It is a principal marking tool in a fitting shop and is made in various forms and sizes. It consists of a cast iron sliding base fitted with a vertical steel rod. The marker or scriber is fitted into an adjustable device carrying a knurled screw at one end, as shown in Fig. 2.6. By means of this screw the scriber can be loosened or tightened to set it at any desired inclination, moved to and fro inside the hole accommodating it or adjust its height along the vertical pillar. Normally it is used in conjunction with either a surface plate or marking table. Its specific use is in locating centres of round rods held in V. Block, scribing straight lines on work held firmly in its position by means of a suitable device like angle plate and also in drawing a number of lines parallel to a true surface. The instrument just described is a very simple form of surface gauge. It has now largely been replaced by a more accurate instrument called universal surface gauge.
