Abstract: An attachment for a framer's square which permits the framer's square to be self supporting on a flat, horizontal surface. The attachment has an elongated support bar with two clips which may be inserted over a blade of a framer's square. This attachment, when inserted on the inner edge of the framer's square, facilitates the scribing of a right-angle line to a rounded edge and when placed on an outer edge, permits the square to be free standing.

Abstract: A drafting table includes vertical and horizontal straight edged supports together with drive mechanisms for moving the vertical straight edge such that it will always point to a viewing point and for moving the horizontal straight edges in plural different modes. In a first mode, the two horizontal straight edges are moved such that their edges always point to respective vanishing points. In a second mode the horizontal straight edges are moved such that one continues to point to a vanishing point while the other maintains a fixed angle with respect to horizontal, and so that their edges always intersect at a point along the line of view. The drive mechanisms for the horizontal straight edge supports can be disabled, reversed or their drive ratios changed in accordance with the particular drawing being made.

Abstract: A drawing instrument and locking apparatus therefor in which the locking apparatus can be made of polyethylene, polypropylene or the like and is not subject to fragmentation or permanent damage during normal use. A displaceable member of the locking apparatus is displaceable into a groove of a drawing board to lock the drawing instrument in position thereon. An outer ring member freely rotatable through 360 degrees around the displaceable member when the displaceable member is in its raised condition engages the displaceable member when the displaceable member is in its depressed condition upon rotation of the ring member to unlock the apparatus.

Abstract: A drafting machine includes a pair of perpendicular straight edges slidably mounted with respect to reference scales integrally mounted within the drafting machine. A fine adjustment mechanism includes a worm and spur gear combination for moving the straight edges with respect to the scales. An override mechanism allows the straight edges to move freely with respect to the scales. The drafting machine preferably includes a second adjustable scales adjacent each reference scales for ease and accuracy in measuring.

Abstract: A drawing board suitable for use in preparing perspective drawings is provided with a pair of arcuate guide surfaces facing towards one another and situated towards one side of the drawing board, with a recess or depression between the arcuate guide surfaces, so that a drawing instrument having projections capable of engaging the arcuate guide surfaces, can be readily moved from one arcuate guide surface to the other to enable the drawing instrument to point towards vanishing points on either side of the drawing board. The drawing board may have straight guide edges, as well as additional arcuate guide edges, one of which may be directed towards a central vanishing point. The multi-purpose board can be used to produce various types of perspective drawings and seven vanishing points are shown.