A drill 5 in which the cutting face of each insert is generally flat but is convexly curved toward the platform adjacent the second corner so as to form {HEAD ~ the curved portion} of {TAIL ~ the cutting edge} 
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A drill 5 in which the cutting face of each insert is generally flat but is convexly curved toward the platform adjacent the second corner so as to form { HEAD ~ the curved portion } of { TAIL ~ the cutting edge }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL