Abstract:
A finger guard for use with a T-square having a head and a blade includes an elongated body, two finger-shielding surfaces extending along a longitudinal axis of said body for accommodating an installer&#39;s thumb, a lower edge on the body that is attachable to the blade of the T-square, and a peak edge opposite the lower edge and separating upper ends of the surfaces.

Description:
BACKGROUND 
       [0001]    The present invention relates to straight edges used as cutting guides, and more specifically to T-squares used in the installation of building panels such as wallboard. 
         [0002]    In the construction industry, during the installation of building panels such as gypsum wallboard or the like, installers often need to cut the panels into sizes smaller than the standard 4×8 foot size. To obtain a straight edge on the cut panel, installers traditionally employ metal T-squares. Generally, installers set a sheet of wallboard upright with the rough side facing the installer and place a head of the T-square upon a top edge of the panel. In most cases, the head is oriented horizontally. Next, the typically vertically oriented blade of the T-square is aligned with the line to be cut. The installer then steadies the T-square in position with one hand and with the opposite foot or knee resting against a lower portion of the blade, and runs a utility knife along the side of the T-square from top to bottom to score the cut. After scoring and removing the T-square, the installer applies impact pressure or simply kicks the score to “snap” the drywall. This ensures a clean edge. In some cases, the installer runs the utility knife along the back of the drywall sheet to finish the cut. 
         [0003]    When using the guiding edge of conventional T-squares, the user applies an inward lateral pressure to keep the knife against the guide edge. In some cases, this causes the knife to jump over the edge towards the user&#39;s hand holding the T-square in position. There have been instances of user&#39;s hands being cut due to these knife jumps. 
         [0004]    To reduce incidents of such cuts, some installers have fastened a full-length L-shaped metal bracket in the middle of the T-square blade to help guard against accidental knife jumps. Although this design offers added protection to the installer&#39;s hand, the raised body of the bracket on the lower two-thirds of the T-square creates an obstacle for users trying to stabilize the bottom of the T-square with their foot or knee. Furthermore, depending on the orientation of the assembly, the full length L-shape design creates a bias for either right or left-handed users. In addition, in some cases the conventional L-brackets obscure the numerical indicia on the T-square, or are uncomfortable for extended use. 
       BRIEF SUMMARY OF THE INVENTION 
       [0005]    The aforementioned drawbacks of the prior art are addressed by the present T-square having an attached ergonomic finger guard for providing a barrier between the cutting blade and the installer&#39;s hand. To comfortably fit the natural contours of a user&#39;s thumbs, the finger guard is designed with ergonomically shaped sides. In addition, the symmetrical configuration of the present finger guard facilitates ease of assembly and use by either right or left-handed users. To avoid interfering with support and/or stabilization by an installer&#39;s foot, the present finger guard extends at most two-thirds of the length of the T-square blade. The lower portion of the blade that is free of the guard allows the user to stabilize the present T-square with the knee or foot. 
         [0006]    A finger guard for use with a T-square having a head and a blade includes an elongated body, two finger-shielding surfaces extending along a longitudinal axis of the body for accommodating an installer&#39;s thumb, a lower edge on the body that is attachable to the blade of the T-square, and a peak edge opposite the lower edge and separating upper ends of the surfaces. 
         [0007]    In another embodiment, a T-square used as a straight edge for cutting building panels includes a head joined perpendicularly to a blade, a finger guard having an elongated body, two concave finger-shielding surfaces extending a full length of the body, a flat lower edge and a peak edge opposite the lower edge. The body includes at least one fastening formation and at least one boss, the body is attached to an indicia surface of the blade and extends longitudinally toward an axial end of the blade. At least one hole in the blade is provided for engaging a corresponding one of the at least one fastening formations to secure the finger guard to the indicia surface. Also, at least one aperture is provide in the blade for engaging a corresponding one of the at least one boss to locate and align the finger guard on the indicia surface. 
         [0008]    In still another embodiment, a T-square used as a straight edge for cutting building panels includes a head joined perpendicularly to a blade, 
         [0000]    a finger guard having a body that is bilaterally symmetrical along a longitudinal axis. The body extends at most ⅔ of a length of the blade, the guard having two concave finger-shielding surfaces extending a full length of the body. Also included on the guard is a flat lower edge, a peak edge opposite the lower edge, a pair of ramped surfaces joining the peak edge to the lower edge at respective ends of the body. The lower edge is attached flush against an indicia surface of the blade. A plurality of holes, countersunk or counterbored on a non-indicia surface of the blade, are constructed and arranged to be aligned with fastening formations on the body for securing the finger guard to the indicia surface of the blade. Additionally, a plurality of apertures is provided for engaging bosses depending from the body for locating the finger guard on the indicia surface of the blade. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a top perspective view of the present T-square; 
           [0010]      FIG. 2  is an exploded perspective view of the T-square of  FIG. 1 ; 
           [0011]      FIG. 3  is an enlarged top perspective view of the present finger guard on the present T-square; 
           [0012]      FIG. 3A  is an end view of the present finger guard on the present T-square; and 
           [0013]      FIG. 4  is a cross-section taken along the line  4 - 4  in  FIG. 3  in the direction generally indicated. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0014]    Referring now to  FIGS. 1 and 2 , the present T-square is generally designated  10  and is formed by perpendicularly joining a head  12  to a blade  14 . Fasteners  15  are used to join the head  12  to the blade  14 . The head  12  varies in length, but is typically shorter than the blade  14 , which preferably ranges between 48″ and 54″ in length to correspond to standard widths of construction panels such as gypsum wallboard. As is well known in the art, head  12  and the blade  14  each have one indicia surface  16  and one non-indicia surface  18 . Each respective indicia surface  16  has measurement marks  20  along outside edges. 
         [0015]    A lip  22 , used for locating and aligning the T-square on the edge of a work surface, is joined perpendicularly on an inner edge  24  of the head  12  and extends rearwardly from the non-indicia surface  18  oriented as shown in  FIG. 1 . Similarly, one or more ribs  26  are also joined perpendicularly with the head  12  and also extend rearwardly from the non-indicia surface  18  of the head  12 . In the preferred embodiment, the lip  22  and the ribs  26  are in spaced, parallel relationship to each other. 
         [0016]    Referring now to  FIGS. 2-4 , to secure one or more finger guards to the indicia surface  16 , one or more holes  28  are linearly aligned along the long axis of the blade  14 . To maintain a flat surface on the non-indicia surface  18  of the T-square  10 , the holes  28  are countersunk or counterbored on the non-indicia surface  18  to accommodate suitable fasteners in a countersunk orientation. In addition, these holes  28  are distally located from a junction  30  of the head  12  and the blade  14  to facilitate removal of a finger guard. Three holes  28  are used in the preferred embodiment, however, the number, positioning, and configuration of the holes  28  may vary to suit the application. Additionally, the blade  14  has one or more apertures  32  constructed and arranged to engage bosses  34  depending from a finger guard, generally designated  40 . Two apertures  32 , one at each longitudinal or axial end of the finger guard  40 , are preferred to receive the bosses and locate and align the guard on the indicia surface  16 . The bosses  34  provide support to the finger guard  40  against laterally directed forces received at upper and lower ends of the guard. 
         [0017]    Referring now to  FIGS. 1-4 , the ergonomic finger guard  40  has an elongated body  42  with a flat lower edge  44  that is attached flush against the indicia surface  16  of the blade  14  and extends toward an axial or longitudinal end  46  of the blade  14 . Preferably, the guard  40  is made of molded ABS blend plastic, but other durable plastics, or materials such as zinc, aluminum, or wood may also be used. An important feature of the present guard  40  is that it is bilaterally symmetrical along its longitudinal axis and has two, preferably identical concave finger-shielding surfaces  48 ,  50  preferably extending the full length of the body  42  to accommodate either the right or left thumb depending on the preference of the installer. Thus, this configuration allows for the guard  40  to be used ambidextrously. 
         [0018]    In addition to the concave finger-shielding surfaces  48 ,  50  and the flat lower edge  44 , the guard  40  has a peak edge  52  opposite the lower edge  44  and separating upper ends  54  of the shielding surfaces. A hollow interior chamber  56  is defined by the surfaces  48 ,  50 , the peak edge  52  and the lower edge  44 . The lower edge  44  is joined to the peak edge  52  by a ramped surface  58  to provide a smooth transition between the peak edge and the lower edge for enhanced ergonomics and to avoid user exposure to sharp edges. Preferably, the interior chamber  56  of the guard  40  is hollow, although a solid interior is contemplated. 
         [0019]    While other dimensions are contemplated depending on the application, a preferred height H ( FIG. 4 ) of the peak edge  52  is ½″ (1.27 cm) and a preferred length L ( FIG. 4 ) of the guard  40  is 7½″ (19.05 cm). The ratio of the height H to the length L is less than 1.0. The height H preferably ranges between ¼″ and 1½″ (0.625 cm and 3.81 cm), and the length L is preferably between 3″ and 36″ (7.62 cm and 91.44 cm). 
         [0020]    To allow an installer to place a knee or foot on the T-square  10  for stabilization during cutting or scoring of a building panel, the length L of the finger guard  40  is at most two-thirds of the length of the blade  14  of the T-square  10 . Preferably, the above-identified range in the length L is approximately no more than 30″ (76.2 cm) on a 48″ (121.92 cm) T-square and no more than 36″ (91.44 cm) on a 54″ (137.16 cm) T-square. Such a configuration leaves a significant portion of the blade  14  upon which the installer may place a foot or knee without discomfort. Moreover, the configuration of the guard  40  and the T-square  10  does not detract from its protective function during the scoring or cutting of building panels, as the majority of knife jumps occur during the first few inches of a cut due to the uncertain path of the knife. 
         [0021]    While other widths W are contemplated, a preferred width ( FIG. 3 ) of the guard  40  is ⅝″ (1.5875 cm) so that the measurement marks  20  on the indicia surface  16  of the blade  14  are visible for measurement purposes upon installation of the guard on the blade. 
         [0022]    Referring now to  FIG. 4 , to secure the guard  40  flush against the indicia surface  16  of the blade  14 , the guard has at least one and preferably a plurality of fastening formations  60 , linearly aligned along the longitudinal axis of the body  42  and extending from an inside surface  62  of the peak edge  52  to a point even with the lower edge  44 . Such fastening formations  60  are internally threaded and aligned with the linearly disposed holes  28  on the T-square  10 . The formations  60  are threadably engaged by fasteners  64  such that heads  66  of the fasteners are flush with the non-indicia surface  16 . The bosses  34  depend from the inside surface  62  and extend past the lower edge  44  and are constructed and arranged to engage the apertures  32  on the blade  14  of the T-square  10  to properly locate and align the finger guard  40  prior to insertion of the fasteners  64 . As is known in the molding art, at least one core out void  68  is provided to facilitate molding of the peak edge  52  to prevent warping of the guard  40 . 
         [0023]    As disclosed above, the present T-square  10  features a guard that accommodates right or left-handed users. Furthermore, the present T-square  10  not only offers protection against knife jumps, but also allows for a user to enhance stability by providing a section of the blade upon which the user may place a knee or foot while scoring a wallboard panel or other construction panel. 
         [0024]    While a particular embodiment of the present T-square with finger guard has been described herein, it will be appreciated by those skilled in the art that changes and modifications may be made thereto without departing from the invention in its broader aspects and as set forth in the following claims.