Abstract:
Adjustable drafting template characterized by relatively slideable members which may be positioned to form openings for drawing figures with two parallel sides of different widths and lengths having ends of various shapes; also, circles, chordal portions thereof, squares, portions thereof, and equilateral triangles.

Description:
BACKGROUND OF THE INVENTION 
     In the drafting art certain symbols and geometric figures of various sizes are repetitively required on a drawing. To avoid the time consuming procedure of drawing such figures, employing conventional instruments, such as triangles, compass, protractor, etc., it has long been the practice to provide templates with apertures therein, the edges of which are so shaped to form the desired figure by moving a pencil or pen around opening guide edges. Thus, templates having various size circles, ellipses, squares, hexagons, etc. are familiar. Due to the non-adjustability of such templates, however, they are limited somewhat in utility in that only one predetermined figure may be drawn with each aperture, or, if only a portion of the aperture is employed, then conventional drafting instruments must also be employed. Thus, if a slot with semi-circular ends is desired, one half of a circular aperture may be employed for each end and the figure completed by connecting such ends, employing a straight edge of any suitable form. This saves little time over the use of compass and T-square, or the like, and suffers the further disadvantage that skill is always required to join lines in exact alignment in contradistinction to a template wherein the line is continuous, the only points of alignment being at its starting and finishing point, which with a template, are usually overlapped. 
     Adjustable templates have also been proposed so that a predetermined size and shape of figure may be selected. The U.S. Patent to Lane No. 2,720,706 is exemplary of such type of template in which figures of several shapes having straight sides may be drawn. Until such time that an adjustable template is devised with which any shape and any size figure may be drawn, templates of this type will have their limitations in utility. Such limitations are not objectionable, however, if a specific template serves the major purposes of a draftman for a particular type of drawing. Moreover, in view of the relatively low cost of simple limited utility templates, as compared to a yet undevised and necessarily complicated adjustable all purpose template, the use of several limited utility templates will probably always be more economically practical. 
     SUMMARY OF THE INVENTION 
     The present invention relates to the class of adjustable drafting templates, just referred to, which has particular utility in electronic circuit drawings and others employing often repeated conventional figures or symbols of different sizes. The conventional shapes are squares, rectangles, circles and elongated slots with semi-circular ends, employed in many types of mechanical drawings. The electronic symbols include elongated figures with parallel sides and a flat base at one end and a pointed or semi-circular shape at the other end. Isosceles triangles and semi-circles may also be drawn as special forms of these shapes. 
     Several modifications are contemplated within the purview of the invention. In its most comprehensive form all of the shapes referred to may be drawn with one template. In its more limited form only a selected portion of such shapes may be drawn. 
     The generic form of the invention comprises a pair of rectilinearly slideable members which define slots of variable width and length having parallel sides and selected shaped ends. 
     In its more refined form, the members may be positively locked together and in all forms disclosed interchangeable parts may be employed to extend the field of utility. 
     In accordance with the foregoing, the general object of the invention is to provide improvements in adjustable limited utility templates. 
     Another object is to optionally extend such utility by the use of interchangeable components. 
     Another object is to provide a template having a plurality of adjustable apertures therein for drawing a certain set of figures. 
     A further object is to provide a portion of the foregoing template for drawing a portion of the set of predetermined figures. 
     Still further objects, advantages, and salient features will become more apparent from the detailed description to follow, the appended claims, and the accompanying drawing, to now be briefly described. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a top plan of one form of the invention; 
     FIG. 2 is an enlarged section taken on line 2--2, FIG. 1; 
     FIG. 3 is a broken-away isometric view taken substantially on line 3--3, FIG. 1; 
     FIG. 4 is a top plan of an alternative form of the invention, portions being broken away; 
     FIG. 5 is an enlarged section taken on line 5--5, FIG. 4; and 
     FIG. 6 is a top plan of a portion of FIG. 4, illustrating a modification thereof. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring now to the drawing in detail, and first to FIG. 1, template 10 is a flat plate of plastic, celluloid or other material, preferably transparent, as commonly employed for drafting instruments such as triangles, French curves, fixed shapes, aperture templates, or the like, of the order of about 1/8&#34; thickness. 
     The left half of the plate is provided with a plurality of parallel elongated apertures or slots 12a, 12b, 12c, etc., which increase in width, their widths being identified by suitable indicia 14. The right ends 16a, 16b, 16c, etc. of the slots are semi-circular and the left ends 18a, 18b, etc. are straight and perpendicular to the parallel edges. Preferably, the slots are of about the same length and their ends substantially aligned in the stacked arrangement illustrated to most effectively utilize the area of the plate. 
     A cursor or slideable member 20 extends across the slots and is suitably guided to move rectilinearly parallel thereto. The left edge of the cursor is provided with a plurality of isosceles triangle shaped cut-outs 22a, 22b, 22c, etc. disposed symetrically with respect to the slots. The right edge 24 of the cursor is straight and perpendicular to the edges of the slots. In the position shown, a plurality of isosceles triangles of different sizes may be drawn by moving an implement, such as a pencil or pen around the edges of the triangular openings. When the cursor 20 is moved to the right from that shown, the openings will be formed by parallel sides, a base or end perpendicular thereto and another end formed by two corresponding sides of an isosceles triangle, that is, as an arrow head with a flat base. 
     The slots at the right side of straight edge 24 are similar to those just described except that the ends are semicircular rather than triangular. These could thus be characterized as bullet-head symbols with flat bases. When cursor 20 is moved to the right such symbols or figures are shortened until they become semicircles. 
     Referring now to right cursor 20A, this differs from cursor 20 in that cut-outs 26a,26b,26c, etc., are semicircular, rather than triangular. The slots are the same as in the left half except that their ends are reversed. In the position shown, the openings at the left of cursor 20A are elongated slots with parallel sides and semicircular ends. When it is moved to its extreme left position the openings become circles. The openings at the right of the straight edge are rectangles in the position shown. When the cursor is moved to near its extreme right position (at indicia 27) they become squares. Further movement chops the squares into small rectangles. 
     Other suitable indicia 28 is preferably employed to identify the length of the openings. Also, small holes 29 are preferably provided for locating the center line of its associated slot. 
     CURSOR CONSTRUCTION 
     Each of the cursors so far described is preferably provided with means for locking it in desired position and a description of one will serve for both. Referring to FIG. 3, a stud-like member 30 comprises a generally octagonal base 32 having a slot 34 therein, a round shank 36 and square terminal end 38 with a slot 40. Base 32 forms a resilient cam, by reason of its slot, and is proportioned to fit between a pair of adjacent legs 44 (FIG. 1) defining edges of a slot. When rotated, it cams against such legs forming a lock. Knob 42 fits the square shank and is resiliently retained thereon by end 38 which is provided with opposed detents 46. 
     The cursor is also provided with portions 48 which fit and slide between the various legs and maintain its direction of movement perpendicular to the axes of the slots. As best shown in FIG. 2, its outer edges are provided with resilient V-shaped guides 50 which slide in corresponding grooves in the opposite edges of plate 10. A bevel 52 is also provided for inserting a knife edge for removing the cursor when desired. 
     As best shown in FIG. 3, the straight and cut-out edges of the cursor are provided with bevels 54 so that the pencil guiding edges on the cursor lie in the same plane as the top surface of plate 10 to obviate slight errors in forming the end shapes which might otherwise occur. 
     Referring now to FIG. 4, this construction provides the same template shapes as FIG. 1 but in a somewhat less expensive form of construction. The central portion 110 may be considered analogous to plate 10 with its various slots and portions 120, 120A, may be considered analogous to cursors 20, 20A. In this construction, the three members lie in the same plane with the fingers on members 120, 120A slideably disposed in the slots of central member 110. Tie bars 56, extending across the width of member 110, may be provided to maintain the fingers of central member 110 in precise spaced parallel arrangement by welds 58 (FIG. 5). The outermost fingers are also preferably provided with v-shaped slides 60 to maintain the various portions in the same plane. 
     MODIFICATIONS 
     Fig. 1 
     the slots on the left side vary in width from 1/8&#34;  to 3/4&#34; by increments of 1/8&#34;. The slots on the right side vary in width from 3/16&#34; to 13/16&#34;, also by increments of 1/8&#34;. Thus, slots are provided from 1/8&#34; to 13/16&#34; by increments of 1/16&#34;. If it is desired to employ 1/16&#34; increments with a limited shape of figures, then a cursor like 20A (not shown) may be substituted for cursor 20. As will be understood, it will differ from cursor 20 in that its semi-circular edges will point toward the like edges of cursor 20A. With this construction, circles from 1/8&#34; to 13/16&#34; diameter may be drawn in increments of 1/16&#34;. As will be apparent, slots of like width with semi-circular ends may also be drawn. As will be further apparent, a cursor like cursor 20 (not shown) may be substituted for cursor 20A with its triangular edges pointing to the right. Similarly, arrow-headed slots may be drawn, differing in width by increments of 1/16&#34;. 
     Fig. 4 
     fig. 6 illustrates the upper right portion of FIG. 4. With this construction only the right half of plate 110 is employed, together with the right slide member 120A shown in FIG. 4 and an auxiliary member 220A is provided of the shape shown in the left side of FIG. 4, these being interchangeable. With this construction all of the figures which may be drawn with the FIG. 4 construction may be drawn by the FIG. 6 construction. Otherwise stated, FIG. 4 duplicates the same width slots at each side of its center which are provided with sliders having different shaped ends. In FIG. 6 the duplication of the slots is eliminated and two interchangeable sliders 120A, 220A are provided having different shaped ends. 
     Further Modifications and Choices 
     If the user&#39;s needs are principally for circles, slots with semi-circular ends, squares and rectangles, then the right halves only, of FIGS. 1 or 4 may be provided. If a greater number of figure widths are desired then the entire structure of FIGS. 1 or 4 may be provided with slots of intermediate width and the appropriate cursor. If the user&#39;s principal needs are for arrow or bullet head figures then the left halves of FIGS. 1 or 4 may be provided, and similarly, if a greater number of figure widths are desired then the entire structure of FIGS. 1 or 4 may be provided with slots of intermediate width. If the user&#39;s needs are for both types of the groups of figures referred to, then the FIGS. 1 or 4 construction should be preferred if the user is to be limited to only one template. 
     In view of the exemplary combinations and variations, it will be apparent that further modifications are possible which are contemplated within the purview of the invention as set forth by the appended claims.