Wiggler (tool)
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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 a mill or drill. The device is used to accurately determine the edge/s (and therefore the center, using simple math) of a workpiece during the set-up phase of a machining operation.
A Sticky Pin is an improvised wiggler consisting of a piece of plasticine and a sewing pin, but the principle of use is the same.
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The Edge-Finder is put into the chuck of the machine then powered-up to rotate in the tool; the work-piece is then moved towards the Edge-Finder by means of the lathe or mill's feed-screws. When the work-piece and the Edge-Finder come into contact, the rotating motion of the Edge-Finder visibly changes. In terms of the Edge-Finder, which has to be run at about 800-1400 r.p.m. (although some machinist's state that a much lower speed of around 150 r.p.m. is sufficient: always follow the manufacturer's instructions!) what is evident is that as the Edge-Finder gets closer to the workpiece, the head starts to align to the shaft concentrically, but this is not where the edge of the workpiece has been met; 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 a diameter of the Wiggler away from the edge of the work-piece. From this known point the machine may be further indexed, by means of feed-screws, to accurately locate other features of the work-piece, as dictated by the layout design or blueprint.
To locate the center of a hole in a work-piece, the above described procedure must 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, usually on an XYZ-axis machinist's vise or feed-table) to a point equidistant between the edges: i.e., the center.
[edit] Electronic edge finder
Sometimes also referred as digital edge finder this instrument can locate edges of workpieces and also height offsets. It works in a NON-rotating spindle which is a great advantage over its mechanical counterparts. It is battery operated and works by lighting 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)
[edit] External links
- 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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