Abstract:
A device comprising a swivel mount and its method of use are described. The device can be used in pairs with a variety of different power tools useful for working on metal or wood. The purpose of the tool is to insure a precise linear alignment between the measuring device and the moving part of the power tool that removes material from the wood or metal. The swivel mount includes a mounting block, a ball shank, and a swivel body mounted on the ball of the shank. The swivel mount attaches to one portion of the measuring device that is linearly adjustable with respect to the material removing part of the power tool. A second swivel mount attaches to a portion of the power tool that maintains a fixed distance with respect to the moving part of the power tool.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of application Ser. No. 11/604,138, filed Nov. 24, 2006, which claims priority of provisional patent application Ser. No. 60/741,261, filed Dec. 1, 2005. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to the field of woodworking and metal working equipment. More particularly, the invention relates to mounting brackets and their use to facilitate precise measurements when performing an operation on a work piece. 
     BACKGROUND OF THE INVENTION 
     The old adage among carpenters, woodworkers and machinists in order to avoid costly and time-consuming mistakes is “measure twice and cut once”. This guideline is normally learned only through the experiences of making many mistakes in the workshop. 
     Woodworkers and machinists are constantly seeking more accurate and reliable techniques for sawing, routing, milling, turning, and drilling wood and metal. One variable that has consistently evaded precision is the requirements for accurately gauging the amount of material to be removed during a processing step. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The present invention relates to a swivel mounting device that comprises a mounting block for mounting the device on a power tool such as a woodworking or metal working machine. The swivel mounting device includes a ball shank with a shaft having one end secured to a mounting block, and the second end terminating in a ball. A swivel body is mounted on the ball end of the shank. This swivel body is capable of being clamped or otherwise affixed to a portion of a measuring device such as calipers. The swivel body includes a recess in which the ball of the ball shank is retained. The measuring device is typically secured in a slot in the swivel body. The mounting block is attached to the power equipment by suitable means such as a magnet, cement or clamp. 
     The invention also relates to a method of making accurate measurements when working with a power tool used for the removal of material from an object. The method compensates for angularity mis-alignment between the power tool and a measuring device that defines a spatial relationship between the material removal portion of the tool and a portion of the object to be removed. The method comprises providing a first swivel device for holding a first portion of the measuring device. This first device is mounted on a portion of the power tool that maintains a fixed spatial relationship with the material removal part of the tool. A second device holds a second portion of the measuring device that is movable with respect to the material removal part of the tool. The two swivel devices are spaced apart from one another and allow for changes in the angularity between the measuring device and the power tool without changing the linear spacing between the stationary and the movable portions of the measuring device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of the device of the present invention; 
         FIG. 2  is an exploded view of the device shown in  FIG. 1 ; 
         FIG. 3  is a top view of the swivel mount of  FIG. 1 ; 
         FIG. 4  is a view taken along lines  4 - 4 ′ of  FIG. 3 ; 
         FIG. 5  is a perspective view showing a variation of the present invention; 
         FIG. 6  is an exploded view of the device shown in  FIG. 5 ; 
         FIG. 7  is an elevational side view of the device of  FIG. 5 ; 
         FIG. 8  is a cross sectional view taken along lines  2 - 2 ′ of  FIG. 7 ; 
         FIG. 9   a  is a schematic view showing the a pair of the devices of the present invention used in association with a table saw; and 
         FIG. 9   b  is a close-up view of the devices of the present invention mounted on the table saw of  FIG. 9   a.    
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The swivel mount of the present invention is useful on power equipment such as table saws, jig saws, band saws, milling machines, bench drills, turret lathes, planers and routers of the types typically used for working on wood and metal. As shown in  FIGS. 1-4 , the device  10  comprises three principal components. These are a mounting block  20 , a ball shank  40 , and a swivel body  60 . The mounting block  20  allows the device to be coupled to the power equipment. In one embodiment, the mounting block is attached to a base plate  22  by two Allen head screws  32  inserted through holes  36  in the block into corresponding holes  24  in the base plate  22 . This base plate  22  is adapted to be mounted on the power equipment by extending the set screws  32  through the base plate  22  into threaded holes in the equipment. The device may also be coupled to the table saw or other equipment by the use of a magnet or an adhesive a well as clamps or other mechanical attachments of the type well known to the skilled artisan. 
     The ball shank  40  typically consists of a hardened steel ball  42  at one end of a shaft  44 . The free end  46  of the shaft is inserted into a hole  38  in the mounting block  20  and is secured in place by suitable means such as a set screw  28  threaded into hole  30 . The ball  42  of the ball shank  40  is mounted within a recess  68  of the swivel body  60 . The shaft  44  preferably has a flat section  48  (shown in  FIGS. 1 and 2 ) against which the set screw  28  is tightened to secure the shaft to the mounting block  20  and to prevent rotation of the shaft in the mounting block  20  while not inhibiting oscillation of the swivel body  60  around the ball end of the shank  40 . 
     Two of the devices of the present invention are used in tandem with one another and are attached to two parts of a measuring device, at least one of which is movable in a linear direction toward and away from the other. For example, one device may be connected to a stationary jaw of calipers as shown in  FIGS. 9   a  and  9   b . The other device is secured to the other movable jaw which may be coupled, mechanically or electrically to a suitable readout such as a digital or a linear scale. 
     As shown in  FIGS. 3 and 4 , the swivel body  60  contains a slot  62  to hold one of the jaws of a caliper and two threaded holes  64  to receive a pair of set screws  66  to secure the swivel body to the jaw. A recess  68  extends into the body from one surface to receive the ball  42  of the ball shank  40 . The shaft  44  of the ball shank extends through a hole  72  in the surface of the swivel body  60  that is opposite the recess  68 . A cap  70 , typically made from the same material as the swivel body, is threaded or cemented into the opening of the recess  68  to anchor the ball  42  in place. The cap  70  is shown with two holes  76  adapted to receive a tool for tightening and loosening the cap. Instead of the two holes, the cap can be slotted for use with a screwdriver to facilitate tightening and loosening of the cap. The cap should be sufficiently tight to secure the ball against linear movement while allowing it to rotate within the recess. If necessary, a small amount of a lubricant may be used to ensure smooth rotational movement of the ball  42  vis-à-vis the recess  68 . The oscillation of the swivel body  60  relative to the ball shank  40  serves to compensate for non linear movement of the measuring device with respect to the power equipment while at the same time maintaining an extremely close tolerance as the jaws of the calipers move relative to one another in a linear direction. 
     The free end  46  of the shank is adapted to be secured by a set screw  28  threaded in a hole  30  in the mounting block  20 . The ball inserted into the swivel mount allows non-linear movement such as changes of the angle between the calipers and the power equipment without changing alignment of the jaws of the calipers in the linear direction of movement, thus preserving the accuracy of the measurements. Therefore, the need for absolute rigidity between the calipers or other measuring device and the power equipment is eliminated. 
       FIGS. 5-8  show another option for holding the ball of the shank in the swivel body. As with the embodiment in  FIGS. 1-4 , the device  110  is adapted to be mounted on a piece of woodworking or metal working equipment (not shown) using a base plate  122  that is magnetically, adhesively or mechanically coupled to the equipment. The mounting block  120  is secured to the base plate with a pair of Allen head screws  132  extending through holes  136  (shown in  FIG. 6 ) in the block. The free end  146  of the ball shank  140  is inserted into the mounting block through hole  138  and is secured in place with set screw  128  threaded into hole  130  and tightened against the planar portion  148  of the shaft  144  as previously described. The swivel body  160  has a slot  162  to receive one of the caliper jaws (not shown) and includes a pair of set screws  166  threaded into holes  164 . The swivel body contains a blind recess  168  (shown in  FIG. 8 ) opening into the body from the bottom. Because the blind recess  168  is accessible from beneath the body, the top  176  of the body may be recessed or set back above the slot if desired. As shown in cross section in  FIG. 8 , the annular ring  174  slips around the shank and is threaded, cemented or press fit into the bottom of the swivel block in the opening of the recess  168  to retain the ball in the recess, while not inhibiting relative angular movement of the swivel body  160  with respect to the ball  142 . As can be seen, the hardened metal ball  142  of the ball shank  140  engages the recess  168  in the swivel mount  160 . The free end  146  of the shank  144  is secured by the set screw  128  in hole  130  in the mounting block  120 . The ball inserted into the swivel mount allows non-linear movement such as changes of the angle between the calipers and the power equipment without changing alignment of the jaws of the calipers in the linear direction of movement, thus preserving the accuracy of the measurements. When a pair of the devices of the invention are used on a table saw, router table or band saw, the mounting block of one device  10   a  is attached to the rip fence or other guide and mounting block of the other device  10   b  is attached to the table. This is seen in  FIGS. 9   a  and  9   b  showing a table saw  80  equipped with a traditional rip fence  82 . The fence is welded or otherwise secured to a metal bar  84  that is at right angle to the fence and that moves at right angles to the direction of cut. Calipers  86  include a first jaw  88 , and a second jaw  90  movable relative to the first jaw. A digital readout  92  is mounted on the calipers to measure the opening between the two jaws. The first jaw  88  of the calipers is secured in the slot  62   a  of the first swivel mount  10   a , and the second jaw is secured in the slot  62   b  of the second swivel mount  10   b . The two jaws of the caliper move at right angles to the planar face of the saw blade ( 96  in  FIG. 9   b ). The swivel feature of the mounting devices allows them to grip the respective jaws of the calipers at virtually any angle without impeding the linear movement of the jaws with respect to one another. 
     One fence that has been found to be particularly capable of providing a true cut when used with a variety of table saws is the Biesemeyer fence. Other fences on which one of the devices of the present invention can be mounted are available from suppliers such as Black &amp; Decker, Craftsman, Delta, Dewalt, Ryobi and Shopsmith. Generally, these fences are used with the supplier&#39;s own particular brand of saw or router table. 
     The mounting block may be machined from any suitable metal such as steel or may be made from a polymeric substance such as Delrin, nylon or polypropylene, by machining or molding. The digital calipers that are useful in the practice of the present invention are available from such manufacturers as Brown &amp; Sharp, Mahr, Mitutoyo, and Starrett. 
     Instead of digital calipers, analog calipers and other linear measuring device such as a precision yardstick or ruler may be used to achieve a high level of accuracy in the linear measurements. 
     While the invention has been described in combination with embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing teachings. Accordingly, the invention is intended to embrace all such alternatives, modifications and variations as fall within the spirit and scope of the invention as shown and described herein.