The pitch of one piece parallel spring movement for fine adjustment. On two and four circular springs with dimensional errors in the minimum thickness.

No pitch exists in the movement, when a load is applied on the ideal point of a parallel spring movement. Dimensional inaccuracies, however, brings the reduction of capability of fine adjustment. Using the results in the previous report concerning the movement with leaf springs, the authors show the influence of dimensional errors of two and four circular springs on the pitch. Some points clarified in this paper are as follows, (1) Two Spring Movement: The error of the minimum thickness causes no pitch as long as the circular spring is symmetrical. The horizontal deviation of the center of the upper spring from that of the lower causes the pitch proportional to the amount of the deviation. (2) Four Spring Movement: If the two springs of the upper side have the same dimensional errors symmetrical about a vertical line passing through the midpoint of the lower side, no pitch appears in the movement