The guide arm has a mount for fitting said machine tool and said housing has at least one top track wheel, at least one side track wheel and at least one oblique track wheel adapted for rolling along the top, {TAIL ~ side} and {HEAD ~ edge} of the elongate track, respectively 
The guide arm has a mount for fitting said machine tool and said housing has at least one top track wheel , at least one side track wheel and at least one oblique track wheel adapted for rolling along the top , { TAIL ~ side } and { HEAD ~ edge } of the elongate track , respectively
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH 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 OTH OTH OTH OTH OTH OTH