The method 7, wherein {HEAD ~ the center roller} rotates independently of {TAIL ~ the first edge roller} 
rotates independently of
The method 7 , wherein { HEAD ~ the center roller } rotates independently of { TAIL ~ the first edge roller }
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL