CNC mill tool touch sensor

A simple, self contained tool touch sensor using a CR120 battery. Top disk is brass - not to damage the cutter - and insulated with a 0.1mm mica wafer cemented with a very thin layer of epoxy to the body and to the top disk and the inside cavity, including the resistor, filled with epoxy. Battery cover and body threaded to M13x1 After assembly the top is surface ground parallel to bottom. Height measured with a micrometer and recorded.