BACKGROUND OF THE INVENTION 
       [0001]    1. Field Of The Invention 
         [0002]    This invention relates generally to the field of metal-working tools and relates more particularly to a compound leverage hand seamer having removable blades. 
         [0003]    2. Description Of The Related Art 
         [0004]    Hand seamers, also known as hand brakes, are portable hand tools that are used for bending and flattening sheet metal such as flashing for roof and window applications. Conventional hand seamers are constructed from two levers that are pivotably connected to one another at a point intermediate their ends. A first end of each lever terminates in a substantially planar, rectangular blade. A second end of each lever defines an elongated handle, sometimes also referred to as a hand grip. By moving the handles of the seamer toward one another, a user causes the blades of the seamer to pivotably move toward one another and ultimately clamp together in a flatly abutting relationship. Modern hand seamers commonly incorporate a conventional compound leverage handle configuration for allowing the blades of a seamer to be clamped firmly together by applying relatively less force to the handles as compared to traditional, non-compound leverage hand seamers. 
         [0005]    To use a conventional hand seamer, a user firmly clamps an area of sheet metal flatly between the blades of the seamer. The user then manually rotates the seamer to bend the clamped portion of metal to a desired angle relative to the surrounding sheet metal, causing the metal to be folded along a line defined by the top edges of the clamped blades. The hand seamer thereby allows a user to create clean, straight fold lines in sheet metal which is otherwise difficult to manipulate by hand. A hand seamer can be employed in a similar manner to grip and flatten, or unbend, a segment of bent sheet metal. 
         [0006]    A problem commonly associated with both traditional and compound leverage hand seamers is that the blades of such seamers are integral with, and are not removable from, the rest of the tool. Therefore, if the blades are damaged in such a way that renders them ineffective or unusable, such as by being severely scratched, dented or cracked, the entire tool must be disposed of and replaced. 
         [0007]    Another problem commonly associated with existing hand seamers is that the blades of a particular hand seamer are of a predetermined, fixed size that cannot be easily modified by a user. Hand seamers are thus typically offered in a variety of different blade sizes (e.g. 3″×1″, 6″×2″, 9″×1″, etc) for accommodating different size applications. A particular hand seamer is therefore generally only appropriate for handling a particular size of job. For example, if a user needs to bend or flatten an immovable piece of sheet metal that is located in an area having only three inches of surrounding clearance, a user would not be able to use a hand seamer having 6″ long blades for the task. Conversely, if a user needs to create a 6″ long bend in a piece of sheet metal, a hand seamer having 3″ long blades would not be as appropriate for the task as a hand seamer having 6″ long blades. Frequent users of hand seamers are therefore required to purchase, store, and maintain several different sizes of hand seamers to ensure preparedness for various different tasks. This can be costly and burdensome. 
         [0008]    It is therefore an object and feature of the present invention to provide a hand seamer with blades that can be easily replaced independently from the rest of the tool when one or both of the blades become ineffective or unusable. 
         [0009]    It is a further object and feature of the present invention to provide such a hand seamer with interchangeable blades of various different sizes for accommodating a variety of different tasks without requiring a user to purchase and maintain several different tools. 
       BRIEF SUMMARY OF THE INVENTION 
       [0010]    In accordance with the present invention, there is provided an improved compound leverage hand seamer with removable blades. The hand seamer includes a pair of pivotably connected handles and a pair of pivotably connected seamer heads. Each of the seamer heads is connected to one of the handles at a first end and terminates at a second end in a substantially planar head segment having a flat, inwardly-facing mounting surface. A substantially planar, rectangular blade is removably mounted to the mounting surface of each of the seamer heads in a flatly abutting relationship therewith, preferably by a pair of threaded fasteners that engage mounting holes in the seamer heads and in the blades. By forcibly moving the handles of the seamer toward one another, the blades can be firmly clamped together. The improved hand seamer can thereby be used in the manner of a conventional hand seamer for griping and bending sheet metal. 
         [0011]    If one or both of the blades of the improved hand seamer become worn or damaged over the course of use, the fasteners that hold the blades to the seamer heads can be removed, such as with a conventional screwdriver, and the blades can be replaced with a new set of similar blades. Therefore, unlike traditional hand seamers having non-removable blades, a damaged blade does not render the entire tool useless or ineffective. Similarly, if a user of the improved hand seamer encounters a task that requires smaller or larger blades than the blades that are currently mounted to the seamer heads, the existing blades can be removed from the seamer heads and a set of blades of a more appropriate size can be installed. The user of the hand seamer therefore does not have to own and maintain multiple, different-sized hand seamers for performing different-sized tasks. 
         [0012]    Additional blades are preferably provided for the improved hand seamer in incremental lengths of 1 inch and incremental widths of 0.5 inches, and preferably range from a shortest length of 3 inches to a longest length of 9 inches and a narrowest width of 1 inch to a widest width of 5 inches. Such additional blades can be provided with the improved hand seamer as part of a set or can be sold to consumers separately. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0013]      FIG. 1  is a perspective view illustrating the preferred embodiment of the present invention. 
           [0014]      FIG. 2  is side view illustrating the preferred embodiment of the present invention shown in  FIG. 1 . 
           [0015]      FIG. 3  is an exploded perspective view illustrating the preferred embodiment of the present invention shown in  FIG. 1 . 
           [0016]      FIG. 4  is an exploded rear perspective view illustrating the preferred embodiment of the present invention shown in  FIG. 1 . 
           [0017]      FIG. 5  is a perspective view illustrating a first alternative embodiment of the present invention shown in  FIG. 1  with longer and wider blades. 
           [0018]      FIG. 6  is a perspective view illustrating a second alternative embodiment of the present invention shown in  FIG. 1  with longer blades. 
           [0019]      FIG. 7  is a perspective view illustrating a third alternative embodiment of the present invention shown in  FIG. 1  with longer and wider blades. 
       
    
    
       [0020]    In describing the preferred embodiment of the invention which is illustrated in the drawings, specific terminology will be resorted to for the sake of clarity. However, it is not intended that the invention be limited to the specific term so selected and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0021]    Referring to  FIGS. 1-4 , an illustrative embodiment of the hand seamer in accordance with the present invention is indicated generally by the numeral  10 . For the sake of convenience and clarity, terms such as “top,” “bottom,” “up,” “down,” “inward,” “outward,” “lateral,” and “longitudinal” will be used herein to describe the relative placement and orientation of the various components of the hand seamer  10 , all with respect to the geometry and orientation of the first exemplary embodiment of the device as it appears in  FIG. 1 . The terminology will include the words specifically mentioned, derivatives thereof, and words of similar import. However, these terms of orientation are used for simplicity of the description and it should be apparent that the tool may be used in many other orientations. 
         [0022]    Referring to  FIGS. 1 and 2 , the hand seamer  10  generally includes a pair of compound leverage handles  12  and  14  with rubberized hand-grips  16  and  18 , two pivotably-interconnected seamer heads  20  and  22 , and two removable blades  24  and  26 . The compound leverage handles  12  and  14  of the hand seamer  10  are of a conventional, spring-loaded variety that are well known in the art and will therefore not be discussed in great detail herein. It should be understood, however, that any other suitable type of compound leverage or non-compound leverage handles can be substituted for the handles  12  and  14  without departing from the present invention. 
         [0023]    The seamer heads  20  and  22  of the hand seamer  10  are similar to the seamer heads of conventional compound leverage hand seamers insofar as they are generally T-shaped with elongated neck segments  28  and  30 . The neck segments  28  and  30  are pivotably connected to the handles  12  and  14  by pivot pins  32  and  34  at a first end and terminate in perpendicular head segments  36  and  38  at a second end. The neck segments  28  and  30  of the seamer heads  20  and  22  are pivotably connected to one another in a conventional manner by a main pivot pin  40  that passes transversely through a pair of laterally-aligned connecting lobes  42  and  44  that extend inwardly from each of the neck segments  28  and  30 . This configuration allows the neck segments  28  and  30  of the seamer heads  20  and  22  to be pivoted relative to one another about the axis of the main pivot  40  pin without intersecting or colliding with each other. The hand seamer  10  thereby operates in the manner of conventional compound leverage hand seamers, with forcible movement of the hand grips  16  and  18  toward one another causing the head segments  36  and  38  of the hand seamer  10  to pivotably move toward one another. 
         [0024]    Referring now to  FIGS. 3 and 4 , the head segments  36  and  38  and blades  24  and  26  of the hand seamer  10  are substantially identical and will therefore be described in detail with regard to the head segment  38  and the blade  26  only. The head segment  36  and blade  24  are removed in  FIGS. 3 and 4  for the sake of clarity. It should thus be noted that the view of the hand seamer  10  shown in  FIG. 4  is merely an inverted view of the hand seamer  10  shown in  FIG. 3 . The head segment  38  has an inwardly-facing mating surface  42  that is substantially flat and rectangular. Two laterally-spaced mounting holes  44  and  46  extend through the head segment  38  in a perpendicular relationship with the mating surface  42  for accepting a pair of mounting fasteners  48  and  50 , which will be described in greater detail below. The mounting holes  44  and  46  are positioned ½ inch inside the lateral edges of the mating surface  42 , although it is contemplated that the mounting holes  44  and  46  can be positioned nearer to, or more distant from, the lateral edges of the mating surface  42 . 
         [0025]    The blade  26  is a substantially planar, rectangular plate that is preferably formed of conventional steel of the type used to fabricate common hand tools, although it is contemplated that the blade  26  can be formed of any other suitably rigid and durable material, including, but not limited to high carbon steel and titanium. Importantly, the blade  26  should be rigid enough to be able create a clean, straight fold line in a piece of sheet metal (as described below), but resilient enough to resist chipping and cracking when placed under force in the course of normal use. The blade  26  has an outwardly-facing mating surface  52  and an opposing, inwardly-facing engagement surface  54 . The engagement surface  54  of the blade is preferably textured with a plurality of narrow, wave-shaped grooves (not shown) for providing a tread-like, frictional surface for securely gripping sheet metal. It is contemplated that the engagement surface  64  of blade can incorporate a variety of alternative textured groove patterns for achieving a similar purpose, such as a diamond-shaped pattern, a concentric circle pattern or a zig-zag pattern. Any such alternative surface patterns should not, however, incorporate sharp projections or other features that could cause damage to a segment of sheet metal being gripped by the hand seamer  10 . 
         [0026]    Two laterally-spaced, threaded mounting holes  56  and  58  extend through the blade  26  in a perpendicular relationship with the mounting and engagement surfaces  52  and  54 . The mounting holes  56  and  58  are preferably equidistant from the lateral center of the blade  26 . The on-center distance between the mounting holes  56  and  58  is equal to the on-center distance between the mounting holes  44  and  46  in the head segment  38 , and the radii of the mounting holes  56  and  58  are preferably equal to the radii of the mounting holes  44  and  46  in the head segment  38 . An alternative embodiment of the invention is contemplated in which the mounting holes  56  and  58  extend from the mating surface  52  only partially through the blade  26 , thereby leaving the engagement surface  54  of the blade  26  continuous and unbroken. 
         [0027]    Still referring to  FIGS. 3 and 4 , the blade  26  is mounted to the head segment  38  of the hand seamer  10  by two threaded fasteners  48  and  50  that extend through the mounting holes  44  and  46  in the head segment and threadedly engage the mounting holes  56  and  58  in the blade  26 . The blade  26  is thereby securely mounted to the seamer head  22 , with the mating surface  52  of the blade  26  flatly abutting the mating surface  42  of the head segment  38 . The fasteners  48  and  50  are preferably flat-tipped, flathead hex screws, although it is contemplated that any other type of removable fasteners, such as various other types of screws and threaded bolts, can be substituted for the fasteners  48  and  50 . Annular recesses  60  and  62  are preferably formed in the outwardly-facing surface of the head segment  38  surrounding the mounting holes  44  and  46  for matingly accepting the heads of the fasteners  48  and  50  and allowing the heads to sit flush with the outwardly-facing surface of the head segment  38  when the fasteners  48  and  50  are fully tightened. The flat tips of the fasteners  48  and  50  preferably sit flush, or just short of flush, with the engagement surface  54  of the blade  26  when the fasteners  48  and  50  are fully tightened. 
         [0028]    It is contemplated that direction of the fasteners  48  and  50  can be reversed, with the fasteners  48  and  50  being inserted through the engagement surface  54  of the blade  26  instead of through the outwardly-facing surface of the head segment  38 . In such a configuration, annular recesses are preferably formed in the engagement surface  54  surrounding the mounting holes  56  and  58  for matingly accepting the fastener heads in the manner described above, thereby preventing the fastener heads from protruding from the engagement surface  54  of the blade  26  and possibly damaging sheet metal gripped by the hand seamer  10 . It is further contemplated that a greater or fewer number of removable fasteners can be used to secure the blade  26  to the seamer head  22  in the manner described above, with a commensurate number of threaded mounting holes formed through the blade  26  and the through head segment  38 . 
         [0029]    The assembled hand seamer  10  is operated in substantially the same manner as a conventional compound leverage hand seamer, with the seamer heads  20  and  22  being pivotably movable between a closed position (shown in  FIG. 1 ) and an open position (not pictured) in response to forcible movement of the hand grips  16  and  18  toward and away from each other, respectively. During typical use of the hand seamer  10 , an operator first clamps a segment of sheet metal between the blades  24  and  26 . The operator then bends the sheet metal by rotating the hand seamer  10  about the forward-most, inner edge of one of the blades  24  and  26 . The clamped segment of metal is bent to a desired angle, and a clean, straight fold line is thereby formed in the metal by the edge of the blade. A bent segment of sheet metal can be clamped and unbent by employing the hand seamer  10  in a similar manner. 
         [0030]    The blades illustrated in  FIGS. 1-4  are 3 inches long and 1 inch wide. However, an additional number of incrementally longer, shorter, narrower and wider blades having similarly positioned mounting holes can be used with the hand seamer  10  in a similar manner. For example, if a user is confronted with a task requiring a hand seamer with 5 inch long, 2 inch wide blades, the user can simply remove the 3 inch long, 1 inch wide blades from the head segments  36  and  38  by unscrewing the threaded fasteners, such as with a conventional hex-head screwdriver. The user can then install 5 inch long, 3 inch wide blades, such as the blades  100  and  102  shown in  FIG. 5 , on the seamer heads  20  and  22  with the same fasteners. It is contemplated that such additional blades sets can be purchased by consumers separately, apart from the hand seamer  10 , or with the hand seamer  10  as a set. 
         [0031]    Additional blades are preferably provided in incremental lengths of 1 inch (e.g. 3 in, 4 in, 5 in, 6 in etc.) and incremental widths of 0.5 inches (e.g. 1 in, 1.5 in, 2 in etc.), and preferably range from a shortest length of 3 inches to a longest length of 9 inches and a narrowest width of 1 inch to a widest width of 5 inches. For example, a pair of 6 inch long, 1 inch wide blades  200  and  202  is shown installed on the hand seamer  10  in  FIG. 6 , and a pair of 9 inch long, 2 inch wide blades  300  and  302  is shown installed on the hand seamer  10  in  FIG. 7 . Although the length and width ranges set forth above are preferred, it is contemplated that blades of virtually any length and any width can be used with the hand seamer  10  without departing from the present invention. 
         [0032]    This detailed description in connection with the drawings is intended principally as a description of the presently preferred embodiments of the invention, and is not intended to represent the only form in which the present invention may be constructed or utilized. The description sets forth the designs, functions, means, and methods of implementing the invention in connection with the illustrated embodiments. It is to be understood, however, that the same or equivalent functions and features may be accomplished by different embodiments that are also intended to be encompassed within the spirit and scope of the invention and that various modifications may be adopted without departing from the invention or scope of the following claims.
An improved compound leverage hand seamer with removable blades. The hand seamer includes a pair of pivotably connected handles and a pair of pivotably connected seamer heads. Each of the seamer heads is connected to one of the handles at a first end and terminates at a second end in a substantially planar head segment having a flat, inwardly-facing mounting surface. A substantially planar, rectangular blade is removably mounted to the mounting surface of each of the seamer heads in a flatly abutting relationship therewith by a pair of threaded fasteners that engage threaded mounting holes in the blades and in the seamer heads. The blades can be conveniently removed and replaced if they become worn or damaged, or if user wishes, to install smaller or larger blades on the hand seamer.