole ▁of ▁depth ▁greater ▁than ▁ten ▁times ▁the ▁diameter ▁of ▁the ▁hole . ▁These ▁types ▁of ▁holes ▁require ▁special ▁equipment ▁to ▁maintain ▁the ▁straight ness ▁and ▁toler ances . ▁Other ▁consider ations ▁are ▁round ness ▁and ▁surface ▁finish . ▁ ▁Deep ▁hole ▁dr illing ▁is ▁generally ▁achiev able ▁with ▁a ▁few ▁tool ing ▁methods , ▁usually ▁gun ▁dr illing ▁or ▁B TA ▁dr illing . ▁These ▁are ▁differenti ated ▁due ▁to ▁the ▁cool ant ▁entry ▁method ▁( internal ▁or ▁external ) ▁and ▁chip ▁removal ▁method ▁( internal ▁or ▁external ). ▁Using ▁methods ▁such ▁as ▁a ▁rot ating ▁tool ▁and ▁counter - rot ating ▁work pie ce ▁are ▁common ▁techniques ▁to ▁achieve ▁required ▁straight ness ▁toler ances . ▁Second ary ▁tool ing ▁methods ▁include ▁tre p anning , ▁sk iving ▁and ▁burn ishing , ▁pull ▁b oring , ▁or ▁bott le ▁b oring . ▁Finally , ▁a ▁new ▁kind ▁of ▁dr illing ▁technology ▁is ▁available ▁to ▁face ▁this ▁issue : ▁v ibration ▁dr illing . ▁This ▁technology ▁breaks ▁up ▁the ▁ch ips ▁by ▁a ▁small ▁controlled ▁ax ial ▁v ibration ▁of ▁the ▁dr ill . ▁The ▁small ▁ch ips ▁are ▁easily ▁removed ▁by ▁the ▁fl utes ▁of ▁the ▁dr ill . ▁ ▁A ▁high ▁te ch ▁monitoring ▁system ▁is ▁used ▁to ▁control ▁force , ▁tor que , ▁v ibr ations , ▁and ▁ac oust ic ▁emission . ▁ ▁V ibration ▁is ▁considered ▁a ▁major