The invention relates to an internal circulation photoelectric type edge finder which comprises an end cover, an electric conduction body, a
resistor, a double-spring component, an insulation sleeve, a battery, a
ceramic gasket and a probe. The electric conduction body is of a cylindrical structure with a circular-ring-shaped baffle ring at one end and unequal-
diameter through holes in the middle, the probe is arranged at the end, provided with the baffle ring, of the electric conduction body through the double-spring component in the through holes of the electric conduction body, the end cover is provided with a switch and is connected with the other end of the electric conduction body, the
ceramic gasket is arranged between the probe and the electric conduction body and is connected with the electric conduction body, the battery and the
resistor are arranged in the through holes of the electric conduction body, the insulation sleeve is arranged between the double-spring component and the inner walls of the through holes of the electric conduction body, and in the working state, the switch, a power source, the
resistor, the double-spring component, the probe and the baffle ring form a work loop. According to the edge finder, edge finding operation can be performed on all parts (conductive and non-conductive parts), and the edge finder has the advantages of being simple in structure, short in
response time, easy to operate, wide in application range and the like.