Print hammers of printing head in dot line printer

A plurality of print hammers in a printing head of a dot line printer for printing with an ink ribbon multiple dot lines in a single shuttling direction and for providing a character line by the combination of the multiple dot lines in accordance with reciprocal motions of said printing head while feeding a printing sheet in a line to line direction, the print hammers comprising:

• a plurality of hammer springs extending side by side in the shuttling direction, each of the hammer springs having free ends;
• and
• a plurality of printing pins corresponding in number to said plurality of hammer springs and positioned at the free ends of the hammer springs and positioned offset from one another in the line to line direction for simultaneously multiple dot line printing in the single shuttling direction, each of the printing pins having a printing pin face abutting the printing sheet through the ink ribbon, the printing pin face being defined by a plurality of ridge lines each one of which extends obliquely with respect to the single shuttling direction for facilitating grinding of the printing pins such that only a selected printing pin is ground during a grinding operation, each of said ridge lines of said printing pin face of each of said printing pins is joined to two others of said ridge lines to define groups of neighboring ridge lines, wherein a first group of neighboring ridge lines extends symmetrically with a second group of neighboring ridge lines with respect to a center line of the printing pin face, and wherein said center line extends in the line to line direction and a combination of the ridge lines which define the printing pin face has a polygonal shape.