Patent Publication Number: US-6659440-B2

Title: Portable support assembly for a workpiece

Description:
The present application claims priority to U.S. Provisional Application of Levy, Ser. No. 60/255,881, filed Dec. 18, 2000 the entirety of which is hereby incorporated into the present application by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention is generally related to portable workpiece support assemblies. 
     BACKGROUND 
     Many construction projects require two types of workpiece supports: sawhorses and workbenches. Typically, a sawhorse provides an elongated, relatively narrow support surface that is used to support a portion of a workpiece. For example, sawhorses are frequently used in pairs to support a relatively large workpiece such as a board or a panel of sheet rack or plywood. The sawhorses are usually spaced apart from one another in use supporting a workpiece and each sawhorse supports an end portion of the workpiece. The workpiece support surface of a sawhorse is of relatively little use when used by itself because it is so narrow. Workbenches, on the other hand, provide relatively wide, table-like support surfaces that can be used, for example, to support relatively smaller workpieces in their entirety. 
     It is inconvenient for workers to carry both a pair of sawhorses and workbench to a work site. These items also require significant storage space when not in use. Workspace is often at a premium at a work site because of the size and number of tools required and because of the size and quantity of building materials. It is therefore desirable that the amount of space required for a sawhorse and a portable workbench be kept to a minimum. 
     A need exists for a foldable, portable workpiece support assembly that is readily convertible between 1) a sawhorse configuration and 2) a workbench configuration which provides a tabletop having a tabletop surface constructed and arranged to support an entire workpiece in a self-sustaining manner. 
     SUMMARY OF THE INVENTION 
     The above identified need can be met by providing a workpiece support assembly that includes an elongated workpiece support structure and a pair of support members. The support members are pivotally connected to one another towards upper ends thereof and are pivotally movable between a) an open operative position and b) a folded position. The pair of support members are constructed and arranged when in their open operative position to support the workpiece support structure horizontally, in spaced relation above a ground surface. The workpiece support structure has an elongated, workpiece support surface constructed and arranged to support a portion of a workpiece. The workpiece support assembly also includes a tabletop assembly. The tabletop assembly includes a tabletop and a tabletop support structure. The tabletop assembly is movable into a deployed position in which the tabletop is disposed substantially horizontally in overlying relation to the workpiece support structure, with the pair of support members in their open operative position. The deployed tabletop presents an upper tabletop surface to support a workpiece. The upper tabletop surface is larger than the elongated, workpiece support surface. The tabletop assembly is movable, with the pair of support members in their open operative position, into a storage position which exposes the elongated workpiece support surface. 
     The workpiece support assembly can advantageously be used with a vise assembly that includes a housing structure, a movable member movably mounted for movement with respect to the housing structure, and a fixed member. A threaded member is rotatably mounted in the housing structure and is threadedly engaged with the movable member such that rotation of the threaded member moves the movable member with respect to the housing structure. The housing structure and the fixed member are releasably lockable with respect to the tabletop surface when the tabletop assembly is deployed so that a workpiece placed between the movable member and the fixed member can be held in a fixed position with respect to the tabletop surface by moving the movable member against the workpiece by rotating the threaded member so that the workpiece is gripped between the movable member and the fixed member. 
     Other aspects, features, and advantages of the present invention will become apparent from the following detailed description, the accompanying drawings, and the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a workpiece support assembly constructed according to the principles of the present invention and showing a pair of vise assemblies mounted thereon; 
     FIG. 2 is a perspective view of the workpiece support assembly showing the assembly in its sawhorse configuration; 
     FIG. 3 is a perspective view of the workpiece support assembly in its closed folded configuration; 
     FIG. 4 is a side elevational view of the workpiece support assembly in its closed folded configuration; 
     FIG. 5 is a side elevational view of the workpiece support assembly in its sawhorse configuration; 
     FIG. 6 is a side elevational view of the workpiece support assembly showing a tabletop assembly thereof in a position between its closed folded position and its deployed position; 
     FIG. 7 is a side elevational view of the workpiece support assembly in its workbench configuration; 
     FIG. 8 is an isolated perspective view of a tabletop of the tabletop assembly showing and showing the pair of vise assemblies mounted thereon; 
     FIG. 9 is a perspective view of a first portion of the vise assembly showing a movable member in its extended position relative to a housing structure; 
     FIG. 10 is a perspective view of a second portion of the vise assembly; 
     FIG. 11 is a partially exploded front view of the first portion of the vise assembly; 
     FIG. 12 is a view similar to FIG. 11 except showing a rear view of the vise assembly; 
     FIG. 13 is a cross-sectional view taken generally through the line  13 — 13  as shown in FIG. 9 except showing the movable member in its extended position; 
     FIG. 14 is a cross-sectional view similar to FIG. 13 except showing the movable member in its retracted position; 
     FIG. 15 is a partial perspective view of a tabletop according to another embodiment of the present invention; 
     FIG. 16 is an isolated perspective view of the tabletop shown in FIG. 15; 
     FIG. 17 is a perspective view of the tabletop shown in FIG. 15 shown with a reinforcing element in exploded relation therewith; 
     FIG. 18 is a partial perspective view of a workpiece support assembly constructed according to the principles of the present invention shown in use with the tabletop shown in FIG. 15; and 
     FIG. 19 is a detailed perspective view of a locking assembly. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 is a perspective view of a workpiece support assembly  10  constructed according to the principles of the present invention. The workpiece support assembly  10  is convertible between a) a sawhorse configuration (see FIG. 2, for example) which provides an elongated workpiece support surface  12  constructed and arranged to support a portion of a workpiece (not shown), particularly in cooperation with another assembly  10  and b) a workbench configuration (see FIG. 1, for example) which provides a tabletop surface  14  constructed and arranged to support an entire workpiece (not shown) in a self-sustaining manner. The support assembly  10  is foldable into a relatively flat configuration (see FIGS. 3 and 4, for example) to facilitate transport and storage. The flat configuration allows, for example, several support assemblies  10  to be stacked in a pile for storage. 
     The structure of the workpiece support assembly  10  can best be understood from FIGS. 1-3 and  6 . The support assembly  10  includes an elongated support structure  16  and a pair of support members  18 ,  20 . The pair of support members  18 ,  20  are pivotally connected to one another towards upper ends thereof (in a manner described below). The support members  18 ,  20  are pivotally movable between a) an open operative position (see FIGS. 1 and 2, for example) and b) a folded position (see FIGS. 3 and 4, for example). The pair of support members  18 ,  20  support the workpiece support structure  16 . Specifically, the pair of support members  18 ,  20  are constructed and arranged when in their open operative position to support the workpiece support structure  16  horizontally, in spaced relation above a ground surface. 
     The support assembly  10  further includes a tabletop assembly  22 , which provides the tabletop surface  14  when the support assembly  10  is in its workbench configuration. The tabletop assembly  22  includes a tabletop  24  and tabletop support structure  26 . The tabletop assembly  22  is movable when the support members  18 ,  20  are in their open operative position into a deployed position (see FIG. 1, for example) in which the tabletop  24  is disposed substantially horizontally in overlying relation to the workpiece support structure  16  and presents the upper tabletop surface  14  to support a workpiece. The upper tabletop surface is larger than the elongated, workpiece support surface. The tabletop support structure  26  is connected to the tabletop  24  in the workbench configuration (shown in FIG. 1, for example) and cooperates with the workpiece support structure  16  to support the tabletop surface  14  in a level position (relative to a level ground surface). The tabletop assembly  22  is movable into a folded closed or storage position (see FIG. 2, for example) in which the tabletop  24  and the tabletop support structure  26  are adjacent to one of the support members  18 . When the tabletop assembly is moved into its storage position, the elongated workpiece support surface of the workpiece support structure is exposed. Thus, the sawhorse configuration of the workpiece support assembly  10  is realized when the tabletop assembly  22  is in its storage position and the support members  18 ,  20  are in their open operative position (see FIG. 2, for example). 
     Preferably the workpiece support structure  16 , the support members  18 ,  20 , the tabletop  24  and the tabletop support structure  26  are constructed of a high strength, lightweight molded plastic material, although any material of suitable strength, including any appropriate metal, wood, or polymeric material, for example, can be used in all or a portion of their construction. 
     The mounting of the support members  18 ,  20  to each other and the mounting of the workpiece support structure  16  on the members  18 ,  20  is best appreciated from FIGS. 2-3. Preferably the members  18 ,  20  are pivotally mounted to each other at respective upper ends thereof by an elongated metallic rod  30 . The rod  30  is also engaged with structure (not visible in the figures) integrally molded on the under side of the workpiece support structure  16  to mount the workpiece support structure  16  on the pair of support members  18 ,  20 . 
     Each support member  18 ,  20  includes a pair of molded plastic legs  32 ,  34 , respectively. The leg comprising each pair of legs are held in spaced relation by integrally molded upper and lower cross support structures  36 ,  38  and  40 ,  42 , respectively. A folding shelf assembly  44  is mounted between perspective upper cross support structures  38 ,  42  of the support members  18 ,  20 . 
     The details of the pivotal mounting of the support members  18 ,  20  to one another and to the workpiece support structure  16  and the details of the construction of the folding shelf assembly  44  are not discussed in detail in the present application but can be understood from examining commonly assigned U.S. patent application Ser. No. 09/372,669 now U.S. Pat. No. 6,298,946 which application is hereby incorporated by reference in its entirety into the present application for all material disclose therein. 
     The folding shelf assembly  44  limits of the movement of the support members  18 ,  20  in their opening direction and holds the members  18 ,  20  in their open operative position. A digit receiving opening  46  is formed in each side of the shelf assembly  44 . Each opening  46  is constructed and arranged to receive, for example, a finger or thumb of a worker using the assembly  10  to begin upward folding movement of the shelf assembly  44  and thereby begin the movement of the support members  18 ,  20  toward one another into their folded position. 
     Outwardly facing surfaces of the workpiece support structure  16  are provided with a series of labeled (i.e., labeled with numbers and measurement units, for example) lines or line-forming structures  48  that comprise a ruler for taking linear measurements of a workpiece. The labels and the line-forming structures  48  can be, for example, integrally molded, raised surfaces, a layer of ink or other type of pigmented material, a plastic of a different color from the surrounding material, and so on. 
     Preferably, the tabletop support structure  26  is provided by a pair of elongated support arms  50 . The tabletop assembly  22  is mounted to one of the support members such as support member  18 . It can be appreciated that the support members  18 ,  20  are of essentially identical construction so that workpiece support assembly  10  can be constructed by mounting the tabletop assembly  22  to either of the support members  18 ,  20 . Because the support members  18 ,  20  are essentially identical, only support member  18  will be discussed in detail, but the discussion applies equally to support member  20 . It can be appreciated that the support members  18 ,  20  abut one another when in their folded position. It is contemplated, however, to provide an embodiment of the workpiece support assembly in which one support member is received (wholly or partially) within an appropriately shaped recess or opening in the other support member for compact storage when the workpiece support assembly is in its closed folded position. An example of this construction is shown in the above-incorporated application Ser. No. 09/372,669 now U.S. Pat. No. 6,298,946. It can be understood that the tabletop assembly  22  can be constructed to be mountable to either support member  18 ,  20 . 
     A pair of connecting members  52  are each secured to the free end portion of a respective leg  32  of the support member  18  (each of the legs of the support member  18  being designated by the same reference numeral  32 ). Preferably each connecting member  52  is of molded plastic construction. Preferably, each connecting member  52  is mounted to the associated leg  32  using a snap-fit construction and a plurality of fasteners such as screws. The construction allows, for example, the tabletop assembly  22  to be removed from the sawhorse portion of the workpiece support assembly  10  if the user so desires. Each connecting member  52  can be removably mounted to the associated leg  32  in a wide range of ways, however, including, for example, by using any appropriate fasteners, by a snap-fit type of construction, with an adhesive or with any combination of these methods. It is also contemplated that each connecting member  52  be integrally formed (of a molded plastic, for instance) with the associated leg  32 . 
     Preferably the arms  50  are pivotally connected between the associated connecting member  52  and arm-receiving structure  54  formed on the tabletop  24  in a position adjacent an edge portion of and on the underside of the tabletop  24 . In the exemplary embodiment of the work support assembly  10 , the pivotal mounting of the arms is accomplished by rivets  56  secured within aligned openings (not shown) in, respectively, the connecting members  52 , the arms  50 , and the arm-receiving structure  54 . As best seen in FIG. 2, the underside of the tabletop  24  has integral grooves or recesses  58  of appropriate size and shape to receive the arms  50  for compact storage when the tabletop assembly  22  is in its closed, folded position adjacent the support member  18 . Because the connecting members  52  are preferably removably mounted to the support member  18 , the tabletop assembly  22  can, as mentioned, optionally be removed from the assembly  10 . It is also contemplated to construct a tabletop assembly for mounting to a sawhorse as an after market-type product. 
     The details of the construction of the tabletop  24  can be best understood from FIGS. 2 and 3 (which show the underside of the tabletop) and from FIG. 8 (which shows the tabletop  24  in isolation). The tabletop  24  includes an integrally molded carrying handle  60  for carrying the work support assembly  10  in its folded position (FIG. 3, for example). It can be appreciated from FIG. 3 that the folded position of the workpiece support assembly  10  is realized when the tabletop assembly  22  is in its storage position and the support members  18 ,  20  are in their folded position. The tabletop  24  further includes a plurality of integrally molded open storage compartments  62 ,  64  and a closeable central storage compartment (not visible) having a lid  66 . 
     The lid  66  is preferably of molded plastic construction and is shaped to have a pair of hinge structures  68  formed along one edge thereof and an integral latch structure  70  formed along an opposite edge. Preferably each hinge structure  68  is constructed and arranged to snap fit into pivotal engagement with appropriately shaped hinge receiving structure (not shown) integrally formed on the tabletop  24 . The latch structure  70  is constructed and arranged to snap-fit into releaseably latched engagement with latch receiving structure (not visible) integrally formed on the tabletop  24 . The lid  66  is flush with and forms part of the work support surface  14  of the tabletop  24  when the lid  66  is in its closed position. The central storage compartment can be used to store one or more vise assemblies (described below) when the vise assemblies are not in use. 
     A pair of table latches  72  are pivotally mounted on opposite edges of the tabletop  24  and are operable to latchingly engage associated end portions of the workpiece support structure  16  to releaseably lock the tabletop  24  thereto when the support assembly  10  is in its workbench configuration (see FIG. 1, for example). When the work support assembly  10  is in its workbench configuration, the elongated support structure  16  is received within a groove  74  formed on the underside the tabletop  24 . The groove  74  (best seen in FIG. 3) is defined by a series of aligned notches  76  formed in a plurality of reinforcing ribs or wall members  78  formed on the underside of the tabletop  24 . The ribs  78  rigidify and strengthen the tabletop  24 . The notches  76  are sized to snugly receive the workpiece support structure  16 . The table latches  72  prevent upward movement of the tabletop  24  away from the workpiece support structure  16 . Thus, it can be understood the cooperation of this groove  74  and the table latches  72  securely holds the tabletop  24  on the elongated support structure  16  when the tabletop assembly  22  is in its deployed position. 
     A recess  80  is integrally formed in the tabletop  24  adjacent a respective table latch  72  for storage of the latch when the tabletop assembly  22  is in its storage position and not in use as a workbench. The recesses  80  allow the work surface  14  of the tabletop  24  to be placed against an outer flat surface portion of the support member  18  when the tabletop assembly  22  is in its closed storage position. This allows the tabletop assembly  22  to be flat against the support member  18  when the support members  18 ,  20  are in their open operative position to allow the support assembly  10  to be used in its sawhorse configuration without interference from tabletop assembly  22  and allows the support assembly  10  to be easily stored or stacked when the support members  18 ,  20  are in their closed position because the assembly  10  is essentially flat. 
     A plurality of spaced, aligned openings  82  are provided in the work surface  14  of the tabletop  24 . The openings  82  are constructed and arranged to releaseably lockingly receive a vise assembly  84 . 
     The structure and operation of the vise assembly  84  is best understood from FIGS. 9-14. The vise assembly generally includes two separate portions or pieces  86 ,  88 . The first portion  86  of the vise assembly  84  includes a housing structure  90  and a movable member  92  (both of which may be constructed of a molded plastic material as shown, a metal material, or any other material of suitable strength) mounted for movement with respect to housing structure  90 . The second portion  88  of vise assembly  84  is preferably of one-piece construction and will be referred to herein as the “fixed member” because, as will become apparent, when the vise assembly  84  is in use, the second portion  88  is in a fixed position with respect to the work surface  14 . The fixed portion  88  of the vise assembly is preferably made of molded plastic material, although a metal material can be used in the construction. 
     The manner in which the movable member  92  is mounted within a housing structure  90  is best appreciated from FIGS. 11-14. Specifically, a threaded member  94  rotatably mounted within a housing structure  90  is threadedly engaged with the movable member  92  such that rotation of the threaded member  94  moves the movable member  92  generally between extended and retracted positions with respect to the housing structure  90 . The threaded member can be made of a molded plastic material, a metal material (as shown) or any other material of suitable strength. The extended position of the movable member  92  is shown in FIG.  9  and in cross-section in FIG.  13 . The retracted position of the movable member  92  is shown in cross section in FIG.  14 . 
     As best appreciated from the cross sections (FIGS.  13  and  14 ), a crank handle  96  is mounted on one end of the threaded member  94  by rivet or pin  97  and a radially enlarged end structure  98  is integrally formed on the opposite end of the threaded member  94 . The radially enlarged structure  98  limits outward threaded movement of the movable member  92  with respect to the housing structure  90 . It can also be appreciated from the cross sections of FIGS. 13 and 14 that one end of the threaded member  94  is rotatably mounted in an opening  100  formed within the housing structure  90  and that the threaded member  94  is prevented from moving axially by cooperation of the handle  96  and an annular shoulder  102  integrally formed on the threaded member  94 . 
     Rotation of the handle  96  causes rotation of the threaded member  94  which in turn causes rectilinear movement of the movable member  92  between its extended and retracted positions. As best appreciated from FIGS. 11 and 12, a pair of guide posts  106  are integrally formed within the interior of the movable member  92  and are received within channels  108  of complementary configuration formed within the housing structure  90 . Each channel  108  is formed within an axially extending structure  110  integrally formed within the housing structure  92 . Preferably the exterior of each axially extending structure  110  is splined and tapered. The splined structure strengthens and rigidifies each axially extending structure  110  and, in combination with the tapering, reduces any frictional engagement between the exterior of the axially extending structures  110  and upper and lower interior walls surfaces  114 ,  116  of the housing structure  92 . 
     The housing structure  92  and fixed member  88  each include locking structure constructed and arranged to allow each portion  86 ,  88  of the vise assembly  84  to be releaseably locked with respect to the support surface  14  of the tabletop  24 . Specifically, each locking structure is comprised of a downwardly extending essentially cylindrical shaft or post  118  and a radially extending locking tab  120  (i.e., radial with respect to the central axis of the post  118 ) formed thereon. Each opening  82  in the tabletop  24  is slotted (slots are not shown) in an axial direction of the opening to receive the tab  120  and thereby allow the post  118  to move into a selected opening  82 . When the post  118  is fully inserted, each opening  82  further includes a circumferentially extending locking slot (not shown) which allows limited circumferential movement of the tab  120  and therefore limited rotation of the post  118  within the opening when the post  118  is fully inserted therein. Movement of the tab  120  through the locking slot releasably locks that associated portion of the vise assembly onto the surface  14  of the tabletop  24 . 
     Another example of an arrangement for locking the first and second portions  86 ,  88  of the vice assembly  84  can be appreciated from FIGS. 10 and 15. FIG. 15 shows an alternative embodiment of a tabletop  140  (described below) in isolation. A post  118  of the second portion  88  (see FIG. 10) includes a lock engaging element in the form of the tab  120 . A wall structure  107  of each opening (such as opening  109  of tabletop  140  shown in FIG. 15) may be provided with a complimentary lock engaging element, shown in this example embodiment in the form of a groove  111  integrally formed in the plastic of the wall of the tabletop opening  109 . The complimentary lock engaging element, or groove,  111  in each opening is constructed and arranged to releasably lockingly engage the tab  120  on the second portion  88 . More specifically, the groove  111  and the tab  120  cooperate to help the user to determine when the portion  88  has been sufficiently rotated in a locking direction during installation on the tabletop  140 . More specifically, as the user rotates portion  88 , in a locking direction, the user will feel an initial resistance to rotation when the tab  120  of the post  118  of the second portion  88  (FIG. 10) contacts the wall structure  107 . Further rotation in the locking direction causes the tab  120  to enter and engage the groove  111 . The user will be able to tell when the tab  120  enters the groove  111  by the difference in resistance to rotation. The user will be able to tell, therefore, when he or she has rotated the second portion  88  sufficiently for installation. The engagement between tab  120  and the groove  111  will also help to keep the portion  88  properly aligned with the opposing first portion of the vice assembly. It can also be appreciated that a first portion (not shown) of the vice assembly can be provided with structure similar to that on the second portion  88  to aid in installation and alignment of the first portion. Thus, it can be understood that when the lock engaging elements, that is tabs  120 , on the posts  118 , engage respective lock engaging elements, that is grooves  111 , in a respective opening, workpiece gripping surfaces  115  on the movable and fixed members  92 ,  88 , respectively, are generally in opposing relation to one another, spaced from one another and generally parallel so that they are positioned to engage a workpiece place therebetween. 
     Operation 
     The operation of the workpiece support assembly  10  can best be understood from FIGS. 4-7. FIG. 4 shows the support assembly  10  in its closed folded position. In this position, the tabletop assembly  22  is in its storage position in which it is adjacent support member  18 , and the support members  18 ,  20  are together in their folded position. To use the support assembly  10  as a sawhorse, the support members  18 ,  20  are pivoted apart into their open operative position (FIG.  5 ). The folding shelf assembly  44  is in its unfolded open position and can be used to support tools or building materials while the assembly  10  is in use as a sawhorse. The tabletop assembly  22  is still in its storage position and is thus out of the way of a person using the assembly  10  as a sawhorse. The surface  12  is too narrow to be used by itself in supporting a workpiece for most construction tasks. Typically, a long workpiece such as a board or sheet of plywood is suspended between the narrow surfaces  12  of a pair of workpiece support assemblies  10 . 
     When a worker wishes to use the relatively wide support surface  14 , the workpiece support assembly  10  can be moved into its workbench configuration. To accomplish this, the tabletop  24  is moved into its deployed position by essentially pivoting it on the support arms  50 . This movement can be understood from comparing FIGS. 5-7. The tabletop  24  is placed in overlying relation to the workpiece support structure  16  with the groove  74  (not visible in FIGS. 5-7, but shown, for example, in FIG. 3) formed on the underside of the tabletop  24  placed over the workpiece support structure  16 . The table latches  72  are moved into latching engagement with respective ends of the workpiece support structure  16 . FIG. 7 shows the tabletop assembly  22  in its deployed position. The deployed tabletop  24  is supported by the cooperation of the arms  50  of the tabletop support structure  26  and the workpiece support structure  16 . 
     A vise assembly  84  can be used to hold a workpiece on the work surface  14  of the tabletop  24  when the workpiece support assembly  10  is in its workbench configuration. To use a vise assembly  84 , a worker removes the first and second portions  86 ,  88  of the assembly  84  from the central storage compartment of the tabletop  24  by opening the lid  66 . It can be understood that the use of the central storage compartment to store one or more of the vise assemblies  84  is optional. The central storage compartment can be used to store other items as well, and is large enough to store one or more vise assemblies  84 . 
     The first portion  86  of the vise assembly  84  is secured with respect to the work surface  14  by inserting the shaft  118  on the housing structure  90  into a selected opening  82  of the tabletop  24 . When the shaft  118  is fully inserted in the selected opening  82 , the housing structure  90  is turned or rotated to move the tab  120  into locking engagement with the circumferentially extending locking slot to lock the first portion  86  of the vise assembly  84  in its operating position on the tabletop  24 . The fixed member  88  of the vise assembly  84  is mounted in a selected opening  82  in the same manner. In a preferred embodiment of the vise assembly  84  and tabletop  24 , each portion  86 ,  88  of the vise assembly  84  is required to be pivoted or rotated approximately 45 degrees to move the each portion  86 ,  88  from its releasing position into stopped locking position and vice versa. 
     In the exemplary embodiment of the tabletop assembly  22  shown, two series or “lines” of opening&#39;s  82  are provided on the tabletop  24 . The two series are designated  130 ,  132 , respectively, and are best seen in FIG.  8 . Preferably the two portions  86 ,  88  of a vise assembly  84  are placed in openings the same series  130  or  132 , but this is not required. All of the opening  82  are identical and each portion  86 ,  88  can be mounted in any opening  82 . It can be understood that the two portions  86 ,  88  of the vise assembly  84  are removed from locked engagement with the tabletop  24  by reversing the above-described sequence of operations for locking each portion  86 ,  88  the tabletop  24 . That is, to remove each portion, each portion  86 ,  88  is pivoted from its locked, operative position into its unlocked position and then pulled upwardly away from the work surface  14  of the tabletop  24 . 
     Preferably the housing structure  90  is releasably secured along an edge portion of the tabletop  24  so that the crank handle  96  extends outwardly beyond the work surface  14  to facilitate manual cranking movement of the handle  96 . The fixed member  88  is then mounted to the tabletop  24  in a position relative to the housing structure  90  close enough so that movement of the movable member  92  toward its extended position grips the selected workpiece therebetween. Preferably, the fixed member  88  is placed as close as possible to the housing structure  90  while still accommodating the workpiece therebetween so that the user is required to turn the handle  96  as little as possible to grip the workpiece. The user can grip a workpiece using a single vise assembly  84  for smaller workpieces or can use a pair of vise assemblies  84  for larger workpieces. 
     To grip a workpiece in a vise assembly  84 , the workpiece is placed between the two portions  86 ,  88  and the movable member  92  of the first portion  86  is moved towards its extended position using the crank handle  96  and into biasing engagement with the workpiece. The fixed portion  88  is positioned close enough to the housing structure  90  so that the workpiece is gripped between the movable member  92  and the fixed member  88  of the vise assembly  84  before the movable member  92  reaches its full extended position. The workpiece is released from the vise assembly  84  by rotating the crank handle  96  in the opposite direction to move the movable member  92  away from and out of biasing engagement with the workpiece. 
     The movable member  92  of the exemplary vise assembly  84  has a range of movement between extended and retracted positions of only approximately four cm, but workpieces of a wide range of sizes can be gripped by the vise assembly  84  by repositioning the fixed member (along series of openings) relative to the housing structure  90  of the vise assembly  84 . 
     Thus, the fixed member  88  can be repositioned relative to the first portion  86  of the vise assembly  84  to accommodate a wide range of workpiece sizes, even if the range of movement of the movable member  92  relative to the housing structure  90  (that is, the range between its extended and retracted positions) is relatively small. Because each vise assembly  84  is relatively small, a pair of vise assemblies  84  can easily be stored in the central compartment and covered with the lid  66  when not in use. 
     The locking engagement between each tab  120  on the two portions of the vise assembly and the tabletop  24  prevents the two portions  86 ,  88  of the vise assembly  84  from being displaced upwardly away from the work surface  14  when the crank handle  96  is being tightened. The tabs  120  also prevent each portion  86 ,  88  of the vise assembly  84  from “bending” backwards (i.e., away from one another) as the vise assembly  84  is tightened. 
     Preferably there are two bars of metal  138  affixed to the under portion of the tabletop  24 . Each metal bar  138  is positioned such that it extends under the tabletop  24  generally between the first portion and second portion  86 ,  88  of a respective vise assembly  84 . The metal bars  138  strengthen and rigidify the tabletop  24 , thereby preventing the tabletop  24  from bending or buckling while using one or both vise assemblies  84  to grip a workpiece. Each bar  138  is preferably secured to the tabletop  24  by screws or other fasteners. 
     Another embodiment of a tabletop  140  of a tabletop assembly is shown in FIGS. 15-17. Structures and portions of the tabletop  140  that are identical to the tabletop  24  are identified with identical reference numbers and are not discussed further. The tabletop  140  includes a plurality of molded plastic core structures  142  integrally formed in the molded plastic of the tabletop, instead of the metal bars  138  that are affixed to tabletop  24 , as seen in FIG.  2 . Each core structure  142  has a closed cross section and extends under the upwardly facing surface of the tabletop. The core structures  142  are generally perpendicular to the elongated support structure  16  when the tabletop assembly is deployed. The closed cross sections of the core structures  142  are constructed and arranged to rigidify the tabletop. A plurality of elongated reinforcing elements  144  can optionally be secured within a hollow interior space  146  of a respective core structure  142  to further rigidify the tabletop  140 . In the example tabletop  140 , the reinforcing elements  144  are in the form of a plurality of metal strips or bars, one of which is shown in exploded relation with an associated core structure  142  in FIG.  17 . The reinforcing elements  144  can be formed of any appropriate material including any appropriate metal, a solid plastic, wood, and so on. Each reinforcing element  144  can be secured within the interior space  146  of the associated core structure  142  with any appropriate fasteners (not shown) through openings  150  (see FIG.  15 ). 
     Each vise assembly  84  has many advantages including that each portion  86 ,  88  of each assembly  84  is very small, yet, because of the two-piece construction, both very small and very large workpieces can be gripped using the vise assembly  84 . The two-piece construction allows a threaded member  94  of relatively short length to be used in the construction of the vise assembly  84  because the range of movement of the movable member does not need to be very large to accommodate both large and small workpieces. 
     It can be appreciated that the embodiments and descriptions of the workpiece support assembly and the vise assembly are intended to be exemplary only and not intended to limit the scope of the invention. Other embodiments of the work support assembly are contemplated and within the scope of the invention. For example, although the tabletop assembly is essentially permanently mounted to the work support assembly in the exemplary embodiment (where “permanently” means that the tabletop assembly is not normally removed during normal use of the support assembly), is contemplated to provide a work support assembly of two-piece construction in which the tabletop assembly is a separate piece of the assembly. When the work support assembly is of two-piece construction, the tabletop support structure can be mounted between the tabletop and a support member of the workpiece support assembly or, alternatively, one end of the tabletop support structure can be mounted to the tabletop in the opposite end can engage the ground directly. It is also contemplated to mount a tabletop assembly on an adjustable sawhorse of the types shown in the commonly assigned Ser. No. 09/372,669. 
     It is also contemplated to provide a locking assembly to releasably lock the tabletop assembly in its storage position. An example locking assembly  160  is shown in FIGS. 18 and 19. The locking assembly  160  is shown mounted on a workpiece support assembly  162  that includes tabletop  140 . The workpiece support assemblies  10 ,  162  are identical except that assembly  162  includes tabletop  140  and locking assembly  160 . Identical structures between the two assemblies  10 ,  162  are identified with identical reference numbers and are not discussed in further detail. 
     The locking assembly  160  is comprised of a pair of molded plastic projections  164  (see FIG. 19) on one support member  18  and a molded plastic opening or recess  166  formed in the tabletop  140 . Movement of the tabletop  140  into its storage position moves the pair of projections  164  on to a snap fit locking relation with the opening  166 . To release the tabletop  140  from its locked storage position, the pair of projections  164  are moved manually into a released relation with the recess  166 . More specifically, the plastic projections  164  are resilient, flexible structures that include gripping surfaces  170  that engage an outer edge surface  172  of the opening  166  in the unflexed position of the projections  164  to lock the tabletop  140  in its storage position. To deploy the tabletop, the user manually presses on outer surfaces  168 , which flex the projections  164  toward one another so that surfaces  170 ,  172  move out of engagement with one another to release the tabletop  140 . Movement of the tabletop  140  back into its storage position causes edge portions of the opening  166  to contact the angled surfaces  168 . Further movement of the tabletop  140  toward its storage position moves the two projections  164  toward one another to allow the projections to pass through the opening  166 . When the tabletop  140  reaches its storage position, the projections move back to their unflexed positions which engage surfaces  170 ,  172  to automatically lock the tabletop  140  in its storage position. 
     When the pair of support members  18 ,  20  are in their open position and the tabletop  140  is in its storage position, the tabletop  140  is releasably locked to the support member  18  in essentially side-by-side parallel relation therewith. When the tabletop is releasably locked in its storage position, the support members  18 ,  20  can be moved between their open operative and folded positions. When the tabletop  140  is releasably locked in its storage position and when the pair of support members  18 ,  20  are in their folded position, the support members  18 ,  20  and the tabletop  140  are disposed in essentially side-by-side parallel relation with one another. It is, of course, possible for the pair of projections to be provided on the table top  140 , while an opening with which the projections lockingly engage may be formed within the support member  18 . 
     Other embodiments of the vise assembly are also contemplated. For example, is contemplated to realize a vise assembly using two portions which both include movable members. For example, it is contemplated to construct a vise assembly using a pair of first portions  86  of the assembly  84 . 
     Thus, it can be understood that while the invention has been disclosed and described with reference with a limited number of embodiments, it will be apparent that variations and modifications may be made to each embodiment without departing from the spirit and scope of the invention. Therefore, the following claims are intended to cover all such modifications, variations, and equivalents thereof in accordance with the principles and advantages noted herein.