In the arrangement of FIG 8 it may be desirable to provide increased relief behind each primary cutter 21 to reduce {TAIL ~ the area} of {HEAD ~ wear} flat which develops behind the cutting edge as the cutter wears down 
In the arrangement of FIG 8 it may be desirable to provide increased relief behind each primary cutter 21 to reduce { TAIL ~ the area } of { HEAD ~ wear } flat which develops behind the cutting edge as the cutter wears down
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH