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Edge Finder

Set of wigglers

A wiggler, edge finder, digital 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.

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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 In terms of the Edge finder, which has to be run at an RPM of about 800-1400 what is evident, is a as the center finder gets closer to the workpiece, the head starts to align to the shaft concentrically. This is not where the edge of the worpiece has been met. Then when the workpiece has been met by the center finder head, the head jumps about 1/32 to the right. To align the wiggler is a different procedure which is what makes it so different. 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 arithmetic 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.

Electronic edge finder

Sometimes also referred as digital edge finder this instruments can locate edges of workpieces and also height offsets. It works in a NON-rotating spindle, this is a great advantage over its mechanical counterparts. It is battery operated and works by lightening up its internal LED (usually red)when the electrical circuit formed by the instrument and the machine is closed. The light is visible through its 4 widowed openings. A repeatability of 0.0002 inches or 0.005 mm is obtained (Salazar)

• Wiggler usage
• This shows you how to use a wiggler to center a rotary table.
• Electronic edge finder vs 3d alignment indicator.

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