Abstract:
A method of reciprocating a spindle of a reciprocating saw, including the steps of reciprocating the front end of the spindle along a first path during the cutting stroke and along the same first path during the return stroke, and adjusting the saw such that the front end reciprocates along a second path during the cutting stroke and along the same second path during the return stroke, the second path being oblique to the first path. The present invention also provides a method of reciprocating a spindle of a reciprocating saw, including the steps of moving the front end along a first cutting path during the cutting stroke, the first cutting path characterized by movement at least partially in a first cutting direction, returning the front end along a return stroke (e.g., along the first cutting path), and adjusting the saw such that the front end moves along a second cutting path during the cutting stroke, the second cutting path characterized by movement at least partially in a second cutting direction.

Description:
RELATED APPLICATION 
     This is a continuation of patent application Ser. No. 09/474,033, filed Dec. 28, 1999, which is a continuation of patent application Ser. No. 09/020,436, filed Feb. 9, 1998, now abandoned, which is a continuation of application Ser. No. 08/699,448, filed Aug. 19, 1996, now abandoned. 
    
    
     FIELD OF THE INVENTION 
     The present invention generally relates to the field of reciprocating saws. 
     BACKGROUND OF THE INVENTION 
     Reciprocating saws are used to cut a variety of objects, such as metal pipes, wood and drywall. Such saws typically include a housing and a spindle mounted in the housing for reciprocating motion along an axis that is parallel to the longitudinal extent of the spindle. An electric motor provides power to the spindle through a mechanical reciprocating device that converts the rotary motion of a motor shaft to reciprocating motion. Such mechanical reciprocating devices can, for example, include an eccentric drive, as disclosed in U.S. Pat. No. 5,079,844, or a wobble plate drive, as disclosed in U.S. Pat. Nos. 5,025,562 and 5,050,307. 
     In some reciprocating saws, the spindle reciprocates in an orbital motion as opposed to a straight line reciprocating motion. The orbital motion is characterized by a forward (i.e., in the cutting direction) motion of the saw blade as the saw blade is being retracted toward the saw on the cutting stroke, and a corresponding rearward (i.e., opposite the cutting direction) motion of the saw blade as the saw blade is being extended away from the saw on the return stroke. The result is a circuitous, or orbital, path of the saw blade. Such orbital motion is believed to improve the speed at which the saw cuts a workpiece by driving the saw blade into the workpiece during the cutting stroke and withdrawing the saw blade from the workpiece during the return stroke. 
     Orbital motion has been achieved in a number of different ways. For example, in U.S. Pat. Nos. 4,238,884 and 4,628,605, a forward force (in the cutting direction) is applied by a blade roller directly to the saw blade during the cutting stroke, and forward motion of the saw blade is accommodated by a forgiving interconnection between the spindle and the drive mechanism. In U.S. Pat. No. 5,212,887, the spindle reciprocates through a pivotally-mounted bushing, and the back end of the spindle is connected to an eccentric member that provides forward-rearward motion to the spindle. In U.S. Pat. Nos. 4,962,588 and 4,550,501, the back end of the spindle is moved forward-rearward by connection to a cam surface on a rotating gear, and in U.S. Pat. No. 5,392,519 the back end of the spindle in moved forward-rearward by connection to an eccentric member. 
     SUMMARY OF THE INVENTION 
     The utilization of blade rollers, cam surfaces, and eccentric members can be unnecessarily complicated and expensive. Further, such devices tend to wear down, and some can introduce unwanted vibrations into the saw. Accordingly, it is an object of the present invention to provide a saw that approaches the better cutting performance of orbital saws without the complexity required for orbital motion. It is a related object of the present invention to achieve a forward motion of the saw blade during the cutting stroke without resorting to orbital motion. 
     The above-noted objects are achieved by a method of reciprocating a spindle of a reciprocating saw, the spindle having a front end adapted to receive a saw blade movable through a cutting stroke and a return stroke. The method comprises the steps of reciprocating the front end along a first path (e.g., a neutral path) during the cutting stroke and along the same first path during the return stroke, and adjusting the saw such that the front end reciprocates along a second path during the cutting stroke and along the same second path during the return stroke. The second path is oblique to the first path. By virtue of this method, the front end of the spindle follows a path that is not orbital, and therefore can be achieved using a much simpler mechanism. In addition, the front end of the spindle can be moved in a neutral path or, alternatively, in an oblique path that plunges into the workpiece. 
     In another aspect, the present invention provides a method of reciprocating a spindle of a reciprocating saw, the spindle having a first cutting direction and a second cutting direction opposite the first cutting direction. The method comprises the steps of moving the front end along a first cutting path during the cutting stroke, the first cutting path characterized by movement at least partially in the first cutting direction, returning the front end along a return stroke (e.g., along the first cutting path), and adjusting the saw such that the front end moves along a second cutting path during the cutting stroke, the second cutting path characterized by movement at least partially in the second cutting direction. Preferably, the saw can also be adjusted such that the front end moves along a neutral cutting path during the cutting stroke, the neutral cutting path characterized by movement substantially perpendicular to the first and second cutting directions. By virtue of this method, the saw can be used to achieve a plunge cut in either down-cutting or up-cutting situations. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partial side section view of a reciprocating saw embodying the present invention with the guide member in a down-cutting position and the spindle in a fully retracted position. 
     FIG. 2 is the partial side section view of FIG. 1 with the spindle in a fully extended position. 
     FIG. 3 is a front view of the reciprocating saw shown in FIG.  1 . 
     FIG. 4 is a partial right side view of the reciprocating saw shown in FIG.  1 . 
     FIG. 5 is a section view taken along line  5 — 5  in FIG.  1 . 
     FIG. 6 is a section view taken along line  6 — 6  in FIG.  1 . 
     FIG. 7 is a right side view of the reciprocating saw taken along line  7 — 7  in FIG.  5 . 
     FIG. 8 is a section view taken along line  8 — 8  in FIG.  5 . 
     FIG. 9 is a section view taken along line  9 — 9  in FIG.  5 . 
     FIG. 10 is a perspective assembly view of the housing insert, follower member, eccentric cam member and adjustment knob. 
     FIG. 11 is a partial side view of the internal drive components of the reciprocating saw of FIG. 1 with the guide member in a neutral or non-rocking position. 
     FIG. 12 is a partial side view of the internal drive components of the reciprocating saw of FIG. 1 with the guide member in an up-cutting position. 
    
    
     DETAILED DESCRIPTION 
     FIGS. 1 and 2 illustrate a reciprocating saw  20  embodying the present invention. The reciprocating saw  20  generally includes a main housing  22 , a spindle  24  reciprocatably mounted within the housing  22 , and a counterweight  26  reciprocatably mounted with the housing  22 . The spindle  24  includes a front end  28  that supports a saw blade  30 , which is designed to cut in a cutting direction  32  (i.e., in the direction of the saw teeth) opposite a non-cutting direction  34 . The spindle  24  reciprocates the saw blade  30  through a cutting stroke (usually toward the housing  22 ) and a return stroke (usually away from the housing  22 ). The counterweight  26  provides a vibration-reducing force that at least partially counteracts the forces created by movement of the spindle  24  and the saw blade  30 . 
     A drive means in the form of an electric motor (not shown) is mounted in the housing  22 . The motor includes a drive pinion  36  that engages a gear  38  mounted on a jack shaft  40  that is rotatably mounted within the housing  22 . A wobble shaft  42  is positioned over the jack shaft  40  and is designed to drive primary and secondary wobble plates  44 , 46  in a conventional manner. The primary wobble plate  44  includes a primary drive arm  48  that extends through a slot  50  (FIG. 6) in the counterweight  26  to drivingly engage the reciprocating spindle  24 . The secondary wobble plate  46  includes a secondary drive arm  52  that drivingly engages the counterweight  26 . 
     In addition to being mounted for reciprocating motion, the reciprocating spindle  24  is also mounted for rocking motion relative to the housing  22 . Such rocking motion is facilitated by a spherical bearing sleeve  54  pivotably mounted within the housing  22 . The spherical bearing sleeve  54  rocks relative to the housing  22 , and the reciprocating spindle  24  reciprocates through the bearing sleeve  54 . In should be appreciated that, instead of a spherical bearing sleeve  54 , the bearing sleeve  54  could comprise a plane bearing sleeve mounted to the housing  22  for pivoting motion about a horizontal axis. 
     The illustrated reciprocating spindle  24  is designed to move in three distinct motions: a down-cutting rocking motion, a neutral or non-rocking motion, and an up-cutting rocking motion. FIGS. 1 and 2 illustrate the down-cutting rocking motion. Such motion is generated due to the interconnection between the spindle  24  and an inclined track member  56 . Such interconnection is provided by the interconnection between a rear end  58  of the spindle  24  and the counterweight  26 , and further by the interconnection between the counterweight  26  and the inclined track member  56 . More specifically, the rear end  58  of the spindle  24  is designed to be supported by and to slide within the counterweight  26 . Accordingly, any oblique motion (i.e., angled relative to the longitudinal extent of the reciprocating spindle  24 ) of the counterweight  26  will result in oblique motion of the rear end of the spindle  24  and rocking motion of the spindle  24  about the spherical bearing sleeve  54 . 
     Referring to FIG. 5, in addition to riding on the reciprocating spindle  24 , the counterweight  26  is slidably interconnected with the track member  56 . In this regard, two follower members in the form of bearings  60  are secured to opposing sides of the counterweight  26  and slidably engage a slot  62  in the track member  56 . Because the track member  56  is inclined relative to the longitudinal extent of the counterweight  26  (as shown in FIG.  1 ), the sliding interaction between the counterweight  26  and the track member  56  will result in oblique movement of the counterweight  26  as the counterweight  26  is reciprocated within the housing  22 . More specifically, as the counterweight  26  is moved from the position shown in FIG. 1 to the position shown in FIG. 2, the counterweight  26  moves downwardly (as viewed in FIGS. 1 and 2) within the housing  22 , resulting in upward movement of both the front end  28  of the spindle  24  and the corresponding saw blade  30 . During this upward movement of the saw blade  30 , the spindle  24  is being extended. As the spindle  24  is being retracted, the counterweight  26  is extended and moved upward slightly, following the track member  56 . Such upward movement of the counterweight  26  results in downward movement of the saw blade  30 . Accordingly, it can be seen that the saw blade  30  moves downward slightly (i.e., in the cutting direction  32 ) during the cutting stroke, and upward slightly (i.e., in the non-cutting direction  34 ) during the return stroke. However, the cutting stroke and return stroke occur along the same path, and therefore the path of the saw blade  30  is not orbital. 
     In the illustrated embodiment, the slot  62  in the track member  56  is substantially linear. Alternatively, the slot could be curved. 
     Turning to FIG. 6, in order to accommodate oblique movement of the counterweight  26 , the interconnection between the secondary drive arm  52  and the counterweight  26  is provided by a spherical slide bearing  64 . More specifically, the spherical slide bearing  64  provides for rocking motion between the secondary drive arm  52  and the counterweight  26 , and the secondary drive arm  52  is also slidable within the spherical slide bearing  64  to accommodate transverse movement of the counterweight  26  relative to the secondary drive arm  52 . Similarly, the primary drive arm  48  is interconnected with the spindle  24  by a spherical slide bearing (not shown). 
     In order to allow the path of the saw blade  30  to be adjusted, the angle of the track member  56  is adjustable. More specifically, referring to FIGS. 3-5 and  7 - 9 , the track member  56  is pivotally mounted to a housing insert  66  by a pivot member  68 . Adjustment of the angle of the track member  56  is accomplished by rotating an adjustment knob  70 . The adjustment knob  70  can be rotated to provide rotation to an eccentric cam member  72  having an eccentric pin  74  that slidably engages an adjustment slot  76  in the track member  56 . As the eccentric cam member  72  is rotated, the eccentric pin  74  provides transverse movement to the front end  78  of the track member  56 , thereby causing rotation of the track member  56  about the pivot member  68 . 
     Referring to FIG. 10, to secure the position of the track member  56 , the adjustment knob  70  is provided with two teeth  80  designed to selectively engage three pairs of corresponding recesses  82  in the housing insert  66 . The adjustment knob  70  is biased toward the housing insert  66  by a spring  84  and a corresponding spring stop  86  secured to the eccentric cam member  72 . Rotation of the adjustment knob  70  is accomplished by pulling the adjustment knob  70  away from the housing insert  66  until the teeth  80  are disengaged from the recesses  82  in the housing insert  66 . Subsequently, the adjustment knob  70  can be rotated until the teeth  80  are aligned with a different pair of recesses  82 . The adjustment knob  70  can then be released whereby the spring  84  will force the adjustment knob  70  and corresponding teeth  80  toward the housing insert  66  and into the corresponding recesses  82 . The positions of the three pairs of recesses  82  in the housing insert  66  correspond with the three desired motions of the saw blade  30 : down-cutting rocking motion, neutral or non-rocking motion, and up-cutting rocking motion. 
     FIG. 11 illustrates the reciprocating saw  20  with the track member  56  in the neutral or non-rocking position, resulting in movement of the front end  28  of the reciprocating spindle  24  in a path different than described above with respect to FIG.  1 . Such positioning of the track member  56  is accomplished by rotating the adjustment knob  70 , as described above in more detail. With the track member  56  in this position, the counterweight  26  and spindle  24  will not significantly rock about the spherical bearing sleeve  54 , thereby resulting in a neutral or non-rocking motion of the saw blade  30 . The neutral motion of the saw blade  30  is generally illustrated in FIG. 11 with the fully extended position of the saw blade  30  shown in solid lines and the fully retracted position of the saw blade  30  shown in broken lines. With the track member  56  in this position, the reciprocating saw  20  can be used for either up-cutting (as illustrated) or down-cutting. 
     FIG. 12 illustrates the reciprocating saw  20  with the track member  56  positioned in an up-cutting rocking position, resulting in movement of the front end  28  of the reciprocating spindle  24  in a path different than described above with respect to FIGS. 1 and 11. As noted above, such positioning of the track member  56  is accomplished by rotating the adjustment knob  70  to the appropriate position. With the track member  56  in this position, the saw blade  30  will follow the illustrated path, with the fully extended position of the saw blade  30  shown in solid lines and the fully retracted position of the saw blade  30  shown in broken lines. With the track member  56  in this position, the reciprocating saw  20  can be used for up-cutting in a cutting direction opposite that shown in FIG.  1 . 
     To summarize, the down-cutting rocking motion of the saw blade  32  is illustrated in FIGS. 1 and 2. During the cutting stroke (moving from the position shown in FIG. 2 to the position shown in FIG.  1 ), the spindle  24  is retracted, and the counterweight  26  moves upwardly along the track member  56 . As a result, a point on the saw blade (e.g., the tip of the saw blade  32 ) follows a curvilinear path, moving both toward the housing  22  (to the right in FIGS. 1 and 2) and downwardly (in the cutting direction  32 ). During the return stroke (moving from the position shown in FIG. 1 to the position shown in FIG.  2 ), the tip of the saw blade  32  returns along this curvilinear path (moves away from the housing  22  (to the left in FIGS. 1 and 2) and upwardly (in the non-cutting direction  34 )) as the spindle  24  is extended and as the counterweight  26  moves downwardly along the track member  56 . The tip of the saw blade  32  thus follows the same curvilinear path in the return stroke and in the cutting stroke. 
     The neutral, non-rocking motion of the saw blade  32  is illustrated in FIG.  11 . During the cutting stroke (from the position shown in solid lines to the position shown in broken lines), the spindle  24  is retracted, and the counterweight  26  moves along the neutrally-positioned track member  56 . As a result, the tip of the saw blade  32  follows a linear path, moving only toward the housing  22  (to the right in FIG.  11 ). During the return stroke (moving from the position shown in broken lines to the position shown in solid lines), the tip of the saw blade  32  returns along this linear path (moving only away from the housing  22  (to the left in FIG. 11) as the spindle  24  is extended and as the counterweight  26  moves along the neutrally-positioned track member  56 . The tip of the saw blade  32  thus follows the same linear path in the return stroke and in the cutting stroke. 
     Finally, the up-cutting rocking motion of the saw blade  32  is illustrated in FIG.  12 . During the cutting stroke (moving from the position shown in solid lines to the position shown in broken lines), the spindle  24  is retracted, and the counterweight  26  moves downwardly along the track member  56 . As a result, the tip of the saw blade  32  follows a curvilinear path (different from the curvilinear path illustrated in FIGS.  1  and  2 ), moving both toward the housing  22  (to the right in FIG. 12) and upwardly. During the return stroke (in FIG. 12, moving from the position shown in broken lines to the position shown in solid lines), the tip of the saw blade  32  returns along this curvilinear path (moves away from the housing  22  (to the left in FIG. 12) and downwardly) as the spindle  24  is extended and as the counterweight  26  moves upwardly along the track member  56 . The tip of the saw blade  32  thus follows the same curvilinear path in the return stroke and in the cutting stroke. 
     The foregoing description of the present invention has been presented for purposes of illustration and description. Furthermore, the description is not intended to limit the invention to the form disclosed herein. Consequently, variations and modifications commensurate with the above teachings, and the skill or knowledge of the relevant art, are within the scope of the present invention. The embodiments described herein are further intended to explain best modes known for practicing the invention and to enable others skilled in the art to utilize the invention in such, or other, embodiments and with various modifications required by the particular applications or uses of the present invention. It is intended that the appended claims be construed to include alternative embodiments to the extent permitted by the prior art.