US20120152219A1

US20120152219A1 - Surprisingly Superior Crossbow Serving

Info

Publication number: US20120152219A1
Application number: US12/973,012
Authority: US
Inventors: Mathew A. McPherson
Original assignee: MCP IP LLC
Current assignee: MCP IP LLC
Priority date: 2010-12-20
Filing date: 2010-12-20
Publication date: 2012-06-21

Abstract

A bowstring for use with a crossbow, the bowstring including a plurality of strands and a first serving material wrapped around the entire length of the plurality of strands between opposite looped ends, such that the first serving material is self-secured to the bowstring and a method of making the same. A second serving material is wrapped around selected portions of the first serving material to provide a composite crossbow bowstring of surprisingly improved durability and performance. The second serving material having a first end, a second end and middle portion extending therebetween. The middle portion of the second serving material being wrapped over at least a portion of the first end and the second end such that the second serving material is self-secured to the first serving material and the stands of the bowstring.

Description

FIELD OF THE INVENTION

The present invention relates to bowstrings for crossbows which are made from a plurality of high strength strands which may be a blend of at least two fibers, some of the fibers being formed of a first material and some of the fibers being formed of a second material. The blend of fibers results in a bowstring having high tensile strength and good resistance to creep and/or string elongation. The bowstring may also include a first serving material wrapped around the entire length of the plurality of strands between the opposite looped ends such that the first serving material is self-secured to the bowstring and a method of making the same. A second serving material may be wrapped around selective portions of the first serving material to provide a composite crossbow bowstring of improved durability and performance. The second serving material may include a first end, a second end and middle portion extending therebetween. The middle portion of the second serving material being wrapped over at least a portion of the first end and the second end such that the second serving material is self-secured to the first serving material and the strands of the bowstring. The present invention is related to the bowstrings, crossbows, and apparatus described in U.S. Pat. Nos. 6,267,108; 7,182,079; 7,231,915; 7,434,574; 5,676,123; 5,752,496; and 6,651,463 the entire contents all of which are incorporated by reference herein in their entireties.

BACKGROUND OF THE INVENTION

In the last century, certain bowstrings have been manufactured from manmade fibers with DACRON® polyester available from DuPont, being the most popularly used material through the later 1980's. DACRON® B-50 was the most commonly used of the DACRON® fiber materials with the “50” being used to refer to a single strand breaking strength (tensile strength) of about 50 pounds. This material exhibited very consistent mechanical properties and performance, had good abrasion resistance, and exhibited durability when used in bowstrings.
Another type of bowstring is the KEVLAR® poly-paraphenylene terephthalamide (aramid fiber), which is formed of another popular synthetic material as available from DuPont. KEVLAR® exhibited a higher tensile strength at break, and thus higher breaking strength per strand, and also had a much higher modulus of elasticity as compared to DACRON®. The higher modulus of elasticity for KEVLAR® resulted in improved performance characteristics, and the higher tensile strength allowed for a reduced number of strands, which more than compensated for its higher density. Lighter mass weight technically results in a higher arrow launch velocity. However, KEVLAR® exhibited a limited life expectancy, sometimes producing only 1000 to 1500 shots per string. The use of KEVLAR® was predominantly limited to traditional bows specifically designed for use with KEVLAR® bowstrings, and its use was limited to a relatively small number of top level tournament archers due to its low resistance to cyclic bending fatigue.
Another type of bowstring is formed from a synthetic string material known as SPECTRA® which is formed of 1000 ultra high molecular weight polyethylene fiber available from the High Performance Fibers Group of AlliedSignal, Inc. Bowstring material manufactured of SPECTRA® polyethylene is available from Brownell under the tradename of FAST FLIGHT®.
The SPECTRA® fiber was also a very high strength fiber with a very high modulus of elasticity and a density less than the fiber used in DACRON® B-50. This material, in addition to being lightweight, and having high strength and high modulus, also exhibits excellent durability and excellent abrasion resistance. Significantly improved performance was exhibited by bows using SPECTRA® 1000 (FAST FLIGHT® bowstrings) as compared to DACRON® B-50 bowstrings, with one particular improvement being higher arrow launch velocity exhibited with the SPECTRA® made bowstrings.
However, SPECTRA® material may be subject to creep. Creep or stretch of the bowstring is a typical problem encountered by archers using the SPECTRA® made bowstrings. When the bow is subject to a load, both when the bow is in the brace condition and when the bowstring is drawn and released for arrow propulsion, the string elongates in proportion to the load applied. For many materials, the string returns to its original length once the load is removed. If a material exhibits creep, however, the string does not fully return to its original length, and the string will elongate or stretch permanently over a given period of time. Time, temperature, and the applied load can influence the rate and severity of the stretching due to creep. This obviously affects the performance of the bow.
Another ultra high molecular weight polyethylene is sold under the tradename of DYNEEMA® available from DSM-Toyobo, which is made by a different process than SPECTRA®.
Since the appearance of SPECTRA® there have been several other new synthetic fibers introduced which have been utilized in the manufacture of bowstrings. Examples of these materials include VECTRAN® liquid crystal polymer (LCP) available from Hoechst Celanese Corp. and ZYLON® poly (p-phenylene-2-6-benzobisoxazole) available from Toyobo Co.
VECTRAN® does not exhibit poor creep characteristics as compared to SPECTRA® and provides high tensile strength and modulus. However, VECTRAN®, like KEVLAR®, also suffers from lower abrasion resistance and a short life expectancy, but to a lesser degree than the latter. Another disadvantage of VECTRAN® is that it has a lower modulus of elasticity than SPECTRA® which ultimately results in lower arrow velocities than can be achieved with SPECTRA®.
ZYLON® is made up of rigid rod chain molecules of poly (p-phenylene-2,6-benzobisoxazole) (PBO). ZYLON® fibers exhibit some of the best mechanical properties available and have high strength, high modulus, and no negative creep characteristics. One disadvantage that has been observed with the ZYLON® material itself is that its strength may be affected by sunlight. This has restricted its use in bowstrings. The serving of the entire crossbow bowstring between the opposite looped ends with a first serving, according to the disclosure herein, may protect the underlying crossbow bowstring from outside elements, such as physical contact and degradation of the crossbow bowstring, from exposure to hazards and/or sunlight, thereby improving the useful life of the crossbow bowstring.
Another type of bowstring has utilized a blended material, “S4”, wherein SPECTRA® polyethylene and VECTRAN® LCP were actually blended at a 50/50 ratio at the fiber level rather than at the strand level. These materials have also been blended at a ratio of 68% SPECTRA® polyethylene to 32% VECTRAN® LCP and marketed under the tradename of “450 Plus”.
U.S. Pat. No. 5,884,617 describes bowstrings constructed of braided strands, preferably comprising flat braids, from a high strength mixture of yarns comprising abrasion-resistant fibers and yarns comprising high strength, creep resistant fibers. The types of bowstrings referenced in U.S. Pat. No. 5,884,617 are incorporated by reference herein.
It is a recognized practice to apply serving line to portions of an archery bowstring. The center serving on the bowstring is intended to protect the bowstring in the area that it is applied from premature wear and abrasion due to the nocking and losing of an arrow or crossbow bolt.
A bowstring may be assembled from multiple strands and displayed in position for applying serving line to the nock and loop end areas. Such a procedure is described in “Making a Bow String” Archer's Digest, 5th Edition, 1991, DBI Books. The procedure may be time consuming, inefficient and inaccurate. This publication is also incorporated herein by reference in its entirety.
Bowstrings may be formed using one of two basic methods. One method consists of laying out multiple strands of a given length of a bowstring material and then dividing that material at the ends into two or more equal bundles and twisting or braiding these bundles into one single string or rope-like structure. The rope-like structure is then brought back on itself and is braided or twisted back into the original material to form an end loop.
A second method may be referred to as an endless string. Using this method, a continuous strand of bowstring material is wrapped around two posts spaced apart at a distance which is approximately equal to that desired for the final bowstring length. The string is wrapped around the two posts until the desired number of strands is reached. The starting and ending point of the string is then tied together forming a splice. A separate piece of bowstring material is then typically wrapped or served over the area of the splice, and end loops are formed by folding the served area back on itself, and continuing to serve or wrap over the two sides of the string resulting in one multi-stranded bowstring with a loop at each end. The bowstrings thus made are usually held at one end while the other end is rotated to add twists to the main body of the strands which have not been served to bring the overall string length to a desired dimension that will result in the proper functioning of the bow on which the string is to be used. A bowstring so constructed is functional and can be used to launch arrows or bolts, but unless one also wraps or serves the central portion of the string that comes in contact with the arrow or bolt, the string will have a much shorter useful life expectancy than desired. Therefore it is desirable to serve or wrap the bowstring in the area that comes in contact with the arrow or bolt and the means of losing the arrow or bolt. In almost all cases the bowstrings are served or wrapped in this area and it is referred to as the center serving. The center serving's purpose is to protect the central area of the bowstring from the wear that results from the attachment of the arrow or bolt and the means used to loose the arrow or bolt at launch.
FIGS. 1-4 illustrate a prior art center serving wherein a center serving is applied over a multiple strand bowstring body. A serving tool is typically employed for this purpose. A serving tool is described, for example, in U.S. Pat. No. 5,538,197, the entire contents of which is incorporated by reference herein. To begin the wrapping process, approximately one foot of serving material may be pulled from the serving tool. The end of the serving material may be held while the opposite end of the serving material, which is attached to the serving tool, is wrapped around bowstring twice. The loose end of the serving is then laid back over the bowstring as shown in FIG. 2.
In FIG. 3, the end attached to serving tool may then be wrapped over the laid back end in a continuous spiral fashion thereby encapsulating the bundled bowstring. Generally it is desirable to apply this serving as tight as possible with the idea that it will remain in position when finished. To finish off the central serving one can lay a loop of serving material parallel to the bowstring with the loop pointing in the direction of the end of the serving and extending beyond where the serving is to end as shown in FIG. 4. The serving material may then be wrapped over loop. When the desired length of serving is obtained, the end of serving material may be fed back through the loop and with end held tightly, where upon loop ends may be pulled tight resulting in the loop being drawn under the serving material. End of serving material may exit from serving, and is pulled as tightly as possible and any excess material may be removed.
In some embodiments the serving material is required to be applied very tightly so that it will maintain its position during use. Some manufacturers have taken extra precautions to limit serving movement during use by applying the serving over a bowstring which is treated in the serving area with an adhesive or have applied materials over the serving in an attempt to hold the serving in position and to keep it from separating. These additional steps both add to the cost of manufacturing and increase the amount of clean-up time because of adhesive residue.
Over the useful life of the bowstring some archers have added twists to the bowstring to compensate for the natural elongation of the bowstring material. The additional twists added to the bowstring may decrease the diameter of the bowstring resulting in loosening of the center serving.
Thus, while it has long been the practice to serve or wrap the bowstring and/or power cables at or proximate to the loop ends, and in a central portion, it has also been a problem to keep that center serving tight and properly located in the central section of the bowstring.
In the past the increased load pressure applied to the end servings of some bowstrings, as they are bent by the eccentrics, may result in separation of the end servings which can leave the string unprotected and subject to increased wear. Such wear may be even more evident with a single cam crossbow, and high performance twin cam crossbows, because these cams provide even higher load pressure and bending where the high points or steep angles on the eccentric (or cam) contact the end servings.
In the past bowstring strands have experienced separation following use where the bowstring fibers are left unprotected from the elements and the individual strands of the bowstring can become exposed to dirt and/or dust which can get between the individual strands and eventually wear by the eccentric. The separation is unsightly and, left unprotected, bowstring can become worn and break.
The present invention provides an improved method of wrapping the bowstring such that it is tight and remains properly positioned over time.

SUMMARY OF THE INVENTION

In some embodiments the present invention relates to a bowstring for a crossbow that exhibits significantly improved properties as related to life expectancy, negligible creep, and/or string elongation and enhanced crossbow performance.
In some embodiments, the present invention relates to a bowstring made up of a plurality of strands, where each strand may be formed one or a plurality of different fibers, each fiber may have a minimum modulus of elasticity of about 8,000,000 psi and a minimum ultimate tensile of about 350,000 psi.
In some embodiments, the present invention relates to a bowstring made of a plurality of strands where each strand may be formed of a blend of at least two different fibers. In some embodiments the bowstring may be formed of a composition such that about 10 wt-% to 30 wt-% of the bowstring is liquid crystal polymer and 70 wt-% to about 90 wt-% of the bowstring is ultra high molecular weight polyolefin.
In some embodiments, the present invention further relates to a crossbow having a bowstring of the present invention. In some embodiments, a crossbow may include a limb mounting portion, a first limb supported by the mounting portion, and a second limb supported by the mounting portion. A pulley or cam is pivotally mounted upon the first limb for rotation about a first axle. The pulley or cam includes a track. A cam assembly may be pivotally mounted upon the second limb for rotation about a second axle. The cam assembly has a primary string payout track along its periphery to accommodate a cable therein, a secondary string payout track to accommodate a cable therein and an anchor or take-up track to accommodate a cable therein. The ratio of the length of the take-up track to the length of the primary string payout track may be less than about 0.4. The crossbow in some embodiments also includes a bowstring or cable extending between the rotation members. The crossbow as referenced herein includes reference to the modern crossbows which may employ a track type crossbow design and/or a trackless design.
Desirably, in some embodiments the crossbow will further comprise a power cable and an anchor cable. The power cable may have a first end portion terminating in a first end anchored to a pulley or cam assembly and a second end portion terminating in a second end anchored to the cam assembly. The first end portion may be received in the primary string payout track and the second end portion may be received in the secondary string payout track. A portion of the power cable is trained about the pulley or cam and received in the pulley track to form a bow-string section and a return section. The anchor cable extends between the first limb and the cam assembly and is received in the anchor or take-up track.
In the track type crossbow design, a bolt shaft rests in a track located in the stock of the crossbow in the full drawn cocked position. The bolt is launched from the crossbow by being pushed down the track with the bowstring and the bolt both maintaining intimate contact with the track until the bolt has cleared the bow. The bolt used in this type of crossbow is usually blunt at the rear end of the bolt. The bowstring that propels the bolt simply pushes against the blunt end to propel the bolt from the crossbow.
In the trackless type crossbow design, the bolt is supported on a bolt rest towards the front of the bolt shaft and the rear of the bolt is supported by being nocked to the bowstring in the same manner as is used in conventional bows.
In some embodiments, the present invention results in the application of a first serving around the entire length of the bowstring between the opposite looped ends and a second serving over portions of the first serving. The first and second servings are not only tight, but are also secured onto the main body of the bowstring in a manner that keeps them properly located and does not allow the servings to migrate up or down the bowstring in use.
In some embodiments, the first and second servings are secured positively to the bowstring both at the beginning and end of the serving, which keeps the serving from migrating up or down the bowstring in use and should the bowstring elongate over its useful life and need to be twisted to bring it back into length, such action will actually tend to further tighten the first and second servings making it even less susceptible to movement.
Other aspects of the invention are described in the Detailed Description and in the claims below.
These and other more detailed and specific understanding of the invention will become apparent from a consideration of the following Detailed Description of the Invention in view of the Drawings.
For the purpose of this disclosure, all US patents and patent applications and all other publications referenced herein are incorporated herein by reference in their entirety.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-4 illustrate a prior art process of applying a center serving to a bowstring.

FIG. 5 illustrates a four post bowstring lay-up fixture.

FIG. 6 illustrates a two-post bowstring lay-up fixture.

FIG. 7 shows an enlarged image of the same two-post bowstring lay-up fixture as that shown in FIG. 6.

FIG. 8 shows an enlarged image of string halves which are brought together and served.

FIG. 9 illustrates an alternative method of finishing a string loop.

FIGS. 10 and 10 a show two alternative bowstring lay-ups having different twist and loop treatments.

FIG. 11 illustrates a basic single bowstring strand composition.

FIG. 12 illustrates a single bowstring strand composed of two commingled yarn titers.

FIG. 13 shows an alternative view of a single strand composed of two different yarn titers.

FIG. 14 illustrates a single bowstring strand which has been combined using a clockwise twist.

FIG. 15 illustrates a single bowstring strand that has been combined using a counter clockwise twist.

FIG. 16 illustrates a bowstring composed of two separate bundles of clockwise and counterclockwise strands.

FIG. 17 illustrates a bowstring composed of clockwise and counter clockwise strands which are intermingled.

FIG. 18 illustrates a compound crossbow employing the bowstrings of the present invention.

FIG. 19 illustrates one embodiment of a process of applying a center serving to a bowstring.

FIG. 20 illustrates one embodiment of a process of applying a center serving to a bowstring.

FIG. 21 illustrates one embodiment of a process of applying a center serving to a bowstring.

FIG. 22 illustrates one embodiment of a process of applying a center serving to a bowstring.

FIG. 23 illustrates one embodiment of a process of applying a center serving to a bowstring.

FIG. 24 illustrates one embodiment of a process of applying a center serving to a bowstring.

FIG. 25 illustrates one embodiment of a crossbow bowstring.

FIG. 25 a illustrates a detail partial cutaway view of one embodiment of a crossbow bowstring of FIG. 25.

FIG. 26 illustrates one embodiment of a crossbow bowstring.

FIG. 26 a illustrates a detail partial cutaway view of one embodiment of a crossbow bowstring of FIG. 26.

FIG. 27 illustrates a partial cross-sectional side view of one embodiment of the crossbow bowstring taken along the line 27-27 of FIG. 25.

DETAILED DESCRIPTIONS OF THE PREFERRED EMBODIMENTS

In at least one embodiment a crossbow bowstrings may be formed of a plurality of strands which in turn may be made of one or a plurality of fibers. In some embodiments each fiber may be formed of a first material, and/or a combination of a first material and one or more second materials. In at least one embodiment, the first and second materials may be selected so as to have high moduli of elasticity that are substantially similar, and at least one of the materials may have a high ultimate strength as determined by measuring tensile at break. Suitably, the modulus of elasticity of each of the materials for the fibers may be greater or less than about 8,000,000 psi. In some embodiments, the ultimate tensile strength of at least one of the materials for the fibers may be greater than or less than about 350,000 psi.
As used herein, in some embodiments, the term “ultra high molecular weight” (UHMW) shall be used to refer to those polyolefin (PO) polymers having a molecular weight of greater than about one million, and more suitable from about 3-6 million and a density of greater than about 9 grams per cubic centimeter or 0.0325 pounds per cubic inch.
As used herein, in some embodiments, the term “string” shall be used to describe a bundle or plurality of strands, where each strand may be formed of at least two different fibers or monofilaments. In some embodiments, a yarn titer may be made up of a plurality of fibers and in turn one or more yarn titers may be twisted together to form a strand of bowstring material. The bundle or plurality of strands may remain straight, or may be twisted or braided to form the crossbow bowstring.
In some embodiments materials which may be used in making the strands of the present invention include liquid crystal polymers (LCP) and ultra high molecular weight polyolefin's (UHMW-PO). An example of a useful LCP fiber is VECTRAN® HS or M available from Hoechst Celanese Corp., which is based on VECTRA® A950 polymer resin available from Hoechst Celanese Corp. Examples of useful UHMW-PO fibers include SPECTRA® 1000 ultra high molecular weight polyethylene (UHMW-PE) available from the High Performance Fibers Group of AlliedSignal and DYNEEMA®. UHMW-PE may be available from DMS-Toyobo.
In some embodiments, bowstrings and power cables used on a crossbow may be formed from any suitable material including, but not limited to SPECTRA® polyethylene fibers, DACRON® polyester, KEVLAR® poly-paraphenylene terephthalamide (aramid fiber), and so forth. DACRON® fibers are available under the tradename of DACRON® B-50 from Brownell II, for example, wherein the “50” refers to a single strand breaking strength (tensile strength) of about 50 pounds. SPECTRA® 1000 ultra high molecular weight polyethylene fiber available is available from the High Performance Fibers Group of AlliedSignal, Inc. Bowstring material manufactured of SPECTRA® polyethylene is available from Brownell under the tradename of FAST FLIGHT®. Bowstring material manufactured by BCY Inc. is available under the tradename of DynaFLIGHT® 97 which is 100% SK75 DYNEEMA® ultrahigh molecular weight polyethylene and 8125 which is 92% SK75 DYNEEMA®. DYNEEMA® fibers are available from DSM-Toyobo.
In other embodiments, the liquid crystal polymers may be formed of VECTRAN® liquid crystal polymer (LCP) available from Hoechst Celanese Corp. and ZYLON® poly(p-phenylene-2-6-benzobisoxazole) available from Toyobo Co.
In some embodiments, blended fiber bowstrings may also be employed. Examples of blended fiber bowstrings may be found in commonly assigned U.S. Pat. No. 6,651,643, the entire contents of which are incorporated by reference herein in its entirety.
A commercially available example of a blended bowstring material is 450 Plus which is a blend of 70% DYNEEMA® SK75 and 30% VECTRAN® fibers available from BCY Inc.
In some embodiments the above referenced fibers, UHMW-PE and LCP, exhibit modulus of elasticity which are relatively close in value, and ultimate strength which are relatively close in value. The UHMW-PE fibers typically have a modulus of elasticity of about 1.25 times 10 sup. 6 to 1.5 times 10 sup. 6 psi, and an ultimate tensile strength of about 3.5 times 10 sup. 5 to about 5 times 10 sup. 5 psi, and the LCP fibers typically have a modulus of elasticity of about 9.5 times 10 sup.5 psi and an ultimate tensile strength of about 4.2 times 10 sup. 5 psi.
In some embodiments, the strands may be made of a blend of yarn titers some of which are ultra high molecular weight polyethylene (UHNW-PE) such as SPECTRA® or DYNEEMA®, and some of which are liquid crystal polymer (LCP) such as VECTRAN®. Using a blend such as this, the performance and durability of the SPECTRA® or DYNEEMA® UHMW-PE's may be maintained and the addition of VECTRAN® may improve the resistance to creep and/or string elongation. Therefore, the performance of the bowstring depends on how well the two materials perform together.
In some embodiments as described herein, 30 wt-% or less of the bowstring may be LCP and 70 wt-% or more of the bowstring may be UHMW-PO. In other embodiments about 10 wt-% to 30 wt-% of the bowstring may be LCP and 70 wt-% to about 90 wt-% of the bowstring UHMW-PO. In other embodiments, about 20 wt-% to 30 wt-% of the bowstring may be LCP and 70 wt-% to about 80 wt-% of the bowstring may be UHMW-PO.
In the above described embodiments, there are enough LCP fibers, as determined by the weight percent of the LCP present in the bowstring, to inhibit the creep and/or string elongation characteristics of the UHMW-PO without measurably decreasing the performance of the UHMW-PO.
In one specific embodiment, 23.5 wt-% of the bowstring may be VECTRAN® HS LCP and 76.5 wt-% of the bowstring may be SPECTRA® 1000 UHMW-PE.
One other factor to be considered when determining the existence and/or the amount of LCP and the existence and/or the amount of UHMW-PO for a desired level of performance is the denier of each fiber. The blending of at least two fibers may be advantageous for those fibers that exhibit notch sensitivity because of the additional cushioning provided for those fibers. An example of a method for achieving optimal blending is air commingling of the fibers.
In some embodiments, when selecting the specific blend of fibers for each strand ultimately used in the bowstring, the denier (g/9000 m) or weight of each fiber may also be taken into account. The finer the denier that is used, the greater the cushioning effect on the LCP, and the greater the longevity of the strand material when exposed to cyclic bending. However, the finer the denier, the greater the cost, so the selection is also based on the economics of buying a finer denier. For LCP, the denier is suitably 400 or less based on the foregoing reasons. This is not to say that a higher denier LCP could not be used. For the UHMW-PO, the denier is suitably 600 or more, and even more suitably about 800 to about 1800.
In some embodiments, an example of a blend of fibers which may be useful herein and which may provide the desired performance characteristics is a 1425 denier blend that includes 1025 denier SPECTRA® 1000 fiber and 400 denier VECTRAN® HS fiber which yields a blend wherein 28 wt-% of bowstring is VECTRAN® LCP and 72 wt-% of the bowstring is SPECTRA® UHMW-PE.
Another example of a blend useful herein is a 1600 denier blend which includes 400 and 800 denier DYNEEMA® UHMW-PE and 400 denier VECTRAN® LCP which yields a blend wherein 25 wt-% of the bowstring is VECTRAN® LCP and 75 wt-% of the bowstring is SPECTRA® UHMW-PE.
Another specific example of a blend of fibers useful in making the strands and bowstrings of the present invention is a 1700 denier blend that includes 1300 denier SPECTRA® 1000 fiber and 400 denier VECTRAN® fiber which yields a blend which ultimately provides a bowstring composition which is 24 wt-% VECTRAN® LCP and 76 wt-% SPECTRA® UHMW-PE.
Each of these blends is found to have a sufficient amount of LCP to effectively reduce the amount of creep and/or string elongation exhibited in a bowstring when combined with UHMW-PE. Further, this amount of LCP has been found to have a minimal adverse affect on the performance characteristics of the UHMW-PE material. In other embodiments, any combination and/or proportion of fibers as described herein may be utilized to provide a crossbow bowstring having the desired performance characteristics.
In some embodiments, servings may also be made from a variety of materials including fishing line material, polyethylene fiber material, polyester, poly-paraphenylene terephthalamide (aramid fiber). In some embodiments, the servings may be applied over selected portions of the bowstring and/or second cable and/or anchor cable in a circumferential side-by-side fashion. In some embodiments, center servings and end servings may be applied to the bowstring and/or second cable and/or anchor cable.
In at least one embodiment, FIG. 5 illustrates generally a typical four-post manual fixture for laying up one embodiment of a bowstring which may be used with a crossbow. Starting end 102 of a single strand 130 may be tied off at post 142. Strand 130 is typically supplied on a spool. Single strand 130 may be wrapped around each post 142 of fixture 110 about 3-12 times resulting in a bowstring 115 (FIG. 8) with about 6-24 strands ending at finishing end 106 of single strand 130. The bundle of 3-12 stands, half the number of strands of the finished bowstring, is represented at 104. The bundle of 6-24 strands, now a bowstring, is represented at 115. Starting end 102 and finishing end 106 may then be tied together and wrapped in the area of the tie to assure that the bundle of strands 104 is securely held together. Alternatively, FIG. 6, illustrates generally at 120 a simple two-post lay-up structure for finishing the end loops on the bowstring 115. In some embodiments, commercially manufactured bowstrings are made on semi-automated equipment using a procedure similar to those described above.
FIGS. 7, 8, and 9 illustrate enlarged views of circled area 117 in FIG. 6. As an be seen from FIG. 7, approximately half of the total strands of the final bowstring 115, may be located on either side of post 103.
To finish the lay up of the bowstring 115, in some embodiments, the starting 112 or finishing 116 end may be used to bind both sides of the strands 104 together to make the final bowstring 115 with a series of knots or with separate serving(s) 112 as shown in FIG. 8. An alternative end loop arrangement is shown in FIG. 9 wherein the previously served portion 118 of the string 115 is looped around a single post 103 and two halves 104, each having half the number of strands of finished string 115, i.e. each having 3-12 strands, are served together at 113 to form the bowstring 115.
In an alternative embodiment, FIGS. 10 and 10 a illustrate generally at 115 and 115 a, two different embodiments of a finished bowstring. Each string may be formed of a plurality of strands 130. (FIG. 11) In each embodiment, each strand 130 may be formed by twisting one or more yarn titers 134 of UHMW-PE with one or more yarn titers 132 of LCP, as shown in FIGS. 11 and 12, either twisted clockwise or counterclockwise a predetermined number of times per unit length. The individual strands 130 thus formed may then laid up on a fixture 110 or 120 as shown in FIGS. 5 and 6 and the free ends 102, 106 tied off and bound, i.e. served, to create the bowstring 115, 115 a. If the free ends 102, 106 occur at the same end of the string lay-up, they are often tied or bound together. If, on the other hand, the free ends 102, 106 occur at opposite ends of the lay-up, then each may be tied off and/or bound as described previously. The individual strands 130, may be served together at the end loops 108, 108 a at the ends 112, 112 a and intermediately 114, 114 a on the bowstring.
In some embodiments, between 6 and 24 strands, and more typically between 8 and 22 individual strands may make up the bowstring, but this number may be more or less depending on the size, i.e. the diameter, of each strand and the draw weight of the crossbow on which the bowstring is employed. The finished bowstring should be of a certain diameter, particularly where the bolt is nocked. The bowstrings should also be within certain diameter tolerances at the served or bound ends 112 to provide an optimum fit with the cam grooves in which they may be fitted.
Optionally, in some embodiments the individual yarn titers 132, 134 as shown in FIG. 12, may be combined using air for commingling of the fibers 136, 138 of the yarn titers 132, 134 as they are being twisted into a single strand 130 of bowstring material.
In one embodiment, as described in U.S. Pat. No. 5,752,496, incorporated by reference herein in its entirety, a bowstring may be formed of a number of strands that have been twisted in the clockwise direction, and a number of strands that have been twisted in the counterclockwise direction, the number of each of which may be approximately equal. The number in either direction may vary slightly, however, and a given number of strands twisted in a given direction may be increased to offset the likelihood that the bowstring itself may be twisted during the process of making and mounting the bowstring on a crossbow.
In one embodiment, FIG. 11 illustrates generally at 130, one way of making a strand. Strand 130 may be made of at least two yarn titers 132, 134. In one embodiment, one yarn titer is liquid crystal polymer (LCP) and one yarn titer is ultra high molecular weight polyolefin (UHMW-PO) such as polyethylene (UHMW-PE). More typically, 132 may be a plurality of yarn titers and 134 may be a plurality of yarn titers which may then be twisted together to make a strand. The yarn titers may be twisted individually about one another in a clockwise direction to form an individual strand. Alternatively, the yarn titers may be twisted together in the opposing direction. FIG. 13 illustrates the same strand 130 after twisting yarn titers 132, 134 about one another.
In some embodiments, FIGS. 14 and 15 illustrate generally at 140, 150 alternative twist patterns used in making individual strands. In FIGS. 14 and 15, the strands may be made of at least two yarn titers, one of which may be LCP and one of which may be UHMW-PO. In some embodiments, there may be a plurality of each type of yarn titer used in making the strand. The bowstring would then be made of a plurality of strands. FIG. 14 shows a strand designated generally at 140 twisted in a counterclockwise direction for a predetermined number of twists per unit length. FIG. 15 shows a strand designated generally at 150 twisted in a clockwise direction for a predetermined number of twists per unit length. The number of twists in a strand may be typically about 2-5 twists per inch. The strands as shown, may then be bundled to make a bowstring. As noted above, about 6-24, and more typically about 8-22 strands may make up a bowstring but this may be more or less depending on the size of each strand, i.e. the diameter.
In at least one embodiment, FIGS. 16 and 17 illustrate generally at 160, 166 two different methods of grouping the individual strands into a bowstring. While these are exemplary as to how the strands might be grouped together, they are not intended as exclusive of the ways in which this could be done, nor are they intended to limit the scope of the invention as such. In FIG. 16, the clockwise twisted strands 154 and the counterclockwise twisted strands 152 are grouped separately first to form one grouping of clockwise twisted strands 154 and a separate grouping of counterclockwise twisted strands 152. These two groupings are then bound together in parallel fashion at 155 without intermixing. In both groups, there are a substantially equal number of strands 152 and strands 154. In FIG. 17 the clockwise twisted strands 154 and counterclockwise twisted strands 152 are intermixed and substantially equally dispersed throughout the bowstring 166 in a random fashion.
The method identified herein as used to form strands of a bowstring are provided to illustrate certain embodiments of how a strand and bowstring may be made, one of skill in the art would understand that a strand may be made in different ways without departing from the scope of the present invention. As noted above, the bowstrings are made up of a plurality or bundle of strands. The strands in some embodiments may be made of at least two different yarn titers, the two different yarn titers being made of a first material and a second material different from the first material. Preferably, the bowstrings in some embodiments may be in a non-braided configuration.
In some embodiments, FIG. 18 illustrates a Crossbow generally at 200. Crossbow 200 has a limb mounting portion 230 from which first and second limbs 220, 240 extend outwardly. Rotation assemblies 270, 280 are rotatably mounted on first and second limbs 220, 240. Another type of Crossbow is described in U.S. Pat. No. 6,267,108 incorporated by reference herein in its entirety. The bowstring of the present invention, however, is not limited to any particular type of Crossbow or archery bow.
In some embodiments as depicted in FIGS. 19-24 a process of applying a center serving to a bowstring is shown. The serving and process of forming the serving described herein, may be employed for either endless or Flemish style bowstrings.
In at least one embodiment, FIG. 19 depicts a partial longitudinal side view of an embodiment of a bowstring which has been laid up and the looped ends formed (not shown). The bowstring is typically held under some degree of tension using any means known in the art such as two posts or hooks spaced at the desirable distance apart in order to bring each of the individual strands which form the bowstring under adequate tension. The bowstring may or may not be twisted at this time but in most cases there will probably be some number of twists in the bowstring. The number of twists is suitably less at this time than the number required to bring the string into proper finished length. The process described herein, is directed to an embodiment of a bowstring that either is or will be twisted in the clockwise direction to bring the bowstring to its final desired length. The present invention is not, however, limited to bowstrings twisted in a clockwise direction.
In at least one embodiment as shown in FIG. 19, individual strands 325 of bowstring 320 are separated, which may occur at the center of bowstring 320, or which may occur proximate to an end, to form an opening 330. Desirably, an equal number of strands 325 are located on either side of opening 330. End 310 of serving material 308 is inserted through opening 330 such that it protrudes to a desirable length, through the opening 330 of the bowstring 320.
In some embodiments, end 312 of serving material 308 may be held in serving tool (not shown) while loose end 310 of serving material 308 is held to the left of the serving tool. Two wraps around the bowstring in a counterclockwise direction represented at 314 may then made using serving tool (not shown). One example of a serving tool is described for example in U.S. Pat. No. 5,538,197 the entire content of which is incorporated by reference herein in its entirety.
In some embodiments, the loose end 310 of the serving material 308 may then be brought back across the dual wraps 314 to the right side of wraps 314 as shown in FIG. 20. Of course, all of the steps may be done in the opposite direction as well. The serving material 308 may then be wrapped counterclockwise around bowstring 320 any desired number of times as shown in FIG. 21. As can be seen in FIG. 21, the serving material may be wrapped over the end 310 of serving material 308 such that serving material 308 is being wrapped over itself. Also, the number of wraps of serving material around the bowstring may be varied.
In some embodiments, the remainder of the serving material may be secured to the bowstring by using two half hitches at a position which may be a desired distance to the right of the serving (not shown). The bowstring is served in the counterclockwise direction until the desired length of serving is obtained. The loose end of the serving may then be cut near the present serving position and covered by several more wraps of serving.
In some embodiments, approximately 6-12 inches of serving material may then be pulled from the serving tool at end 312. A half hitch knot 334 may be tied around the bowstring as shown in FIG. 22 adjacent the previous wraps. This knot may be loosely cinched at this time.
In at least one embodiment, the individual bowstring strands 325 may again be separated into two bundles 320 a and 320 b depicted in FIG. 22. Bundle 320 a may have an equal number of strands to bundle 320 b. The end 312 of serving material 308 and serving tool (not shown) may then be placed through the opening 340 formed between bundles 320 a and 320 b. It may be necessary to temporarily relieve pressure on the bowstring at this point such that the bundles may be separated. The serving material may then be cinched next to the previously made half hitch represented by reference numeral 342 in FIG. 23.
In some embodiments, at a desired distance from the previous serving, another serving may be started, this time in a clockwise or opposing direction. Shown in FIG. 23, backwraps 332 may have been created in a clockwise or opposing direction.
In some embodiments, end portion 312 of serving material may then be held over the served portion 344 of the bowstring 320 shown in FIG. 23. The serving material 313 which is protruding through opening 340 may then be wrapped in a counterclockwise direction as shown at 346 in FIG. 24 until all of the backwraps are consumed. Using the serving tool (not shown), the end 312 of the serving material may then be pulled tight and trimmed 315 close to the serving. The entire process may be reversed for a bowstring which is to be twisted in the counterclockwise direction.
In at least one embodiment, a second serving material is affixed and/or engaged over the bowstring and first serving material centrally with respect to the crossbow bowstring. In some embodiments the second serving may be attached to the first serving as previously described with respect to FIGS. 3 and 4. In certain other embodiments two half hitches may be used at opposite ends of the second serving to secure the second serving upon the first serving.
At least one embodiment of the crossbow bowstring is depicted in FIGS. 25, 25 a, 26 and 26 a. FIGS. 25 a and 26 a represent detail cut away views of the crossbow bowstring. In FIG. 25 a a plurality of parallel strands 402 are wrapped in a first serving 404. At least a portion of the first serving 404 is wrapped in a second serving 406. In one embodiment as shown in FIG. 25, a first serving 404 is bound and/or wrapped around the entire length of the parallel strands 402 between the opposite loop ends 408. A second serving 406 may be wrapped around and secured to the exterior of the first serving 404 at a central portion corresponding to a nock location for a bolt or projectile which may be called an arrow. In some embodiments, a second serving 406 may be wrapped around and secured to the first serving proximate to each of the opposite loop ends 408 or at other locations on the first serving 404.
In some embodiments, a crossbow bowstring so constructed is functional and may be used to launch bolts, but unless one also wraps or serves the central portion of the crossbow bowstring that comes in contact with the bolt, the bowstring may have a much shorter useful life expectancy than desired. Therefore, it may be desirable to also serve or wrap the bowstring in the area that comes in contact with the bolt and the means of losing the bolt. The center serving's purpose is to protect the central area of the bowstring from the wear that results from the attachment of the bolt and the means used to loose the bolt at launch.
In some embodiments a crossbow bowstring may be served with a first serving and an additional second serving at locations in which the crossbow bowstring contacts any crossbow rails which may be wear points to improve the useful life of the bowstring.
In FIG. 26 a, one embodiment of the crossbow bowstring is depicted having twisted and/or braided strands 410. A first serving 404 is bound and/or wrapped around the entire length of the twisted and/or braided strands 410 between the opposite loop ends 408. A second serving 406 may be wrapped around and secured to the exterior of the first serving 404 at a central portion corresponding to a nock location for a bolt or projectile which may be called an arrow. In some embodiments, a second serving 406 may be wrapped around and secured to the first serving proximate to each of the opposite loop ends 408 or at other locations on the first serving 404.
In some embodiments the second serving 406 may be wrapped around and secured to the first serving 404, in the same direction as the first serving 404. In other embodiments the second serving 406 may be wrapped around and secured to the first serving 404 in an opposing direction as related to the direction of wrapping for the first serving 404.
In some embodiments the crossbow bowstring may be broadly classified to include reference to a second cable and/or anchor cable as commonly used in association with a compound crossbow. In certain embodiments the second cable and/or anchor cable are also formed of parallel strands 402 or braided strands 410 as disclosed herein. In certain embodiments the entire length of the second cable and/or anchor cable, between the opposite looped ends 408 may also be wrapped in a first serving 404. In certain embodiments, portions of the second cable and/or anchor cable may additionally be wrapped in a second serving 406 as disclosed herein.
The wrapping of only certain portions of the parallel strands 402 or braided strands 410 of a crossbow bowstring, a second cable and/or anchor cable, in a first serving 404, necessarily exposes other portions of the bowstring and second cable and/or anchor cable to the elements, including moisture, brush or other hazards, which may cause the exposed parallel 402 or braided strands 410 to fray and/or wear. The exposure of certain portions of the bowstring and second cable and/or anchor cable to the elements may therefore reduce the strength of the bowstring and/or cables, reducing the useful life thereof. In addition, portions of the parallel 402 or braided strands 410 which are exposed to the elements may be more susceptible to string elongation as compared to the portions of the bowstring and/or second cable and/or anchor cable which have been previously wrapped in a first serving 404.
In some embodiments the wrapping of the entire crossbow bowstring, second cable and/or anchor cable, between the opposite ends in a first serving 404, vastly improves the performance and useful life of the crossbow bowstring, second cable and/or anchor cable. In some embodiments the wrapping of the entire crossbow bowstring, second cable and/or anchor cable, between the opposite ends in a first serving 404, may significantly reduce string elongation associated with the use of a crossbow bowstring, second cable and/or anchor cable.
In some embodiments the inclusion of a second serving 406 at a central location over a first serving 404 for a crossbow bowstring, significantly increases the useful life of the crossbow bowstring by reducing wear occurring at a nock location on the first serving.
In other embodiments, additional portions or sections of a crossbow bowstring, second cable and/or anchor cable completely wrapped between the opposite ends in a first serving 404, may include sections of a second serving 406 over the first serving 404. Additional sections or portions of a second serving 406 may be utilized proximate to the opposite looped ends 408 or in areas where the bowstring, second cable and/or anchor cable contact or engage a pulley and/or cam or other contact surface on a crossbow.
In some embodiments, during the formation of the bowstring the end of the serving may be attached to serving tool which may then be wrapped over the laid back end in a continuous spiral fashion encapsulating the bundled bowstring. In some embodiments it is desirable to apply this serving as tight as possible with the idea that it will remain in position when finished. To finish off the central serving one may lay a loop of serving material parallel to the bowstring with the loop pointing in the direction of the end of the serving and extending beyond where the serving is to end. The serving material may then be wrapped over loop. When the desired length of serving is obtained, the end of serving material may be fed back through the loop and with end held tightly, loop ends may be pulled tight resulting in the loop to be drawn under the serving material. End of serving material exits from serving, and is pulled as tightly as possible and any excess material maybe removed.
In at least one embodiment, the center serving may not only be tight, but may also be secured onto the main body of the bowstring in a manner that keeps it properly located and does not allow the serving to migrate up or down the bowstring during use. In at least one embodiment, the serving is secured positively to the bowstring both at the beginning and end of the serving, which keeps the serving from migrating up or down the bowstring in use.
In the past, the ends of a crossbow bowstring serving may have had a tendency to walk out or experience serving separation. In some embodiments the use of a first serving 404 extending the entire length of the crossbow bowstring between the opposite loop ends 408 may reduce serving separation. In some embodiment when the first serving 404 extends the entire length of the crossbow bowstring to a location proximate to a terminal (e.g. the end loops around a peg), then the first serving 404 may not migrate relative to the crossbow bowstring and/or experience serving separation relative to the bowstring.
In some embodiments, the second serving 406 may be secured to the first serving 404 at opposite ends of the second serving 406 through the use of half-hitch affixation techniques as previously described. In alternative embodiments, the second serving 406 may be secured to the first serving 404 at opposite ends of the second serving 406 through the techniques as previously identified with respect to FIGS. 3 and 4.
In some embodiments as depicted in FIG. 27, the vertical strands are depicted by reference numeral 402. Exterior to the vertical strands 402 is the first serving 404. Between adjacent winds of the first serving 404 a valley 412 occurs. In some embodiments one wind of the second serving 406 is disposed in each valley 412. The tightening of the second serving 406 may force the second serving 406 inwardly toward the strands 402 pressing the second servings 406 into the respective valleys 412. The placement of the winds of the second serving 406 info the valleys 412 in some embodiments establishes a mechanical and/or frictional engagement between the first serving 404 and the second serving 406 which in turn minimizes and/or prevents the second serving 406 from migrating, and/or separating relative to the first serving 404. It should be noted that the placement of the second serving 406 within the valleys 412 as described herein is equally applicable a bowstring which includes twisted strands 410 as depicted in FIG. 26.
In the past some users replace bowstrings when a serving is worn through or appears to be worn. In some embodiments the second serving 406 may be considered to be a sacrificial serving layer. In some embodiments, when the second serving 406 exhibits wear, then the second serving 406 may be replaced without replacement of the first serving 404 and/or the entire bowstring.
In some embodiments a first serving 404 may initiate and be disposed around a plurality of strands 402, 410 proximate to one end or a terminal. The first serving 404 may then extend toward a central area and pass more than half way to the opposite end or terminal of the bowstring. At a desired distance from the first terminal, the direction of the first serving 404 may be reversed whereupon the first serving 404 may be disposed on top of itself to form the second serving portion 406 which will extend a desired length in the reverse direction toward the first end or terminal. The second serving portion 406 (overlap of first serving 404 upon itself) will extend a desired length dimension toward the original end or terminal. The second serving portion 406 may then reverse direction to overlap the second serving portion 406 with a third layer or third serving portion which extends in the initial direction toward the central area and second end or terminal for the bowstring. The third serving portion will extend towards the second end or terminal until such time as the overlap with the second serving portion 406 terminates whereupon the third serving portion seamlessly transitions back into a first serving 404 over the bowstring towards the second end or terminal. The first serving will then terminate and be secured to the bowstring proximate to the second end or terminal. A bowstring having overlapping servings in this embodiment may be formed by a continuous portion of serving material eliminating the necessity for separate serving elements and the attachment of the separate serving elements together. The continuous serving material disposed in the overlapping directions described in this embodiment may reduce migration and/or serving separation along the bowstring.
In some embodiments the overlapping serving layers may be disposed at any location along a bowstring. In other embodiments, the number of overlapping lays of serving material on a bowstring may exceed three layers.
In some embodiments of a crossbow a first cable functions as a bowstring and includes a nock point between the first and second ends. Nock points may optionally be formed of a thread material wound around the bowstring and tied. Nock points are positioned such that a bolt having its shaft supported by a rest and its nock engaged by the bowstring will be perpendicular to the undrawn cable in the undrawn condition. The nock points which are located on either side of the nock position of the bolt on the bowstring serve to indicate the proper position of the bowstring in relation to the trigger latch when the crossbow is cocked. In some cases, these nock point indicators may be painted on the bow string.
Some embodiments of the Crossbow contemplate the use of cam assemblies having different designs. In some embodiments, a cam assembly having a ratio of the length of the take-up track to the length of the primary string pay-out track of less than about 0.4 will be used. In some embodiments the cams may be characterized in that the ratio of the length of the take-up track to the length of the working portion of the main string pay-out track on the level nocking point cams is more than about 0.4. A cam assembly characterized as having a ratio of the length of the take-up track and the length of the total primary and secondary track pay-out tracks of less or greater than about 0.3 may also be used.
In some embodiments the cam assembly may comprise a counteracting weight. The counteracting weight may be constructed from a fairly flexible material such as rubber, plastic or other flexible material. Other suitable materials include aluminum, hardened rubber or tungsten carbide. The counterweight may define or include an enclosed hollow which may contain a counteracting weight material such as a fluid or other flowable material such as oil, water or liquid mercury and may alternatively or additionally include a plurality of particulate matter such as sand or beads composed of steel, lead, tungsten, brass, plastic, rubber or other material including but not limited to metal alloys. In alternative embodiments the hollow may partially contain any variety or combination of counter acting weight material. In some embodiments, a counter weight may also be provided in idler or pulley.
The above disclosure is intended to be illustrative and not exhaustive. This description will suggest many variations and alternatives to one of ordinary skill in this art. All these alternatives and variations are intended to be included within the scope of the attached claims. Those familiar with the art may recognize other equivalents to the specific embodiments described herein which equivalents are also intended to be encompassed by the claims attached hereto.
The above descriptions and embodiments are intended for illustrative and exemplary purposes only, and are not intended to limit the scope of the present invention. While this invention may be embodied in many different forms, there are described certain alternative embodiments of the invention. This description is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiments illustrated.
All published documents, including all US patent documents, mentioned anywhere in this application are hereby expressly incorporated herein by reference in their entirety. Any copending patent applications, mentioned anywhere in this application are also hereby expressly incorporated herein by reference in their entirety.

Claims

1. A method of serving a crossbow bowstring the method comprising the steps of:

a) providing a crossbow bowstring comprising a plurality of strands, said plurality of strands having a length and opposite ends;

b) wrapping a first serving material around the entire length of said plurality of strands between said opposite ends; and

c) wrapping a second serving material over at least a portion of said first serving material to form a second wrapped portion, the second serving material having a first end and a second end extending in opposing directions from a middle portion.

2. The method of claim 1, further comprising looping said first end over said second wrapped portion and wrapping a portion of said middle portion of said second serving material over said first end.

3. The method of claim 1 wherein said plurality of strands are twisted clockwise or counterclockwise.

4. The method of claim 3 wherein the plurality of strands are twisted clockwise and said first direction is counterclockwise.

5. The method of claim 3 wherein said plurality of strands are twisted counterclockwise and said first direction is clockwise.

6. The method of claim 1 wherein said plurality of strands are separated into two bundles such that each bundle has an equal number of strands.

7. The method of claim 1 wherein said plurality of strands are separated into two bundles such that each bundle has an unequal number of strands.

8. The method of claim 2 further comprising the step of wrapping at least a portion of said middle portion around said bowstring in a second direction opposite to said first serving material.

9. The method of claim 8 wherein said first direction is counterclockwise and said second direction is clockwise.

10. The method of claim 8 wherein said first direction is clockwise and said second direction is counterclockwise.

11. A crossbow comprising:

a mounting portion;

a first limb supported by the mounting portion said first limb having a first rotation member;

a second limb supported by the mounting portion said second limb having a second rotation member;

a bowstring extending between said first rotation member and said second rotation member, said bowstring comprising:

i.) a plurality of strands having a length and a pair of opposite ends;

ii.) a first serving material wrapped around the entire length of said plurality of strands between said opposite ends; and

iii.) a second serving material wrapped around at least a central portion of said first serving material.

12. A crossbow bowstring comprising:

a) a plurality of strands, said plurality of strands having a length and opposite ends;

b) a first serving, said first serving material being wrapped around the entire length of said plurality of strands between said opposite ends; and

c) a second serving material, said second serving material being wrapped over at least a central portion of said first serving material to form a second wrapped portion, the second serving material having a first end and a second end extending in opposing directions from a middle portion.

13. The crossbow bowstring according to claim 12 wherein said first end is looped over said second wrapped portion and at least a portion of said middle portion of said second serving material is wrapped over said first end.

14. A bowstring comprising:

a) a plurality of strands, said plurality of strands having a length and opposite ends; and

b) a first serving material wrapped around the entire length of said plurality of strands between said opposite ends.