Abstract:
A benchtop saw, such as a compound miter saw, has a bevel angle locking actuator for locking the bevel angle of the saw blade which is easier for the operator to reach than prior art bevel angle locking actuators that are located at the rear of the saw. The bevel angle locking actuator is mounted forward of the rear of the saw on the saw support assembly, which is in turn rotatably mounted to the saw&#39;s base assembly. Also disclosed is a bevel angle locking system which permits remote mounting of a bevel angle locking actuator.

Description:
[0001]     This application is a continuation of, claims priority to, and incorporates by reference in its entirety, the following U.S. patent application Ser. No. 10/717,536, entitled “BEVEL ANGLE LOCKING ACTUATOR AND BEVEL ANGLE LOCKING SYSTEM FOR A SAW” filed Nov. 21, 2003, which claims priority from U.S. provisional patent application Ser. No. 60/428,931 filed on Nov. 26, 2002. 
     
    
     BACKGROUND  
       [0002]     This invention generally relates to bench top saws that permit adjustment of the bevel angle of cut, including, but not limited to compound miter saws. This invention provides a bevel angle locking actuator and bevel angle locking system for locking the saw at a desired bevel angle.  
         [0003]     Bench top saws are characterized by the ability to place the saw on a surface and use the saw to cut a workpiece while the saw is being supported on the surface. The surface could be a table or bench top, floor, etc.  
         [0004]     Compound miter saws typically comprise a base assembly having a turntable rotatably mounted on a base to turn about a vertical axis, and a saw support assembly pivotally mounted to the turntable to turn about a horizontal axis where the vertical axis is normal to the top surface of the base assembly and the horizontal axis is parallel with the top surface of the base assembly. Miter saws also typically comprise a saw unit pivotally mounted to the saw support assembly to plunge a saw blade into a workpiece resting on the base assembly. The saw blade of the saw unit turns to cut the workpiece, and defines a cutting plane that is parallel with the horizontal axis. The base assembly also typically has a fence attached to the base for aligning a workpiece on the base assembly and holding it in position during a cut.  
         [0005]     A compound miter saw permits compound angle cuts to be made on a workpiece. The compound angle cut of a compound miter saw includes a miter angle component and a bevel angle component. The miter angle is the angle of cut adjusted by rotating the turntable and the saw blade about the vertical axis. The bevel angle is the angle of cut adjusted by rotating the saw support assembly and the saw blade about the horizontal axis. The compound miter saw permits the operator to independently adjust both the miter angle and the bevel angle to make the desired compound angle cut. The operator may also adjust solely the miter angle or the bevel angle to make a simpler cut with only a miter angle or bevel angle component.  
         [0006]     Other types of bench top saws besides compound miter saws also permit adjustment of the bevel angle of cut, and the invention is applicable to these saws, as well. For example, a saw which permits adjustment of the bevel angle but not of the miter angle may include a saw support assembly mounted to a base (without a turntable), where the saw support assembly pivots about a horizontal axis relative to the base to adjust the bevel angle of cut. As another example, a saw which permits adjustment of both the bevel angle and the miter angle, but is different from typical compound miter saws, may include a saw support assembly mounted to a base, where the saw support assembly pivots about a horizontal axis relative to the base to adjust the bevel angle of cut, and may include a fence which is adjustably mounted on the base to adjust the miter angle of cut.  
         [0007]     In order to set-up a typical compound miter saw for a cut including a bevel angle component, the bevel angle is first adjusted by rotating the saw support assembly and the saw unit about the horizontal axis to the desired bevel angle. The saw support assembly must then be locked relative to the base assembly to retain the desired bevel angle while the cut is performed. Prior art bevel angle locking systems typically clamp together opposing surfaces of the saw support assembly and the base assembly to hold the bevel angle with friction. The bevel angle locking system described in U.S. Pat. No. 5,235,889 (“the &#39;889 patent”) is illustrative. Typically these bevel angle locking systems have comprised a shaft or pin anchored to the base assembly, such as shaft  81  in  FIG. 7  of the &#39;889 patent. The shaft or pin extends from the base assembly and projects through the saw support assembly. A handle or nut is attached onto the end of the shaft or pin, such as handle  78  in  FIG. 7  of the &#39;889 patent. When the handle is turned, the saw support assembly is pushed against the base assembly and friction prevents the saw support assembly from rotating relative to the base assembly.  
         [0008]     One drawback of the type of bevel angle locking system described above is that the actuator, the handle or nut, is located at the rear of the saw. The operator must reach around to the back of the saw to loosen or tighten the handle or nut for unlocking or locking the bevel angle, a task which is often awkward and cumbersome.  
         [0009]     One advantageous feature of the present invention is an actuator for locking the bevel angle provided in a position forward of the rear of the saw, a position where an operator may more easily access the actuator. This feature and other advantageous features of the invention will be described hereinafter with reference to the illustrative embodiments of the invention depicted in the drawing figures.  
     
    
     BRIEF DESCRIPTION OF THE DRAWING FIGURES  
       [0010]      FIG. 1  is an isometric view of an exemplary compound miter saw incorporating an illustrative embodiment of the bevel angle locking actuator and an illustrative embodiment of the bevel angle locking system of the present invention.  
         [0011]      FIG. 2  is an isometric view of the bevel angle locking actuator and bevel angle locking system of  FIG. 1  in an unlocked position.  
         [0012]      FIG. 3  is a detail, plan view of the bevel angle locking system in the same position as in  FIG. 2 .  
         [0013]      FIG. 4  is an isometric view of the bevel angle locking actuator and bevel angle locking system of  FIG. 1  in a locked position.  
         [0014]      FIG. 5  is a detail, plan view of the bevel angle locking system in the same position as in  FIG. 4 .  
         [0015]      FIG. 6  is an exploded view of some of the components of the illustrative bevel angle locking actuator and illustrative bevel angle locking system of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0016]     An exemplary compound miter saw is shown in  FIGS. 1-6 . The principles of the invention described herein may be applied in a similar manner to any type of compound miter saw, or to any type of bench top saw which permits adjustment of the bevel angle of cut. A bench top saw is a saw which can be placed on a surface and used to cut a workpiece while the saw is supported on the surface.  
         [0017]     An illustrative embodiment of a bevel angle locking actuator and an illustrative embodiment of a bevel angle locking system are incorporated into the compound miter saw shown in  FIGS. 1-6 . It should be understood that the principles of the invention are capable of being practiced in other embodiments dissimilar in certain respects to the illustrated embodiments depicted in the drawing figures. The illustrative embodiments will be used to teach the principles of the invention, but the scope of the invention is not intended to be limited to the illustrative embodiments. In particular, it should be understood that the illustrative bevel locking actuator may be used with a bevel locking system different from the one shown in the drawing figures, and vice et versa.  
         [0018]     An exemplary compound miter saw is shown in  FIG. 1  comprising a base assembly  100  which can include a base  110  and a turntable  120 . The turntable  120  is rotatably supported by the base  110  to turn about a vertical axis of rotation. The vertical axis of rotation of the turntable  120  is approximately normal to the top surface  101  of the base assembly  100 . The base  110  may be placed upon and supported by a surface such as a table or bench top, or floor during use of the saw. A handle  121  can be grasped by the user to rotate the turntable  120  on the base  110  about the vertical axis to adjust the miter angle of cut. A miter lock is provided to lock the turntable  120  at a desired miter angle. A detent system may also be provided for assisting the operator in adjusting the turntable  120  to commonly used miter angles. The detent system may have an override actuator  122 , commonly a lever, mounted in close proximity to the handle  121 .  
         [0019]     The base assembly  100  may also include a fence assembly  130 . The fence assembly  130  may be mounted to the base  110  and overlap a portion of the turntable  120 , as shown in  FIG. 1 . A top surface  101  of the base assembly  100  and the front surface of the fence assembly  130  together support a workpiece during cutting.  
         [0020]     A saw support assembly  200  is rotationally mounted to the base assembly  100  at the turntable  120  to rotate about a horizontal first rotational axis. The saw support assembly  200  is rotationally mounted so that the first rotational axis is approximately parallel to the top surface  101  of the base assembly  100 , and may also be approximately coplanar with the top surface  101 . The saw support assembly  200  rotates relative to the base assembly  100  to adjust the bevel angle of cut.  
         [0021]     In this illustrative embodiment, the rotational connection of the saw support assembly  200  to the base assembly  100  is made at a knuckle  140 . The knuckle  140  has a female conical surface  141  formed thereon. The saw support assembly  200  has a male conical surface  221  formed thereon. The female conical surface  141  and the male conical surface  221  are in contact with one another and support the saw support assembly  200  for rotational movement. This type of rotational mounting for a saw support assembly with a male and female conical surface, sometimes called a trunnion, is described in U.S. Pat. No. 5,235,889. Of course, the location of the male and female conical surface could be reversed with the male conical surface being formed on the base assembly  100  and the female conical surface being formed on the saw support assembly  200 .  
         [0022]     Other arrangements for rotationally mounting the saw support assembly  200  to the base assembly  100  which permit adjustment of the bevel angle are also possible and the principles of this invention may apply to miter saws with those other arrangements, as well. For example, some miter saws, such as the one illustrated in U.S. Pat. No. 5,425,294, use flat surfaces on the base assembly and the saw support assembly as well as a pin to rotationally support the saw support assembly on the base assembly (see  FIG. 10  of the &#39;294 patent). Other miter saws may simply use a pin extending from the base assembly to the saw support assembly to rotationally support the saw support assembly.  
         [0023]     A saw unit  300  is pivotally mounted to the saw support assembly  200 . In the illustrated embodiment, the saw unit  300  may include an upper arm  310 . The saw support assembly  200  may include a lower arm  210 . The upper arm  310  and the lower arm  210  are pivotally connected with a pin  311 . The saw unit  300  mounts a saw motor  320  which drives a saw blade  321 . The saw blade  321  turns at a high speed to cut the workpiece and defines a cutting plane. The cutting plane is at least approximately parallel to the first rotational axis of saw support assembly  200 , and may be approximately coplanar with the first rotational axis. Also, the pivoting axis of upper arm  310  relative to the lower arm  210  is approximately normal to the cutting plane of saw blade  321 . The saw support assembly  200  and the saw unit  300  rotate together, in unison, about the first rotational axis when the bevel angle of the saw blade  321  is adjusted.  
         [0024]     The saw support assembly  200  pivots the saw unit  300  about pin  311  to plunge the saw blade  321  into a workpiece resting on the top surface  101  of the base assembly  100 . A handle  330  is connected to the saw unit  300  and is graspable by the user to control the plunging of the saw blade  321  into the workpiece. The handle  330  includes a power switch  331  for actuating the saw motor  320 .  
         [0025]     The base assembly  100 , the saw support assembly  200 , or even perhaps the saw unit  300  may also include a slide mechanism which permits the saw blade  321  to translate relative to the top surface  101 . In the illustrated embodiment, the slide mechanism  150  is part of the base assembly  100 . The slide mechanism comprises two slide rods  151 ,  152 . The slide rods  151 ,  152  are supported by and slide out from the turntable  120  in a known manner. The knuckle  140  is mounted to the end of slide rods  151 ,  152 . A slide mechanism may instead be part of a saw support assembly. In that case, a knuckle can be directly mounted to a turntable, or can be integrally formed with a turntable.  
         [0026]     As discussed above, in the exemplary embodiment of the compound miter saw, the saw support assembly  200  comprises a lower arm  210 . The saw support assembly may include other structure in addition to, or in place of the lower arm  210  to pivotally attach to the base assembly  100  and provide support to the saw unit  300  above the base assembly. Likewise, in the exemplary embodiment of the compound miter saw the saw unit  300  comprises an upper arm  310 . However, the saw unit  300  may include other structure in addition to, or in place of the upper arm  310  to attach to the saw support assembly  200  and support the saw motor  320 , saw blade  321 , and handle  330 .  
         [0027]     As shown in  FIG. 6 , in the illustrated embodiment the male conical surface  221  of the saw support assembly  200  is formed on a trunnion insert  220 . The trunnion insert  220  is attached to the lower arm  210  during assembly of the miter saw with threaded fasteners (not shown). The trunnion insert  220  includes a cylindrical portion  222  on the end of which is formed the male conical surface  221 . The cylindrical portion  222  engages a bore  211  formed through the lower arm  210  in such a manner that the male conical surface  221  extends out from the lower arm  210  towards the knuckle  140 . One advantage of forming the male conical surface  221  on the trunnion insert  220  is simplified machining. The male conical surface  221  can be more easily machined on the relatively small trunnion insert  220  than on the lower arm  210 . Another advantage is that the trunnion insert  220  can be formed from a different material than the rest of the lower arm  210 . For example, the lower arm  210  could be formed from cast aluminum, while the trunnion insert  220  can be formed from cast iron. Aluminum on aluminum wear surfaces can be problematic. If the knuckle  140 , including the female conical surface  141 , is formed from cast aluminum, it may be advantageous to form the male conical surface on a separate cast iron trunnion insert  220  rather than on the cast aluminum lower arm  210  to avoid aluminum on aluminum wear surfaces—and still manufacture the lower arm from cast aluminum to minimize weight. The advantages of a separate insert on the saw support assembly  200  on which is formed the surface that contacts the base assembly  100  can be realized whether the contact surface is a conical surface, or a straight surface. Of course, despite the disadvantages, the contact surface could be directly formed on the lower arm  210 .  
         [0028]     The compound miter saw of  FIGS. 1-6  includes an illustrative embodiment of a bevel angle locking actuator  290 . The bevel angle locking actuator  290  is mounted to the saw support assembly  200  so that the bevel angle locking actuator  290  rotates in unison with the saw support assembly about the first rotational axis when the bevel angle is adjusted. Positioning the bevel angle locking actuator  290  on the saw support assembly  200  presents several advantages over previous designs where the bevel angle locking actuator was mounted at the rear of the saw. The bevel angle locking actuator  290  is more easily accessible to the operator of the saw when mounted to the saw support assembly  200 . When the bevel angle locking actuator was mounted at the rear of a compound miter saw, reaching around to lock the bevel angle sometimes required extreme manipulations of the operator&#39;s wrist and arm.  
         [0029]     Also, the bevel angle locking actuator  290  is easily visible to the operator when using the saw. A visual confirmation that the bevel angle of the saw is locked can be obtained by a quick glance at the position of the bevel angle locking actuator  290 . When the bevel angle locking actuator was mounted at the rear of the saw, some compound miter saws prevented an easy view of its position and no way to visually confirm that the bevel angle was locked.  
         [0030]     The illustrative embodiment of the bevel angle locking actuator  290  comprises an elongated lever  291  and a handle  292 . The elongated lever  291  can be stamped from sheet metal such as aluminum sheet or steel sheet. The handle  292  can be formed of injection molded plastic. The bevel angle locking actuator  290  could also comprise a rotating handle or knob, or any other actuator desirable for the particular application. The lever  291  is advantageous in that it provides a long lever arm so that a relatively large amount of force can be brought to bear in the bevel angle locking system to lock the bevel angle with only a relatively small force applied to the lever. It would be difficult to position a long lever at the rear of a compound miter saw as it would likely project far out from the profile of the saw and be damaged or inadvertently unlocked when the saw is transported. With the saw support assembly mounted arrangement of bevel angle locking actuator  290 , however, the lever  291  can be shaped to match and closely conform to the profile of lower arm  210 . Thus, the lever  291  can be more protected from inadvertent actuation and damage, and be less obtrusive and more compact. As seen in  FIG. 4 , the lever  291  can be arranged so that when it is in its locked position, the longitudinal axis of the lever is generally parallel with the immediately surrounding structure of lower arm  210 . As seen in  FIG. 2 , when the lever  291  is unlocked, the longitudinal axis of the lever can be generally vertical to give the operator a strong visual cue that the bevel angle is unlocked.  
         [0031]     A bevel angle locking actuator mounted to the saw support assembly can be used to actuate any appropriate type of bevel angle locking system. One bevel angle locking system which works well with a saw support assembly mounted bevel angle locking actuator is shown on the compound miter saw in  FIGS. 1-6 . However, this illustrative embodiment of a bevel angle locking system is not the only system which can be used with a saw support assembly mounted bevel angle locking actuator.  
         [0032]     In the illustrative embodiment of the bevel angle locking system, the male conical surface  221  and the female conical surface  141  are compressed together in order to lock the position of the saw support assembly  200  relative to the base assembly  100  and lock the bevel angle. This is done by sliding a bevel locking linkage  230  to wedge the bevel locking linkage between two surfaces causing the male conical surface  221  and the female conical surface  141  to be pushed together. In this exemplary embodiment, sliding the bevel locking linkage  230  causes it to be wedged between cam surfaces  223  formed on the trunnion insert  220 , and a bevel locking flange  240 . The bevel locking flange  240  abuts a nut  250  threaded onto a pin or bolt  260 . Bolt  260  is approximately coaxial with the first rotational axis of the saw support assembly  200 . Bolt  260  is anchored to the knuckle  140  and passes through the knuckle and through the lower arm  210  and the trunnion insert  220 . When the bevel locking linkage  230  is wedged between cam surfaces  223  and bevel locking flange  240 , the bevel locking linkage pushes the trunnion insert  220  into firm engagement with the knuckle  140 . A reaction force causes the bevel locking linkage  230  to push against the bevel locking flange  240 . Bevel locking flange  240  in turn pushes against nut  250 . Nut  250  in turn pulls on and tensions bolt  260 . Bolt  260  is anchored to the knuckle  140 .  
         [0033]     In the illustrative embodiment of the bevel angle locking system, the bevel locking linkage  230  moves almost in a straight line motion in a direction approximately normal to the longitudinal axis of bolt  260 . In other embodiments, the linkage could move in different directions, and even in pivoting or other curved motions. In the illustrative embodiment of the bevel angle locking system, the cam surfaces are formed on trunnion insert  220 . In other embodiments, the angled cam surfaces could be formed on other structure of the saw support assembly  200 , or could be formed on the bevel locking flange  240 , or even on the bevel locking linkage  230  itself. In other embodiments, the bevel locking flange  240  may be integrally formed with the nut  250 , or the bevel locking flange  240  may be attached to the bolt  260  in some other appropriate manner.  
         [0034]     In another embodiment, a bevel locking linkage could be wedged against a flange connected to a second shaft, a shaft parallel to the bolt  260  but spaced laterally therefrom. U.S. Pat. No. 5,425,294 shows a miter saw design with two shafts, a first shaft  4  and a second shaft connected to handle  5 . In the &#39;294 patent, handle  5  is turned to push the saw support assembly against the base assembly. A bevel locking linkage could be associated with the second shaft in the &#39;294 patent so that when the linkage slides and is wedged, the second shaft will be tensioned and the bevel angle will be locked. However, compression of the saw support assembly  200  against the base assembly  100  around and at the bolt  260  is thought to be the best option leading to the most consistent alignment of the saw blade  321  with the base assembly  100 . Because the bolt  260  is coaxial with the axis of rotation of the saw support assembly  200 , pushing against the saw support assembly  200  evenly around the bolt  260  balances and centers the force of the saw support assembly  200  against the base assembly  100  and helps to ensure the most accurate alignment of the two assemblies.  
         [0035]     The bevel locking linkage  230  is caused to slide by a slider-crank mechanism comprising a crank shaft  270 . Crank shaft  270  is rotationally supported by the lower arm  210  of saw support assembly  200  and includes an eccentric shaft portion  271 . The eccentric shaft portion  271  is linked to the bevel locking linkage  230 . The bevel locking linkage  230  has a curved portion  231  on the end thereof which creates a pocket into which the eccentric shaft portion  271  fits. The eccentric shaft portion  271  is retained in the pocket by a block  232  which is attached to the bevel locking linkage  230  with a fastener (not shown).  
         [0036]     One end of crank shaft  270  is fixed to the bevel angle locking actuator  290 . As the operator pivots the bevel angle locking actuator  290 , the crank shaft  270  rotates and the bevel locking linkage  230  is caused to slide up and down.  FIG. 2  shows the bevel angle locking actuator  290  in the unlocked or up position where the bevel locking linkage  230  is pushed downward and the bevel angle is unlocked.  FIG. 3  is a detail, plan view of the bevel angle locking actuator  290  and the bevel locking linkage  230  in the position shown in  FIG. 2 . A spring  280  (see  FIGS. 5 and 6 ) can be positioned between the trunnion insert  220  and the bevel locking flange  240 . In this unlocked position, the spring  280  ensures a sufficient amount of force against the saw support assembly  200  to keep the saw support assembly  200  from disengaging too much from the base assembly  100  so that the operator does not feel too much play between the saw support assembly and the base assembly when the bevel angle is unlocked.  
         [0037]      FIG. 4  shows the bevel angle locking actuator  290  in the locked or down position where the bevel locking linkage  230  is pulled upward and the bevel angle is locked.  FIG. 5  is a detail, plan view of the bevel angle locking actuator  290  and the bevel locking linkage  230  in the position shown in  FIG. 4 .  
         [0038]     This embodiment of a bevel angle locking system has several advantages over prior art systems. First, this embodiment permits mounting the actuator for the system somewhere other than at the rear of the saw. Second, the force of the saw support assembly  200  against the base assembly  100  is approximately evenly balanced around the first rotational axis of the saw support assembly to ensure consistent and accurate placement of the saw blade  321  relative to the base assembly and the workpiece. Third, this system is capable of holding the bevel angle and the saw support assembly firmly.  
         [0039]     The principles of the inventive bevel angle locking actuator and bevel angle locking system have been described through a description of and through reference to drawings illustrating illustrative embodiments. The principles of the invention are applicable to produce other embodiments, dissimilar in some respects to the illustrative embodiments, to fit particular needs. The scope of invention protected hereby is not limited to the illustrative embodiments.