| 摘要 |
<p>A drawing instrument which is a compass or dividers has a leg and an arm, or two legs, pivoted together at inner ends thereof, and has a bow top having fork limbs embracing the assembly of pivoted ends of the leg and arm or of the two legs, the leg and arm, or the legs, and the limbs of the bow top, having therein pivot holes receiving a pivot which pivots together the leg and arm, or the legs, and the bow top; and the bow top has locating means co-operable with the inner ends of the leg and arm, or of the legs, to prevent, during assembly of the instrument before installation of the pivot, movement of said ends towards the bow top beyond a position in which the said pivot holes in said ends and in the bow top are aligned for receiving the pivot. There is provided a centralising member keyed in place between said inner ends of the leg and arm, or of the two legs, before installation of the pivot. The aforesaid locating means preferably comprises two pairs of shoulders disposed one pair on the inside face of, and integral with, each fork limb of the bow top, with the two shoulders of each pair being spaced apart to receive between them a respective one of the aforesaid inner ends.</p> |
