Abstract:
A workbench is equipped with a clamping device that has a moveable element. A holding system has a top with a fibrous or pierceable material that is disposed upon the workbench near the clamping device. The system employs at least one block having a working face and a connecting face. The working face is adapted to oppose the moveable element. The block has on its connecting face at least one connector for securing the block in place on the top against clamping forces from the clamping device. The connector includes a first hub and a second hub, each having on one side thereof a plurality of spiral prongs. The spiral prongs on the first hub spiral in a direction opposite that of the spiral prongs on the second hub. The connector also has a manually operable link connected between the hubs for relatively rotating them in opposite directions in order to releasably connect to the fibrous or pierceable material of the top. A workpiece is placed between the block and the moveable element. The clamping device is operated to clamp the workpiece between the moveable element and the block.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. patent application Ser. No. 10/772,662, filed Feb. 5, 2004, the contents of which are hereby incorporated by reference herein. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to workpiece holding systems, and in particular, to systems cooperating with workbenches. 
     2. Description of Related Art 
     Workpieces are often held in a fixed position on a platform or workbench when being machined or milled. A workpiece may be held in a machinist&#39;s vise between two heavy steel jaws that can be brought together by a manually operable screw. 
     Woodworking vises may have a wooden block that is mounted on rails on the front or the end of a workbench. A hand operated screw can bring the block inward to clamp a workpiece to an edge of the workbench. In some cases the vise will have in addition a stationary block so that the moveable block can be driven toward the stationary block on the edge of a workbench. 
     Often a workpiece is larger than the maximum opening of a vise on a workbench. In that case the workbench can have a series of holes for holding one or more dogs, typically pegs that face the vise. 
     If the vise has a moveable jaw that rises above the topside of the workbench, this jaw can push a workpiece against the dog or dogs. In some cases the top of the moveable jaw is coplanar with the topside of the workbench in which case one or more dog-like fixtures can be attached to the top the moveable jaw. Accordingly, a workpiece can be clamped between these fixtures and dogs on the workbench by moving the moveable jaw inward toward the dogs on the workbench. 
     The bench dogs can be placed in only the limited number of holes formed in the workbench. In some cases the dog&#39;s position is inconvenient and the workpiece may be too long or short relative to the dog. In still other cases the edge of the workpiece facing the dogs may be irregular but the dogs would be unable to provide the finely adjusted backstop needed to firmly and securely engage the irregular workpiece. While shims or spacers can be used to accommodate the irregularities, these require careful machining and will lengthen the time needed to perform the simple task of clamping. 
     See also U.S. Patent Application Publication No. 2004/0069980 and the following U.S. Patents: D367,438; D374,609; 226,453; U.S. Pat. Nos. 2,033,039; 2,205,550; 2,354,810; 2,407,879; 2,668,304; 2,809,067; 3,176,979; 3,222,744; 3,386,763; 3,634,178; 3,813,094; 3,849,839; 3,964,364; 4,003,549; 4,009,786 4,007,516; 4,165,811; 4,308,646; 4,338,836; 4,498,827; 4,505,468; 4,518,277; 4,526,363; 4,605,216; 4,641,826; 4,645,193; 4,705,442; 4,761,027; 5,007,616; 5,496,021; 5,624,110; 5,624,167; 5,728,116; 6,296,656; 6,468,309; 6,494,657; 6,520,464; 4,474,489; 4,532,622; 4,711,596; 5,133,617; 5,651,570; 5,873,379; 5,899,621; 6,123,035; 6,336,766; 6,616,369; 6,726,421; 6,726,422; and 7,100,854. 
     SUMMARY OF THE INVENTION 
     In accordance with the illustrative embodiments demonstrating features and advantages of the present invention, there is provided a holding system for a workbench equipped with a clamping device having a moveable element. The holding system includes a top adapted to be disposed upon the workbench proximate the clamping device. The top has a fibrous or pierceable material. The holding system also includes at least one block having a working face and a connecting face. The working face is adapted to oppose the moveable element. The block has on its connecting face at least one connector for securing the block in place on the top against clamping forces from the clamping device. The connector includes a first hub and a second hub. Each of the hubs has on one side thereof a plurality of spiral prongs. The spiral prongs on the first hub spiral in a direction opposite that of the spiral prongs on the second hub. The connector also has a manually operable link connected between the first and the second hub for relatively rotating them in opposite directions in order to releasably connect to the fibrous or pierceable material of the top. 
     In accordance with another aspect of the invention a clamping method is provided applying one or more blocks having an underlying connector to a workbench equipped with a fibrous or pierceable material on top as well as being equipped with a clamping device having a moveable element. This connector includes concentrically nested hubs with oppositely spiraling prongs. The method includes the step of adjoining the connector of the block to the fibrous or pierceable material. Another step is counter-rotating the hubs in the connector to embed their spiral prongs in the fibrous or pierceable material atop the workbench. The method also includes the step of placing a workpiece between the block and the moveable element. Also included is the step of operating the clamping device to clamp the workpiece between the moveable element and the block. 
     In accordance with yet another aspect of the invention there is provided a workbench including a frame with a platform. Also included is a clamping device mounted to the frame and having a moveable element. The workbench includes a top mounted on the platform proximate the clamping device. The top includes a fibrous or pierceable material at least partially covering the platform. The workbench has a plurality of blocks each having a working face and a connecting face. This working face is adapted to oppose the moveable element. The blocks each have on its connecting face at least one connector for concurrently securing the plurality of blocks in place on the top against clamping forces from the clamping device. For at least one of the blocks, the at least one connector is two in number with one being mounted on the connecting face and the other being mounted elsewhere. The connector includes a first hub and a second hub. The first hub is rotatably mounted to the connecting face of the corresponding one of the blocks. The second hub is annular. The first hub has a circular outline and is concentrically and rotatably mounted in the second hub. Each of the hubs has on one side thereof a plurality of spiral prongs arranged in at least one circular row. The spiral prongs on the first hub spiral in a direction opposite that of the spiral prongs on the second hub to provide a right and a left hand thread. Each of the spiral prongs rise less than its overall exposed length. The connector also has a manually operable lever connected between the first and the second hub and extending outside them for relatively rotating them in opposite directions, at most 1/16 of a turn in order to releasably connect to the fibrous or pierceable material of the top. 
     By employing apparatus and methods of the foregoing type, an improved holding or clamping technique is achieved. In one embodiment a top with a fibrous material or other penetrable material is secured upon a workbench. 
     The blocks disclosed herein have some of their faces fitted with connectors designed to attached to the top. Each of these connectors has a central hub concentrically and rotatably mounted inside an annular hub. Both hubs can rotate relative to each other and to the block. Both hubs support outwardly projecting spiral prongs. The prongs on one hub spiral in the opposite direction of the prongs on the other hub. 
     The spiral prongs on the hubs may be considered helical, with one set presenting a right handed thread and the other a left handed thread. These prongs may be relatively short and in many embodiments will be less than 1/16 of a turn, although the turning angle will vary with the size of the hub holding the prong. 
     Because of their relative shortness, the manufacturing of the prongs can be simplified. Specifically, the prongs may be made to follow the arc of a circle, that is, each prong may lie along a plane and need not follow the three dimensional path of a true helix. In a disclosed embodiment, each prong lies in a relatively shallow plane, for example, a plane with an angle of elevation of about 30°. 
     The two hubs are rotated relative to each other in the disclosed embodiment by manually operating a link. The link may be a lever that is pivotally connected to both hubs. The lever extends outwardly beyond the annular hub to allow a user to swing the lever. 
     A connector designed in this manner can be very easily operated. A user need only place a block&#39;s connector on the top that is disposed upon the workbench. Then the user will operate the link lever to relatively rotate the two hubs and their prongs. The two sets of prongs spiral in opposite directions into the penetrable material of the top. 
     These blocks can be arranged strategically on the workbench&#39;s penetrable top at positions facing the movable element of a vise or other clamping device. A disclosed vise has a movable jaw whose top is coplanar with the upper surface of the workbench. The top of this movable jaw is fitted with one or more fixtures and one edge of a workpiece is placed against these fixtures. The opposite edge of the workpiece lies on the penetrable top that is disposed upon the workbench. Along this opposite edge one or more blocks are placed with their connectors adjoining the penetrable top. The position of the blocks can be finely adjusted since their positioning does not rely on the existence of a dog hole. Moreover, the blocks can be adjusted to accommodate irregularities in the workpiece. 
     After the connectors are secured to the penetrable top as described above, the movable jaw can be moved inwardly to press the workpiece against the blocks. Thereafter, the workpiece will remain in place as it is drilled, planed, abraded, or otherwise machined or finished. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above brief description as well as other objects, features and advantages of the present invention will be more fully appreciated by reference to the following detailed description of illustrative embodiments in accordance with the present invention when taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a perspective view of a holding system for a workbench in accordance with principles of the present invention; 
         FIG. 2  is a perspective view of one of the blocks of  FIG. 1 ; 
         FIG. 3  is a perspective view of the connector on the block of  FIG. 2 ; 
         FIG. 4  is a plan view of the outside of the connector of  FIG. 3 ; 
         FIG. 5  is a fragmentary, bottom view of one of the hubs and prongs of  FIG. 3 ; 
         FIG. 6  is a fragmentary side view of the hub and prongs of  FIG. 5 ; 
         FIG. 7  is a fragmentary side view of a hub and prongs that is an alternate to that of  FIG. 6 ; 
         FIG. 8  is a perspective view of a block that is an alternate to that shown in  FIG. 2 ; and 
         FIG. 9  is an perspective view of a block that is an alternate to that shown in  FIGS. 2 and 8 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIG. 1 , workbench B may have a platform P made of wood, metal, composites, laminated panels, etc. Platform P may be supported on a conventional frame L comprising legs, braces, spanners, and the like. The area on the topside of the platform P may be designed in accordance with the anticipated size of workpieces, the space available, etc. 
     Workbench B has a clamping device in the form of an end vise with stationary jaw element V 1  and moveable jaw element V 2  interconnected by slider rails (not shown). Jaw V 2  may be moved toward (or away from) jaw V 1  by rotating screw J with handle H. The tops of jaws V 1  and V 2  are coplanar with the topside of platform P. In some cases a similar vise may be installed along the front edge of bench B. 
     A series of dog holes D are shown in workbench B. Three are visible and in most embodiments additional holes will be placed in a variety of positions. Holes D are designed to hold dogs (not shown), namely, square pegs that leave exposed an upper stub with a flat facing the vise V 1 /V 2 . An inside end of a workpiece may be placed against such a dog or dogs, while the outside end of the workpiece can be placed against fixtures F that are removably mounted on the top of movable jaw V 2 . By rotating screw J with handle H, fixtures F on movable jaw V 2  can press a workpiece against the dogs. 
     In this embodiment the topside of platform P is fitted with a top  24  that includes a fibrous or penetrable material. In some embodiments material  24  will be a section of loop pile carpeting installed near the vise V 1 /V 2 . The material of top  24  may be held in place by cement, tacks, staples, or other fastening means. In this embodiment, material  24  is folded over the edge of platform P and stationary jaw V 1  will be attached over this fold to hold material  24  in place. In some cases material  24  may be secured atop a panel that has subjacent pegs that fit into corresponding dog holes D. 
     Instead of loop pile carpeting, the penetrable or fibrous material  24  can be made with a fibrous sheet such as felt (about 6 mm thick, for example) or with a relatively thick fabric such as burlap. Alternatively, material  24  can be one or two layers of a relatively thin fabric such as linen. In some embodiments the penetrable material may be the loop fabric used in conventional hook and loop fasteners. In other cases the material  24  itself may be made of a penetrable material such as a sponge-like substance, clay, polystyrene foam, a soft plastic, an elastomer, etc. In still other embodiments the material  24  may have an external mesh or grid with sufficient underlying clearance to accept prongs, which prongs will be described presently. For example, the material  24  can be an open frame covered with metal screening much like the screening used in windows and doors. 
     While material  24  is shown covering only a portion of the topside of platform P, in some embodiments the material will cover all or substantially all of platform P. In other cases material  24  may be a fibrous panel (e.g., a plastic board covered with felt) placed in a recess such as recess R. In such a case the top of the material  24  will be approximately flush with the rest of the topside of platform P. 
     A workpiece W is shown in phantom lying on penetrable material  24  with its outer edge against one of the fixtures F. In this case the inside edge W 1  of workpiece W is undulating, almost S-shaped. A pair of rectangular blocks  10  are positioned against the undulating edge W 1  of workpiece W. Blocks  10  and top  24  are considered part of a holding system. 
     It will be appreciated that depending upon the size and shape of the workpiece W a different number of blocks  10  may be employed. As described further hereinafter, blocks  10  can be finely positioned along penetrable material  24 . Accordingly, the blocks will each have one of its faces positioned tangentially at two spaced positions along edge W 1 . Thus, these working faces of blocks  10  engaging workpiece W need not be parallel to the opposing faces of fixtures F. 
     While illustrated herein with a cubic shape, block  10  can have another multi-faceted parallelepiped or polyhedral shape, arranged to have maximum symmetry, little symmetry or no symmetry. In other embodiments the block may have curved faces, e.g., a cylinder, a sphere, an ovoid, a paraboloid, a cone, a surface of revolution, a section of one of the foregoing, or some other arbitrary shape. 
     Blocks  10  have on their underside (connecting face) a connector. Tab  20 A of such a connector is visible in this view. As will be explained presently, these connectors can be used to releasably attach blocks  10  to material  24 . 
     Referring to  FIGS. 2-4 , connector  12  is the previously mentioned connector on block  10 . Connector  12  has a central first hub  16  encircled by an annular, second hub  14 . Annular hub  14  may have essentially cylindrical inside and outside circumferences, while hub  16  may be essentially a cylinder with a circular outline. Alternatively, the interfacing surfaces of hubs  14  and  16  may be joined by an annular bead that snaps into an annular groove. Hubs  14  and  16  may be made from plastic, metal, ceramic, wood, or other materials. 
     Hub  14  has a pair of radially aligned steps that descend onto opposite ends of recess  14 A. Hub  16  has a wedge-shaped recess  16 A having approximately the same angular compass as recess  14 A. Recesses  14 A and  16 A provide clearance for manually operable link  20 , shown as a flat blade with straight edges, a rounded proximal end, and a distal end with transverse tab  20 A. 
     Link  20  is pivotally connected at its proximal end to hub  16  near the inside corner of recess  16 A. Link  20  is also pivotally connected to hub  14  at the center of recess  14 A. Link  20  extends to the outside of hub  14  and by manipulating its distal tab  20 A can act as a manually operable lever. Using hub  16  as a frame of reference, if link  20  is rotated clockwise (counterclockwise) hub  14  will rotate clockwise (counterclockwise). 
     In most embodiments hubs  14  and  16  will both counter-rotate concentrically and relative to object  10 . Accordingly, threaded axle  22  extends along the axis of hub  16  and may be threaded into a bearing (not shown) in the connecting face of block  10 . Alternatively, axle  22  may be threaded into block  10  to an adjustable depth to adjust the height of block  10  from the platform (platform P of  FIG. 1 ). In any event, hub  16  will still be able to rotate relative to block  10 . 
     Referring to  FIG. 4 , hubs  14  and  16  have a plurality of spiral prongs N and N′, respectively. Prongs N are arranged in two circular concentric rows of twenty prongs each, that is, forty altogether on hub  14 . Prongs N′ are arranged in two circular concentric rows of twelve prongs each, that is, twenty-four altogether on hub  16 . Prongs N′ are shaped and distributed in the same way, except for being a mirror image of the arrangement of prongs N. Thus prongs N spiral in the opposite direction of prongs N′, thereby providing left and right hand threads. 
     Referring to  FIGS. 5 and 6 , prongs N are shown arranged into concentric circular rows identified as an outside row R 1  and an inside row R 2 . A portion of the outside row is illustrated by itself in  FIG. 6 . Each prong N has a portion Na embedded in hub  14  to support an exposed portion Nb having an overall exposed length s 1 . Portion Na may be embedded by being molded in place. While distinct embedded prongs are illustrated, in some embodiments the prong will be a feature molded upon the face of the hub. 
     In this embodiment prongs N have a circular cross-section and their distal tips may be sharpened by being ground at an angle to produce an elliptical feature Nc. However, different cross-sections are contemplated and sharpening is optional. 
     Embedded prong portion Na is straight and lies in an upright reference plane that is parallel to the axis of hub  14  and tangent to the circle defining the prong row (in  FIG. 6  row R 1 ). This point of tangency is defined at the transition between portion Na and portion Nb. Both portions Na and Nb lie in a canted plane C that is perpendicular to the reference plane. This canted plane C intersects the axis and the surface of hub  14  at angle v, which defines the angle of elevation of prong N. 
     The exposed portion Nb of prong N is shown curved in  FIG. 5 , which is a plan view and therefore essentially a projection of prongs N onto the surface of hub  14 . Prongs N are shown there following circular paths associated with their respective rows R 1  and R 2 ; although strictly speaking, to project onto a circle, prong portion Nb would follow an elliptical path in canted plane C. While exposed portion Nb can follow such an elliptical path to project the ideal circular path, as a practical matter there is almost no significant difference between bending the portion Nb into this elliptical path or approximating the elliptical path with a circular bend. This follows from the fact that prong portion Nb follows a relatively small turning arc u of about 15°. In particular, since there are twenty prongs N per row, the prong to prong spacing is 18°. 
     Ideally, the exposed portions of the prongs will follow a helical path and therefore will not lie on a plane.  FIG. 7  shows a prong N 1  whose exposed portion follows such a helical path. A line tangent to such a path can be set to have the same angle of elevation v as before, but, being helical, the path will rise faster and reach a greater height s 3  for the same turning arc. 
     Referring again to  FIG. 6 , prongs N should be thin enough and long enough to pierce and efficiently anchor to the target material. If the prongs are too thin they will tend to bend or break and will not effectively penetrate the target material and stay anchored thereto. Also, if the prongs are too long, they may require rotation through a greater angle, which will tend to slow the speed of penetration and increase the torque needed to penetrate. In addition, the angle of elevation v of prongs N should be steep enough to ensure that the prongs penetrate to a sufficient depth without skimming over the surface of the target material. On the other hand, an excessively steep angle of penetration will provide insufficient anchoring strength and the prongs will tend to slip out of the target material. 
     For prongs intended to anchor onto loop pile carpeting (e.g., carpet pile 3 mm deep with 4 mm loop circumference) an exposed prong length s 1  of 0.25 to 0.35 inch (6.4 to 8.9 mm) at an angle of elevation of 30°±10° works satisfactorily. For the embodiment of  FIG. 6  prong N will have a nominal rise s 2  of 0.15 inch (3.8 mm). For the embodiment of  FIG. 7  rise s 3  will be nominally 0.19 inch (4.8 mm). For effective anchoring, the exposed length s 1  will exceed the rise (rise s 2  in  FIG. 6  and rise s 3  in  FIG. 7 ). In one embodiment prongs N were made of steel piano wire, 0.033 inch (0.84 mm) in diameter. 
     It will be understood that the foregoing dimensions and materials can be varied depending upon the target material, desired anchoring strength, desired angle of rotation, strength of the prongs, etc. For penetrable material thinner than ordinary loop pile carpeting, prongs N and N′ will typically be scaled down in proportion to the reduced thickness of the penetrable material. In general, the length, number, spacing, angle of elevation and other characteristics of prongs N and N′ may be altered to accommodate different penetrable materials. 
     Also, if the prong-bearing hub will have a greater diameter, the number of prongs per row can be scaled up appropriately while keeping approximately the same prong length. So if, for example, the hub diameter is doubled in comparison to the foregoing embodiment, the number of prongs will be doubled as well for the same prong length. 
     In any event, by rotating lever  20  counterclockwise ( FIG. 3 ), prongs N and N′ ( FIG. 3 ) counter-rotate with hubs  14  and  16 , respectively. Being helical, or approximately helical, prongs N and N′ screw and anchor into the penetrable material  24  of  FIG. 1 . 
     In this embodiment hubs  14  and  16  rotate 15° or less, i.e. no more than the angle u of  FIG. 5 . Here the angle of rotation is no more than one-twenty fourth of a turn. To make an anchor quick-acting it is advantageous to have the angle of rotation at most one-sixteenth of a turn. It will be appreciated that the relative rotation between hubs  14  and  16  will be additive, that is, 30° or less. However as a practical matter, the relative rotation need not reach its full potential angular displacement to achieve satisfactory anchoring. In any event, prongs N and N′ of the two hubs spiral into substrate  24  of  FIG. 4  and lock in place. 
     With blocks  10  now locked into position as shown in  FIG. 1 , a user may now turn handle H to drive movable jaw element V 2  inwardly. Consequently, fixture F will drive the workpiece W against the two blocks  10 . Because blocks  10  are positioned to accurately mate with curved edge W 1  of workpiece W, the workpiece is securely held in position. Thereafter, workpiece W may be drilled, abraded, planed, or otherwise machined or finished. 
     To release workpiece W handle H is used to turn screw J in a direction to move jaw V 2  outwardly. Next, connectors  12  may be released by pushing lever  20  in the reverse direction (clockwise in  FIG. 3 ) to rotate hub  14  clockwise relative to hub  16 . Consequently, prongs N and N′ will unscrew. Blocks  10  can then be released for storage or for repositioning. 
     Referring to  FIG. 8 , alternative block  110  is a rectangular parallelepiped having a V-shaped notch  110 A, which may be used to engage a rounded feature of a workpiece. Also, since its faces are perpendicular, notch  110 A may receive the square corner of a workpiece. While the face of block  110  having notch  110 A may be used as a working face, in some cases one of the smaller, adjacent, upright faces of block  110  may be used as a working face instead. 
     In this embodiment, the underlying connecting face of block  110  has a pair of connectors, only their operating levers  120  being visible in this view. These connectors are identical to connector  12  of  FIG. 3 . Having double connectors, block  110  is able to provide twice as much clamping force as the block of  FIG. 2 . Block  110  may be used in a manner similar to that previously described for block  10  of  FIG. 1 . 
     Referring to  FIG. 9 , alternative block  210  is a rectangular parallelepiped except for a cylindrically curved working face  210 B. From the perspective of  FIG. 9  the two faces adjacent to the lower edge and right edge of working face  210 B have a connector (only their operating levers  220  being visible in this view). These two connectors are identical to connector  12  of  FIG. 3 . Either one of these two connector-bearing faces may be referred to as a connecting face, in which case the other one will be referred to as an auxiliary face. 
     Either of the connectors of block  210  may be used to attach the block to material  24  of  FIG. 1 . Because either of the connectors may be employed, the axis of curvature of face  210 B may be either horizontal or vertical depending upon the choice of connector. Again, block  210  may be used in a manner similar to that previously described for block  10  of  FIG. 1 . 
     Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.