Oscillating scissors

Abstract

A reciprocating power tool comprising: a camshaft rotatably driven by a motor, the camshaft having a first cam nose and a second cam nose, the camshaft defining a central axis, and the first cam nose and the second cam nose being rotationally offset from each other about the central axis of the camshaft; an inner shaft assembly comprising: a first connecting member functionally coupled to the first cam nose, the first connecting member having a first engagement interface; a first shaft coupled to the first engagement interface and reciprocated by the first connecting member; and a first blade having an outer circumference defined by a first plurality of cutting teeth, the first blade being coupled to the first shaft;and an outer shaft arrangement comprising: a second connecting member functionally coupled to the second cam, the second connecting member having a second engagement interface; a second shaft coupled to the second engagement interface and reciprocated by the second connecting member; and a second blade having an outer circumference defined by a second plurality of cutting teeth, the second blade being coupled to the second shaft, the first connecting member, the second connecting member, the first shaft, and the second shaft each defining a center of mass, and the centers of mass of the first connecting member, the second connecting member, the first shaft, and the second shaft all lying within 1 centimeter (cm) of a center-of-mass axis.

Description

FIELD The present disclosure relates generally to outdoor power equipment and, more particularly, to reciprocating shears. BACKGROUND Landscaping and garden maintenance were traditionally performed by hand using non-powered hand tools. Over time, advances have been made in the introduction of powered hand tools, such as powered lawn mowers, powered edgers, powered string trimmers, powered dethatchers, powered blowers, and the like. The use of powered hand tools has significantly reduced the time and effort required for landscaping. Advances in powered hand tools have led to more efficient power tools that provide greater convenience for the user. Reciprocating power tools are used for trimming, edging, and bordering. Reciprocating power tools generally use multiple blades that move relative to each other. Each movement can be referred to as a stroke. Each blade has a plurality of teeth. The teeth are spaced apart by gaps. As the blades move relative to each other, material is fed into the gaps between the blades and subsequently cut by the teeth. At the end of the stroke, the blades then move in the opposite direction, cutting more material that has been fed into the gaps previously occupied by the teeth. This process is repeated several times per minute, up to 3,000 times per minute. The high-speed operation of a reciprocating power tool creates an imbalance that results in vibrations that are transmitted to the user. With prolonged use, these vibrations can become uncomfortable and prevent the user from completing a landscaping job. Accordingly, improved reciprocating power tools are desired in engineering. Reciprocating shears, in particular, that offer smoother handling and lower vibrations would be advantageous. SHORT DESCRIPTION Aspects and advantages of the invention according to the present disclosure will be set forth in part in the description which follows, or may be obvious from the description, or may be learned by practical application of the technology. According to one embodiment, a reciprocating power tool is provided. The reciprocating power tool includes a camshaft rotatably driven by a motor, the camshaft including a first cam lobe and a second cam lobe, the camshaft defining a central axis, and the first cam lobe and the second cam lobe being rotationally offset from each other about the central axis of the camshaft; an inner shaft assembly comprising: a first link operatively coupled to the first cam lobe, the first link having a first engagement interface; a first shaft coupled to the first engagement interface and reciprocally driven by the first link; and a first blade having an outer periphery defined by a first plurality of cutting teeth, the first blade coupled to the first shaft;and an outer shaft assembly comprising: a second connecting member operatively coupled to the second cam lobe, the second connecting member having a second engagement interface; a second shaft coupled to the second engagement interface and reciprocally driven by the second connecting member; and a second blade having an outer periphery defined by a second plurality of cutting teeth, the second blade coupled to the second shaft, the first connecting member, the second connecting member, the first shaft, and the second shaft each defining a center of mass, and the centers of mass of the first connecting member, the second connecting member, the first shaft, and the second shaft all being within 1 centimeter (cm) of a center of mass axis. In accordance with another embodiment, a reciprocating power tool is provided. The reciprocating power tool includes a first blade and a second blade, the first blade being driven by a first shaft assembly, the second blade being driven by a second shaft assembly, the first and second blade assemblies being reciprocally driven by a camshaft, the first shaft assembly defining a first moment of inertia, the second shaft assembly defining a second moment of inertia, and the first and second moments of inertia being within 5% of each other. In accordance with another embodiment, a reciprocating power tool is provided. The reciprocating power tool includes a first blade; a second blade coaxially aligned with the first blade; and a slide plate removably connected to one of the first and second blades, the slide plate being selected from a plurality of slide plates each defining a different height. These and other features, aspects, and advantages of the present invention will become more fully understood with reference to the following description and the appended claims. The accompanying drawings, which are incorporated in and constitute a part of this description, illustrate embodiments of the technology and, together with the description, serve to explain the principles of the technology. BRIEF DESCRIPTION OF THE DRAWINGS A complete and enabling disclosure of the present invention, including the best mode of making and using the present systems and methods directed to one skilled in the art, is set forth in the description that refers to the accompanying figures, in which: Fig. 1 is a perspective view of a reciprocating power tool in accordance with embodiments of the present disclosure; Fig. 2 is an enlarged view of a portion of the reciprocating power tool in accordance with embodiments of the present disclosure; Fig. 3 is a cross-sectional view of the portion of the reciprocating power tool in accordance with embodiments of the present disclosure, taken along line AA in Fig. 2; Fig. 4 is a plan view of the portion of the reciprocating power tool in accordance with embodiments of the present disclosure, taken with the housing cover removed; Fig.5 is a perspective view of a connecting member associated with the reciprocating power tool according to embodiments of the present disclosure; FIG. 6 is a perspective view of a connecting member associated with the reciprocating power tool in accordance with embodiments of the present disclosure; FIG. 7 is a shaft connected to the reciprocating power tool according to embodiments of the present disclosure; FIG. 8 is a shaft associated with the reciprocating power tool according to embodiments of the present disclosure; FIG. 9 is a side view of a portion of the reciprocating power tool according to embodiments of the present disclosure, including a first slide plate; FIG.10 is a side view of a portion of the reciprocating power tool according to embodiments of the present disclosure with a second slide plate; FIG. 11 is a perspective cross-sectional view of a portion of the reciprocating power tool according to embodiments of the present disclosure, taken along line BB in FIG. 2; FIG. 12 is a plan view of a blade of the reciprocating power tool according to embodiments of the present disclosure; FIG. 13 is a side view of an edger according to embodiments of the present disclosure; FIG. 14 is a schematic cross-sectional view of a portion of the reciprocating power tool according to embodiments of the present disclosure; FIG. 15 is a plan view of a reciprocating blade set of the reciprocating power tool according to embodiments of the present disclosure in a first position; FIG.16 is a top view of the reciprocating blade set of the reciprocating power tool according to embodiments of the present disclosure in a second position; FIG. 17 is a top view of the reciprocating blade set of the reciprocating power tool according to embodiments of the present disclosure in a third position; and FIG. 18 is a top view of the reciprocating blade set of the reciprocating power tool according to embodiments of the present disclosure in a fourth position. DETAILED DESCRIPTION Reference will now be made in detail to embodiments of the present invention, one or more examples of which are illustrated in the drawings. The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Furthermore, each example is given to illustrate and not to limit the technology. Indeed, it will be apparent to those skilled in the art that modifications and variations may be made in the present technology without departing from the scope or spirit of the claimed technology. For example, features shown or described as part of one embodiment may be used with another embodiment to yield yet another embodiment.It is therefore intended that the present disclosure encompass such modifications and variations as fall within the scope of the appended claims and their equivalents. Numerical and letter designations are used throughout the detailed description to refer to features in the drawings. The same or similar designations in the drawings and description have been used to refer to the same or similar parts of the invention. The terms "first," "second," and "third" may be used interchangeably herein to distinguish one component from another and are not intended to denote the location or importance of any individual component. The singular forms "a," "an," and "the" include plural designations unless the context clearly indicates otherwise. The terms "coupled," "attached," "attached to," and the like refer to direct coupling, fixation, or attachment as well as indirect coupling, fixation, or attachment via one or more intermediate components or features, unless otherwise noted herein. The terms "comprises," "includes," "includes," "includes," "has," "having," or any other variation thereof, are intended to cover non-exclusive inclusion.For example, a process, method, article, or apparatus that includes a list of features is not necessarily limited to those features, but may include other features not explicitly listed or pertinent to the process, method, article, or apparatus. Unless explicitly stated otherwise, "or" refers to an inclusive or and not an exclusive or. For example, a condition A or B is satisfied if one of the following conditions is true: A is true (or present) and B is false (or absent), A is false (or absent) and B is true (or present), and both A and B are true (or present). Terms of approximation such as "approximately," "generally," "approximately," or "substantially" include values that are within ten percent above or below the specified value. When used in connection with an angle or direction, such terms include values that are within ten degrees greater or less than the specified angle or direction. For example, "generally vertical" includes directions within ten degrees of vertical in any direction, e.g., clockwise or counterclockwise. Benefits, other advantages, and solutions to problems are described below with reference to specific embodiments. However, the benefits, advantages, solutions to problems, and features that may cause an advantage, benefit, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature of any or all of the claims. Generally, the reciprocating power tools described herein drive reciprocating blades to cut material. The blades include two blades reciprocated by first and second coaxially extending shaft assemblies. The shaft assemblies are driven by a camshaft coupled to a drive shaft extending from a motor. The components of the first and second shaft assemblies have similar masses, moments of inertia, and center of gravity heights. Furthermore, the first and second shaft assemblies include components whose centers of mass are all arranged along a straight line corresponding to an axis of rotation of those components. The reciprocating power tool can transmit less vibration and shock to the user, resulting in a better user experience. Fig. 1 shows a reciprocating power tool 100 in accordance with an exemplary embodiment. The reciprocating power tool 100 can be used for trimming, edging, pruning, cutting, and many other types of landscaping and gardening. The reciprocating power tool 100 is lightweight and hand-portable and includes one or more user-engageable areas, such as a first handle 102 and a second handle 104, for holding and maneuvering the reciprocating power tool 100 across a work area. In some cases, the reciprocating power tool 100 can be used with a harness (not shown), such as a single or double shoulder harness, to assist operators who work for long periods or who cannot easily support and maneuver the weight of the reciprocating power tool 100. The reciprocating power tool 100 generally includes a housing 106, a working head 108, and a shaft 110 extending between the housing 106 and the working head 108. The first handle 102 may be at least partially formed by the housing 106. The second handle 104 may be spaced from the first handle 102 and disposed on the shaft 110. The housing 106 defines an interior space 112 in which a motor 114 is disposed. The motor 114 is shown schematically in Fig. 1 and need not be oriented, sized, or arranged as shown. The motor 114 may be a DC electric motor, such as a brushless DC electric motor. The motor 114 may be powered by a power source, such as a removable battery 116, an integrated battery (not shown), a cable connected to an external outlet, or another power source. In some cases, the power source may include a plurality of power sources, such as two removable batteries 116. In Fig.1, only one removable battery 116 is illustrated, however, it should be understood that certain embodiments of the reciprocating power tool 100 may utilize dual battery configurations to increase power at the workhead 108 and extend operating life between charges. The battery 116 may include a battery terminal 118 connected to a housing terminal (not shown) to electrically couple the battery 116 to the motor 114. A power transmission system, such as a power cable or wiring harness 120, may extend from the housing terminal to the motor 114 to supply power to the motor 114 when the battery 116 is connected to the housing 106. Using the power provided by battery 116, an output shaft 122 of motor 114 can selectively drive a distal end of a drive shaft 124 when an operator pulls a trigger 126, located, for example, on first handle 102. In some cases, trigger 126 can have variable input sensitivity so that the operator can control the speed of motor 114 by adjusting a relative position of trigger 126. When the operator pulls trigger 126, the speed of motor 114 increases, resulting in faster rotation of drive shaft 124. Conversely, when the operator releases trigger 126, the speed of motor 114 decreases, resulting in a slower rotating drive shaft 124. A safety switch 128 can also be used to prevent motor 114 from inadvertently driving drive shaft 124. The drive shaft 124 extends from the housing 106 through the shaft 110 and is connected to the workhead 108 to drive one or more blades, as described in more detail below. In one embodiment, the relative position of the housing 106 and the workhead 108 may be adjustable to allow for customized positioning and to adapt to different users and functions of the workhead 108. For example, the shaft 110 may have an adjustable length so that the housing 106 and the workhead 108 can be moved together or apart. The housing 106 and the workhead 108 may also, or alternatively, be rotatable relative to each other to allow for different angular orientations of the workhead 108. For example, the workhead 108 may sometimes be used in a horizontal orientation, while at other times it may be used in a vertical orientation.The user may wish to maintain the positioning of the housing 106 to allow for easy gripping and operability. To enable these and other adjustments, the shaft 110 may include an adjustment member 130 that locks and unlocks the segments 110A and 110B of the shaft 110 relative to each other, allowing the segments 110A and 110B to slide or rotate relative to each other. Once the shaft 110 has reached the desired length or orientation, the adjustment member 130 may be locked to prevent further changes. The drive shaft 124 may similarly include an adjustable interface to allow adjustments to the shaft 110. As a non-limiting example, the drive shaft 124 may include a plurality of telescoping segments rotatably connected to one another, e.g., by a splined interface.The telescopic segments can rotate together through the pinned interface and can also slide telescopically relative to each other to allow adjustments to the shaft 110. Fig. 2 shows a close-up of the working head 108 according to an exemplary embodiment. The working head 108 may include a housing 132 defining an interior volume 134 (Fig. 4). The housing 132 may be formed from a plurality of discrete, separate components, such as a base 134 and a cover 136 removably connected to the base 134. As a non-limiting example, the base 134 and the cover 136 may be selectively connected to each other by one or more fasteners 138, such as bolts, snap fasteners, retaining rings, or the like. The shaft 110 defines a proximal end 140 connected to the housing 132. In some cases, the housing 132 may define an opening 142 into which the shaft 110 extends. Once the shaft 110 is properly positioned within the opening 142, one or more fasteners 144 are tightened to compress the opening 142 and form an interference fit between the housing 132 and the shaft 110, thereby securing the shaft 110 to the working head 108.In other examples, the shaft 110 may be secured within the opening 142 by an adhesive disposed between the shaft 110 and a sidewall of the opening 142, a threaded interface between the shaft 110 and the sidewall of the opening 142, a threaded or unthreaded fastener extending through the shaft 110 and the housing 132, or by using any other suitable method or device. In one embodiment, a blade guard 146 extends from the shaft 110 or the housing 132, or both. In the illustrated embodiment, the blade guard 146 is connected to the housing 132 using the one or more fasteners 144 as described above. The blade guard 146 protects the operator from flying debris and from inadvertent contact with a reciprocating blade set 148 during operation of the reciprocating power tool 100. The reciprocating blade set 148 generally includes a plurality of blades, such as a first blade 150 and a second blade 152. The first and second blades 150 and 152 reciprocate relative to each other during operation of the reciprocating power tool 100, as described in more detail below. The first and second blades 150 each include a central hub 154 that rotates about an axis of rotation A. A plurality of teeth 156 extend radially outward from the central hub 154 of each of the first and second blades 150 and 152. Each of the plurality of teeth 156 includes at least one cutting edge 158 defined along a lateral side of the tooth 156. In one embodiment, each of the plurality of teeth 156 can have a plurality of cutting edges 158, such as a first cutting edge 158A defined along a first lateral aspect of the tooth 156 and a second cutting edge 158B defined along a second lateral aspect of the tooth 156 opposite the first lateral aspect. A circumferential gap 160 is defined between adjacent teeth 156 of the first and second blades 150 and 152.The gap 160 of the first and second blades 150 and 152 may together form an effective gap whose size changes during the reciprocating movement of the blade set 148. In some cases, all effective gaps of the reciprocating blade set 148 may always be the same size. In other cases, the reciprocating blade set 148 may simultaneously have effective gaps of different sizes. For example, the teeth 156 may have widths measured circumferentially about the axis A that are smaller than the widths of the gaps 160 measured circumferentially about the axis A. This has the consequence that when one effective gap becomes smaller, an adjacent effective gap becomes larger, and vice versa. For simplicity, the following description refers to an embodiment in which the effective gaps of the reciprocating blade set 148 are all the same size, i.e.The teeth 158 and the gaps 160 are all of a common size; however, it is understood that other operating schemes are also included herein. When the first and second blades 150 and 152 are aligned in a first relative rotational position, the gaps 160 of the first and second blades 150 and 152 are aligned such that the effective gap size of the reciprocating blade set 148 is equal to a gap size of each of the first and second blades 150 and 152. When the first and second blades 150 and 152 are aligned in a second relative rotational position, the gaps 160 of the first and second blades 150 and 152 are offset from each other such that the effective gap size of the reciprocating blade set 148 is zero. When the reciprocating blade set 148 is in the first relative rotational position, material such as grass, branches, leaves, and the like can enter the effective gaps of the reciprocating blade set 148.As the reciprocating blade set 148 moves from the first relative rotational position to the second relative rotational position, the effective gap size decreases. As a result, any material within the effective gap is compressed between the cutting edges 158 of the converging teeth 156, i.e., a tooth 156 of the first blade 150 and a tooth 156 of the second blade 152. When the reciprocating blade set 148 reaches the second relative rotational position, any material previously contained within the effective gap is cut by the converging teeth 156 of the first and second blades 150 and 152. In some cases, the first and second blades 150 and 152 may continue to rotate relative to each other beyond the second relative rotational position. This may create effective gaps between various teeth 156 of the first and second blades 150 and 152. In a final relative rotational position, the first and second blades 150 and 152 begin to rotate in opposite directions relative to each other. The process described above is repeated, this time in reverse, and the material contained in the effective gaps is cut by the converging teeth 156 of the first and second blades 150 and 152. Each rotational movement of the first and second blades 150 and 152 may be referred to as a stroke.At full operating speed, the reciprocating power tool 100 is capable of at least 500 strokes per minute (SPM), for example, at least 750 SPM, for example, at least 1000 SPM, for example, at least 1250 SPM, for example, at least 1500 SPM, for example, at least 1750 SPM, for example, at least 2000 SPM, for example, at least 2250 SPM, for example, at least 2500 SPM, for example, at least 2750 SPM. Fig. 3 shows a side cross-sectional view of the work head 108, taken along line AA in Fig. 2 . As shown, the drive shaft 124 enters the housing 132 of the work head 108. The drive shaft 124 is coupled to a bevel pinion 162 having a toothed surface 164. The bevel pinion 162 is supported relative to the housing 132 by one or more bearings 166, such as ball bearings, needle bearings, or the like. The torque of the motor 114 (Fig. 1 ) is transmitted through the drive shaft 124 to rotate the bevel pinion 162. The toothed surface 164 of the bevel pinion is meshed with a complementary toothed surface 168 of a bevel gear 170. The motor torque is transmitted by the bevel pinion 162 to drive the bevel gear 170 about a rotational axis B. The bevel gear 170 is coupled to a camshaft 172. The bevel gear 170 may, for example, define a central opening 174 through which the camshaft 172 extends at least partially. The camshaft 172 may be rotationally connected to the bevel gear 170, e.g., by a spline, an interference fit, a threaded or non-threaded fastener, an adhesive, or the like. The bevel gear 170 may transmit torque from the engine 114 (Fig. 1) to drive the camshaft 172 for rotation about the rotational axis B. The camshaft 172 may include an elongated body 176 defining a first bearing interface 178, a first cam lobe 180, a second cam lobe 182, a bevel gear interface 184, and a second bearing interface 186. The first and second bearing interfaces 178 and 186 may be disposed at opposite ends of the elongated body 176 and may each be supported by a bearing 188 and 190, respectively, to allow the camshaft 172 to rotate about the rotational axis B. The first and second cam lobes 180 and 182 may be disposed between the bearings 188 and 190. In one embodiment, the first and second cam lobes 180 and 182 are disposed between the bevel gear interface 184 and the bearing 188. The first cam lobe 180 is shown above the second cam lobe 182. The first cam lobe 180 may be referred to as the upper cam lobe and the second cam lobe 180 may be referred to as the lower cam lobe. The first and second cam lobes 180 and 182 can be rotated relative to one another about the central axis of the camshaft 172, i.e., the rotational axis B. For example, the first and second cam lobes 180 and 182 can be rotated relative to one another by at least 10°, for example at least 45°, for example at least 90°, for example at least 145°. In one embodiment, the first and second cam lobes 180 and 182 are rotated relative to one another by 180°. Accordingly, a cam shoulder associated with the first cam lobe 180 can be aligned with the second cam lobe 182, viewed along the rotational axis B, and a cam shoulder associated with the second cam lobe 182 can be aligned with the first cam lobe 180, viewed along the rotational axis B. Fig. 4 shows a top view of the working head 108 with the cover 136 removed, exposing the interior volume 134 of the working head 108. As illustrated, the first and second cam lobes 180 and 182 are offset from the rotational axis B in equal and opposite directions. Each of the first and second cam lobes 180 and 182 defines a generally arcuate outer perimeter 192. In the illustrated embodiment, the outer perimeters 192 of both the first and second cam lobes 180 and 182 lie along circles. 3 and 4, the first cam lobe 180 interfaces with a first cam lobe receiving portion 194 of a first link 196. As described below, the first link 196 can transmit motion from the first cam lobe 180 to the first blade 150 to reciprocate the first blade 150 about the rotational axis A (FIG. 2). The first cam lobe receiving portion 194 can define a recess or opening in the first link 196 that can receive at least a portion of the first cam lobe 180. In one embodiment, the first cam lobe receiving portion 194 is an opening that extends through the entire thickness of the first link 196.The thickness of the first connecting member 196 may be sized to match or substantially match the thickness of the first cam lobe 180 such that the opposite ends of the first cam lobe 180 are coplanar with the opposite ends of the first connecting member 196. The first cam receiving portion 194 may have an elongated shape (e.g., Fig. 4) to allow 360° rotation of the camshaft 172. In one embodiment, the first cam receiving portion 194 may have a width measured perpendicular to the rotational axis B that is approximately equal to or slightly greater than the maximum dimension (e.g., diameter) of the first cam body 180.In one embodiment, the first cam lobe receiving portion 194 may define a length, measured perpendicular to the rotational axis B and the width of the first cam lobe receiving portion 194, that is approximately equal to or slightly greater than twice the diameter of the first cam lobe 180 less the diameter of the elongated body 176 at the location from which the first cam lobe 180 protrudes. When the first cam lobe 180 is driven by the camshaft 172 about the rotational axis B, the outer periphery 192 of the first cam lobe 180 abuts a peripheral surface 198 of the first cam lobe receiving portion 194, thereby biasing the peripheral surface 198 of the first link 196 and causing the first link 196 to rotate about a rotational axis C. The drive surfaces 200 and 202 are defined by portions of the peripheral surface 198 that, when biased by the first cam lobe 180, cause rotation of the first link 196 about the rotational axis C. Those portions of the circumferential surface 198 which do not cause the first link 196 to rotate about the rotation axis C when biased by the first cam nose 180 are part of the intermediate surfaces 204 and 206. In the embodiment illustrated in Fig. 4, the circumferential surface 198 is a continuous (closed) surface. That is, the first connecting member 196 includes a body that defines the entire length of the circumferential surface 198, with the drive surfaces 200 and 202 and the intermediate surfaces 204 and 206 forming a continuous surface of the first connecting member 196. In another embodiment, the circumferential surface 198 is a discontinuous (open) surface, with at least a portion of one of the intermediate surfaces 204 or 206 omitted. The second cam lobe 182 may form a similar interface with a second cam lobe receiving portion 208 of a second link 210. Referring to Fig. 3, the second link 210 may be oriented parallel to the first link 196. The second link 210 may be disposed adjacent to the first link 196 and rotate about the rotation axis C as the second cam lobe 182 moves within the second cam receiving portion 208. While the description of the interaction between the second cam lobe 182 and the second link 210 is omitted, it should be understood that the interface between the second cam lobe 182, the second link 210, and the second cam receiving portion 208 may have one or more of the same or similar characteristics as the interface between the first cam lobe 180, the first link 196, and the first cam receiving portion 194. Fig. 5 shows the first connecting member 196 according to an exemplary embodiment. Fig. 6 shows the second connecting member 210 according to an exemplary embodiment. The first connecting member 196 has a first side 212 and a second side 214 spaced from the first side 212 by a thickness of the first connecting member 196. The second connecting member 210 has a first side 216 and a second side 218 spaced from the first side 216 by a thickness of the second connecting member 210. The first side 212 of the first connecting member 196 may be disposed adjacent to the first side 216 of the second connecting member 210. One or both of the first and second links 196 and 210 may include a receiving feature to receive the other of the first and second links 196 and 210 while allowing the first and second links 196 and 210 to be disposed side by side.For example, the receiving feature may include a cut-out lip 220 in the first link 196 to receive a protruding surface 222 of the second link 210. In one embodiment, the first link 196 includes a body 224 defining the first cam-receiving portion 194, an opening 226 defining a first engagement interface 228, and a counterweight portion 230. The first cam-receiving portion 194 may be disposed at a first end 232 of the body 224, and the counterweight portion 230 may be disposed at a second end 234 of the body 224. The first engagement interface 228 may be disposed between the first cam-receiving portion 194 and the counterweight portion 230. In one embodiment, the first engagement interface 228 is disposed closer to the second end 234 of the body 224 than to the first end 232 of the body 224. However, a center of mass CM of the body 224 may be disposed at the first engagement interface 228. In particular, the center of mass CM of the body 224 may be arranged on the axis of rotation C about which the first link 196 moves.In one embodiment, the second link 210 includes a body 236 defining the second cam-receiving portion 208, an opening 238 defining a second engagement interface 240, and a counterweight portion 242. The second cam-receiving portion 208 may be disposed at a first end 244 of the body 236, and the counterweight portion 242 may be disposed at a second end 246 of the body 236. The second engagement interface 240 may be disposed between the second cam-receiving portion 208 and the counterweight portion 242. In one embodiment, the second engagement interface 240 is disposed closer to the second end 246 of the body 236 than to the first end 244 of the body 236. However, a center of mass CM of the body 236 may be disposed at the second engagement interface 240. In particular, the center of mass CM of the body 236 may be arranged on the axis of rotation C around which the second member 210 moves.Referring again to Fig. 3, the first link 196 may be coupled to a first shaft 248, sometimes referred to as an inner shaft, and the second link 210 may be coupled to a second shaft 250, sometimes referred to as an outer shaft. The first and second links 196 and 210 may be rotatably mounted with respect to the first and second shafts 248 and 250, respectively. That is, the rotational movement of the first link 196 created by the movement of the first cam lobe 180 against the drive surfaces 200 and 202 ( Fig. 4 ) causes an equal rotational movement of the first shaft 248. Thus, the reciprocating movement of the first link 196 causes reciprocating movement of the first shaft 248.Similarly, the rotational movement of the second link 210 caused by the movement of the second cam lobe 182 against the drive surfaces (not shown) of the second link 210 causes a like rotational movement of the second shaft 250. Thus, the reciprocating movement of the second link 210 causes a reciprocating movement of the second shaft 250. Fig. 7 shows the first (inner) shaft 248 according to an exemplary embodiment. Fig. 8 shows the second (outer) shaft 250 in accordance with an exemplary embodiment. As described below, at least a portion of the first shaft 248 may be disposed within a portion of the second shaft 250. In one embodiment, the first shaft 248 extends through opposite ends of the second shaft 250. For example, a first portion of the first shaft 248 may extend from a first end of the second shaft 250 and be connected to the first link 196, and a second portion of the first shaft 248 may extend from a second end of the second shaft 250 and be connected to the first blade 150. The first and second shafts 250 and 252 may be arranged coaxially along the rotational axis C and may rotate freely relative to each other about the rotational axis C.The bearing 251 can facilitate a low-friction interface between the first and second shafts 250 and 252 while still maintaining the first and second shafts 250 and 252 in coaxial alignment with each other. Referring to Fig. 7, the first shaft 248 may generally include a hub 252 and a plurality of spokes 254 extending radially outward from the hub 252. In one embodiment, the hub 252 and the spokes 254 may lie along a same or generally same plane, with the plane oriented perpendicular to the rotational axis C. At least some of the spokes 254 define engagement features 256, such as openings, e.g., threaded openings, for coupling the first blade 150 to the first shaft 248 using fasteners 257 (Fig. 3). In the illustrated embodiment, the first shaft 248 includes three spokes 254. In other embodiments, the first shaft 248 may have at least four spokes 254, for example, at least five spokes 254, or even at least six spokes 254. The spokes 254 may be evenly spaced from each other about the rotation axis C. An axle 258 extends from the hub 252 in a direction along the rotational axis C. In one embodiment, the axle 258 is integral with the hub 252. In another embodiment, the axle 258 and the hub 252 are separate parts that are temporarily or permanently connected to each other. The axle 258 defines a length LA1, measured between a first end 260 of the axle 258 and a second end 262 of the axle 258. The axis 258 further defines a width WA1, measured through a largest dimension of the axis 258 in a direction perpendicular to the length LA1. The axle 258 includes a first complementary engagement feature 264 configured to cooperate with the first engagement feature 228 of the first connecting member 196 to rotatably connect the first connecting member 196 and the first shaft 248. In one embodiment, the first engagement feature 228 and the first complementary engagement feature 264 define a wedge-shaped interface. For example, the first engagement feature 228 of the first connecting member 196 ( FIG. 5 ) may have a ridged or toothed profile that mates with a complementary ridged or toothed profile of the first complementary engagement feature 264 on the first shaft 248.To assemble the first connecting member 196 and the first shaft 248 together, the axle 258 and the first engagement feature 228 can be aligned and translated together along the rotational axis C until the first engagement feature 228 and the first complementary engagement feature 264 engage each other. A fastener 266 (FIG. 3) can then be installed on the first shaft 248 to hold the first connecting member 196 on the first shaft 248. In one embodiment, the fastener 266 includes a nut (which may be referred to as an internal shaft nut) that can be threaded onto a threaded interface 268 of the axle 258.The fastener 266 and the interface 268 may alternatively comprise a bayonet interface, a press fit, an adhesive interface, a pin interface in which a pin extends through aligned openings extending through the fastener 266 and the axle 258, a crimped fastener 266, a snap-in retainer such as a snap ring, or the like. Referring to Fig. 8, the second shaft 250 may have a generally similar structure to the first shaft 248. For example, the second shaft 250 may include a hub 270 and a plurality of spokes 272 extending radially outward from the hub 270. In one embodiment, the hub 270 and the spokes 272 may lie along a same or substantially the same plane, with the plane oriented perpendicular to the axis of rotation C. At least some of the spokes 272 define engagement features 274, such as openings, e.g., threaded openings, for coupling the second blade 152 to the second shaft 250 using fasteners 275 (Fig. 3). In the illustrated embodiment, the second shaft 250 includes three spokes 272. In other embodiments, the second shaft 250 may include at least four spokes 272, for example at least five spokes 272 or even at least six spokes 272.The spokes 272 may be evenly spaced from each other about the rotation axis C. An axle 276 extends from the hub 270 in a direction along the axis of rotation C. In one embodiment, the axle 276 is integrated with the hub 270. In another embodiment, the axle 276 and the hub 270 are discrete (separate) parts that are temporarily or permanently connected to each other. The axle 276 defines a length LA2, measured between a first end 278 of the axle 276 and a second end 280 of the axle 276. The axle 276 has an opening 282 extending between the first and second ends 278 and 280. The opening 282 defines a width WA2, measured by a smallest dimension of the opening 282 in a direction perpendicular to the length LA2. The width WA2 of the opening 282 is greater than the width WA1 of the axis 258 of the first shaft 248 such that the axle 258 fits within the opening 282.In one embodiment, WA2 is at least 1.001 WA1, such as at least 1.005 WA1, such as at least 1.01 WA1, such as 1.02 WA1, such as 1.05 WA1. Sufficient spacing between the sidewalls of opening 282 and axis 258 allows for unobstructed relative rotation between the first and second shafts 248 and 250. The length LA1 of axis 258 is greater than the length LA2 of axis 276. In one embodiment, LA1 is at least 1.05 LA2, such as at least 1.1 LA2, such as at least 1.2 LA2, such as at least 1.25 LA2, such as at least 1.3 LA2. The axle 276 includes a second complementary engagement feature 284 configured to cooperate with the second engagement feature 240 of the second link 210 to rotatably connect the second link 210 and the second shaft 250. In one embodiment, the second engagement feature 228 and the second complementary engagement feature 284 define a wedge-shaped interface. For example, the second engagement feature 240 of the second link 210 (Fig. 6) may have a serrated or toothed profile that mates with a complementary serrated or toothed profile of the second complementary engagement feature 284 on the second shaft 250.To install the second link 210 and the second shaft 250 together, the axle 276 and the second shaft 250 can be aligned and translated together along the rotational axis C until the second engagement feature 228 and the second complementary engagement feature 284 engage each other. 3, 7 and 8, the first and second links 196 and 210 may be disposed side by side in a direction along the rotation axis C. In one embodiment, a low-friction interface (not shown) may be disposed between the first and second links 196 and 210 to allow relative movement therebetween. The fastener 266 may prevent the first link 196 from moving in a first direction along the rotation axis C. The compressive force of the fastener 266 passes through the first link 196, reaches the second link 210, and prevents the second link 210 from moving in the first direction along the rotation axis C.In one embodiment, the second shaft 250 may include a structure 286, such as a notch extending circumferentially around the axis 276, that cooperates with a retaining member 288, such as a retaining clip, to prevent the second link 210 from moving in a second direction along the rotational axis C, the second direction being opposite the first direction. When the fastener 266 is tightened along the threaded interface 268, the first and second link members 196 and 210 may self-align relative to the first and second cam lobes 180 and 182.That is, the structure 286, the retaining member 288, and the threaded interface 268 can be arranged such that tightening the fastener 266 to a desired specification effects interface alignment between the first connecting member 196 and the first cam nose 180 and the second connecting member 210 and the second cam nose 182. The axis 276 of the second shaft 250 may include a bearing surface 290 configured to cooperate with one or more bearings 292 to support the second shaft 250 along the rotational axis C. The bearing(s) 292 may include roller bearings, needle bearings, journal bearings, or the like. The bearings 292 may be held in place by a support structure 294, such as a C-shaped retaining ring. The axis 276 of the second shaft 250 may further include a sealing surface 296 configured to engage a seal 298, such as a rotary seal, a lip seal, or the like. The seal 298 may extend between the sealing surface 296 and a sealing surface 300 of the housing 132 to prevent contaminants from entering the interior volume 134 of the housing 132.A seal 302 may be disposed between the first and second shafts 248 and 250 to further prevent contaminants from entering the interior volume 134. 15 through 18 show a plan view of the camshaft 172 and the reciprocating blade set 148 reciprocating during use. In particular, Fig. 15 shows the reciprocating blade set 148 in a first position, Fig. 16 shows the reciprocating blade set 148 in a second position, Fig. 17 shows the reciprocating blade set 148 in a third position, and Fig. 18 shows the reciprocating blade set 148 in a fourth position. The reciprocating blade set 148 moves from the first position to the second position, from the second position to the third position, and from the third position to the fourth position. Once in the fourth position, the reciprocating blade set 148 moves to the first position, and the cycle repeats.Alternatively, the reciprocating blade set 148 can operate in the reverse direction, moving from the fourth position to the third position, from the third position to the second position, and from the second position to the first position. The first and second cam lobes 180 and 182 rotate about the camshaft 172, e.g., the rotational axis B, and drive the first and second links 196 and 210. The first and second links 196 and 210 are coupled to the first and second blades 150 and 152, respectively, of the reciprocating blade set 148 to drive the first and second blades 150 and 152 in opposite directions. According to one embodiment, and as shown in Figures 15 to 18, the teeth 156 of the first and second blades 150 and 152 may be arranged such that the converging teeth 156 of the first and second blades 150 and 152 rotationally overlap in each of the first, second, third, and fourth positions. In this way, the reciprocating blade set 148 may make four cuts during each cycle, e.g., between traveling from the first position back to the first position. In another embodiment, the teeth 156 of the first and second blades 150 and 152 may be rotationally offset from one another or spaced apart such that the converging teeth 156 of the first and second blades 150 and 152 do not overlap in at least one of the first, second, third, or fourth positions (or at any point during travel therebetween). For example, the converging teeth 156 in the first and third positions (Fig.15 and 17 ) and overlap in the second and fourth positions ( FIGS. 16 and 18 ). Alternatively, the converging teeth 156 may rotationally overlap in the second and fourth positions ( FIGS. 16 and 18 ) and rotationally offset in the first and third positions ( FIGS. 15 and 17 ). In this manner, the reciprocating blade set 148 may make fewer than four cuts, e.g., two cuts, during each cycle, e.g., between traveling from the first position back to the first position. With reference to FIGS. 2, 9, and 10, the reciprocating power tool 100 may further include a slide plate 304. The slide plate 304 may be removably connected to the work head 108. The slide plate 304 may be selected from a plurality of slide plates 304, each having a different characteristic. For example, a first slide plate 304A is shown in FIG. 9, and a second slide plate 304B is shown in FIG. 10. The first and second slide plates 304A and 304B may each define a height H1 and H2, respectively. The heights H1 and H2 may be measured in a direction along the rotational axis C of the blades 150 and 152. The heights H1 and H2 are different from each other. As a non-limiting example, H1 may be 1" and H2 may be 3", for example. Other heights can be 1.5", 2", 2.5", 3.5", 4", 4.5", 5", etc.A user can switch between the different slide plates 304 to change the effective cutting height HE of the reciprocating blade set 148 relative to a bottom surface 306 of the slide plate 304. The user can switch from the first slide plate 304A to the second slide plate 304B to increase the effective cutting height HE. Conversely, the user can switch from the second slide plate 304B to the first slide plate 304A to decrease the effective cutting height HE. Fig. 3 shows an exemplary embodiment of the work head 108 without the slide plate 304 connected thereto. As shown, the first shaft 248 defines a recess 308. The recess 308 includes a slide plate engagement point 310 with a threaded interface that threadably receives a complementary slide plate engagement point 312, such as a slide plate retaining bolt 313. The slide plate 304 may have a central opening (not shown) through which the slide plate retaining bolt 313 extends. After aligning the slide plate 304 and the slide plate retaining screw 313 with the recess 308, the user can tighten the slide plate retaining screw 313 with the threaded interface to secure the slide plate 304 relative to the reciprocating power tool 100.To replace the slide plates 304, the user removes the slide plate retaining screw and the current slide plate 304 and repeats the steps described above with another slide plate 304 to secure the other slide plate relative to the reciprocating power tool 100. Fig. 11 shows a perspective cross-sectional view of the work head 108, as viewed along line BB in Fig. 2, with the slide plate 304 connected to the reciprocating power tool 100 according to another exemplary embodiment. As shown, the reciprocating blade set 148 includes a first engagement feature 314 forming the complementary slide plate engagement point. The first engagement feature 314 may be part of the second blade 152 and define an opening or recess extending into the second blade 152. The slide plate 304 may include a second engagement feature 316 configured to releasably cooperate with the first engagement feature 314 to selectively connect the slide plate 304 to the work head 108. For example, the second locking feature 316 may include a flange 318 extending from a main body portion 320 of the slide plate 304.The flange 318 may be radially deflectable relative to the rotational axis C and include a head portion 322 that engages the first engagement feature 314. By deflecting the flange 318, the head portion 322 may move in a direction along the rotational axis C into the opening or recess of the first engagement feature 314. Once the head portion 322 is aligned with the first engagement feature 314, the flange 318 returns to its unloaded state to engage the opening or recess and selectively connect the slide plate 304 to the working head 108. The user can release the sliding plate 304 from the working head 108 by deflecting the flange 318 again so that the head portion 322 can exit the opening or recess so that the sliding plate 304 can be moved away from the working head 108 in a direction along the rotation axis C. 11 and 12, the first blade 150 may include one or more openings 324 through which the second engagement feature 316, e.g., the flange 318 and the head portion 322, may extend when the slide plate 314 is connected to the working head 108. The opening(s) 324 may be sized larger than the second engagement feature 316 in the circumferential direction to allow reciprocating movement between the first and second knives 150 and 152 without the second engagement feature 316 abutting the circumferential ends 326A and 326B of the opening 324. The first and second engagement features 314 and 316 described above may be referred to as an engagement interface 326. In one embodiment, the slide plate 304 may be coupled to the work head 108 through a plurality of engagement interfaces, such as the aforementioned engagement interface 326 and one or more additional engagement interfaces, such as a second engagement interface 328. The engagement interfaces may be evenly spaced about the rotational axis C. Fig. 13 shows an exemplary embodiment of the reciprocating power tool 100 used as an edger 330. The edger 330 includes a reciprocating blade set 332 having the same or similar characteristics as the reciprocating blade set 148 described above. Instead of a continuously rotating cutting tool that rotates 360° around a central point, the reciprocating blade set 332 can operate in a banded rotation range. The cutting teeth 338, arranged along the circumference of the first and second blades 334 and 336, repeatedly converge to cut material located within the effective gap of the first and second blades 334 and 336. A guide wheel 340 can support the reciprocating blade set 332 and allow a user to push the edger 330 across a floor surface below.A guard 342 may cover at least a portion of the reciprocating blade set 332 to prevent flying debris from striking the user. In one embodiment, the edge cutter 330 may be formed by rotating the working head 108 of the reciprocating power tool 100, e.g., using the adjustment member 130 shown in Fig. 1. The guard 342 and the guide wheel 340 may be coupled to the working head 108 or another part of the reciprocating power tool 100 to provide a functional structure for edging operations. The reciprocating power tools 100 described herein can provide an improved user experience. For example, the power tools 100 described herein can transmit less vibration and wobble to the user compared to conventional power tools. Power tools often generate vibration frequencies as a result of motor vibration, shaft and rotational imbalances, center of mass imbalances, center of gravity height imbalances, moment of inertia imbalances, etc. Each of these imbalances creates harmonic resonances that, when combined, transmit vibrations to the user holding the power tool. Prolonged exposure to such vibration forces can cause excessive user fatigue, resulting in premature termination of work activity.The power tools 100 described here reduce user fatigue and enable a longer, more enjoyable working experience. Fig. 14 shows a schematic cross-sectional view of the inner (first) shaft assembly and the outer (second) shaft assembly in accordance with one embodiment. The inner shaft assembly generally includes the first connecting member 196, the first shaft 248, and the first blade 150. The outer shaft assembly generally includes the second connecting member 210, the second shaft 250, and the second blade 152. In one embodiment, the inner shaft assembly further includes the slide plate retaining bolt 313, the fasteners 257, the inner shaft nut 266, and a blade cap. The outer shaft assembly further includes the bushing 251 and the fasteners 275. Tables 1 and 2 show the component characteristics of the inner and outer shaft assemblies. Table 1 - Inner Shaft Assembly Table 1 - Inner Shaft Assembly Inner shaft 16.04 110.00 8 128.328-55.93 6-56.37 Retaining bolt for sliding plate 252910,00820,232-63,80,35 First sheet3162610,008253,008-70,151483 Fastening element 54430,00813,056-634 Blade cap611610,00848,928-78,2348,92 First connecting link1203510,00896,28-17,4655,6 Inner shaft nut 268810,00821,504-10,61,8 TOTAL 581.31630 Table 2 - Outer shaft arrangement Table 2 - Outer shaft arrangement Outer shaft 2528610.008202.288-53.2106.6-56.42 Bearing89310,0085,7152-52,240,43 Second sheet 3157510,008252,6-70,151483,8 Fastening element 54430,00813,056-74,964 Second connecting link1124010,00889,92-22,6855,2 TOTAL 563.61650 According to Table 1, the inner shaft assembly has a mass of 581.3 g and a moment of inertia about the rotation axis C of 1630 kg*mm2. The inner shaft assembly has a system center of gravity height of -56.37 mm. The center of gravity height is measured relative to a plane oriented perpendicular to the rotation axis C and is represented in Fig. 3 by line 344. Negative values for the center of gravity height represent distances below line 344, i.e., in the direction of the reciprocal blade set 148, while positive values represent distances above line 344. Line 344 can be selected at any height along the rotation axis C. According to Table 2, the outer shaft assembly has a mass of 563.6 g and a moment of inertia about the rotation axis C of 1650 kg*mm2. The outer shaft assembly has a system center of gravity height of -56.42 mm. Table 3 shows a comparison of the inner and outer shaft assemblies. Table 3 - Comparison between inner and outer shaft arrangements Table 3 - Comparison between inner and outer shaft arrangements Inner shaft arrangement 581.31630-56.37 Outer shaft assembly 563.61 650-56.42 Deviation 17,820,360,05 Percentage deviation 3.1% 1.25% 0.09% In one embodiment, the inner and outer shaft assemblies may differ in mass by less than 10%, e.g., less than 8%, e.g., less than 6%, e.g., less than 5%, e.g., less than 4%. As shown in Table 3, the inner and outer shafts differ in mass by 17.8 grams, or 3.1%. The inner and outer shaft assemblies may differ in moments of inertia about the rotation axis C by less than 10%, e.g., less than 8%, e.g., less than 6%, e.g., less than 5%, e.g., less than 4%, e.g., less than 2%. The inner and outer shaft assemblies differ in their moments of inertia about the rotation axis C by 20.36 kg*mm2, or 1.25%. As shown in Table 3, the inner and outer shafts may differ in their center of gravity heights by less than 5%, e.g. by less than 4%, e.g. by less than 3%, e.g. by less than 2%, e.g. by less than 1%, e.g. by less than 0.5%, e.g.by less than 0.25%, e.g., by less than 0.2%. As shown in Table 3, the inner and outer shaft arrangements differ in their center of gravity heights by 0.05 mm or 0.09%. Balancing the mass, moment of inertia, and center of gravity height reduces the vibration characteristics generated in the workhead 108 (Fig. 2) during the high-speed reciprocating motion of the first and second blades 150 and 152, thereby reducing the transmission of vibration frequencies to the user holding the first and second handles 102 and 104 (Fig. 1). The user can therefore use the reciprocating power tool for extended periods without experiencing significant fatigue or physical strain. As shown in Fig. 14, each of the first shaft 148, the second shaft 150, the first link 196, the second link 210, the first blade 150, and the second blade 152 defines a center of mass CM. The first shaft 148 defines a first center of mass CM1. The second shaft 150 defines a second center of mass CM2. The first link 196 defines a third center of mass CM3. The second link 210 defines a fourth center of mass CM4. The first blade 150 defines a fifth center of mass CM5. The second blade 152 defines a sixth center of mass CM6.In one embodiment, the centers of mass CM1-6 of the first shaft 148, the second shaft 150, the first link 196, the second link 210, the first blade 150, and the second blade 152 are aligned with an accuracy of ± 2 centimeters (cm) to a center of mass axis 346, which represents a best-fit line of the centers of mass CM of the first shaft 148, the second shaft 150, the first link 196, the second link 210, the first blade 150, and the second blade 152. That is, the centers of mass CM1-6 of the first shaft 148, the second shaft 150, the first link 196, the second link 210, the first blade 150, and the second blade 152 can all be within ± 2 cm of a straight line 346.In another embodiment, the centers of mass CM1-6 of the first shaft 148, the second shaft 150, the first link 196, the second link 210, the first blade 150, and the second blade 152 are aligned within ± 1.5 cm of the center of mass axis 346, for example, within ± 1 cm of the center of mass axis 346, for example, within ± 0.75 cm of the center of mass axis 346, for example, within ± 0.5 cm of the center of mass axis 346, for example, within ± 0.25 cm of the center of mass axis 346, for example, within ± 0.1 cm of the center of mass axis 346, for example, within ± 0.05 cm of the center of mass axis 346, for example, within ± 0.01 cm of the center of mass axis 346.In a particular embodiment, the centers of mass CM1-6 of the first shaft 148, the second shaft 150, the first link 196, the second link 210, the first blade 150, and the second blade 152 all lie on the center of mass axis 346. The center of gravity axis 346 is aligned parallel to the rotation axis C. In one embodiment, the center of gravity axis 344 is coaxial with the rotation axis C. Thus, the effective centers of gravity CM of the inner and outer shaft assemblies can be balanced along the rotation axis C, even though the first and second connecting members 196 and 210 are cantilevered relative to the rotation axis C. To further reduce the transmission of vibrations to the user, the rotational axis B of the camshaft 172 is parallel to the rotational axis C. Due to the proximity of the first and second cams 180 and 182 and their relatively similar size and shape to each other, the effects of the imbalance exhibited by the camshaft 172 during rotation on the system performance and experience are negligible. Further aspects of the invention are provided by one or more of the following embodiments: Embodiment 1. A reciprocating power tool comprising: a camshaft rotatably driven by a motor, the camshaft including a first cam lobe and a second cam lobe, the camshaft defining a central axis, and the first cam lobe and the second cam lobe being rotationally offset from each other about the central axis of the camshaft; an inner shaft assembly comprising: a first link operatively coupled to the first cam lobe, the first link having a first engagement interface; a first shaft coupled to the first engagement interface and reciprocally driven by the first link; and a first blade having an outer periphery defined by a first plurality of cutting teeth,wherein the first blade is coupled to the first shaft; and an outer shaft assembly comprising: a second connecting member operatively coupled to the second cam, the second connecting member having a second engagement interface; a second shaft coupled to the second engagement interface and reciprocally driven by the second connecting member; and a second blade having an outer periphery defined by a second plurality of cutting teeth, the second blade being coupled to the second shaft, the first connecting member, the second connecting member, the first shaft, and the second shaft each defining a center of mass, and the centers of mass of the first connecting member, the second connecting member,the first shaft and the second shaft are all within 1 centimeter (cm) of a center of mass axis. Embodiment 2. The reciprocating power tool of embodiment 1, wherein the first and second blades each define a center of mass, and wherein the centers of mass of the first and second blades are along the center of mass axis. Embodiment 3. The reciprocating power tool of either embodiment 1 or 2, wherein: the inner shaft assembly further comprises: a slide plate bolt configured to releasably couple a slide plate to the first shaft; one or more fasteners coupling the first blade to the first shaft; and an inner shaft nut coupled to the first shaft to maintain the first link connected to the first shaft, and the outer shaft assembly further comprises: a bearing; and one or more fasteners,which couple the second blade to the second shaft. Embodiment 4. The reciprocating power tool of embodiment 3, wherein the inner shaft assembly defines a first moment of inertia, wherein the outer shaft assembly defines a second moment of inertia, and wherein the first and second moments of inertia are within 5% of each other. Embodiment 5. The reciprocating power tool of either embodiment 3 or 4, wherein the inner shaft assembly defines a first height associated with a center of gravity of the inner shaft assembly, wherein the outer shaft assembly defines a second height associated with a center of gravity of the outer shaft assembly, wherein the first and second heights are measured from a reference plane oriented perpendicular to a rotational axis of the inner and outer shaft assemblies.and wherein the first and second heights are within 2% of each other.Embodiment 6. The reciprocating power tool of any of embodiments 3, 4, or 5, wherein the inner shaft assembly defines a first total mass, the outer shaft assembly defines a second total mass, and the first and second total masses are within 5% of each other.Embodiment 7. The reciprocating power tool of any of the preceding embodiments, further comprising a drive shaft having a distal end driven by the motor and a proximal end including a bevel pinion that drives a bevel gear of the camshaft to rotate the camshaft.Embodiment 8. The reciprocating power tool of any of the preceding embodiments,wherein the camshaft is aligned parallel to the center of mass axis. Embodiment 9. The reciprocating power tool according to any one of the preceding embodiments, wherein the first link comprises a body defining a first cam nose receiving portion that receives the first cam nose, an opening defining the first engagement interface, and a counterweight portion, wherein the first engagement interface is disposed between the first cam nose receiving portion and the counterweight portion, and wherein a center of mass of the body is disposed at the first engagement interface. Embodiment 10. The reciprocating power tool according to any one of the preceding embodiments, wherein the second link comprises a body defining a second cam nose receiving portion that receives the second cam nose, an opening defining the second engagement interface,and a counterweight portion, wherein the second engagement interface is disposed between the second cam nose receiving area and the counterweight portion, and wherein a center of mass of the body is disposed at the second engagement interface.Embodiment 11. The reciprocating power tool of any one of embodiments 1 or 2, further comprising a slide plate bolt configured to releasably connect a slide plate to the inner shaft assembly, wherein the slide plate is selectable from a plurality of slide plates, each defining a different guide height.Embodiment 12. The reciprocating power tool of any one of embodiments 1 or 2, wherein the work head includes one or more slide plate engagement points, wherein the reciprocating power tool further comprises a slide plate having one or more complementary slide plate engagement points,which are configured to be releasably coupled to the one or more slide plate engagement points. Embodiment 13. The reciprocating power tool of embodiment 12, wherein the one or more slide plate engagement points each comprise a first engagement feature disposed on the second blade, wherein the one or more complementary slide plate engagement points each comprise a second engagement feature, and wherein each of the first and second engagement features is configured to be releasably coupled to each other to retain the slide plate on the workhead. Embodiment 14. The reciprocating power tool of either embodiment 12 or 13, wherein the first blade has one or more openings through which the one or more complementary slide plate engagement points extend,when the sliding plate is coupled to the second blade. Embodiment 15. The reciprocating power tool having a first blade and a second blade, the first blade being driven by a first shaft assembly, the second blade being driven by a second shaft assembly, the first and second blade assemblies being reciprocally driven by a camshaft, the first shaft assembly defining a first moment of inertia, the second shaft assembly defining a second moment of inertia, and the first and second moments of inertia being within 5% of each other. Embodiment 16. The reciprocating power tool according to embodiment 15, the first shaft assembly defining a first height associated with a center of gravity of the first shaft assembly, the second shaft assembly defining a second height associated with a center of gravity of the second shaft assembly,wherein the first and second heights are measured from a reference plane oriented perpendicular to a rotational axis of the first and second shaft assemblies, and wherein the first and second heights are within 2% of each other. Embodiment 17. The reciprocating power tool of any one of embodiments 15 or 16, wherein the first shaft assembly defines a first total mass, wherein the second shaft assembly defines a second total mass, and wherein the first and second total masses are within 5% of each other. Embodiment 18. The reciprocating power tool of any one of embodiments 15, 16, or 17, further comprising a slide plate removably connected to one of the first or second shaft assemblies, wherein the slide plate is selected from a plurality of slide plates each defining a different guide height. Embodiment 19. A reciprocating power tool,comprising: a first blade; a second blade coaxially aligned with the first blade; and a slide plate removably coupled to one of the first and second blades, wherein the slide plate is selected from a plurality of slide plates each defining a different height.Embodiment 20. The reciprocating power tool of embodiment 19, wherein the first blade is disposed between the second blade and the slide plate, and wherein a portion of the slide plate extends through the first plate to removably couple to the second plate. This written description uses examples to disclose the invention, including the best mode contemplated, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims and may include other examples that occur to one skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements that differ only insubstantially from the literal language of the claims.

Claims

A reciprocating power tool comprising:a camshaft rotatably driven by a motor, the camshaft having a first cam lobe and a second cam lobe, the camshaft defining a central axis, and the first cam lobe and the second cam lobe being rotationally offset from each other about the central axis of the camshaft;an inner shaft assembly comprising:a first link operatively coupled to the first cam lobe, the first link having a first engagement interface;a first shaft coupled to the first engagement interface and reciprocated by the first link; anda first blade having an outer periphery defined by a first plurality of cutting teeth, the first blade coupled to the first shaft;andan outer shaft assembly comprising:a second link operatively coupled to the second cam, the second link having a second engagement interface;a second shaft coupled to the second engagement interface and reciprocated by the second link; anda second blade having an outer periphery defined by a second plurality of cutting teeth, the second blade coupled to the second shaft, the first link, the second link, the first shaft, and the second shaft each defining a center of mass, and the centers of mass of the first link, the second link, the first shaft, and the second shaft all being within 1 centimeter (cm) of a center of mass axis.; The reciprocating power tool of claim 1, wherein the first and second blades each define a center of mass, and wherein the centers of mass of the first and second blades lie along the center of mass axis. The reciprocating power tool of claim 1 or 2, wherein: the inner shaft assembly further comprises: a slide plate bolt configured to releasably couple a slide plate to the first shaft; one or more fasteners connecting the first blade to the first shaft; and an inner shaft nut coupled to the first shaft to maintain the first link connected to the first shaft, and the outer shaft assembly further comprises: a bearing; and one or more fasteners connecting the second blade to the second shaft. The reciprocating power tool of claim 3, wherein the inner shaft assembly defines a first moment of inertia, the outer shaft assembly defines a second moment of inertia, and the first and second moments of inertia are within 5% of each other. The reciprocating power tool according to one of claims 3 or 4, wherein the inner shaft assembly defines a first height associated with a center of gravity of the inner shaft assembly, the outer shaft assembly defining a second height associated with a center of gravity of the outer shaft assembly, the first and second heights being measured from a reference plane oriented perpendicular to a rotational axis of the inner and outer shaft assemblies, and the first and second heights being within 2% of each other. The reciprocating power tool of any one of claims 3, 4 or 5, wherein the inner shaft assembly defines a first total mass, the outer shaft assembly defines a second total mass, and the first and second total masses are within 5% of each other. The reciprocating power tool according to any one of the preceding claims, further comprising a drive shaft having a distal end driven by the motor and a proximal end including a bevel pinion that drives a bevel gear of the camshaft to rotate the camshaft. The reciprocating power tool according to any one of the preceding claims, wherein the camshaft is aligned parallel to the center of mass axis. The reciprocating power tool according to any one of the preceding claims, wherein the first link comprises a body defining a first cam nose receiving area receiving the first cam nose, an opening defining the first engagement interface, and a counterweight portion, wherein the first engagement interface is disposed between the first cam nose receiving area and the counterweight portion, and wherein a center of mass of the body is disposed at the first engagement interface. The reciprocating power tool according to any one of the preceding claims, wherein the second link comprises a body defining a second cam nose receiving area receiving the second cam nose, an opening defining the second engagement interface, and a counterweight portion, wherein the second engagement interface is disposed between the second cam nose receiving area and the counterweight portion, and wherein a center of mass of the body is disposed at the second engagement interface. The reciprocating power tool according to one of claims 1 or 2, further comprising a slide plate bolt configured to releasably couple a slide plate to the inner shaft assembly, wherein the slide plate is selectable from a plurality of slide plates each defining a different guide height. The reciprocating power tool of claim 1 or 2, wherein the work head includes one or more slide plate engagement points, the reciprocating power tool further comprising a slide plate having one or more complementary slide plate engagement points configured to be removably coupled to the one or more slide plate engagement points. The reciprocating power tool of claim 12, wherein the one or more slide plate engagement points each comprise a first engagement feature disposed on the second blade, wherein the one or more complementary slide plate engagement points each comprise a second engagement feature, and wherein the first and second engagement features are each configured to be releasably coupled to one another to retain the slide plate to the workhead. The reciprocating power tool of claim 12 or 13, wherein the first blade includes one or more apertures through which the one or more complementary slide plate engagement points extend when the slide plate is connected to the second blade. A reciprocating power tool having a first blade and a second blade, the first blade being driven by a first shaft assembly, the second blade being driven by a second shaft assembly, the first and second blade assemblies being reciprocated by a camshaft, the first shaft assembly defining a first moment of inertia, the second shaft assembly defining a second moment of inertia, and the first and second moments of inertia being within 5% of each other. The reciprocating power tool of claim 15, wherein the first shaft assembly defines a first height associated with a center of gravity of the first shaft assembly, the second shaft assembly defines a second height associated with a center of gravity of the second shaft assembly, the first and second heights being measured from a reference plane oriented perpendicular to a rotational axis of the first and second shaft assemblies, and the first and second heights being within 2% of each other. The reciprocating power tool of claim 15 or 16, wherein the first shaft assembly defines a first total mass, the second shaft assembly defines a second total mass, and the first and second total masses are within 5% of each other. The reciprocating power tool of any one of claims 15, 16 or 17, further comprising a slide plate removably connected to one of the first or second shaft assemblies, the slide plate being selected from a plurality of slide plates each defining a different guide height. A reciprocating power tool comprising:a first blade;a second blade coaxially aligned with the first blade; anda slide plate removably coupled to one of the first or second blades, the slide plate being selected from a plurality of slide plates each defining a different height. The reciprocating power tool of claim 19, wherein the first blade is disposed between the second blade and the slide plate, and wherein a portion of the slide plate extends through the first plate to be removably connected to the second plate.

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