▁the ▁hole . ▁This ▁is ▁successful ▁until ▁the ▁ch ips ▁pack ▁too ▁tight ly , ▁either ▁because ▁of ▁deeper ▁than ▁normal ▁holes ▁or ▁ins u fficient ▁backing ▁off ▁( rem oving ▁the ▁dr ill ▁slightly ▁or ▁totally ▁from ▁the ▁hole ▁while ▁dr illing ). ▁C ut ting ▁fluid ▁is ▁sometimes ▁used ▁to ▁ease ▁this ▁problem ▁and ▁to ▁prolong ▁the ▁tool ' s ▁life ▁by ▁cool ing ▁and ▁lub ric ating ▁the ▁tip ▁and ▁chip ▁flow . ▁C ool ant ▁may ▁be ▁introduced ▁via ▁holes ▁through ▁the ▁dr ill ▁sh ank , ▁which ▁is ▁common ▁when ▁using ▁a ▁gun ▁dr ill . ▁ ▁When ▁cutting ▁al umin um ▁in ▁particular , ▁cutting ▁fluid ▁helps ▁ensure ▁a ▁smooth ▁and ▁accurate ▁hole ▁while ▁prevent ing ▁the ▁metal ▁from ▁gra bb ing ▁the ▁dr ill ▁bit ▁in ▁the ▁process ▁of ▁dr illing ▁the ▁hole . ▁When ▁cutting ▁br ass , ▁and ▁other ▁soft ▁met als ▁that ▁can ▁grab ▁the ▁dr ill ▁bit ▁and ▁causes ▁" ch atter ", ▁a ▁face ▁of ▁appro x . ▁ 1 - 2 ▁mill im eters ▁can ▁be ▁ground ▁on ▁the ▁cutting ▁edge ▁to ▁create ▁an ▁obt use ▁angle ▁of ▁ 9 1 ▁to ▁ 9 3 ▁degrees . ▁This ▁prevents ▁" ch atter " ▁during ▁which ▁the ▁dr ill ▁tears ▁rather ▁than ▁cut s ▁the ▁metal . ▁However , ▁with ▁that ▁shape ▁of ▁bit ▁cutting ▁edge , ▁the ▁ ▁dr ill ▁is ▁pushing ▁the ▁metal ▁away , ▁rather ▁than ▁gra bb ing ▁the ▁metal . ▁This ▁creates ▁high ▁fr iction ▁and