Process for manufacturing dials having graduated circles for surveying instruments and surveying instrument having a dial obtained by said process

摘要

975,349. Marking dials of surveying instruments. FILOTECNICA SALMOIRAGHI S.p.A. July 3, 1963 [July 13, 1962], No. 26352/63. Headings G1J and G1X. In a process for manufacturing dials having graduated circles a, for surveying instruments. simultaneously with marking of each single mark b or zone of marks of the circle a and concentrically with that circle, there is marked at a constant and prefixed angular displacement e.g. 90 degrees a corresponding single small arc d of an index circle c, so that the corresponding arc d may be superimposed on the respective mark or marks b, Fig. 2, by a suitable viewing system when in use. Thus as the mark b corresponding to 0 degrees is marked in the circle a the corresponding arc d is marked at 90 degrees and is indexed with an asterisk. When the dial is in use it must be ensured that these two marks coincide in the field of view e of the microscope used, and thereafter angles to be measured as given by the marks b will be indicated by the corresponding arc d eliminating errors due to unavoidable eccentric mounting of the dial. The arcs d are preferably spaced from each other by a distance less than the height of the marks b.