Copying needle
The copying needle , also called mapping needle or pike needle , is a tool for "sharp" (permanent and non-removable) marking of a point on a drawing medium (paper, cardboard, foil, etc.).
The term copying needle stems from the fact that a point on a drawing carrier can be transferred to an underlying drawing carrier by piercing it.
A needle with which a point can be marked is usually fastened in a holder with the help of a collet . The needle has a typical diameter of 0.25 mm. A cavity is often provided in the handle / housing of the mapping needle, which can accommodate replacement needles. In some versions the mapping needle is equipped with a magnifying glass for precise handling.
Basically, a “point” is dimensionless and defined as the intersection of two lines (which only know the dimension of the longitudinal extension and have no “width”). In practice, a point can only be represented by an area with the smallest possible dimensions. The prick of a fine needle comes very close to this requirement in contrast to the trace of a pencil and was technically sufficient for the accuracy of creating the measuring table sheets .