03 to 0 04 mm thus preventing the dots in these two dot lines from overlapping although the print hammer pins for printing the dots in the seventh dot line printed during the first scan and dots in the second dot line printed during the second scan are described above as being positioned so that the interval between adjacent hammers is within the range of 0 015 and 0 02 mm any range is acceptable as long the range insures overlap of adjacent dots the measures described in the first and second preferred embodiments for inducing accumulative error in the positive direction and in the negative direction can be combined to provide further advantages as can be appreciated from the above description dots printed in the sheet feed direction with the first scan of the hammer bank is not equi distant but there exists a maximum shift of 0 06 to 0 07 mm in the sheet feed direction however this maximum shift yielded as a result of pin position adjustment is smaller than the accumulative error of 0 13 mm caused by the sheet feed operations and shuttle operations performed between the first scan and the second scan as a result error in the precision of the dot positions in the sheet feed direction is spread out so that overall quality of the printed characters improves gaps between dots in the eighth dot line printed during the first scan and dots in the third dot line printed during the second scan.