Abstract: A drafting instrument for tracing ellipses and other curves adapted for the use with templates of such curves, comprising a set of links pivotally connected at each end, and disposed in parallel to constitute two pairs of opposite sides of rhombus link mechanism. The rhombus link mechanism carries in one vertex a needle point for piercing a graphic surface on which a curve is to be retraced for free pivotal movement of the mechanism about this center. Stem secured in other opposite vertex for being constrained along a cutout edge of a template. Two sliding members are respectively supported in grooves on the pair of opposite links. Said slide members are linked together for correlated movement, therein. A stylus guide member is supported by the link for tracing the curve on the graphic surface.

Abstract: Drafting instrument for drawing ellipses using scribe arm and members capable of being pivotally connected at two points along the scribe arm, one of the members being constrained to move along a straight line congruent to the minor axis and the other of the members being constrained to move along a straight line congruent to the major axis, as the members reciprocate along their respective lines, a point of the scribe arm describes an ellipse.

Abstract: An ellipse drawing device is disclosed which utilizes mounted on its lower surface a rotary arm and an elongated plate in conjunction, generating a straight line motion of a point on the elongated plate, grouped in perpendicular relation to the grooves on its upper and parallel surface to guide a stylus carrying arm in the desired course.