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