Wiggler (tool)

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A wiggler, edge finder, center finder or sticky pin refers to a tool used in the rotating spindle of a machine such as mill or drill. The device is used to accurately determine the edge or center of a workpiece during the setup phase of a machining operation.

A sticky pin is an improvised wiggler consisting of a piece of plasticine and a sewing pin, the principle of use is the same.

The Wiggler or Edge-Finder is put in the rotating chuck of the machine tool, the work-piece is then moved towards the Wiggler by means of the lathe or mill's feed screws. When the work-piece and the wiggler come into contact, the rotating motion of the wiggler (or edge-finder) visibly changes (hard to describe here). At this point, the operator of the machinery knows that the axis of the machine chuck is precisely 1/2 the diameter of the wiggler (or edge-finder) away from the edge of the work-piece. From this known point, the machine may be further indexed, by means of the feed screws, to accurately locate other features of the work-piece (as dictated by the design or blue-print).

To locate the center of some hole in a work-piece, the above describe procedure may be repeated on two opposing edges of the hole. A small amount of arithmatic will then allow the operator to index the machine (by means of the feed screws) to a point equidistant between the two edges: the center.