Mechanical edge finder

An edge finder is a technical device which allows the alignment of the axis of a tool with the face of a workpiece.
The pinule is made up of 2 parts held in contact with each other by an internal spring. One part is mounted in the machine spindle and the other part has a very precise diameter rod.
As the tool-holder spindle must have a rotational movement, the machine tools concerned are:
-Milling machine
-Boring machine
-Perseuse