Drafting instrument

A reversible drafting instrument useful for the scribing of lines on a substantially planar surface with such lines at respective angles of 0 degrees, 30 degrees, 60 degrees, 45 degrees, and 90 degrees relative to a base line on such substantially planar surface, comprising:

• an L-shaped planar body having a first, long leg and a second, short leg disposed at a 90 degree angle to each other, each leg having inner and outer edges mutually parallel to the longitudinal axis of such leg, each leg having an outer end inclined at an angle of 45 degrees relative to the outer edge of such leg, with the relative lengths of said legs determined in accordance with the formula (Lso-Wf)/(Lfi+Ws)=sin 30 degrees, where Lso is the length of the outer edge of said second, short leg, Wf is the width of said first, long leg, Lfi is the length of the inner edge of said first, long leg, and Ws is the width of said second, short leg;
• a plurality of glide points interconnected to and extending outwardly a short equal distance from each face of said planar body for the purpose of supporting said planar body in stable parallel relationship with and a short distance above a planar surface upon which said said planar body is placed;
• a non-circular aperture penetrating said planar body with said aperture centered on the line extending from the intersection of the inner edges of said first leg and said second leg to the intersection of the outer edges of said first leg and said second leg of said planar body;
• and
• a reversible handle assembly having a shaft to be received through said aperture, with the cross-sectional configuration and cross-sectional dimensions of said shaft adapted to prevent rotation of said shaft relative to said aperture and with the length of said shaft greater than the thickness of said planar body, and having a pair of end caps each interconnected to a different end of said shaft, with the thickness of each of said end caps being less than the distance of extension of each of said glide points from the respective face of said planar body.

In an L-shaped substantially planar drafting instrument having first and second faces and including a first, long leg of greater length than width and of equal width throughout its length and a second, short leg of greater length than width and of equal width throughout its length, with the first leg and the second leg disposed at a right angle to each other and fixedly interconnected whereby each leg has an inner edge and an outer edge, the improvement comprising

• the end of each leg opposite the interconnection between the first leg and the second leg inclined at an angle of 45 degrees relative to the outer edge of such leg;
• the length of said first leg and the length of said second leg proportioned such that an angle of 30 degrees is formed between the inner edge of said first leg and a straight line tangent to the end of said first leg and to the end of said second leg, and an angle of 60 degrees is formed between the outer edge of said second leg and said straight line tangent to the end of said first leg and to the end of said second leg;
• a plurality of glide points divided between the first face and the second face of the drafting instrument and interconnected thereto such that each of said glide points extends a short distance from the respective face of the drafting instrument, with respective glide points disposed on each face so as to provide a stable suspension of the drafting instrument above a substantially planar surface upon which the drafting instrument is placed with the plane of the drafting instrument parallel to the plane of said surface;
• and
• a reversible handle assembly including a handle aperture penetrating the drafting instrument near the intersection of said first and second legs with the axis of said aperture perpendicular to the plane of the drafting instrument, a handle shaft having two ends and being substantially greater in length than the thickness of the drafting instrument between its first and second faces, said handle shaft extending through said aperture in sliding relation therewith along the longitudinal axis of said handle shaft, and a pair of thin substantially planar end caps each interconnected to a different end of said handle shaft with the plane of each of said end caps perpendicular to the longitudinal axis of said handle shaft, with the thickness of each said end cap perpendicular to the plane thereof less than the distance of extension of each of said glide points from the respective face of the drafting instrument and with the with of each said end cap in the plane thereof greater than the width of said handle aperture whereby said end caps retain said handle shaft within said aperture.