Wiggler (tool)

An edge finder (English: wiggler or edge- finder ) is a setting device that allows the machining operations to align the spindle of the machine tool with the rotation axis exactly to the edge of the workpiece. There are mechanical edge finder with an accuracy of about 0.005 mm, and electronic with an accuracy to about 0.002 mm.

The mechanical edge probe is mounted to the spindle of a milling machine, consisting of two stepped cylinders which bear on the thicker diameter and are connected by a spring inside. Already at low number of revolutions of the spindle, typically 600 rpm, produced an eccentricity of the lower cylinder to the rotation axis of the upper, clamped in the tool cylinder. With slow start to the workpiece edge of the axes of the two cylinders are approaching until they are almost centric. Then the probe is touching the edge. Following the procedure, the spindle now even around the cylinder radius, the spindle axis is exactly on the workpiece edge. In a large approximation of the edge finder of the lower cylinder slides visible off to the side.

Following the same principle can be personalized with conical shaped probes the center lines of holes determined.

Electronic edge finders either work according to the same mode of operation and only show to cover the axes through an optical (LED) or audible signal, or the edge finder detects the edge of the workpiece on the closing a circuit when touched. In the latter case, the calibration can be done with a stationary spindle and with higher accuracy.