United States Patent 3815246

A single, versatile drafting tool for drawing an infinite variety of arcs, circles, curves and angles, comprising upper and lower resilient arms, each having a plurality of aligned openings for receiving such as a mechanical pencil or other drawing instrument therein for drawing a variety of arcs and circles, adjustable tension means linking the arms and being adapted to vary the position of the drawing instrument for drawing still other arcs and circles and to set up a bowed condition in one of the arms whereby that arm may be used as a guide for drawing curves, and a T-square head releasably and adjustably fixed to one of the arms whereby the head and arm may be used as a T-square, the head being movable for forming various angles.

Application Number:
Publication Date:
Filing Date:
Primary Class:
International Classes:
B43L9/04; (IPC1-7): B41L9/04
Field of Search:
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US Patent References:
2595081Quilt marker1952-04-29Johnson

Primary Examiner:
Haroian, Harry N.
Attorney, Agent or Firm:
Ross, Ross & Flavin
I claim

1. A drafting tool comprising, a pair of resilient, apertured arms, a drawing implement insertible through the openings in the arms, means for coupling the arms adjacent one of their ends and for varying the positions of the arms, and a needle point on one of the arms.

2. A drafting tool according to claim 1, including a T-square head on one of the arms.

3. A drafting tool according to claim 2, wherein the T-square head is releasably and adjustably fixed to one of the arms.

4. A drafting tool according to claim 1, wherein the means for coupling adjacent ends of the arms comprises a depending flange on each arm, a shaft passing freely through the flanges, a stop on one end of the shaft engaging one of the flanges, and a thumb nut threaded on the other end of the shaft and engageable with the other flange, rotation of the thumb nut setting up a bowed condition in the arms for moving the drawing implement and for use of at least one of the arms as a curved edge guide.

A primary object of the invention is to provide in a single instrument, a drafting aid which may optionally function as an adjustable beam compass, as a curved edge guide, or as a T-square with an adjustable head for drawing various angles.

Another object is to provide a drafting aid of the type described which is simple in its construction and yet extremely accurate and versatile in the drafting results obtained thereby.

These and other objects will be apparent from a consideration of the annexed drawing in which:

FIG. 1 is a fragmentary, broken, top plan view of a drafting tool embodying my invention;

FIG. 2 is a cross-sectional view taken on line 2--2 of FIG. 1;

FIG. 3 is an end elevational view as seen from the right of FIG. 1;

FIG. 4 is a side elevational view showing the drafting tool in use with a drawing inplement in place and the T-square head removed;

FIG. 5 is a side elevational view of the arm coupling and tension adjusting means of the drafting tool of the invention;

FIG. 6 is an end elevational view of the tension adjusting means of FIG. 6; and

FIG. 7 is a cross sectional view taken on line 7--7 of FIG. 2.

The drafting tool of the invention includes spaced, parallel and resilient, upper and lower arms 10 and 12 respectively.

Upper arm 10 has parallel rows of aligned equi-spaced openings 14 therein, while lower arm 12 has rows of parallel aligned, equi-spaced openings 16 therein, the openings in the two arms being vertically aligned with each other.

Upper arm 10 is provided, at one of its ends, with a depending flange 18, while lower arm 12 is provided, at one of its ends, with a depending flange 20 disposed in spaced parallelism to flange 18, for purposes to appear.

Coupling means for coupling the arms 10 and 12 is generally indicated by 22 and includes a shaft 23 which passes freely through aligned openings 24 and 26 in the flanges 18 and 20 respectively, the shaft having a threaded portion 28 at one end thereof adjacent flange 18 and a stop portion 30 at the opposite end thereof adjacent flange 20.

Shaft 23 of coupling means 22 is inserted through the openings 26 and 24 of the flanges 20 and 18 until stop 30 abuts flange 20 at which time the threaded portion 28 extends outwardly through flange 18. A thumb nut 32 is now threaded on said threaded portion and brought into abutment with flange 18.

A finger 34 extends radially outwardly from stop 30 and is adapted to contact a side edge of lower arm 12 to preclude rotation of shaft 23 as thumb nut 32 is rotated.

A needle point 36 depends from an opening 38 in flange 18, the needle point being held in place as by a thumb screw 40 threaded in the flange and bearing at its inner end on the needle point.

When the device is to be used as a beam compass, a drawing instrument in the form of a mechanical drawing pencil P, or pen or steel scribing point, is inserted through a pair of aligned openings 14 and 16 in upper and lower arms 10 and 12 respectively in manner such that the point thereof will rest on the paper or other surface upon which the arc or circle is to be drawn when needle point 36 is inserted therein, all in known manner, with the arc or circle being inscribed as the arms are rotated about a center formed by the needle point.

Various arcs and radii can be selected simply by passing the drawing instrument through different openings in the arms.

Still other arcs and radii can be selected by rotating thumb nut 32 while the drawing instrument is in place in a pair of upper and lower arm openings, rotation of the thumb nut causing the stop to pull on the lower arm through flange 20 thereby effecting incremental movements of the lower end of the drawing instrument.

Such manipulation of the thumb nut also causes upper arm 10 to bow in a manner as shown in FIG. 4 whereby the upper arm can be used as a guide for drawing curves of various configurations.

A T-square head 38 is releasably and adjustably fixed to the upper surface of upper arm 10 forwardly of flange 18 as by a thumb nut 40 threaded on the free end of a screw 42 which passes upwardly through provided openings 43 and 45 in arm 10 and head 38 respectively. In this manner, with upper arm 10 serving as the blade, the device can be used as a T-square, with the head 38 being adjustable to form various angles, or entirely removable when not required.

The arms 10 and 12 will preferably be provided in sets of various lengths whereby, for instance, the lower arm of one set may function as the upper arm of another set for producing smaller arcs or circles.

Therefore, the lower end of flange 20 of lower arm 12 herein is provided with an opening 38' whereby a needle point may be inserted therein as desired if the arm is to be used as the upper arm in another set.

The instrument hereof provides a single versatile drafting tool which can be used to draw arcs, circles, curves, and angles of virtually endless variety.