A first drive unit moves {HEAD ~ the tool} along at least two axes to shape the workpiece similar to {TAIL ~ a desired surface} 
A first drive unit moves { HEAD ~ the tool } along at least two axes to shape the workpiece similar to { TAIL ~ a desired surface }
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL