Abstract:
A portable hand-held fastener driving tool of the type which tends to keep the driver element better aligned with the head of the fastener while it&#39;s being driven. A biasing spring in the fastener track skews the directional path of the fastener as it is being driven, but the biasing spring does not noticeably affect the path of the driver element, thereby compensating for the slight movement of the tool (and driver) due to the tool&#39;s recoil. In an alternative embodiment, a magnet is used rather than a biasing spring, to skew the direction of the fastener as it is being shot by the tool.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority to provisional patent application Ser. No. 61/601,487, titled “SKEWED FASTENER TRACK FOR IMPROVED ALIGNMENT AND FASTENER DRIVABILITY,” filed on Feb. 21, 2012. 
    
    
     TECHNICAL FIELD 
     The technology disclosed herein relates generally to fastener driving equipment and is particularly directed to a portable hand-held tool of the type which tends to keep the driver element better aligned with the head of the fastener while it&#39;s being driven. Embodiments are specifically disclosed that include a biasing spring to “skew” the path of the fastener as it is being driven by the driver element, but the biasing spring does not noticeably affect the path of the driver element, thereby compensating for the slight movement of the tool (and driver) due to the recoil effect. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     None. 
     BACKGROUND 
     Fastener tools tend to recoil when fired due to the forces generated by the acceleration of the fastener driver. This creates relative movement between the nail gun and the fastener as it is driven into the substrate. The driver tip is generally designed to be approximately the same size as the head of the fastener to reduce excessive marking to the substrate. Relatively small movement between the fastener and driver can cause additional marking of the substrate and in some cases the driver can prematurely slip off of the fastener leaving it sticking up above the surface. The technology disclosed herein compensates for the movement of the tool by shifting the fastener location ahead of the driver so at the end of the drive event they are approximately lined up. 
     An analogy is a ferry crossing a river where the sideways movement (known as leeway) due to the wind and current must be taken into account in order to arrive at the desired destination. The dock may be directly across the river but the ferry must aim upstream to compensate for the current. In the case of fastening tools, the recoil has a similar effect as the current does on the ferry. Inertia causes the fastening tool to rotate, and to therefore, the tip moves forward during the drive event. To compensate for this action, the fastener should be ejected ahead of the driver track so, as the tool moves, the driver ends up on the head of the fastener at the end of the drive stroke. 
     SUMMARY 
     It is an advantage for the driver in a fastening tool stay in contact with the head of the fastener for the entire drive event. Misalignment or movement will cause a driver mark next to the fastener which leads to an undesirable mark in the substrate. In more extreme cases, the driver can slip completely off of the fastener and leave it proud. In the case of the Fusion platform tools (sold by Senco Brands, Inc.), this issue is more prevalent due to the relatively high mass of the driver. The technology disclosed herein compensates for the tool recoil to enable the driver to stay on the fastener virtually for the entire drive event. 
     Additional advantages and other novel features will be set forth in part in the description that follows and in part will become apparent to those skilled in the art upon examination of the following or may be learned with the practice of the technology disclosed herein. 
     Still other advantages will become apparent to those skilled in this art from the following description and drawings wherein there is described and shown a preferred embodiment in one of the best modes contemplated for carrying out the technology. As will be realized, the technology disclosed herein is capable of other different embodiments, and its several details are capable of modification in various, obvious aspects all without departing from its principles. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive. 
     To achieve the foregoing and other advantages, and in accordance with one aspect, a driver actuation device for a fastener driving tool is provided, which comprises: (a) a guide body that has a fastener passageway with an exit end, the guide body being configured to receive a fastener that is to be driven from the exit end; (b) a movable driver member that, when actuated for a drive event, moves from a ready position toward a driven position and contacts the fastener, thereby causing the fastener to move in a first direction to generally toward the exit end of the guide body; and (c) a biasing member that causes the fastener to change its path and move in a second direction, still generally toward the exit end of the guide body; wherein: as the driver actuation device reacts because of a recoil action due to the drive event, the driver member also changes its spatial motion so as to move generally in the second direction. 
     In accordance with another aspect, a driver actuation device for a fastener driving tool is provided, which comprises: (a) a guide body that has a fastener passageway with an exit end, the guide body being configured to receive a fastener that is to be driven from the exit end; (b) a movable driver member that, when actuated for a drive event, moves from a ready position toward a driven position and contacts the fastener, thereby causing the fastener to move in a first direction generally toward the exit end of the guide body; and (c) a biasing member that causes the fastener to change its path and move in a second direction, still generally toward the exit end of the guide body; however, the biasing member by itself does not substantially affect the movement direction of the driver member. 
     In accordance with yet another aspect, a method for adjusting the motion of a fastener in a fastener driving tool is provided, in which the method comprises the following steps: (a) providing a driver actuation device, comprising: (i) a guide body having a fastener passageway with an exit end; (ii) a movable driver member; and (iii) a biasing member; (b) initiating a drive event, and moving the driver member from a ready position toward a driven position; (c) using the driver member, contacting a fastener within the fastener passageway, thereby moving the fastener in a first direction generally toward the exit end of the guide body; (d) using the biasing member, changing a path of movement of the fastener so that it moves in a second direction, still generally toward the exit end of the guide body; and (e) by itself, the biasing member does not substantially affect the movement direction of the driver member. 
     Still other advantages will become apparent to those skilled in this art from the following description and drawings wherein there is described and shown a preferred embodiment in one of the best modes contemplated for carrying out the technology. As will be realized, the technology disclosed herein is capable of other different embodiments, and its several details are capable of modification in various, obvious aspects all without departing from its principles. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the technology disclosed herein, and together with the description and claims serve to explain the principles of the technology. In the drawings: 
         FIGS. 1A, 1B, and 1C  are elevational views of the exit end of a conventional fastener driving tool known in the prior art, illustrating three different stages of a firing sequence. 
         FIGS. 2A, 2B, and 2C  are elevational views of the exit end of a fastener driving tool, as constructed according to the principles of the technology disclosed herein, illustrating three different stages of a firing sequence. 
         FIG. 3  is an elevational view of the entire fastener driving tool of  FIG. 2 . 
         FIG. 4  is an elevational view of a back plate and magazine rail of the fastener driving tool of  FIG. 2 . 
         FIG. 5  is an elevational view of a front plate of the fastener driving tool of  FIG. 2 . 
         FIG. 6  is an elevational view of an assembled exit portion of the fastener driving tool of  FIG. 2 , showing the front plate and back plate areas, in which a leaf spring acts as the biasing member. 
         FIG. 7  is an elevational view of an assembled exit portion of a second embodiment of the fastener driving tool of  FIG. 2 , showing the front plate and back plate areas, in which a magnet acts as the biasing member. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the present preferred embodiment, an example of which is illustrated in the accompanying drawings, wherein like numerals indicate the same elements throughout the views. 
     It is to be understood that the technology disclosed herein is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The technology disclosed herein is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms “connected,” “coupled,” and “mounted,” and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. In addition, the terms “connected” and “coupled” and variations thereof are not restricted to physical or mechanical connections or couplings. 
     The terms “first” and “second” preceding an element name, e.g., first inlet, second inlet, etc., are used for identification purposes to distinguish between similar or related elements, results or concepts, and are not intended to necessarily imply order, nor are the terms “first” and “second” intended to preclude the inclusion of additional similar or related elements, results or concepts, unless otherwise indicated. 
     DEFINITIONS 
     Fastening Tools: also known as nail guns, staplers and pinners; also sometimes referred to as fastener driving tools. 
     Proud Fastener: Fastener not driven below the surface of the substrate. 
     Substrate: Wood or composite material that the fastener is being driven into, also referred to as the workpiece. 
     Driver: The part on the nail gun tool that pushes the fastener into the substrate. 
     Fastener: Nail, staple, or pin. 
     Drive Event: the action of the driver starting from its cocked position until it reached its fully extended position. 
     Driver Mark: the mark or dent left in the substrate after the drive event. Ideally this is no larger than the head of the fastener. 
     “Fusion” Tools: Electro-pneumatic line of fastener driving tools sold by Senco Brands, Inc. A detailed description of many aspects of the Fusion tool is provided in U.S. Pat. No. 8,011,547, titled “FASTENER DRIVING TOOL USING A GAS SPRING.” 
     Fastener Track: The track in the fastening tool that guides the fastener to the workpiece. 
     Driver Track: The track in the fastening tool that guides the driver to the workpiece. 
     Operation of Tool 
     Newton&#39;s Third law states that the mutual forces of action and reaction between two bodies are equal, opposite, and collinear. In the case of a fastening tool, this means that the force to accelerate the piston/driver also acts on the body of the fastening tool. Since the fastening tool has much more mass than the driver, its velocity is significantly less, however, it still moves during the drive event, and typically is referred to as a “recoil.” The recoil phenomenon is present in all types of fastening tools, but is more prevalent in the Fusion tools (sold by Senco Brands, Inc.) because they have a particularly heavy driver, since the lift mechanism is coupled to the driver. Proportionately, if more power is desired for larger fasteners and/or harder substrates, increasing the pressure to increase the driver force increases the recoil and exacerbates the problem. Analysis and high-speed photography confirm this issue. See  FIGS. 1A-1C  for an illustration of the timeline. 
     Referring now to  FIG. 1A , a conventional tool (such as an early model Fusion tool, sold by Senco Brands, Inc.), generally designated by the reference numeral  10 , is illustrated as having just begun a drive event. The tool  10  includes a front portion  20 , a safety element  22  that contacts a workpiece surface  50  to initiate a fastener driving cycle (or drive event) if the tool&#39;s trigger is pulled, a magazine  24  that contains at least one fastener, a driver  30 , a fastener  32  being driven, and a back plate portion  34 . In  FIG. 1A , the driver  30  to has moved downward (in this view) and has dislodged the “lead fastener”  32  from the magazine  24 , and this lead fastener has just started being driven into the workpiece at  50 . The leading tip of the fastener is depicted at  52 . When the tool fires, it rotates about its center of gravity (or mass), essentially in a rotational direction as indicated by the arrow “R”. The leading tip of the driver  30  is in contact with the head  54  of the fastener at this time. 
     Referring now to  FIG. 1B , the fastener  32  is now stuck in the substrate  50  as the tool  10  continues to move (in the direction R), slightly bending the fastener. Once the fastener  32  exits the fastener track, the driver  30  can slip off the head  54  of the fastener, thereby leaving it proud in some circumstances. This condition is illustrated in  FIG. 1C . As noted above, the recoil effect in Senco&#39;s Fusion tool is more prevalent due to the relatively high mass of the driver; the recoil can cause a displacement near the exit area (at  110 , see below) of greater than 0.03 inches. 
     Referring now to  FIG. 2A , a tool  100  constructed according to the principles of the technology disclosed herein is illustrated as having just begun a drive event. The tool  100  includes a front portion  120 , a safety element  122  that contacts a workpiece surface  150  to initiate a fastener driving cycle (or drive event) if the tool&#39;s trigger (not shown in this view) is pulled, a magazine  124  that contains at least one fastener, a driver (or “driver member”)  130 , a fastener  132  being driven, and a back plate portion  134 . Tool  100  includes a biasing member  140 , which has a function that will be explained below. In this embodiment, biasing member  140  comprises a leaf spring. 
     It will be understood that the biasing member  140  could easily be made of other mechanical components, such as a rigid piece of material that was hinged on one end, and spring-loaded by use of one or more coil springs, for example. A plastic hinge could also be used, although such devices might not have suitable durability for an industrial-grade power tool. 
     As can be seen in the other views, tool  100  also includes a gas spring storage chamber  102 , a battery  104 , a driver track  144 , a fastener track  146 , and a front plate  126  (on the opposite side of the driver track  144  and the fastener track  146  from the back plate  134 ). There is an “exit area” (or “exit end”) of the tool, as indicated by the reference numeral  110  on  FIG. 2B . The front plate  126  and back plate  134  generally combine into an overall structure, sometimes referred to herein as a “guide body,” that contains passageways for to guiding the driver  130  and for guiding individual fasteners  132 ; these passageways are generally referred to herein as the above-noted driver track  144  and fastener track  146 . 
     The driver  130  begins its driving cycle at a “ready position,” which is upward as viewed in  FIGS. 2A-2C . After the tool  100  is actuated, the driver  130  is pushed downward (in these views) toward a “driven position.” During its movement between the ready position and driven position, the driver contacts one of the fasteners that are held in the magazine  124 . 
     In  FIG. 2A , the driver  130  has moved downward (in this view) and has already dislodged the “lead fastener”  132  from the magazine  124 , and this lead fastener has just started being driven into the workpiece at  150 . The leading tip of the fastener is depicted at  152 . When the tool fires, it tends to rotate about its center of gravity (or mass), essentially in a rotational direction as indicated by the arrow “R”. This rotation is the tool&#39;s reaction to the driver  130  being quickly accelerated; it is commonly referred to as the “recoil.” The biasing member  140  (a leaf spring in this embodiment) tends to bias the fastener  132  toward the front (i.e., to the left in this view) of the driver track  144 . The leading tip of the driver  130  is in contact with the head  154  of the fastener at this time. 
     The technology disclosed herein compensates for the tool recoil by repositioning the fastener in the fastener track during the drive event. After the fastener  132  is separated from the strip in the magazine  124 , the fastener track  146  provides clearance and a spring force to move the fastener  132  relative to the driver  130 . Once the fastener starts to penetrate the substrate  150 , it becomes fixed and no longer moves along with the fastening tool  100 . The overall effect is that, as the tool reacts, (i.e., rotates in the direction R), the fastener  132  moves back into alignment with the movements of the driver  130 . This is the circumstance that is illustrated in  FIG. 2B . 
     The leading tip  152  of the fastener  132  is pushed by a light spring  140  and thus is ejected ahead of the driver track  144  so, as the tool recoils, the driver  130  catches up to the head  154  of the fastener  132  by the end of the drive event. The driver  130  is held in a driver track  144  that moves in conjunction with the fastener tool  100 , so there is inherently motion between the fastener  132  and the tool  100 , once the fastener has entered the substrate  150 . By the time the head  154  of the fastener exits the fastener track  146 , the driver  130  has come back into alignment with the fastener  132 , for a complete drive (see  FIG. 2C ). This ensures that the driver  130  stays on the fastener  132  essentially for the duration of the drive event and minimizes any driver mark and the possibility of slipping off the fastener. 
     The Fusion fastener driving tool starts with a cocked piston and the driver tip slightly above a strip of collated fasteners (stored in a magazine  124 ). The driver  130  is loaded by a gas spring with approximately 160 pounds of force. It is released using an electro-mechanical quick release mechanism which allows the driver to accelerate to a velocity of over 100 feet/second in a few milliseconds. The acceleration during the drive event creates a force that causes the fastener tool  100  to recoil about its center of gravity (see  FIG. 3 ). The “center of rotation” at  105  is located at the center of mass of the tool  100 . 
     The first fastener is held in position for the driver to shear it off from the collated strip of the magazine  124  and push it down the fastener track  146 . The tip  152  of the dislodged fastener  132  is pushed forward (i.e., the direction “forward” in this description is to the left, in the views of  FIGS. 2A-2C  and  FIG. 3 ) by a biasing member  140  (e.g., a leaf spring) into a clearance  128  provided in the fastener track  146 . This biasing action pushes the fastener tip  152  to a second direction that is forward of the driver track  144  at this point in the drive event. Once the fastener  132  enters the substrate  150 , it no longer moves with the rotational motion of fastening tool  100 . 
     The fastening tool  100  continues to rotate during the drive event, which tends to cause a relative horizontal movement between the fastener track  146  and the fastener  132 . The biasing member (e.g., leaf spring  140 ) is designed to not be strong enough to alter the drive path of the driver  130 , so the driver&#39;s path becomes slightly behind the path of the fastener  132 . (Note: in this description, the direction “behind” is to the right, in the views of  FIGS. 2A-2C  and  FIG. 3 .) Since the tool  100  is rotating (see arrow R) about the center of gravity  105  with a horizontal relative movement near the exit area  110 , at the end of the drive event the driver  130  and fastener  132  are in approximate alignment. Even though the recoil effect can cause a displacement of greater than 0.03 inches near the exit area  110 , this effect is corrected by the technology disclosed herein. 
     Another way to describe these actions is that the movable driver  130 , when actuated for a drive event, moves from its ready position toward its driven position, and while doing so, it contacts the fastener  132 . This contact causes the fastener to move in a first direction that is generally toward the exit end  110  of the guide body (i.e., the assembly made to up of the front plate  126 , back plate  134 , and other parts of the tool in that region of the tool). This first direction is along the driver track  144  at the initial time when the driver  130  first begins movement—i.e., before the driver contacts the fastener, and before the tool undergoes a significant amount of reaction motion due to recoil. The biasing member  140  now causes the fastener  132  to change its path and then to move in a second direction, which still is generally toward the exit end  110  of the guide body. As the tool  100  rotates because of the recoil action, the driver  130  also changes its spatial motion—in turn, as an integral part of the tool—so as to move generally in the (same) second direction, and to again contact, or maintain contact with, the head of the fastener  132 . Without this change in vector movements, from the first direction to the second direction, the driver tip might lose contact with the head  154  of the fastener  132 , as described above, and fail to completely drive the fastener into the substrate  150 . 
     It will be understood that the spatial vector movements of the fastener  132  do not change from the first (spatial) direction to the second (spatial) direction in an instant, because of the biasing member  140 . It is more correct to say that there is a gradual transition from the first direction to the second direction as the biasing member  140  has a chance to act upon the fastener  132 , as the fastener moves by the position of the biasing member. These movements, of course, occur quite quickly, so the fastener&#39;s change in direction will essentially appear to an observer to be instantaneous. 
     It will also be understood that another way to describe these actions is that the driver  130  itself changes direction, as the tool  100  undergoes recoil movement. In fact, the driver will change direction (e.g., from the first direction to the second direction) with, or without, the use of any biasing member in the tool. Of course, that attribute is the main reason for equipping the tool  100  with the biasing member  140 , so that the fastener  132  will also change its path of movement from the first direction to the second direction, and in so doing, skewing the travel of the fastener so that its head  154  meets up once again with the contacting tip of the driver  130 , and thereby become completely driven into the substrate  150 . 
       FIG. 3  also illustrates some of the other portions of the tool  100  that are not visible in  FIGS. 2A-2C , such as the gas spring storage chamber  102 , the battery  104 , the handle  106 , the hand-operated trigger  108 , and the location of the center of rotation  105 . The direction of rotation “R” is indicated in this view. It should be noted that the center of rotation  105  is intentionally located near the trigger  108  and handle  106  portions of the tool, to minimize the reaction movements of the tool (due to recoil) as those movements are experienced by the human user. 
       FIG. 4  illustrates the back plate and rail portion of the tool  100  in greater detail. The magazine rail is indicated at  124 , the back plate portion is at  134 , and the biasing member  140  is depicted as a leaf spring, as per this first embodiment. The exit area  110  (or “exit end” portion of the tool) is indicated at the bottom (in this view) of the figure. The back plate  134  forms one side of the fastener track  146 , particularly at the location of the leaf spring  140 . 
       FIG. 5  illustrates the front portion  120  of the tool  100 , specifically the front plate  126 . This front plate  126  forms the other side of the driver track  144  and the other side of the fastener track  146 , as indicated on the figure. There is a relief area  128  for the fastener to travel through, due to the biasing action of the biasing member  140 . The fastener track  146  terminates at the exit area  110 . 
       FIG. 6  illustrates the assembled exit end portion of the tool  100 , in an elevational side view, depicting the tool as it would be used to project a fastener in a downward, near-vertical direction. The front portion  120  includes the front plate  126 ; the rear portion includes the back plate  134  and the fastener magazine  124 . Those two plates  126 ,  134  essentially create the fastener track  146 , which terminates at the exit area  110 . The leaf spring biasing member  140  can be seen, and is attached to the back plate  134  by a rivet  142  in this embodiment. Of course, other methods of attachment could be utilized. As a fastener  132  is shot down the fastener track  146 , its path will be skewed by mechanical force, i.e., the biasing contact of the leaf spring  140  in this first embodiment. 
       FIG. 7  is similar to  FIG. 6 , in that it illustrates the assembled exit end portion of a tool in an elevational side view, depicting the tool as it would be used to project a fastener in a downward, near-vertical direction. However, in  FIG. 7 , a second embodiment is disclosed which uses a magnet as the biasing member  240 . In this second embodiment, the front portion is designated by the reference numeral  220 , which includes a front plate  226 ; a rear portion includes a back plate  234  and a fastener magazine  224 . Those two plates  226 ,  234  essentially create a fastener track  246 , which terminates at an exit area  210 . 
     In this alternative embodiment, when a metal fastener is shot down the fastener track  246 , its path will be skewed by magnetic force, rather than by mechanical to force. The magnet  240  may be positioned flush along the fastener track (within the front plate), or the magnet could be placed in a recess, and perhaps even covered by a thin layer of non-magnetic material (within the front plate), to avoid any possible physical contact with outside objects. The driver (not shown in this view) could be made of a non-magnetic material, although that is not necessary because of its greater mass. 
     Nailing tools that have been available on the market typically have collinear fastener and driver tracks. Although earlier conventional tools recoil, that recoil is generally not to the extent that the Fusion tools recoil, since the Fusion tools have a significantly heavier driver. In any event, conventional nailing tools also can benefit from this technology, although the skew due to recoil may not be as great as what the Fusion tools undergo. 
     In conclusion, some of the features disclosed herein include, but are not limited to: 
     (a) A fastener driving tool with its driver track skewed from the fastener track in order to compensate for tool recoil. 
     (b) The driver track and fastener track may be skewed angularly. 
     (c) The driver track and fastener track may be offset but parallel. 
     (d) A driven fastener can be guided in fastener track magnetically. 
     (e) A driven fastener can be guided in fastener track with a spring. 
     (f) A driven fastener can be guided in fastener track with a following fastener. 
     (g) A fastener driving tool with a fastener track which has a biasing member that affects the direction of movement of fasteners, but that does not substantially affect the movement direction of the driver. 
     As used herein, the term “proximal” can have a meaning of closely positioning one physical object with a second physical object, such that the two objects are perhaps adjacent to one another, although it is not necessarily required that there be no third object positioned therebetween. In the technology disclosed herein, there may be instances in which a “male locating structure” is to be positioned “proximal” to a “female locating structure.” In general, this could mean that the two male and female structures are to be physically abutting to one another, or this could mean that they are “mated” to one another by way of a particular size and shape that essentially keeps one structure oriented in a predetermined direction and at an X-Y (e.g., horizontal and vertical) position with respect to one another, regardless as to whether the two male and female structures actually touch one another along a continuous surface. Or, two structures of any size and shape (whether male, female, or otherwise in shape) may be located somewhat near one another, regardless if they physically abut one another or not; such a relationship could still be termed “proximal.” Or, two or more possible locations for a particular point can be specified in relation to a precise attribute of a physical object, such as being “near” or “at” the end of a stick; all of those possible near/at locations could be deemed “proximal” to the end of that stick. Moreover, the term “proximal” can also have a meaning that relates strictly to a single object, in which the single object may have two ends, and the “distal end” is the end that is positioned somewhat farther away from a subject point (or area) of reference, and the “proximal end” is the other end, which would be positioned somewhat closer to that same subject point (or area) of reference. 
     It will be understood that the various components that are described and/or illustrated herein can be fabricated in various ways, including in multiple parts or as a unitary part for each of these components, without departing from the principles of the technology disclosed herein. For example, a component that is included as a recited element of a claim hereinbelow may be fabricated as a unitary part; or that component may be fabricated as a combined structure of several individual parts that are assembled together. But that “multi-part component” will still fall within the scope of the claimed, recited element for infringement purposes of claim interpretation, even if it appears that the claimed, recited element is described and illustrated herein only as a unitary structure. 
     All documents cited in the Background and in the Detailed Description are, in relevant part, incorporated herein by reference; the citation of any document is not to be construed as an admission that it is prior art with respect to the technology disclosed herein. Two United States patents that are assigned to Senco Brands, Inc. are incorporated herein by reference in their entirety: these patents are U.S. Pat. No. 8,011,547, titled “FASTENER DRIVING TOOL USING A GAS SPRING;” and U.S. Pat. No. 8,011,441, titled “METHOD FOR CONTROLLING A FASTENER DRIVING TOOL USING A GAS SPRING.” 
     The foregoing description of a preferred embodiment has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the to technology disclosed herein to the precise form disclosed, and the technology disclosed herein may be further modified within the spirit and scope of this disclosure. Any examples described or illustrated herein are intended as non-limiting examples, and many modifications or variations of the examples, or of the preferred embodiment(s), are possible in light of the above teachings, without departing from the spirit and scope of the technology disclosed herein. The embodiment(s) was chosen and described in order to illustrate the principles of the technology disclosed herein and its practical application to thereby enable one of ordinary skill in the art to utilize the technology disclosed herein in various embodiments and with various modifications as are suited to particular uses contemplated. This application is therefore intended to cover any variations, uses, or adaptations of the technology disclosed herein using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this technology disclosed herein pertains and which fall within the limits of the appended claims.