Abstract:
Blade tilt mechanisms for table saws are disclosed. The disclosed tilt mechanisms provide easy and intuitive operation. They also provide auto-locking so that a user simply releases a component to lock the blade at a specific angle. The tilt mechanisms also provide defined incremental steps for the tilt of the blade and the steps are typically spaced at 1-degree intervals.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of and priority from U.S. Provisional Patent Application Ser. No. 61/741,493, filed Jul. 20, 2012, which is incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present disclosure relates to table saw mechanisms designed to improve convenience and performance. More specifically, this specification relates to mechanisms used to tilt the blade to make beveled or angled cuts. 
       BACKGROUND 
       [0003]    A table saw is a power tool used to cut a workpiece to a desired size or shape. A table saw includes a work surface or table and a circular blade extending up through the table. A person uses a table saw by placing a piece of wood or other workpiece on the table and feeding it past the spinning blade to make a cut. 
         [0004]    Table saws are typically constructed so that a user can adjust the angle or tilt of the blade relative to the table in order to make beveled or angled cuts. Some table saws include hand wheels that a user turns to tilt the blade. Other table saws include a clamp to hold the blade at a specific angle relative to the table. In those saws, a user changes the blade&#39;s tilt by releasing the clamp, manually tilting the blade to a desired position, and then performing some specific action to re-engage the clamp, such as tightening a knob or moving a lever. 
         [0005]    This specification discloses tilt mechanisms that enable a user to tilt the blade easily and intuitively, that provide an auto-lock feature, and that provide defined and incremental positions for the blade. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  shows a table saw. 
           [0007]      FIG. 2  shows a front view of a tilt mechanism in a table saw. 
           [0008]      FIG. 3  shows perspective view of the tilt mechanism of  FIG. 2 . 
           [0009]      FIG. 4  shows another perspective view if the tilt mechanism of  FIG. 3 . 
           [0010]      FIG. 5  shows a perspective and exploded view of a rack and an engagement member used in the tilt mechanism of  FIG. 2 . 
           [0011]      FIG. 6  shows a side view of the rack and engagement member of  FIG. 5 . 
           [0012]      FIG. 7  shows an engagement member engaging a rack. 
           [0013]      FIG. 8  shows an engagement member disengaged from a rack. 
           [0014]      FIG. 9  shows a spring to counterbalance the weight of the blade, trunnion, motor and related structure. 
           [0015]      FIG. 10  shows a back view of an adjustment mechanism. 
           [0016]      FIG. 11  shows another embodiment of an adjustment mechanism. 
           [0017]      FIG. 12  shows a dial used in the adjustment mechanism shown in  FIG. 11 . 
           [0018]      FIG. 13  shows a view of the adjustment mechanism shown in  FIG. 12  with a hand wheel removed for clarity. 
           [0019]      FIG. 14  shows another embodiment of an adjustment mechanism. 
           [0020]      FIG. 15  shows another embodiment of a tilt mechanism. 
           [0021]      FIG. 16  shows the tilt mechanism of  FIG. 15  with the housing removed for clarity. 
           [0022]      FIG. 17  shows a pin used in the tilt mechanism of  FIG. 15 . 
           [0023]      FIG. 18  shows a spring in a tilt mechanism. 
           [0024]      FIG. 19  shows a tab used in a tilt mechanism. 
           [0025]      FIG. 20  shows another embodiment of spring to counterbalance the weight of the blade, trunnion, motor and related structure. 
           [0026]      FIG. 21  shows an enlarged view of the spring of  FIG. 20 . 
           [0027]      FIG. 22  shows an isolated view of the spring of  FIG. 20 . 
           [0028]      FIG. 23  shows ridges used in a tilt adjustment mechanism. 
           [0029]      FIG. 24  shows tabs used in a tilt adjustment mechanism. 
           [0030]      FIG. 25  shows a saw housing with an arm to support a dial used in a tilt adjustment mechanism. 
           [0031]      FIG. 26  shows a cross-section of the arm shown in  FIG. 25 . 
           [0032]      FIG. 27  shows a dial supported by the arm shown in  FIG. 25 . 
       
    
    
     DETAILED DESCRIPTION 
       [0033]      FIG. 1  shows a table saw  10  including a table  12  and a circular blade  14  extending up through the table. A piece of wood, or other material to be cut, is placed on the table and pushed into contact with the spinning blade to make a cut. The saw includes a motor  16  to spin the blade, and a switch  18  to turn the motor on and off. 
         [0034]    Table saw  10  also includes an elevation mechanism to raise or lower the blade to cut workpieces of varying thicknesses. The elevation mechanism includes a hand wheel and a user turns hand wheel  20  to raise and lower the blade. 
         [0035]    Table saw  10  further includes a tilt mechanism  22  to adjust the angle or tilt of the blade relative to the table in order to make beveled or angled cuts.  FIGS. 2-4  show different views of table saw  10  with the housing removed in order to see tilt mechanism  22 . Various components typically included in a table saw, such as dust shrouds, riving knife mounts, elevation mechanisms, etc., have been removed from  FIGS. 2-4  to more clearly show the tilt mechanism. 
         [0036]    Tilt mechanism  22  includes a rack  24  mounted in the saw to a front trunnion bracket  25 , which in turn is mounted to the underside of table  12 . The bottom of rack  24  includes an arcuate or curved section having teeth  26  with gullets between the teeth. In the embodiment shown, teeth  26  are spaced at 1-degree intervals, although they may be spaced at greater or smaller intervals. Rack  24  may be made from hard plastic or any other suitable material. 
         [0037]    Tilt mechanism  22  also includes an engagement member  28  positioned behind hand wheel  20  and mounted to a trunnion  30 . Trunnion  30  carries the blade and is supported at least in part by front trunnion bracket  25  so that the trunnion can pivot from side to side in order to tilt the blade. 
         [0038]    Engagement member  28  includes a toothed portion  40  configured to mesh with teeth  26  on rack  24 , as seen in  FIGS. 5 and 6 . Engagement member  28  also includes a grip plate  42  configured to be engaged by a user. Grip plate  42  includes bumps  44  to increase friction with a user&#39;s hand, but may alternatively have a textured surface, a smooth surface, or some other surface. 
         [0039]    Grip plate  42  is connected to toothed portion  40  but spaced apart so that the housing of the saw can extend between the grip plate and the toothed portion. In this configuration, grip plate  42  is outside the saw while toothed portion  40  is inside the saw. The connection between grip plate  42  and toothed portion  40  extends through an opening  43  in the housing (the opening is shown in  FIG. 1 ). Opening  43  can be minimized by decreasing the size of the connection between grip plate  42  and toothed portion  40 . 
         [0040]    Engagement member  28  can be made from plastic, and it includes a base  48  used to mount the engagement member to trunnion  30 . A thin section  50  connects base  48  to toothed portion  40  and to grip plate  42 . Thin section  50  acts as a spring and allows toothed portion  40  and grip plate  42  to flex or bend relative to base  48 . 
         [0041]      FIGS. 7 and 8  illustrate how the teeth on engagement member  28  mesh with teeth  26  on rack  24 . As seen in  FIGS. 7 and 8 , grip plate  42  is positioned behind hand wheel  20 . In operation, a user would place his fingers along bumps  44  on grip plate  42  and squeeze or pull the grip plate toward hand wheel  20 . As stated, thin section  50  on engagement member  28  acts as a spring and allows grip plate  42  and toothed portion  40  to flex away from rack  24  so that toothed portion  40  disengages from teeth  26  on rack  24 . After squeezing or flexing the grip plate toward the hand wheel to disengage toothed portion  40  from teeth  26 , the user manually tilts the blade to a desired angle or position by moving engagement member  28  to the right or left. As stated, engagement member  28  is mounted to trunnion  30  supporting the blade, and trunnion  30  is mounted in the saw to pivot to the right or left (when viewing the saw from the front), so the blade tilts as the user moves engagement member  28 . When the blade is at the desired angle, the user simply releases grip plate  42 . The grip plate and toothed portion automatically return back to their original position due to the spring force of thin section  50 , and toothed portion  40  again engages teeth  26  on rack  24  to hold the blade at the desired angle. In this manner, the user can tilt the blade from 0 to 45 degrees. A hinged joint between the base section and the grip plate and toothed portion can replace thin section  50  in other embodiments. Such a hinged joint is shown in  FIGS. 11 and 13 , discussed below, and may include an axle  51  and a spring  53  to bias the grip plate and toothed portion toward rack  24 . Additionally, in some embodiments a spring supported by a bolt threaded into the trunnion may be used to bias the grip plate and toothed portion toward rack  24 , as shown at  99  in  FIG. 18 . 
         [0042]      FIG. 7  shows toothed portion  40  engaging teeth  26  on rack  24  to hold the blade in position.  FIG. 8  shows toothed portion  40  pulled away from and disengaging teeth  26  on rack  24 . In the condition shown in  FIG. 8 , a user may tilt the blade to a desired angle by moving engagement member  28  to the right or left because toothed portion  40  does not engage teeth  26 , as explained. 
         [0043]    Toothed portion  40  of engagement member  28  meshes with teeth  26  on rack  24  to hold the blade in position. Toothed portion  40  includes a plurality of teeth in order to securely mesh with teeth  26  on rack  24  and to support the weight of the blade, trunnion and motor when the blade is tilted. Teeth  26  on rack  24  and the teeth on toothed portion  40  have the same profile and are shaped so that the teeth mesh well with little chance that vibration will cause the teeth to disengage. In the depicted embodiment the teeth have a pitch angle of 14.5-degrees to provide solid abutments to support the weight of the blade, motor, trunnion and related structure, although other pitch angles and profiles are possible. 
         [0044]    As stated, rack  24  may be made from hard plastic or any other suitable material. Rack  24  is also supported in the saw to prevent it from flexing away from engagement member  28 , which might cause the teeth to disengage. In one embodiment, a tab may be added to help keep rack  24  in position so that teeth  26  on the rack and toothed portion  40  on engagement member  28  mesh reliably.  FIG. 19  shows a tab  100  positioned adjacent the bottom of a rack  24  to help keep the rack in position. Tab  100  overlaps a bottom edge of the rack, and the top of the tab is cut at an angle to better match the curved bottom edge of the rack. Tab  100  may be attached to trunnion  30  in various ways, such as with a screw. 
         [0045]      FIG. 9  shows a spring  52  that can be used with the tilt mechanism to offset the weight of the blade, trunnion, motor and related structure. Spring  52  has two arms, one connected to the back side of trunnion  30  and the other connected to a rear trunnion bracket  54 , as shown in  FIG. 9 . When the blade is perpendicular to the table top, the position and weight of the motor creates a force tending to tilt the blade, and spring  52  is positioned to offset that force, at least partially. In the embodiment depicted in  FIG. 9 , spring  52  is compressed so that the arms of the springs push out with a force of approximately 30 to 35 pounds when the blade is perpendicular to the table, although springs applying other forces could be used, including forces ranging from just a few pounds (e.g., 3 to 5 pounds) to 50 pounds or more. As the trunnion tilts, the spring continues to push out to balance the weight of the blade, trunnion, motor, and related structure. Tilting the trunnion toward 45-degrees compresses the spring further so that the spring applies a greater counterbalancing force. 
         [0046]      FIGS. 20-22  show an alternative counterbalance spring  120 . Counterbalance spring  120  includes a coil  122  with straight segments  124  and  126  at each end of the coil at a right angle to each other. The straight segments continue for a length before bending ninety degrees at ends  128  and  130  in directions parallel to the coil and back toward the coil so that the ends are pointing in opposite directions. A bracket  132  is attached to trunnion  30 , and end  128  of spring  120  fits through a set of concentric holes in the bracket, as shown in  FIGS. 19 and 20 . ( FIGS. 20 and 21  show a perspective looking at the underside of a table  12  in order to better see spring  120 .) End  130  of spring  120  fits into and around a projection extending out from the bottom of table  12 , as shown. 
         [0047]    When a user tilts the blade and releases grip plate  42 , toothed portion  40  will spring back toward rack  26  and the teeth will mesh. If the positions of the teeth on toothed portion  40  do not exactly align with teeth  26  on rack  24  when the user releases grip plate  42 , the engagement member will shift slightly due to gravity until the teeth mesh and lock in place. 
         [0048]    As stated, teeth  26  on rack  24  are spaced 1-degree apart, which means the blade can be tilted in 1-degree increments by moving engagement member  28 . This provides the advantage of being able to tilt the blade easily to precise angles, such as 37-degrees. Accordingly, teeth  26  may be thought of as an index or indices to allow a user to tilt a blade to a defined position. 
         [0049]    Tilt mechanism  22  includes an adjustment mechanism  60 , also called a micro-adjust or micro-adjust system, to allow a user to tilt the blade to any angle between the 1-degree increments. Adjustment mechanism  60  is perhaps best shown in  FIG. 2 . It includes a dial  62  positioned outside the saw so that a user can engage and turn the dial. Dial  62  is eccentrically connected to an arm  64 , which is inside the housing of the saw, so the dial and arm “sandwich” the housing. The other end of arm  64  attaches to rack  24 . Because of the eccentric connection between dial  62  and arm  64 , turning dial  62  causes arm  64  to move to the right or left. Arm  64 , in turn, moves rack  24  to the right or left, and rack  24  moves engagement member  28  and blade  14  because of the engagement between toothed portion  40  and teeth  26 . Dial  62  may be constructed with stops to limit the rotation of the dial and thereby limit the possible adjustment. In the depicted embodiment, dial  62  includes internal stops that limit the rotation of the dial to plus or minus 60-degrees. Additionally, the dial should be constructed so that it stays in place when turned, and the depicted embodiment includes an internal O-ring to create friction between the dial and the saw housing to hold the dial in position. Alternatively, ridges or notches between various parts of the dial may be used to hold the dial in position. For example, dial  62  may include a series of ridges  140  along an interior surface of a cylindrical shell  142  that extends out from the backside of the dial, as shown in  FIG. 23 . Cylindrical shell  142  fits within a corresponding cylindrical cavity  144  on arm  64 . Positioned around the cylindrical cavity  144  are a number of tabs  146 , as shown in  FIG. 24 , and each tab includes corresponding ridges or notches configured to mesh with the ridges in shell  142 . Tabs  146  can flex as dial  62  is installed so that cylindrical shell  142  fits between the inner wall of cylindrical cavity  144  and the tabs. The tabs can also flex when dial  62  is rotated. Once the dial is set, the tabs spring back so that the notches in the tabs mate with the notches in the dial to help hold the dial in position. Of course other embodiments are possible. 
         [0050]      FIG. 10  shows the back side of dial  62  and arm  64  in order to show how arm  64  connects to rack  24 . The head of a bolt  66  is captured in a socket in arm  64 , and the threaded end of the bolt engages a nut  67  (shown in  FIG. 2 ) captured in a socket  68  in rack  24 . The bolt can be turned using a 90-degree hex wrench, and turning the bolt adjusts the spacing between rack  24  and arm  64  to properly align the blade and rack in the saw. 
         [0051]    Dial  62  may be supported in the saw by “sandwiching” the housing, as mentioned above. Dial  62  may also be supported by an arm formed as part of the housing, as shown in  FIGS. 25 through 27 .  FIG. 25  shows a housing  150  made as a molded, plastic part, and an arm  152  extends down to provide a support for dial  62 . Supporting the dial with an arm helps maintain the position of the dial if the outer wall of the housing flexes.  FIG. 26  is a cross-sectional view taken along the line A-A in  FIG. 25 , showing arm  152  with holes  154  and  156 . As shown in  FIG. 27 , a bolt  158  and a spacer  160  may extend through holes  154  and  156  to support dial  62 . 
         [0052]      FIGS. 11-13  show another embodiment of an adjustment mechanism. In this embodiment, a dial  70  is threaded on a bolt  72  held by a bracket  74  mounted to table  12 . Dial  70  extends through an opening in the front of the housing so a user can turn the dial to adjust the tilt. Dial  70  includes a threaded projection  76  that threads into a socket  78  in rack  24 . Turning dial  70  turns threads  76 , which in turn move rack  24 . Threads  76  are configured to provide sufficient motion of rack  24  when dial  70  is turned a desired amount. 
         [0053]      FIG. 14  shows another embodiment of an adjustment mechanism. This embodiment includes a handle  78  on an eccentric  79 . The eccentric is linked to an arm  80  connected to rack  24 . The eccentric is supported by a bracket  81  mounted to table  12 . A user turns the handle to turn the eccentric, and the eccentric then moves arm  80  and rack  24  back and forth. 
         [0054]      FIGS. 15-17  show another embodiment of a tilt mechanism that provides and index or indices allowing a user to tilt the blade to defined positions. The mechanism includes an arcuate bracket or index  84  having apertures or holes, such as hole  86  in  FIG. 16 , spaced at defined intervals, such as every 1-degree. A handle  88  is mounted in the saw adjacent index  84 . The back side of the handle includes a pin  90  configured to fit into the holes in index  84 . The handle is adapted to pivot so that a user can move pin  90  into and out of the holes in index  84 . Other structure in the saw provides support for handle  88  and holds handle  88  in position so that pin  90  aligns with the holes in index  84 . Index  84  can be mounted on the outside of the saw&#39;s housing, as shown in  FIG. 15 , or it can be mounted to the inside of the saw provided there is an opening in the housing to allow pin  90  to engage the index. A user operates this tilt mechanism by pulling the handle out, tilting the blade to a desired position, and releasing the handle so that pin  90  moves into one of the holes in the index. The handle can be spring-biased so that pin  90  moves toward index  84  and through a hole when the handle is released. 
         [0055]    A different embodiment of an alternative adjustment mechanism can be used with the tilt mechanism shown in  FIGS. 15-17 . A dial  92  can be positioned in handle  88 , as shown in  FIG. 16 . Pin  90  is mounted to the back of the dial and handle  88  is attached to trunnion  30  so that the trunnion and blade move with the handle. In use, turning the dial moves both the handle and trunnion because pin  90  engages index  84  which is fixed to the saw&#39;s housing. 
         [0056]    Variations of the above-described embodiments are possible within the scope of this disclosure. 
       INDUSTRIAL APPLICABILITY 
       [0057]    The blade tilt mechanisms disclosed herein are applicable to woodworking power tool equipment, and particularly to table saws. The tilt mechanisms discussed above may be referred to as tilt means for positioning the blade at desired angles, tilt means for changing the angle of the blade relative to a work surface, means for tilting, or some other similar appellation. 
         [0058]    It is believed that the disclosure set forth above encompasses multiple distinct inventions with independent utility. While each of these inventions has been disclosed in its preferred form, the specific embodiments thereof as disclosed and illustrated herein are not to be considered in a limiting sense as numerous variations are possible. The subject matter of the inventions includes all novel and non-obvious combinations and sub-combinations of the various elements, features, functions and/or properties disclosed herein. No single feature, function, element or property of the disclosed embodiments is essential to all of the disclosed inventions. Similarly, the recitation of “a” or “a first” element, or the equivalent thereof, should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements. 
         [0059]    It is believed that the following claims particularly point out certain combinations and sub-combinations that are directed to disclosed inventions. Inventions embodied in other combinations and sub-combinations of features, functions, elements and/or properties may be claimed through amendment of the present claims or presentation of new claims in this or a related application. Such amended or new claims, whether they are directed to a different invention or directed to the same invention, whether different, broader, narrower or equal in scope to the original claims, are also regarded as included within the subject matter of the inventions of the present disclosure.