The grinding wheel has {HEAD ~ a generally frusto conical configuration} and {TAIL ~ an outer periphery} defined by first and second axially distinct helical grinding ribs having different contours 
The grinding wheel has { HEAD ~ a generally frusto conical configuration } and { TAIL ~ an outer periphery } defined by first and second axially distinct helical grinding ribs having different contours
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH