A third improvement comprises {HEAD ~ a sweepable member} having {TAIL ~ a chamfered edge} in a sweep direction, the edge making an angle of between about 5 8 degrees with the plane of the path 
having
A third improvement comprises { HEAD ~ a sweepable member } having { TAIL ~ a chamfered edge } in a sweep direction , the edge making an angle of between about 5 8 degrees with the plane of the path
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH