Abstract: A head of a universal parallel ruler having a base 2 supported so as to be movable in parallel on a drafting board comprises a scale mounting plate 16 having an upper portion supported so as to be rotatable on the upper face side of the base 2 and a handle member 34 provided above the scale mounting plate 16, so that an operator can hold the handle member 34 by hand to directly rotate the scale mounting plate 16 for carrying out a plotting operation.

Abstract: A scale balancing device for balancing the weight of the scales of a universal parallel ruler, the device having a head structure having the scales rotatably mounted thereon, a rotating member rotatably mounted on the head structure separate from the scales, the rotating member and the rotatable scales being rotatably interlocked, and a spring having one end rotatably connected to a point on the rotating member eccentric to the axis of rotation thereof and the other end rotatably connected to a non-rotatable part of the head structure, the spring, when the scales are rotated to a position vertically in line with the axis of rotation thereof, having substantially no tension therein and when the scales are rotated ninety degrees from such position, having tension for exerting a maximum force on the eccentric connection point on the rotating member and sufficient in magnitude and having a direction which substantially cancels out the torque on the rotating member from the weight of the scales.

Abstract: A scale balancing device for balancing the weight of a scale of a universal parallel ruler, having a head structure having a rotating scale support rotatably mounted thereon on which the scales are carried, the scale support and scales having a center of gravity when the scale is horizontal spaced horizontally from the axis of rotation of the scale support, a rotating member rotatably mounted on the head structure separate from the rotating support, the rotating member and the scale support being rotatably interlocked, an eccentric member on the rotating member, a spring member having one end connected to the eccentric member and the other end connected to the head structure and tensioned for providing a torque on the rotating member in a direction which substantially cancels out the torque on the rotating member from the weight of the scales, the point of interlocking of the rotating member and the scale support being on the side of the scale support toward the center of gravity when the scale is in the hori

Abstract: A scale balancing device for balancing the weight of the scales of a universal parallel ruler, the device having a head structure having a rotating scale support rotatably mounted thereon on which the scales are carried, a rotating member rotatably mounted on the head structure offset from the rotating support, the rotating member and the scale support being rotatably interlocked, an eccentric member movably mounted on the rotating member for movement radially of the rotating member, and a spring member having one end connected to the eccentric member and the other end connected to the head structure and tensioned for providing a torque on the rotating member in a direction which substantially cancels out the torque on the rotating member from the weight of the scales.

Abstract: A scale balancing device for balancing the weight of the scales of a universal parallel ruler, the device having a head structure having a rotating scale support rotatably mounted thereon on which the scales are carried, a rotating member rotatably mounted on the head structure offset from the rotating support, the rotating member and the scale support being rotatably interlocked, an eccentric member on the rotating member and having a portion projecting axially of the rotating member beyond the axial end surface of the rotating member, and a spring member having one end connected to the projecting portion and the other end connected to the head structure and tensioned for providing a torque on the rotating member in a direction which substantially cancels out the torque on the rotating member from the weight of the scales, whereby during rotation of the rotating member through 360 degrees, the one end of the spring member can continuously engage the projecting portion of the eccentric member and the spring m