Patent Application
20090119939
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.
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.
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's hand holding the T-square in position. There have been instances of user's hands being cut due to these knife jumps.
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'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.
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's hand. To comfortably fit the natural contours of a user'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'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.
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'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.
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.
In still 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 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.
Referring now to
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
Referring now to
Referring now to
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.
While other dimensions are contemplated depending on the application, a preferred height H (
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.
While other widths W are contemplated, a preferred width (
Referring now to
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.
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.
