Patent Publication Number: US-8109261-B2

Title: Archery string nock

Description:
This application claims the benefit of U.S. Provisional Application 61/139,379 filed Dec. 19, 2008 which is hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to archery bows, and more particularly to bowstring weights commonly identified as string nocks or speed nocks. 
     Conventional archery bows, and in particular compound archery bows, include a bowstring and a set of cables that transfer energy from the limbs and cams or pulleys of the bow to the bowstring, and thus to an arrow shot from the bow. To reduce vibration, and to further increase the energy imparted to the arrow by the bow, optional weights, such as string nocks or speed nocks (both referred to as speed nocks herein) are strategically positioned on the bowstring, typically at one or more vibration nodes along the bowstring. 
     Typically, the speed nocks are placed on either or both of the upper and lower portions of the bowstring, near to the cams on a double cam bow, or near the cam and near the pulley on a single cam bow. The size of the speed nock and its location on the bowstring typically increase the energy imparted to the arrow by the bow, and accordingly increase arrow speed. The weight and location of speed nocks are usually unique to the type of bow and related equipment, such as arrows or accessories attached to the bow, and normally differ for the upper and/or lower portions of the bowstring as well. Any changes made to the equipment may require modification in the location of the speed nocks and possibly the weight and or size of the speed nocks. Usually, the optimum weights and locations are achieved by trial and error testing, in which an arrow is shot through a speed-measuring chronograph repeatedly. The placement and/or weights of the speed nocks are adjusted until the fastest arrow speed is identified. 
     Conventional speed nocks are split metal “U” shaped devices, usually having a brass outer portion and an inner portion that is a softer material that engages a serving of the bowstring or the bowstring itself. The “U” shaped device is placed around the bowstring, and the “U” is crimped so that it fully encircles the bowstring, and is held in a specific location. 
     Achieving the desired location, as noted above, is an iterative process with the “U” shaped speed nocks. This process includes initially crimping at least one speed nock to each end of the bowstring near the cams, and shooting multiple arrows, while measuring the arrow speed of each shot with a chronograph. The nocks are un-crimped, moved incrementally along the bowstring, and then re-crimped. The arrows subsequently are shot again and the arrow speed is measured. These steps are repeated until the “sweet spot” is located where the arrow speed peaks. If additional nocks are desired, the process starts anew. 
     For safety reasons, many archers secure the “U” shaped nocks by heat shrinking tubing over the nocks to prevent them from, possibly disengaging the string and causing injury. Application of the heat shrink tubing usually requires unstringing and restringing the bow after the “sweet spots” are determined. 
     The inner portion of most “U” shaped speed nocks is an elastomer that, as mentioned above, engages the bowstring or serving, and alleviates damage to the bowstring. While the elastomer reduces some wear on the string, where multiple crimping and uncrimping steps in the trial and error process are performed, the elastomer or metal part can wear on the individual fibers of the strands of the bowstring, prematurely shortening the life of the bowstring. 
     There are other speed nocks in the market that have a different structure. For example, another speed nock, commercially available from T.R.U. Ball® under the Speed Nok name, includes aluminum parts that define grooves adapted to receive the bowstring. The parts are secured around the bowstring by clamping them together with integral screws. The bowstring remains trapped within the parts. 
     Another example of a speed nock is a segment of rubber or similar elastomeric tubing material that encircles the bowstring. The tubing can be in the form either of individual segments or as segments that are defined by partial cuts in the tubing. In either form, the number of segments needed are estimated and then threaded on the bowstring before stringing the bow. The segments are moved up or down the exterior of the bowstring until the optimum locations are determined. If the estimated number of segments is inadequate, the bow must be un-strung. Additional segments must be threaded on the bowstring, and the bow re-strung. The segments remain in place at the selected locations by the gripping properties of the elastomeric material. 
     Although the above conventional bowstring speed nocks may achieve the desired objective, there remains room for improvement. 
     SUMMARY OF INVENTION 
     A speed nock for a bowstring of an archery bow is provided. The speed nock is readily adjustable to an optimum location to achieve maximum arrow speed. Optionally, the speed nock can be secured without completely removing the bowstring from the archery bow. 
     In one embodiment, the speed nock includes a first enlarged portion and a second enlarged portion connected via a central portion. The central portion has a maximum dimension smaller than maximum dimensions of the first and second enlarged portions. The central portion is positioned between strands of a bowstring so that the strands pinch the central portion, at least assisting in holding the speed nock in place along the bowstring. 
     In another embodiment, the speed nock is geometrically configured to allow ease of insertion and movement, for example sliding, between the strands of the bowstring. The dimensions and/or configuration can be readily altered in manufacturing to provide different weights. 
     In yet another embodiment, the speed nock can be in the form of a three dimensional exercise dumbbell or hourglass. Optionally, greater mass can be symmetrically distributed at the enlarged portions and opposing ends. 
     In still another embodiment, the first and second enlarged portions are adapted to be positioned adjacent the bowstring, with the central portion of the speed nock passing at least partially through the bowstring, trapped in place by strands on opposite sides of the central portion. 
     In a further embodiment, the speed nock can be constructed from a variety of materials such as metal, composites or polymers. 
     In yet a further embodiment, the central portion of the speed nock can be coated, polished or micro-finished so that it has a smooth surface that engages the strands of the bowstring without significantly abrading them. Due to the smoothness, the speed nock optionally can be more easily slid along the bowstring, between the strands, for adjustment, without significantly abrading the strands. 
     In another, further embodiment, a method is provided for increasing the speed of an arrow, shot from an archery bow, with the speed nock. An enlarged portion of the speed nock is inserted through the bowstring, between strands of the string, optionally without un-stringing the bowstring from the bow. Insertion is continued until the central portion is between the strands. The strands pinch the central portion and hold the speed nock in place. Optionally, the bow can be repeatedly shot, and the speed nock moved along the bowstring until a desired speed is achieved. 
     The bowstring speed nock provided herein can be inexpensively manufactured and easily adjusted. The speed nock can function in an efficient and reliable manner, can be easily installed, adjusted, and secured relative to the bowstring without significant potential for damage to the bowstring, and without un-stringing and re-stringing the archery bow if desired. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an archery bow having speed nocks of a current embodiment installed on its bowstring; 
         FIG. 2  is a perspective view of the speed nock; 
         FIG. 3  is a side view of the speed nock; 
         FIG. 4  is an end view of the speed nock; 
         FIG. 5  is a cross section view of the speed nock taken along line  5 - 5  in  FIG. 4 ; 
         FIG. 6  is a close up view of the speed nock installed on the bowstring; 
         FIG. 7  is a perspective view of a speed nock of a first alternative embodiment; 
         FIG. 8  is a side view of the speed nock of the first alternative embodiment; 
         FIG. 9  is an end view of the speed nock of the first alternative embodiment; 
         FIG. 10  is a cross section view of the speed nock of the first alternative embodiment taken along line  10 - 10  in  FIG. 9 ; 
         FIG. 11  is a close up view of the speed nock of the first alternative embodiment installed on the bowstring; 
         FIG. 12  is a side view of a second alternative embodiment of the speed nock; 
         FIG. 13  is a side view of a third alternative embodiment of the speed nock; 
         FIG. 14  is a side view of a fourth alternative embodiment of the speed nock; 
         FIG. 15  is a side view of a fifth alternative embodiment of the speed nock; 
         FIG. 16  is a side view of a sixth alternative embodiment of the speed nock; and 
         FIG. 17  is a side view of a seventh alternative embodiment of the speed nock. 
     
    
    
     DETAILED DESCRIPTION OF THE CURRENT EMBODIMENT 
     I. Overview 
     A current embodiment of the speed nock is generally shown in  FIGS. 1-5  and generally designated by the reference numeral  10 .  FIG. 1  illustrates two speed nocks  10  positioned on a bowstring  101  of an archery bow  100 . As shown in  FIG. 2 , the speed nock  10  includes a first enlarged portion  20  and a second enlarged portion  30  connected via a central portion  40 . The central portion  40  can have a maximum dimension and/or cross section that is less than or smaller than maximum dimensions and/or cross sections of the first and second enlarged portions when the cross sections are taken perpendicular to the longitudinal axis  50  of the speed nock. With reference to  FIG. 6 , the central portion  40  is positioned between strands, which can be individual strands or groups of strands,  103 , 105  of the bowstring. Because the bowstring is taut, the strands  103 ,  105  pinch, clamp or otherwise grab the central portion  40 , assisting or fully holding the speed nock in place along the bowstring. 
     One, two, or more speed nocks  10  can be placed at specific locations on the bowstring  101  between the upper and lower limbs  108 ,  110 , which are generally attached to the riser  102  of the bow. The locations can be at or near the cams  104 , and/or pulleys  106  of the bow, generally 1″, 2″, 3″, 4″ 5″ or other incremental distances from the cams as determined by shooting arrows from the bow and identifying the optimum location for positioning the speed nock(s), as described below. 
     Although shown installed on a single cam compound archery bow, the embodiments of the speed nocks herein are well suited for dual cam systems, cam and a half systems, and other systems including a bowstring and a cable. Further, although illustrated as a compound bow, the embodiments herein can be used in connection with a cross bow, or any bow including a bowstring and a cable. In addition, although referred to as “cams”, that term can include cams, pulleys, wheels, or other mechanical structures that impart a mechanical advantage to energy stored in a bow. 
     II. Construction 
     The construction and components of the speed nock  10  will now be described. The speed nock  10  includes first enlarged portion  20 , second enlarged portion  30 , central portion  40  and a longitudinal axis  50 . The longitudinal axis  50  can include a first end  52 , a second end  54  opposite the first end, and a central region  56  located between the first and the second end. The precise sizes, dimensions, lengths and cross sections of the ends and central region can vary as desired. 
     The dimensions and/or cross section of the speed nock  10  can vary along the longitudinal axis  50 , and from portion to portion. For illustrative purposes, the dimensions can be measured perpendicular to the longitudinal axis, and the cross sections can be taken along the longitudinal axis, perpendicular to that axis. As shown in  FIG. 5 , the central portion  40  can have a maximum cross section taken, for example, at location  41  that is less than or smaller than maximum cross sections of the first and second enlarged portions, taken at locations  21  and  31 . The maximum cross sections of the enlarged portions can be the same or different as desired. 
     Similarly, as shown in  FIG. 5 , the central portion can have a maximum dimension taken, for example, at location  41 , that is less than a smaller than maximum dimensions of the first and second enlarged portions, taken at locations  21  and  31 . The maximum dimensions of the enlarged portions can be the same or different as desired. 
     As shown in  FIGS. 2-4 , the second enlarged portion  30  and the first enlarged portion  20  can be generally symmetric in shape to one another about the central point  53  of the longitudinal axis. These enlarged portions can also be of approximately the same mass so that the speed nock is balanced about the central point  53  of the longitudinal axis ( FIG. 3 ). Of course, if it is desired to make the speed nock unbalanced, the enlarged portions can vary in size, shape and/or mass. 
     In the current embodiment, the enlarged first and second portions  20 ,  30  are in the form of spherical elements aligned with the longitudinal axis  50 . The spherical elements generally are located at the ends  52 ,  54  of the longitudinal axis  50 . The longitudinal axis  50  can be oriented so that it passes approximately through centers  23 ,  33  of the at least partially spherical elements ( FIG. 5 ). Although shown as spherical elements, the enlarged portions can take on a variety of other shapes. Other exemplary shapes include but are not limited to cylinders, joined truncated frustoconical sections, spheroids, truncated spheroids, three dimensional ellipsoids, bulbous shapes or any other geometric shapes. Optionally, the geometric shape can be determined by the shape of the bar stock selected to produce the speed nock. 
     When in the form of generally spherical elements, the enlarged portions  20 ,  30  can include portions that transition to the central portion  40  that do not form part of a true sphere, but rather curve away from the surfaces of the spheres to connect with the central portion  40 . Further, portions of the surface of the sphere can be flattened, slightly bumpy, or generally non-spherical if desired, or as a result of forming the speed nock. 
     As shown in  FIGS. 2-4 , the greater mass of the speed nock  10  is located proximate its extremities or in the enlarged portions  20 ,  30 . Generally, the speed nock can be in the three dimensional form of a dumbbell or hourglass, or any other geometric configuration including a centrally located, reduced cross section suitable for insertion and retention between strands of a bowstring. 
     The weight of the nock can vary by altering the dimensions of the enlarged portions  20 ,  30  for example, by altering the diameter  34  ( FIG. 5 ) of the spherical elements, or some other desired dimension of the respective enlarged portions, whatever their geometric configuration. In general, the speed nock  10  can be configured in a variety of weights, for example, 5, 10, 20, 30, 40, 50, 60 or 70 grains, or any other increment between any of these weights. Moreover, multiple speed nocks can be used together, so that the additive cumulative weight of the speed nocks can be virtually any weight desired. 
     The speed nock  10  can include a central portion  40 , which again can extend along the longitudinal axis  50 . The central portion can also connect both enlarged portions. In general, the central portion can transition smoothly to the respective first and second enlarged portions. This transition  45  ( FIG. 3 ) can be curvilinear, and generally void of any sharp corners or edges that might abrade the bowstring to which the speed nock is joined. Alternatively, the transition can be abrupt, for example where the central portion  40  is a cylinder that intersects an outer surface of a spherical enlarged portion  20 ,  30 . 
     The central portion  40  can generally be considered the reduced dimension portion of the speed nock. It includes dimensions and a cross section taken perpendicular to the longitudinal axis  50  that are reduced or less than the dimensions and/or cross sections of the enlarged portions also taken perpendicular to the longitudinal axis. 
     The central portion  40  can include a finish that can be polished or coated with a smooth coating, or otherwise treated or micro-finished. These surface treatments to the central portion can reduce and/or prevent abrasion of the bowstring strands while inserting and subsequently sliding the speed nock between the strands to its optimum location on the bowstring. The surface treatment can extend generally to the locations  47 , which generally correspond to the outermost regions where the strands of a bowstring might contact the speed nock  10  after it is installed in the bowstring. 
     As best seen in  FIG. 5 , the central portion  40  can be a smooth “U” shaped section transitioning tangentially from the enlarged portions  20 ,  30  to its minimum dimension (as shown, a diameter)  48  that passes through the center point  53  of the speed nock  10 . The central portion  40 , as well as the enlarged portions  20 ,  30  can be symmetric about the longitudinal axis  50 , and further optionally, symmetric about the center point  53 . 
     The speed nock  10  of the current embodiment, and any other embodiment herein, can be produced from a cylindrical rod of rigid material, for example a metal such as steel. Of course, other metals, such as brass, titanium, aluminum, magnesium and the like, as well as ceramics, elastomeric or composite materials may be used as well. The cross section of the rod may be of a variety of geometric shapes including circular, triangular, rectangular, hexagonal, octagonal and other shapes as desired. 
     The string nock can be precision machined from metal, such as steel, however, again a variety of metals can be used. Optionally, the material selected can have a high weight to volume ratio, in other words, it can be extremely dense. Further optionally, the string nock can be painted or similarly coated to resist corrosion or add aesthetic appeal. 
     When the speed nock is to be constructed from metal, it can be manufactured via precision machining, such as CNC machining, from bar stock or other suitable stock. This method of manufacture can achieve precise weight control to satisfy the requirements for various bow configurations. In addition, it can readily produce a micro-finish that permits the speed nock to be moved between the strands of the bowstring, for example, by sliding between those strands along the length of a strung bowstring, with minimal to no abrasion of the strands caused by such movement. Alternatively, the string nock may be precision molded from a composite or polymeric material. 
       FIG. 6  shows the current embodiment speed nock  10  inserted between the strands or groups of strands or fibers  103  and  105  of the bowstring  101 . From this illustration, the manner in which speed nock  10  may be easily slid up or down the bowstring  101  to achieve a desired location is readily discernable. Generally, the speed nock  10  twists in a helical motion while tracking along the grouped strands of the bowstring. After a desired location is identified, a user can attach servings  111  above and/or below the speed nock  10 , around the bowstring, to anchor the nock in that location on the bowstring, and promote the safety of the archer. 
     One or more speed nocks can be applied to a bowstring as desired and as shown in  FIG. 1 . Further, nocks of different weights or nocks of the same weight can be applied at upper and lower ends of the bowstring. For example, a larger and heavier nock can be attached to the end of the bowstring  101  proximate the cam  104 , and a smaller and lighter nock can be attached to the bowstring proximate the pulley  106 . Of course, the same size and type of nocks can be used on both ends as desired as well. When single weights are utilized on both ends of the bowstring, the “sweet spots” of the bowstring can be determined more readily. 
     As shown in  FIG. 6 , an enlarged portion  20  of the speed nock can be inserted through adjacent strands  103 ,  105  of the bowstring  101 . The insertion continues until a smaller portion of the speed nock, that is the central portion  40  is located between the adjacent but separated strands or groups of strands  103 ,  105 . Insertion at that point can be discontinued so that the central portion, for example, the bar joining opposite sides of a generally dumbbell shape, rests between the strands  103 ,  105  with the speed nock generally trapped in the location on the bowstring. In general, the strands  103 ,  105  pinch the central portion  40  of the speed nock to at least assist in holding the speed nock  10  in a selected location along the bowstring  101 . 
     With the one or more speed nocks initially positioned at one or more locations on the bowstring, a user shoots arrows from the bow multiple times, and measures the speed of the arrows with a chronograph or other device. The user iteratively slides the speed nock up or down, along the bowstring, until a maximum speed of the arrows is identified. When the maximum speed is identified, the locations of the speed nocks are considered optimal. At that point, inadvertent movement of the speed nock is prevented by serving the speed nock to the bowstring with servings  111 . The serving can be located above and/or below the speed nock as desired. 
     The speed nocks can be slid up or down, between the strands  103 ,  105  along the axis of the bowstring, until the desired location(s) are achieved, without removing the speed nock from the bowstring, or generally without un-stringing and re-stringing the bowstring from the bow. This can save significant time, and make it easier to maximize speed of the arrows shot from the bow. 
     III. Alternative Embodiments 
     A first alternative embodiment of the speed nock is shown in  FIGS. 7-11  and generally designated  210 . This speed nock is similar to the above described speed nock with several exceptions. For example, this embodiment can include the “U” shaped reduced dimension section or central portion  240  symmetric about the longitudinal axis  250  and the micro finish in the area designated as  247 . The greater masses, as in the above embodiment  10 , can be located near to the ends of the speed nock. However, in this embodiment  20  the shape of the enlarged portions  220 ,  230  can be of a truncated sphere wherein the weight can be controlled by varying the dimension  260  ( FIG. 10 ). The speed nock of this embodiment can also be inserted in and retained on the bowstring between strands or groups of strands as shown in  FIG. 11 . 
     Other alternative embodiments of the speed nock are shown in  FIGS. 12-14  and generally designated  310 ,  410  and  510 . These speed nocks are similar to the above described speed nocks with several exceptions. For example, these embodiments utilize other suitable geometric configurations of the speed nock. As shown in  FIG. 12 , the enlarged portions  320 ,  330  are cones connected with a bar shaped central portion  340 . As shown in  FIG. 13 , the enlarged portions  420 ,  430  and central portion  440  generally form a pulley shaped construction. In  FIG. 14 , the speed nock  510  includes cylindrical enlarged portions  520 ,  530  joined with the central portion  540 . 
     Even more alternative embodiments of the speed nock are shown in  FIGS. 15 and 16  and generally designated  610  and  710 . These speed nocks are similar to the above described speed nocks with several exceptions. For example, these embodiments can include integral projections  634  and  744 . These projections can be shaped and sized to facilitate insertion of the speed nocks through or between adjacent bowstring strands. For example, ends  634  and  744  can separate bowstring strands or groups of strands, and in some cases, obviate the need to use a separate strand separator tool when installing the speed nocks on a bowstring. 
     Yet another alternative embodiment of the speed nock is shown in  FIG. 17  and generally designated  810 . This speed nock is similar to the above described speed nock with several exceptions. For example, the speed nock  10  is a two-piece speed nock. One enlarged portion  830  includes a threaded stud  840  which functions as a central portion or reduced dimension portion, and that threads into an aperture  822  in the other enlarged portion  820 . When threaded into the other enlarged portion, the stud can connect and form a transition between the enlarged portions. Optionally, the end of the stud  840  can be pointed to facilitate insertion through bowstring strands as desired. After the stud is inserted through the strands, the other enlarged portion  820  can be threaded onto the stud to secure the speed nock to the bowstring. 
     The above descriptions are those of the preferred embodiments of the invention. Various alterations and changes can be made without departing from the spirit and broader aspects of the invention as defined in the appended claims, which are to be interpreted in accordance with the principles of patent law including the doctrine of equivalents. Any references to claim elements in the singular, for example, using the articles “a,” “an,” “the,” or “said,” is not to be construed as limiting the element to the singular.