At this, their outer diameter, where {HEAD ~ the geometrical surfaces} actually intersect {TAIL ~ one another}, the thin material sheets are cut off and joined to one another by any appropriate method 
actually intersect
At this , their outer diameter , where { HEAD ~ the geometrical surfaces } actually intersect { TAIL ~ one another } , the thin material sheets are cut off and joined to one another by any appropriate method
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH