Patent Publication Number: US-6701805-B2

Title: Stone working tool having multiple striking edges on reversible-replaceable plates

Description:
FIELD OF THE INVENTION 
     The invention relates to hand tools, and specifically concerns a hammer for shaping stone and masonry by manually striking the stone to break away material at the surface. Multiple working tool edges are provided by plates that are replaceably mounted, preferably on each of two opposite striking faces on the tool. Each plate can be re-oriented on the tool, for placing a fresh edge in a selected exposed position for use. Each plate also can be reversed for moving a fresh set of edges from a protected side to an exposed side of that plate. 
     BACKGROUND 
     Stone working hammers are used to trim natural stone, masonry, and the like (herein generally described as “stone”), for example to size pieces of stone or masonry so as to fit at a given place in a structure, or to normalise the size or shape of stones in a supply to be used for building or paving, etc. A stone working hammer for such a purpose generally comprises a striking head mounted on a handle, to be swung against the stone by the craftsman. At least the part that impacts the stone is advantageously made of a relatively durable material so that the tool has a reasonable service life, such as hardened steel. 
     For detail work, the striking head preferably has a sharply defined striking edge, thus concentrating the point of impact and permitting accurate cutting and trimming of the stone by controlled chipping away of material at selected edges. A striking edge that is sharply defined, however, is also inherently thin at its edge, and wears rapidly with repeated impact. The striking edge becomes rounded, and it is more difficult for the craftsman precisely to cut the stone because the force of the impact is less controllable and localised. 
     It will be appreciated that stone working hammers are thus unlike many familiar sorts of hammers and mallets, such as claw hammers for driving nails, ball peen hammers for metal working, etc., because the edge of the striking face of the stone working hammer is critical, not the mass of the hammer along its midline. When the striking edge of a stone hammer becomes rounded and worn, the head of the hammer must be replaced or sharpened by grinding away material down to a new discrete cutting edge. 
     There are disadvantages associated with sharpening stone hammers. Sharpening procedures may be relatively complex, costly and time consuming. The process is comparable to the steps needed to make a new tool from scratch. A stone hammer is typically sent to a blacksmith to be sharpened. The blacksmith heats the hammer to remove its hardening, and then reshapes the hammer to restore its sharp edges. It is often necessary to re-treat the hammer to harden its working surfaces, for example to nitride, or temper by heat treatment and quenching. A hammer needing sharpening could alternatively be sent to a machinist to grind or mill away material up to planes that meet at the cutting edge. However, the hammer will lose its hardening, thus limiting its usefulness as a stone working tool. Also, grinding the hammer removes steel, which limits the useful lifetime of the hammer. 
     While a worn hammer is being refurbished and sharpened, it is out of service. Given the limited number of blacksmiths in an area, it is conceivable that hammers can be out of service for several months. Thus the stock of hammers kept available must be large enough to account for some of the hammers being out of service at any given time for sharpening. 
     It is also conceivable that the majority of the hammers owned by a stone cutting operation can be out of service at any given time. The striking edge of a stone hammer can be worn to an extent that it needs sharpening after one full day&#39;s use. If the operation is such that it takes the machinist several days to sharpen and return worn stone hammers, then the inventory of stone hammers must be several times the number of users. 
     Stone cutting craftsmen tend to use their tools in a characteristic way. For example a right-handed cutter is likely to wear one edge of the cutting face of a hammer more than another edge, that a left-handed cutter might be more prone to use. Even given that fact, a relatively large investment in a working inventory of stone hammers may be needed. With regular use there is a constant workload on the machinists who refurbish the hammers. After a few sharpening operations the tool is reduced by the trimming operations associated with sharpening and must be replaced. There is a need to reduce or eliminate the associated expense and effort by stone cutting operations to keep an available stock of stone hammers with fresh edges to use for stone cutting and trimming. 
     SUMMARY OF THE INVENTION 
     The invention meets this need by providing quickly, easily, and inexpensively replaced striking plates whose tooling faces and mounting define selectively deployed polygonal straight edges. Preferably, for example, the striking plates have a rectilinear shape and are mounted in a symmetrical manner whereby the plates are removably attachable to a tool head base part at any selected 90 degree increment. Thus a fresh edge on one side of the plate can be moved readily into a given position on the tool for use in cutting. The striking plates are reversible. The number of polygonal edges is thereby doubled. Furthermore, the tool itself preferably has opposite faces, again doubling the number of available edges. As a result, in a rectilinear cutting plate arrangement, as many as sixteen fresh cutting edges can be worn before the tool requires service, and such service can be quickly and conveniently accomplished by replacing the striking plates rather than refurbishing the tool as a whole. 
     Thus according to the invention, a manual stone hammer is provided with at least one polygonal faceplate, and preferably two opposite faceplates, both being individually reversible and thereby providing selectively available striking edges in four times the number of faces of the polygon. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other advantages and features of the present invention will be better understood from the following detailed description of the preferred embodiments of the invention, which is provided in connection with the accompanying drawings. The various features of the drawings may not be to scale. Included in the drawing are the following figures: 
     FIG. 1 is an isometric view of an exemplary embodiment of a stone hammer in accordance with the invention; 
     FIG. 2A is a front elevation view of an exemplary embodiment of a stone hammer in accordance with the invention; 
     FIG. 2B is an exploded illustration of the embodiment of FIG. 2A; 
     FIG. 3 is a exploded front elevation of an exemplary embodiment of a stone hammer according to the invention, wherein bored and countersunk openings and threaded portions are shown in broken lines; 
     FIG. 4A is a top plan view of an exemplary embodiment of a rectilinear faceplate having four openings in accordance with the invention; 
     FIG. 4B is a front elevation view of an exemplary embodiment of the rectilinear faceplate of FIG. 4A; 
     FIG. 4C is a bottom plan view of the exemplary embodiment of FIGS. 4A and 4B; 
     FIG. 5A is a top plan view of an exemplary tool head body according to the invention; 
     FIG. 5B is a front elevation view of the tool head body as shown in FIG. 5A; 
     FIG. 5C is a bottom plan view of the tool head body of FIGS. 5A and 5B; 
     FIG. 6A is an illustration of an exemplary handle defining an elongated shaft for attachment to the tool head; 
     FIG. 6B is an illustration of an exemplary handle, further comprising a finger guard; 
     FIG. 6C is an illustration of an exemplary handle contoured to fit a hand; 
     FIG. 7A is a top plan view of an alternative embodiment of a rectilinear faceplate in accordance with the invention, having two fastener openings defining a line of symmetry; 
     FIG. 7B is a bottom plan view of the embodiment of FIG. 7A; 
     FIG. 7C is a top plan view of a faceplate having a radially symmetric fastener pattern, in particular having one central fastener opening; 
     FIG. 7D is a top planar view of a radially symmetric fastener pattern in a quincunx array; 
     FIG. 8 is a front elevation exploded view of an embodiment of a stone hammer having a wedge shaped faceplate on one side and a rectilinear block faceplate on the opposite side; 
     FIG. 9A is a top view of wedge shaped faceplate in accordance with an embodiment of the invention; 
     FIG. 9B is a front view of the wedge shaped faceplate; 
     FIG. 9C is a side elevation view of wedge shaped faceplate in accordance with an embodiment of the invention, showing fastener openings; 
     FIG. 9D is a bottom plan view of wedge shaped faceplate as in FIGS. 9A-9C; 
     FIG. 10A is a top view of a bushing tool faceplate, in accordance with an embodiment of the present invention; 
     FIG. 10B is a side view of a bushing tool faceplate having striking points on two sides, in accordance with the present invention; 
     FIG. 10C is a side view of another embodiment of a bushing tool faceplate having striking points on one side, in accordance with the present invention; 
     FIG. 11A is a top view of faceplate comprising a chisel point, in accordance with the present invention; and 
     FIG. 11B is a side view of the faceplate of FIG.  11 A. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 is a three-dimensional view of a stone hammer  100  having detachably affixed faceplates  12 , which can be oriented in certain different arrangements to present different edges for use in stone cutting. Stone hammer  100  comprises at least one faceplate  12  defining the edges, and a weight-bearing head  16  on which the faceplate is attached at a selected orientation. FIG. 2A is a front view of the stone hammer  100 , and FIG. 2B is an exploded front view of stone hammer  100  showing the faceplates  12  separated from the head  16 . The faceplates  12  are polygonal, for example rectilinear as shown. Each side of the polygon providing a distinct edge on each of two opposite sides of faceplate  12 . 
     Each faceplate  12  comprises a plurality of approximately right-angled striking edges  22  for trimming stone, masonry, and the like. Each faceplate  12  also comprises at least one opening  20  for attaching the faceplate  12  to the head  16 . In one embodiment of stone hammer  100 , head  16  defines an opening  18  for receiving a handle. 
     In use, a selected striking edge  22  of stone hammer  100  makes contact with a stone, or similar object, to be cut. Normally the user prefers a particular edge of the hammer  100 , for example depending on whether the person is left handed or right handed, or for a particular habitual operation such as striking with an outer edge or a side edge. As any such selected striking edge  22  becomes worn, another striking edge  22  might be selected by reorienting the tool. However instead or in addition to the possibility of reorienting the tool, according to an inventive aspect, the faceplate  12  can be detached, re-oriented and re-attached with a fresher edge in the corresponding position. As described herein in detail, a striking edge may be selected by reversing a faceplate  12  or by rotating a faceplate  12 , by replacing a faceplate  12  with a new faceplate, and by reorienting the whole tool manually for striking with a different edge of the stone hammer  100 , or by any combination thereof. 
     FIG. 3 is a front view of stone hammer  100 , showing faceplates  12  separated from head  16 , and showing by broken lines the openings  20  and recessed portions  34  that are spaced inwardly from the surface. In one embodiment of the stone hammer  100 , faceplates  12  are attachable to head  16  by bolts  24 . In this embodiment, bolts  24  are threaded, and are positioned within openings  20  and threaded into threaded recessed portions  34 . Each opening  20  comprises opposing countersunk or counterbored portions  30  and  32  that serve to protect the heads of bolts  24  by placing them below flush with the surface of the hammer  100 . 
     A counterbore as shown is provided on both ends of each fastener hole, to facilitate reversal of the faceplate  12 . As shown in FIG. 3, a countersunk portion  32  is positioned adjacent head  16 , and accordingly countersunk portion  30  is positioned opposite head  16 . 
     Each faceplate  12  is symmetric, at least about a plane parallel to the mating surface of faceplate  12  and head  16 , to permit reversing. That is, each rectilinear faceplate  12  in the embodiment shown is individually reversible, and upon being reversed, countersunk portion  30  adjacent head  16  exchanges positions with countersunk portion  32  opposite head  16 . The fastener holes still align with the threaded holes in the tool head. As also discussed, the fastener holes also can be equiangularly distributed such that the faceplates  12  can be rotated as opposed to reversed, to a position at which the holes again align. In either case, a result is to bring a fresh striking edge  22  into a given edge position. 
     Rotating a faceplate moves the worn edge to a different position but it remains on the exposed side of the faceplate  12 . Reversing a faceplate  12  provides a new set of striking edges  22  for selection, four being available in the square or rectangular shape shown. To reverse a faceplate  12 , faceplate  12  is detached from head  16 , the orientation of faceplate  12  is reversed (e.g, flipped over), and faceplate  12  is attached to head  16 . Detachment and attachment may be accomplished by simply unthreading and threading bolts  24 , respectively, out of and into threaded portions  34  through opening  20 . Thus a user (e.g., a stone cutter) of the stone hammer  100 , may select another striking edge  22  by individually reversing a faceplate  12 . 
     In the preferred configuration shown, a different striking edge  22  is also selectable for a given position on the tool by rotating the faceplate  12 . FIGS. 4A,  4 B, and  4 C are top, front, and bottom views, respectively of an exemplary rectilinear faceplate  12 . As shown in FIGS. 4A,  4 B, and  4 C, rectilinear faceplate  12  comprises four symmetrically positioned openings  20 . These symmetrically positioned openings  20  are positioned such that each faceplate  12  is symmetric and reversible about each of three orthogonal axes. 
     Accordingly, each faceplate  12  is rotateable in the directions shown by arrows  25 . Each faceplate  12  is individually rotatable in two directions as indicated by arrows  25 , in increments of 90 degrees. Each rectilinear faceplate  12  comprises four striking edges  22  on each of its two opposing sides. Thus, each faceplate  12  comprises eight striking edges. A stone hammer  100  comprising two faceplates  12 , has 16 selectable striking edges  22 . A striking edge  22  may be selected by any combination of reversing a faceplate  12 , rotating a faceplate  12 , and striking with an opposing side of the stone hammer  100 . Also, a striking edge  22  may be selected by replacing the entire faceplate  12 . This provides a number of ways to deploy a fresh striking edge  22 . As a striking edge  22  becomes worn, the user of the stone hammer  100  has the option of selecting another striking edge  22  as described above (reverse faceplate, rotate faceplate, strike with opposing end of hammer), or replacing a faceplate  12  with a another faceplate  12 . 
     A removed faceplate  12  may be discarded or sharpened for subsequent use. However, the structure of the faceplate is relatively uncomplicated, and it is possible to maintain a stock of faceplates much more easily than one can maintain a stock of complete hammers. 
     FIGS. 5A,  5 B, and  5 C are top, front, and bottom views, respectively of head  16  showing hidden views of recessed or counterbore portions  34  and opening  18 . Recessed portions  34  are positioned in head  16  to align with the openings  20  in faceplates  12 . Recessed portions  34  are positioned on opposite ends of head  16  as indicated by the top view (FIG. 5A) and bottom view (FIG. 5C) of head  16 . Thus, head  16  is adapted to receive faceplates  12  at opposing ends of head  16 . 
     The invention has the further advantage that the weight of head  16  can be selectable while using standard forms of faceplate  12 . That is, a user may select a head  16  having a desired weight. Weights may range, inclusively, from 3 pounds to 20 pounds (e.g., full size sledgehammer), for example. 
     A lateral opening  18  is located approximately in the center of head  16  to allow attachment of a handle. The handle can be attached in a conventional manner, such as by slitting the end of a wooden handle and driving a wedge into the slit from the opposite side (not shown). An axial fastener also is possible, or a threaded handle portion that receives a nut on the side opposite from the handle shaft. 
     Although opening  18  is shown as a means for receiving a handle, other means are appropriate. Such other means include a handle permanently attached to the head  16 , or a handle and head formed from a single structure (e.g., molded or cast). Head  16  may comprise various materials, such as metal, wood, plastic, fiberglass, ceramics, and combinations, thereof, for example. 
     Various handles are envisioned, such as the exemplary handles shown in FIGS. 6A,  6 B, and  6 C. According to a preferred aspect, however, the invention is apt for manual use as a hand tool. This is illustrated in the drawings with respect to handle configurations that are apt for manual gripping, for example, comprising a shaft  36 , a finger guard  38 , a contoured handle  39 , or any combination thereof. The contoured handle  39  may have a covering contoured to fit a hand, or the contours may be formed in the handle. 
     FIGS. 7A,  7 B,  7 C, and  7 D are top views of various embodiments of faceplate  12  having various positions of openings  20 . As shown in FIGS. 7A and 7B, openings  20  may be located at opposing corners of faceplate  12 . To accommodate the configurations shown in FIGS. 7A and 7B, head  16  may maintain the configuration of recessed portions  34  as previously described, or alternatively head  16  may have only two threaded portions  34  on each end of head  16 , aligned with the respective openings  20  as shown in FIGS. 7A and 7B. FIG. 7C shows a single opening  20  defined by faceplate  12 . Accordingly, to accommodate this configuration, head  16  has an corresponding recessed portion  34  aligned with the single opening as shown in FIG.  7 C. To accommodate the configuration shown in FIG. 7D, head  16  may comprise any of the previously described configurations of recessed portions  34 , or any combination thereof. 
     FIG. 8 is a front view of a stone hammer comprising a wedge shaped faceplate  40 . Wedge shaped faceplate  40  comprises a striking edge  42  that is central rather than at the lateral edge of the faceplate. The striking edge  42  of faceplate  40  is approximately perpendicular to the striking edge  22  of the more rectilinear faceplate  12 . A stone hammer in accordance with the present invention may comprise any combination of wedge shaped faceplates  40  and rectilinear faceplates  12 . In the exemplary embodiment shown, the stone hammer comprises one wedge shaped faceplate  40  and one rectilinear faceplate  12 . 
     Various types of faceplates are envisioned. FIGS. 9A,  9 B,  9 C, and  9 D are a top view, a front view, a side view, and a bottom view, respectively, of wedge shaped faceplate  40 . As shown in FIGS. 9A,  9 B,  9 C, and  9 D, wedge shaped faceplate  40  comprises openings  20  positioned similarly to the openings  20  as previously described herein with respect to rectilinear faceplate  12 . Accordingly, faceplates  40  and faceplates  12  are interchangeable. The openings  20  in wedge shaped faceplate  40  are countersunk in the top portion of each opening. Furthermore, wedge shaped faceplate  40  may comprises any of the configurations having two or four openings  20  as previously described herein with respect to faceplate  12 . Wedge shaped faceplate  40  is also rotateable in the directions indicated by arrow  25 . 
     Other types of faceplates are illustrated in FIGS. 10 and 11. FIGS. 10A,  10 B, and  10 C are a top view, a side view of one embodiment, and a side view of another embodiment, respectively, of a bushing tool faceplate, in accordance with the present invention. Bushing tools are known in the art and typically used to rough out, finish carve, and/or texture stone. As shown in FIGS. 10A,  10 B, and  10 C, the faceplate comprises a bushing surface having striking points  46  on one side (see FIG. 10B) or having two bushing surfaces each comprising striking points  46  (see FIG.  10 C). FIGS. 11A and 11B are a top view and a side view, respectively, of faceplate comprising a chisel point  48 , in accordance with the present invention. Thus, a stone hammer in accordance with the present invention may comprise faceplates having any of several types of surfaces know in the stone cutting and masonry art. 
     A stone hammer as described herein, provides selectable striking edges. The striking edges may be selected by rotating a faceplate, individually reversing a faceplate, striking with an opposing end of the hammer, replacing a faceplate, or any combination thereof. The need to send the hammer to be sharpened when a striking edge becomes dull is eliminated. A faceplate can be replaced relatively quickly and easily compared to the time and processing needed to refurbish the hammer as a whole. Furthermore, the need for a large inventory of stone hammers is also eliminated. 
     Although the stone hammer has been described in conjunction with one or more embodiments, it will be apparent to those skilled in the art that other alternatives, variations and modifications are apparent in light of the foregoing description as being within the spirit and scope of the invention. For example, the openings  20  in the faceplates need not be countersunk. Alternatively, various combinations of countersunk and non-countersunk openings are possible. In one such configuration, all the openings on one side of the faceplate are countersunk, and the opposing sides of the openings are not countersunk. The faceplates may comprise various types of material, such as metal, S7 tool steel, and other materials appropriate for the specific type of stone/material to be cut. In one exemplary embodiment, a stone hammer in accordance with the present invention comprises faceplates having S7 tool steel, hardened within a range, inclusively, between Rockwell 58 and Rockwell 60. It is not necessary for the head  16  to be hardened. Bolts  24  may comprise various types of heads, such as a slotted head, a Phillips head, an Allen head, a star shaped head, hex bolt head or combination thereof, for example. The faceplates may be attached to the head  16  of the stone hammer by means other than threaded bolts, such as clamping arrangements or the like (not shown). 
     In a polygonal arrangement, the faceplates are rotated by the angular increment of one or any integral number of edges. The four sided symmetrical arrangement shown is positionable at any selected 90-degree increment. It is possible to envision a similarly rectangular faceplate with two fastener holes such that the options are only two, at 180-degrees relative to one another. A polygon with a different number of sides is also possible, such as a hexagon shape with six angular increments at 60-degrees. Of course, a hexagon or the like also could be mounted so as to provide fewer mounting options than the number of faces, e.g. six or three or two, depending on the positioning of the fastener openings provided in the faceplates. The invention is intended to embrace all such alternatives, variations and modifications as may fall within the spirit and scope of the following claims.