Abstract:
The disclosed invention relates to easy-to-use precision tools that locate the mid-line, or center line, of any symmetrical geometric shape, such as triangles, squares, circles, rectangles, parallelograms, trapezoids, and symmetrical polygons. Given two separate points on the edge of a symmetrical geometric shape, these precision tools identify the center line of the geometric shape between those two points, without the need for additional measurements or mathematical calculations. The precision tools can also be used to identify the center points of symmetrical geometric shapes.

Description:
FIELD 
     This invention relates to simple, easy-to-use precision tools that precisely locate the mid-line, or center line, of any symmetrical geometric shape, such as squares, circles, rectangles, parallelograms, and trapezoids. The invention is a single object wherein contact members locate or check the center of a hole or the location of a center line, without the need for measurements or mathematical calculations. 
     BACKGROUND OF THE INVENTION 
     There is a need for a simple-to-use, precision tool that accurately identifies the center lines and center points of a variety of geometric shapes, requiring no more than simple manual manipulations by the user to determine the center lines with mathematical precision. 
     Precision tools exist that can be used to identify the center lines of different geometric shapes, but those instruments are limited in several ways. Similar instruments that are easy to operate incorporate sophisticated construction or automation to identify center lines with mathematical precision. Some manually operated tools yield imprecise approximations of center lines or center points. Other manually operated tools identify center lines or center points with mathematical precision, but require precise measurements or mathematical calculations by the user. Accordingly, there is an urgent need for a simple, manually operated precision tool that will identify the center lines of symmetrical geometric shapes with mathematical precision, without requiring the user to make mathematically precise measurements or calculations. 
     Other similar precision tools are complex constructions requiring power gears and additional pieces for assembly and function. There is a need for a precision tool that determines center lines without the use of automated parts, such as a power-screw mechanism. By simply placing the positioning legs of the precision tool on the edges of a geometric shape, the center is immediately indicated without any further adjustments to position the centering leg or by means of an adjustment screw. This provides a precision tool that is easier to use, and has a design that requires only a few, non-automated parts. Furthermore, this precision tool does not require a power source for operation. 
     There also exist other instruments that could be adapted to identifying the precise center lines of only a few geometric shapes, or only one geometric shape. There exists a need for a precision tool that identifies the center lines of a variety of different symmetrical geometric shapes. 
     Precision tools that identify the center lines of symmetrical geometric shapes operate in a plane that is substantially perpendicular to the geometric shapes. There exists a further need for precision tools that are operated in a plane that is substantially parallel to the geometric shapes, particularly in circumstances where space limitations prevent the use of a substantially perpendicular tool. 
     SUMMARY OF THE INVENTION 
     The disclosed embodiments include a precision tool comprising a base leg, two slidingly adjustable positioning legs, and a means of orienting the positioning legs relative to the base leg so that the base leg forms the center line between the two portioning legs. Accordingly, when the positioning legs are placed upon two separate points on the edge of a geometric shape, the base leg identifies the center line of that geometric shape between those two points, without additional measurements, manipulations, or mathematical calculations. 
     The disclosed invention relates to precision tools that precisely locate the center line of a geometric shape. Unlike a compass, which is a two-legged instrument, the disclosed precision tools comprise a central base leg with two flanking positioning legs that are slidingly attached to the base leg. When the ends of the positioning legs are placed upon two separate points on the edge of the geometric shape, the base leg defines the center line of the geometric shape, without further measurements or mathematical calculations. 
     To precisely define the center line of a geometric shape, the base leg is maintained in a particular orientation relative to the two positioning legs. The base leg is restricted to maintaining an orientation in which the base leg bisects the angle formed by its two flanking positioning legs. As the positioning legs move outward from the base leg (or inward toward it), the first positioning leg forms an angle with the base leg that is the same as the angle formed by the second positioning leg and the base leg. This feature ensures the mathematical precision of the center line identified by the disclosed invention. 
     The precision tool can be used to identify multiple center lines for the same geometric shape, and can identify the center line for every axis of symmetry that a geometric shape possesses. In addition, by plotting two or more center lines, the center point of a geometric shape is identified by the intersection of those center lines, with mathematical precision. 
     One embodiment of the invention further comprises a central leg. The central leg provides means to maintain the positioning legs in a particular orientation relative to the base leg, so that the precision tool accurately identifies the center line between the two separate points on the edge of a geometric shape that are indicated with the positioning legs. 
     Another embodiment of the invention further comprises a simple planetary gear system, instead of a central leg, to ensure that the positioning legs maintain the correct orientation relative to the base leg. In this way, the base leg and positioning legs maintain the necessary orientation so that the precision tool accurately identifies the center line between two separate points on the edge of a geometric shape. The planetary gear system provides an alternative means of adjusting the positioning legs to maintain the required orientation relative to the base leg. 
     Another embodiment of the invention further comprises gears to ensure that the positioning legs maintain the correct orientation relative to the base leg. The interlocking gears maintain the required orientation that ensures that the base leg of the precision tool accurately identifies the center line between two separate points on the edge of a geometric shape. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an illustration of a precision tool with a central leg according to the disclosed embodiments, where the positioning legs are in an opened position. 
         FIG. 2  is an illustration of a precision tool with a central leg according to the disclosed embodiments, where the positioning legs are in a closed position. 
         FIG. 3  is a side view of the precision tool with a central leg. 
         FIGS. 4A-4B  are top and side views of a positioning leg of the precision tool. 
         FIGS. 5A-5B  are top and side views of the central leg of the precision tool. 
         FIGS. 6A-6B  illustrate a top and side view of the base leg of the precision tool. 
         FIG. 7  is an illustration of a further embodiment of a precision tool containing a planetary gear system. 
         FIGS. 8A-8B  illustrate a further embodiment of a precision tool containing gears in an opened position and a closed position. 
     
    
    
     DETAILED DESCRIPTION 
     A “geometric shape” is any closed, two-dimensional shape having at least one axis of symmetry. Examples of geometric shapes include, but are not limited to, squares, rectangles, parallelograms, trapezoids, ellipses, ovals, and circles. Other examples include pentagons, hexagons, and other polygons, as long as they have at least one axis of symmetry. 
     A “center line” is any line which forms an axis of symmetry in a geometric shape. A center line divides a geometric shape into two halves. Each half possesses equal area to each other and is a mirror image of the other half. 
     The disclosed embodiments of the invention relate to a precision tool that readily identifies the center line between two separate points on the edge of a geometric shape. 
     Embodiment 1 
       FIGS. 1-6  illustrate one embodiment of a precision tool of the disclosure. The embodiment shown in  FIGS. 1-2  includes a base leg  10 , two positioning legs  21 ,  22  attached next to each other atop the base leg  10 , and a central leg  31  atop the two positioning legs  21 ,  22 . 
     The base leg  10  is shown in greater detail in  FIGS. 6A-6B . The base leg  10  contains a thru slot  11  positioned in its midline and four openings  12 - 15 . 
     The two positioning legs  21 ,  22  are identical in structure and shown in greater detail in  FIGS. 4A-4B . Each positioning leg  21 ,  22  has three openings  23 - 25 . The first positioning leg  21  is slidingly attached atop the base leg  10  by a fastening means through opening  12  of the base leg  10  and opening  23  of the first positioning leg  21 . The second positioning leg  22  is slidingly attached atop the base leg  10  by a fastening means through opening  13  of the base leg  10  and opening  23  of the second positioning leg  22 . 
     The first positioning leg  21  slidingly attaches to the base leg  10  at opening  12 . The second positioning leg  22  slidingly attaches to the base leg  10  at opening  13 . 
     This embodiment of the precision tool also includes a central leg  31 , which is shown in greater detail in  FIGS. 5A-5B . The central leg  31  is shaped like an capital letter “H” with elongated arms  33 - 36 . There is an open section  37  between elongated arms  33  and  35 . There is another open section  38  between elongated arms  34  and  36 . The crosspiece  32  of the central leg contains an opening  39 . 
     This embodiment is assembled as the base leg  10 , two positioning legs  21 ,  22  attached next to each other atop the base leg  10 , and a central leg  31  atop the two positioning legs  21 ,  22 . 
       FIGS. 2-3  further illustrate the assembled precision tool. When assembled, first positioning leg  21  and second positioning leg  22  lie atop the base leg  10 , with thru slot  11  between them ( FIG. 2 ). Opening  23  of the first positioning leg  21  will be slidingly fastened to opening  12  of the base leg  10  and opening  23  of the second positioning leg  22  will be slidingly fastened to opening  13  of the base leg  10 . Opening  24  of the first positioning leg  21  will align to opening  14  of the base leg  10  and opening  24  of the second positioning leg  22  will align to opening  15  of the base leg  10 . Opening  25  of each positioning leg  21 ,  22  will extend past the base leg  10 . 
     The central leg  31  slidingly attaches to the base leg  10  by a fastening means through opening  39  of the central leg  31  and thru slot  11  of the base leg  10 . The fastening means, for example, a pin, allows the central leg  31  to move laterally along the thru slot  11 , along the midline of the base leg  10 . ( FIG. 2 ). 
     As the two positioning legs  21 ,  22  move outward from the midline of the base leg  10  (or inward toward it), opening  24  of the first positioning leg  21  must be kept in alignment with opening  24  of the second positioning leg  22 , so that a line formed between the two openings is perpendicular to thru slot  11  of the base leg  10 . This restriction maintains the two positioning legs  21 ,  22  in proper alignment with the base leg  10  ( FIGS. 2-3 ), so that the angles formed between the base leg and each positioning leg are angles of equal size and, accordingly, the base leg  10  identifies the center line of a geometric shape. 
     This embodiment of the precision tool can be used to find the center line between two separate points on a geometric shape. To do so, opening  25  of the first positioning leg must be positioned above one point along the edge of the geometric shape and opening  25  of the second positioning leg must be positioned above another point along the edge of the geometric shape. The central leg must be positioned such that opening  24  of the first positioning leg is contained within open section  37  of the central leg and opening  24  of the second positioning leg is contained within open section  38  of the central leg. With the precision tool thus aligned, the base leg will identify the center line between the two points of the geometric figure with mathematical precision. 
     Embodiment 2 
       FIG. 7  illustrates an example of an alternative embodiment of a precision tool of the disclosure. In this embodiment, the relative alignment of the base leg and two positioning legs are maintained by means of simple planetary gear system, instead of the central leg piece described in Embodiment 1. 
     This precision tool is made of a base leg  60 , a first positioning leg  70 , and a second positioning leg  80  that are aligned by a simple planetary system. The simple planetary system has a sun gear  71 , planet gear  61 , curved groove  72 , and ring gear  82 . 
     The base leg  60  forms the bottom piece of the precision tool. The planet gear  61  is attached atop the base leg  60  near the base leg&#39;s apex. The planet gear  61  is attached at point  62  so that the planet gear can only rotate around its own center. 
     First positioning leg  70  contains a curved groove  72  near its apex. A sun gear  71  is fastened atop first positioning leg  70 , positioned closer to the apex than the curved groove  72 . The curved groove  72  describes a partial orbit around the sun gear  71 . 
     First positioning leg  70  is placed atop base leg  60  so that the planet gear  61  protrudes upward through the curved groove  72 . The teeth of planet gear  61  contact the teeth of the sun gear  71 . The ring gear  82  encircles the sun gear  71 , the planet gear  61 , and the curved groove  72 . The inner teeth of the ring gear  82  contact the teeth of the planet gear  61 . 
     The second positioning leg  80  is placed atop the first positioning leg  70  and the ring gear  82 , near the apex of the second positioning leg  80 . The precision tool is fastened together at a single point  84 , attached by a fastening means through the second positioning leg  80 , the center of the sun gear  71 , the first positioning leg  70 , and the base leg  60 . 
     The planetary gear system functions to restrict the movement of the first positioning leg  70  and second positioning leg  80  so that whenever one positioning leg is moved away (or toward) the base leg, the other positioning leg also moves the same distance away (or toward) the base leg  60 . Thus, the unattached ends of the first positioning leg  70  and the second positioning leg  80  always remain equidistant from the base leg  60 . Also, the interior angle between the base leg  60  and the first positioning leg  70  always remains the same size as the interior angle between the base leg  60  and the second positioning leg  80 . Accordingly, the planetary gear system maintains the required orientation between the base leg and the two positioning legs to ensure that the precision tool identifies a geometric shape&#39;s center line with mathematical precision. 
     This embodiment of the precision tool can be used to find the center line between two separate points on a geometric shape. To do so, the unattached ends of the first positioning leg  70  and the second positioning leg  80  are extended outward and placed on two separate points along the edge of the geometric shape. With the precision tool thus aligned, the base leg  60  will identify the center line between the two points of the geometric figure. 
     Embodiment 3 
       FIGS. 8A-8B  illustrate an example of an alternative embodiment of a precision tool of the disclosure. In this embodiment, the relative alignment of the base leg and two positioning legs are maintained by means of gears, instead of the central leg piece described in Embodiment  1  or the simple planetary gear system described in Embodiment  2 . 
     This precision tool is made of a base leg  91 , a first positioning leg  92 , and a second positioning leg  93  that are aligned with gears  94 ,  95 . The first positioning leg  92  is slidingly attached atop the base leg  91  near its apex by means of a gear  94  sandwiched between them. The second positioning leg  93  is slidingly attached atop the base leg  91  near its apex by means of a gear  95  sandwiched between them. Gear  94  is identical to gear  95  and the teeth of the two gears contact each other. The first positioning leg  92  and second positioning leg  93  are the same length. 
     The gears function to restrict the movement of the first positioning leg  92  and second positioning leg  93  so that whenever one positioning leg is moved away (or toward) the base leg  91 , the other positioning leg also moves the same distance away (or toward) the base leg. Thus, the unattached ends of the first positioning leg  92  and the second positioning leg  93  always remain equidistant from the base leg  91 . Also, the interior angle between the base leg  91  and the first positioning leg  92  always remains the same size as the interior angle between the base leg  91  and the second positioning leg  93 . Accordingly, the gears maintain the required orientation between the base leg and the two positioning legs to ensure that the precision tool identifies a geometric shape&#39;s center line with mathematical precision. 
     This embodiment of the precision tool can be used to find the center line between two separate points on a geometric shape. To do so, the unattached ends of the first positioning leg  92  and the second positioning leg  93  are placed on two separate points along the edge of the geometric shape. With the precision tool thus aligned, the base leg  91  will identify the center line between the two points of the geometric figure.