For effective transporting away of chips, the main flute and {TAIL ~ the reamer flutes} preferably have {HEAD ~ the same helix orientation} 
For effective transporting away of chips , the main flute and { TAIL ~ the reamer flutes } preferably have { HEAD ~ the same helix orientation }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD