The apparatus of the present invention also includes means for driving the cutting tool assembly into and out of {TAIL ~ engagement} with {HEAD ~ the tube} 
The apparatus of the present invention also includes means for driving the cutting tool assembly into and out of { TAIL ~ engagement } with { HEAD ~ the tube }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD