Replaceable cutting means substantially encircle {TAIL ~ the rolling cutter shell} for contacting {HEAD ~ the formations} and forming a hole therein 
Replaceable cutting means substantially encircle { TAIL ~ the rolling cutter shell } for contacting { HEAD ~ the formations } and forming a hole therein
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH