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Scriber and Punch

Scribers are hand tools used in the metal trades to mark lines on workpieces, prior to machining. This is used instead of pencils as the marks from pencils cannot be seen as clearly as Scriber marks. They consist simply of a rod of high-carbon steel, in its hardened state, that has been sharpened to a point at one or both ends. They are used by drawing the point over the surface of the workpiece to leave a shallow scratch on its surface.
Due to the nature of metal, and the accuracy generally sought after when machining it, a thick pencil or ink line would either be impossible to lay down accurately or prone to erasure during the machining operation. The crisp, bright mark exposed by the scratch of a scriber is semi-permanent and thin. The process of using the scriber is referred to as marking out and may require the addition of other hand tools and equipment.
Usually a layout stain of some form is used to increase the contrast between the scribed line and the background surface and is washed off with solvent on completion.

A center punch is typically used as an aid to drilling operations; a drill, when brought into contact with a flat surface, will have a tendency to wander on the surface until it gains sufficient purchase to start cutting a hole. A center punch forms a small dimple in which the tip of the drill(if it is small enough) will fit. When drilling larger holes and the web of the drill is wider than the indentation produced by a center punch, the drilling of a pilot hole is usually needed. A center punch usually has a tip, that when viewed on a profile, has sides at a 90 degree angle to one another.

A prick punch, while easily confused with the similar looking center punch, serves an entirely different purpose. A prick punch is primarily used for the purposes of layout. By design it produces a smaller indentation than a center punch, which acts as a useful datum point in layout operations. When layout is complete, the indentation made with a prick punch can be enlarged with a center punch to allow for drilling. A prick punch usually has a tip, that when viewed on a profile, has sides at a 30-60 degree angle to one another.

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