Abstract: The invention concerns a drafting head for a drafting machine, with a gring member (4) having several actuating elements (6, 8, 10) arranged on the gripping member (4) and capable of being actuated by a hand of the user that is resting on the gripping member (4) for the purpose of executing various switching statuses, as for example, disengaging, free- (unrestricted) switching, secured braking (locking) of the normal side, respectively for releasing the locking of the normal side of the drafting head (1). Provided here is at least one actuating element (6, 8) for disengaging and/or free-switching of the normal side of the drafting head (1), and one actuating element (10) for locking the normal side of the drafting head (1). Actuating element (10) for locking is arranged on the gripping member (4) such that it rests against the inner surface of the ball of the thumb of the user hand resting on the gripping member (4).

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 universal parallel ruler is disclosed. It is an arm-type ruler and includes a first base attached to a drawing board, a first arm attached to the first base, a second base attached to the opposite end of the first arm, a second arm attached on one end to the second base, and a third base attached to the opposite end of the second arm. The third base includes a lead having an x-scale and y-scale attached thereto. The scales define an (x,y) coordinate system. When the x and y scales are horizontal and vertical, respectively, a point (X,Y) may be selected on a set of (x,y) coordinate axes defined by the scales. If the scales are tilted by .theta. degrees, the position of the point (X,Y) may be determined along a new set of coordinate axes defined by the tilt angle .theta. of the scales and may be identified by a new coordinate point (x,y) relative to the new coordinate axes as follows:X=L.sub.1 cos .theta..sub.1 +L.sub.2 cos .theta..sub.2Y=L.sub.1 sin .theta..sub.1 +L.sub.2 sin .theta..sub.2x=X cos .theta.