An apparatus for checking the diameter of {HEAD ~ a cylindrical part} in {TAIL ~ orbital motion} about a geometrical axis in a numerical control grinding machine, said apparatus comprising: 
An apparatus for checking the diameter of { HEAD ~ a cylindrical part } in { TAIL ~ orbital motion } about a geometrical axis in a numerical control grinding machine , said apparatus comprising :
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH