Abstract:
A push stick comprises a body providing a bottom surface and a heel member that protrudes beyond the bottom surface; and a slide-out ruler that is selectably positionable to extend from the body. The push stick is a safety device that can be used to push a workpiece past a blade or bit while keeping an operator&#39;s hands out of harm&#39;s way. The ruler allows an operator to use the push stick to make measurements, such as setting the height of a cutting tool relative to a workpiece table.

Description:
TECHNICAL FIELD 
     The invention relates to woodworking equipment. More particularly, the invention relates to push sticks. 
     BACKGROUND 
     In operations such as the ripping, routing or jointing of a workpiece, an operator should use safely equipment to prevent accidental injuries. One type of safety equipment is a push stick, which is a handheld tool including a notch which allows the operator to feed the workpiece remotely to keep the operator&#39;s hands away from dangerous moving parts of the workpiece operation device such a cutting blades or bits. Push sticks also allow the operator to hold a workpiece precisely, such as tightly against the table top of a table saw, while performing the workpiece operation. 
     SUMMARY 
     In general, the invention is directed to a push stick including a ruler. The push stick is a safety device that can be used to push a workpiece past a blade or bit while keeping an operator&#39;s hands out of harm&#39;s way. The ruler allows an operator to use the push stick to make measurements, such as setting the height of a cutting tool relative to a workpiece table. 
     In one embodiment, the invention is directed to a push stick comprising a body providing a bottom surface and a heel member that protrudes beyond the bottom surface; and a slide-out ruler that is selectably positionable to extend from the body. 
     In another embodiment, the invention is directed to a push stick comprising a body providing a measurement surface a bottom surface and a heel member that protrudes beyond the bottom surface; a handle fixed to the body; a slide-out ruler that is selectably positionable to extend from the body in a direction that is about perpendicular to the measurement surface; and a locking mechanism operable to secure the ruler at a selected position relative to the body. 
     The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIGS. 1A and 1B  illustrate a push stick including a slide-out ruler. 
         FIG. 2  illustrates the push stick of  FIGS. 1A and 1B  with the slide-out ruler in an extended position. 
         FIGS. 3A and 3B  are conceptual illustrations of a cross section of push stick of  FIGS. 1A and 1B  include a cam locking mechanism operable to secure the slide-out ruler at a selected position. 
         FIG. 4  illustrates the push stick of  FIGS. 1A and 1B  with the slide-out ruler in an extended position to measure a workpiece. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1A and 1B  illustrate push stick  100 . Push stick  100  is a safety device that can be used to push a workpiece past a blade or bit. Push stick  100  includes slide-out ruler  140 , which may be used to measure the height of a cutting tool such as a blade of a table saw or a router bit.  FIG. 2  illustrates push stick  100  with slide-out ruler  140  in an extended position. Push stick  100  includes only a few discrete components: body  110 , which is integrated with handle  112  as a single component, ruler  140 , magnet  136  and locking tab  130 . 
     Body  110  provides a generally flat bottom surface  111  and heel member  120  that protrudes beyond the bottom surface  111 . Heel member  120  provides forward facing surface  124  that combines with bottom surface  111  to form notch  127 , which operates to engage an edge of a workpiece. In some instances, heel member  120  may also facilitate tracking of the push stick  100  within the guide channel of a worktable. Body  110  is generally planer, but also includes cross-members for additional stiffness. For example, cross-members  121  are shown in  FIGS. 3A and 3B . Body also includes an ornamental oval  138  that is suitable for branding of push stick  100 . 
     Handle  112  is suitable for a user to grip push stick  100  when performing a workpiece operation. Handle  112  includes handle grip  114  including raised sections  116 , which protrude outwardly from handle  112 . Handle  112  is integrated with body  110  as a single component. In other embodiments, body  110  and handle  112  may be separate components. 
     In the configuration shown in  FIGS. 1A and 1B , body  110  and handle  112  may be a polymeric material formed using injection molding techniques. Suitable polymeric materials that can be utilized to form the body  110  and handle  112  include acrylonitrile butadiene styrene (ABS), polypropylene (PP), polyvinylchloride (PVC), or nylon. Other materials may also be suitable. A suitable material for body  110  and handle  112  should be relatively rigid material capable of resisting bending or flexing resulting from pressure exerted thereon by the user. In certain embodiments, for example, body  110  and handle  112  may be fabricated from a glass filled nylon or polycarbonate material. In other embodiments, fabrication techniques other than injection molding may also be used to fabricate body  110  and handle  112 . 
     Slide-out ruler  140  fits within slot  115 , which is formed by body  110 . In a retracted position ( FIGS. 1A and 1B ), ruler  140  fits entirely within the profile of body  110 . When extended, ruler  140  is suitable for making measurements, such as measuring the height of a cutting blade or bit relative to a workpiece table. Ruler  140  is extendable from body  110  in a direction such that is does not intersect with a plane defined by bottom surface  111 . In this manner, the position of ruler  140  will not interfere with the ability of push stick  100  to engage a workpiece. More specifically, ruler  140  is extendable from body  110  in a direction that is about perpendicular to generally flat measurement surface  125 . Measurement surface  125  provides a reference point useful when making measurements with ruler  140 , and is about perpendicular with bottom surface  111 . 
     Locking mechanism  130  is operable to secure ruler  140  at a selected position in slot  115  relative to body  110 . For example, when setting the height of a cutting tool, a user may first secure ruler  140  in an extended position selected to match the desired height of the cutting tool using locking mechanism  130 . Then the user can use the position of measurement surface  125  relative to the distal end of ruler  140  to accurately set the height of the cutting tool. 
     The operation of locking mechanism  130  is shown in detail in  FIGS. 3A and 3B , which represent cross-section A-A of push stick  100  as shown in  FIG. 2 . Locking mechanism  130  includes latch  136  with finger tab  138  and cam  139 . Latch  136  pivots about pin  142 , which is fixed relative to body  110  by protrusions  144 . For example, pin  142  may be a metallic wire. Rotation of latch  136  in direction  150  moves locking mechanism  130  from an open position ( FIG. 3A ) to a closed position ( FIG. 3B ). The rotation of latch  136  in direction  150  causes cam  139  to pivot about pin  142  to secure ruler  140  within slot  115 . In order to secure ruler  140  relative to body  110 , cam  139  passes through aperture  132  in body  110  to press ruler  140  against rib  146  of body  110 , which forms slot  115 . 
     Body  110  also contains magnet  136 , which functions to secure ruler  140  in slot  115 . More specifically, ruler  140  includes a ferrous metal, such a stainless steel. The ferrous metal of ruler  140  experiences an attractive magnetic force from magnet  136 . The magnetic force of magnet  136  ensures a frictional force between ruler  140  and slot  115  when rule  140  is in a retracted position. This frictional force mildly inhibits the motion of ruler  140  from extending from slot  115  when ruler  140  is in a retracted position. Magnet  136  may be secured to body  110  using any suitable technique, e.g., magnet  136  may be secured to body  110  via a press fit or an adhesive. In other embodiments, magnet  136  may be molded directly into body  110 . Other embodiments may not include a magnet; also in some embodiments ruler may not include a ferrous metal, but may be made of a different material such as wood, metal, aluminum, a polymer, injection molded polymer or other material. 
       FIG. 4  illustrates push stick  100  shown in an extended position to measure notch  202  in workpiece  200 . As shown in  FIG. 4 , generally flat measurement surface  125  is aligned with an edge of workpiece  200 , while ruler  140  is extended to measure the depth of notch  202 . As previously described, push stick  100  may be used to perform any number of measurements, including but not limited to, measuring the depth of a cutting tool, such as a table saw blade or router bit. 
     Various embodiments of the invention have been described. In addition, modifications can be made to the described embodiments within the spirit of the invention. For example, the described embodiments included push sticks including injection molded polymeric components. However, other materials and manufacturing techniques may also be used to provide push stick including a slide-out ruler. For example, such push stick may be made from any of a variety of suitable materials including, but not limited to, metal, wood, composites and ceramics. These and other embodiments are within the scope of the following claims.