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