けがき針

A scriber is a hand tool used in metal work to mark lines on workpieces, prior to machining. The process of using a scriber is called scribing and is just part of the process of marking out. It is used instead of pencils or ink lines, because the latter are hard to see, easily erased, and imprecise due to their wide mark; scribe lines are thin and semi-permanent. On non-coated workpieces marking blue is commonly used to increase the contrast of the mark lines.