Abstract:
A cam for a compound archery bow has an adjustable draw cam and a draw stop arm, each releasably and adjustably carried by the cam to permit rapid adjustment of the draw length and let-off characteristics of the cam without having to completely disassemble the bow and without having to replace either of the adjustable draw cam or draw stop arm with different components. Therefore, a plurality of draw lengths as well as let-offs may be achieved by the consumer without having to completely disassemble the bow or purchase a plurality of different, specialized parts. Advantageously, the number of different parts which need to be produced to provide a wide range of draw lengths and let-offs is drastically reduced to greatly facilitate the economical manufacture of cams for archery bows.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to archery bows and, more particularly, to an adjustable cam for an archery bow. 
     2. Description of the Related Art 
     Compound archery bows are well known and may utilize one or more cams to more efficiently store energy in the bow limbs as a drawstring of the bow is drawn. Additionally, a compound bow provides a let-off or reduction of the force required to pull the drawstring during a portion of the draw, and may be adapted to limit the maximum draw length of the bow. Both improve the performance and ease of use of the bow. Compound bows may utilize a single cam and an idler wheel on opposed limbs of the bow or a pair of cams, one at the free end of each limb of the bow. 
     Some archery bows utilize one-piece unitary cams that have one or more grooves formed therein to receive the strings of the bow and one or more posts to which the free end of a bowstring may be attached. To change the characteristics of the bow, such as the draw length, location in the draw and intensity of the let-off of the draw, the user of the bow must completely disassemble the bow and replace the existing cams with replacement cams having different characteristics. Notably, the bow must be disassembled with the use of a bow press to safely remove the bowstring from the limbs which are all under tension. After changing, the cams, the bow must be reassembled and readjusted to enable and optimize its use with the new cams. Further, the new cams are just as inflexible as the old cams in that they have fixed characteristics that cannot be readily altered by a user. Thus, the one-piece cams are very limited, difficult and expensive to change, and very costly to manufacture as several distinct cams must be manufactured for the various draw lengths and let-offs desired by consumers. 
     So-called modular cams have also been used on archery bows. These modular cams have a one-piece main body as in prior cams, and a plurality of individual modules which can be mounted one at a time onto the cam body with each having a different shape and hence, different characteristics in use. Each individual module is distinct from one another and may be individually fixed to the cam in a single location to provide the desired characteristics to the cam and hence the archery bow. For example, modules having different profiles or contours may be placed on a cam to change the intensity of the let-off, which is usually stated as a percent of the draw weight, or the location in the draw where the let-off is initiated. Thus, to vary the let-off within a range of intensity of let-offs, a plurality of independent and distinct modules must be used. 
     Additionally, to limit the draw length of the bow, some cams have been adapted to receive “draw stops” which engage either a string or a limb of the bow at the maximum draw length of the bow to prevent the bow from being overdrawn. Conventional draw stops are typically small knobs attached to the cam by a screw. Such draw stops may vibrate loose from the cam and be lost during use. Still further, the engagement of the small knob with the limb or a bowstring provides a very abrupt stop and a “jerky,” unsmooth feel to the bow that is undesirable to consumers. Still further, movement of the draw stop relative to the cam, or to a module on the cam, can undesirably change the performance, efficiency and accuracy of the bow. An incorrectly placed draw stop can reduce the efficiency of the bow, cause a loss in accuracy of an arrow shot from the bow and result in a decrease in speed of an arrow shot from the bow. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention relates to a cam for a compound archery bow. The cam may include an adjustable draw cam and a draw stop arm each releasably and adjustably carried by the cam to permit rapid adjustment of the draw length and let-off characteristics of the cam without having to completely disassemble the bow, i.e., without having to replace either of the adjustable draw cam or draw stop arm with different components. Therefore, a plurality of draw lengths as well as let-offs may be achieved by the consumer without having to completely disassemble the bow or purchase a plurality of different, specialized parts. Advantageously, the number of different parts needed to produce a wide range of draw lengths and let-offs is drastically reduced to greatly facilitate the economical manufacture of cams for archery bows. 
     Preferably, the draw stop arm is an elongated arm releasably carried by the cam. The draw stop arm engages a bowstring during at least a portion of the rotation of the cam during the draw of the bow, and is movable between a plurality of positions to alter its engagement with the bowstring. Repositioning the draw stop arm affects the draw length and magnitude of the let-off of the bow. The draw stop arm may include an elongated track or groove therein that receives the bowstring at the end of the draw. Preferably, as the bowstring is drawn, it increasingly engages the draw stop arm to provide a softer or more controlled limit to the draw length of the bow. If desired, the groove or track in the arm may have a radius or may be generally arcuate to further control engagement of the bowstring with the arm to provide an improved feel to the user. The draw stop arm may be of substantially any shape and may even comprise more than one piece so long as at the maximum draw length of the bow the string of the bow is engaged by the draw stop over a distance of at least ¼ of an inch and preferably ½ of an inch or more. 
     In the preferred embodiment, the arm is pivotally carried at one end on the cam for pivotal movement about an axle that mounts the cam on the limb of the bow with the other end of the arm movable and releasably securable to the cam in a plurality of positions. Desirably, each position relates to a specific increment of draw length ranging from {fraction (1/16)} of an inch up to 1 inch or more as desired. This provides tremendous flexibility to the user of the bow by enabling them to choose between a wide range of draw lengths and let-offs without having to disassemble the bow. 
     The adjustable draw cam is also releasably carried by the cam. The adjustable draw cam engages the bowstring during the draw of the bow and is movable between a plurality of positions on the cam to vary the draw length of the bow and the locations of and optionally, the intensity of the let-off. The adjustable draw cam may include a track or groove that receives the bowstring. Preferably, the adjustable draw cam includes a comer or radius around which the bowstring is wrapped as the cam rotates during the draw of the bow. A portion of the corner or radius extends generally tangentially to the axle of the cam and defines the point on the cam wherein the let-off begins and which may be referred to as a “break over radius.” After the bowstring engages and wraps around this corner or break over radius, the let-off is initiated to reduce the force needed to pull the drawstring further or to hold the drawstring. The adjustable draw cam may be generally circular and may be axially or eccentrically mounted on the cam. Alternatively, the draw cam may have an irregular shape contoured to maximize the performance and versatility of the bow. By changing the position of the same adjustable draw cam relative to the cam, the position of the break over radius is changed, thereby changing the location at which the let-off is initiated and, in part, the draw length of the bow. 
     Desirably, both the draw stop arm and draw cam are independently movable between a plurality of positions to greatly increase the flexibility of the bow by enabling a consumer to rapidly and easily change the draw length and let-off characteristics. Advantageously, a single cam with a draw stop arm and a draw cam may be used in place of a plurality of one-piece cams or a plurality of differently shaped modules. This greatly simplifies and decreases the number of parts required to provide a wide range of draw lengths and let-off characteristics for a particular bow. 
     Objects, features and advantages of this invention include providing a bow with an adjustable cam that greatly increases the flexibility of the bow, enables an end user to rapidly and easily change the draw length and let-off characteristics of the bow, enables the draw length and let-off characteristics of the bow to be changed without disassembling the bow, greatly reduces the number of parts needed to provide a wide range of draw lengths and let-off characteristics of the bow, drastically reduces the production costs of the bow, provides a controlled and efficient limit to the draw length of the bow, provides repeatable performance of the bow, enables efficient storage and release of energy from the bow at a wide range of draw lengths, is of relatively simple design and economical manufacture and assembly, durable, reliable and has a long, useful life in service. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects, features and advantages of this invention will be apparent from the following detailed description of the preferred embodiments and best mode, appended claims and accompanying drawings in which: 
     FIG. 1 is a side view of a single cam compound archery bow having a cam embodying the present invention; 
     FIG. 2 is a perspective view of the cam of the archery bow; 
     FIG. 3 is a sectional view of the cam of FIG. 2 also taken generally along lines  3 — 3  illustrating a rear face of the cam; 
     FIG. 4 is a sectional view of the cam taken generally along lines  3 — 3  of FIG. 2 illustrating a front face of the cam; 
     FIG. 5 is a perspective view of a first embodiment of a draw cam removed from the cam; 
     FIG. 6 is a perspective view of a draw stop arm removed from the cam; 
     FIG. 7 is a representative graph of draw weight or force versus draw length for a compound archery bow; 
     FIG. 8 is an exploded view of a second embodiment of a cam, the draw cam and draw stop arm; 
     FIG. 9 is a front view of the cam of FIG. 8; 
     FIG. 10 is a perspective view of the cam of FIG. 8 illustrating a rear face of the cam; 
     FIG. 11 is a front view of a third embodiment of a cam with a modified draw cam; 
     FIG. 12 is an end view of the draw cam of FIG. 11; and 
     FIG. 13 is a sectional view of a cam showing an alternate embodiment draw stop arm. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring in more detail to the drawings, FIG. 1 illustrates an archery bow  10  which has a pair of flexible limbs  12 ,  14  each fixed at one end to a separate end of a riser or handle  16  with an idler wheel  18  at the free end of one limb  12  and a earn  20  at the free end of the other limb  14 . Separate axles  22 ,  24  extending through their respective limbs  12 ,  14 , carry the cam  20  and idler wheel  18 . A harness string  26  is split at one end with each split end  28  (only one shown) fixed to the limb  12  on opposed sides of the idler wheel  18  and its other end  30  releasably attached to the cam  20 . A drawstring  32  has both its ends releasably attached to the cam  20  and interconnects the idler wheel  18  and cam  20 . Upon drawing or pulling back the drawstring  32 , energy is stored in the limbs  12 ,  14  of the bow  10 . The stored energy is released upon release of the drawstring  32  permitting the bow  10  to return to its at rest position as shown in FIG.  1 . Alternative string arrangements are possible with some bows utilizing more or less than two strings. As used herein, the term “bowstring” denotes any string of a bow such as the harness string  26 , drawstring  32  or other, as appropriate. 
     As shown in FIG. 2, to permit the draw length and let-off characteristics of the bow  10  to be changed by a user, the cam  20  releasably and adjustably carries a draw stop arm  34  and an adjustable draw cam  36 . As shown in the drawings, the cam  20  is contoured to interact with the harness string  26  and drawstring  32  and thereby store energy in the bow limbs  12 ,  14  in a predetermined manner. As shown in FIG. 7, there is a generally linearly increasing force over a first portion  37  of the draw length, thereafter providing a controlled dwell  38  wherein an essentially constant force is needed to pull the drawstring  32  further for a second duration of the draw, and finally reaching a let off point  39  wherein the force needed to further draw the bow  10  is reduced until the maximum draw length is achieved. Let-off is desirable to reduce the force needed to fully draw the bow  10  and to facilitate holding and aiming the fully drawn bow  10 . The bow  10 , as shown with an idler wheel  18  and one cam  20 , is known as a single cam bow. However, the invention is also applicable to archery bows having two cams  20  and no idler wheel  18 . 
     As shown in FIGS. 2-4, the cam  20  preferably has a one-piece cam body  40  defining three separate and spaced apart tracks or channels in which portions of the harness string  26  and drawstring  32  arc received. A first track  42  is formed in the periphery of a first cam portion  44  of the cam body  40  and is constructed to receive a portion of the drawstring  32  of the bow  10 . Initially, the drawstring  32  is trained around the first cam portion  44  of the cam body  40  in the first track  42  when the bow  10  is in its at rest position. Upon drawing the bow  10 , the cam  20  rotates about its axle  24  and the drawstring  32  is unwrapped or increasingly removed from the first track  42  to permit the drawstring  32  to be pulled away from the handle  16  and limbs  12 ,  14  as the bow  10  is drawn. Various sections  46  of the first cam portion  44  may be cut out to reduce the weight of the cam  20 . An opening  48  through the first cam portion  44  receives the axle  24  mounting the cam  20  to the limb  14 . At least one circular anchor or hook-up post  50  with a circumferential groove is provided on the first cam portion  44  to retain one end of the harness string  26 . A plurality of hook-up posts  50  may be provided wherein the hook-up posts  50  are spaced from one another to change the location of the harness string  26  end which changes the effective length of the harness string  26  and affects the initial loading of the limbs  12 ,  14  of the bow  10 . A plurality of separate openings are formed through the first cam portion  44  and are preferably in two series  52   a-d  and  53   a-e  radially spaced from the axle  24 . The openings  52   a-d ,  53   a-e  are constructed to receive a cap screw  55  or other fastener to, as set forth further herein, locate and releasably position the draw stop arm  34  relative to the first cam portion  44 . As best shown in FIG. 3, the back side  54  of the first portion  44  of the cam  20  is significantly cut away to reduce the weight of the cam  20  and define in part a take-up or intermediate portion  56  of the cam  20 . 
     The take-up or intermediate portion  56  of the cam  20  has a second peripheral groove or track  58  adapted to receive the harness string  26  of the bow  10  as the drawstring  32  is drawn. The harness string  26  is initially received in only a small portion of the second track  58  adjacent to the hook-up post  50  on the first portion  44  of the cam  20  when the bow  10  is in its at rest position. As the drawstring  32  is drawn and the cam  20  rotates about the axle  24 , the second track  58  of the intermediate portion  56  increasingly engages the harness string  26  to reduce the effective length of the harness string  26  and thereby decrease the distance between the free ends of the limbs  12 ,  14  to flex the limbs  12 ,  14  and store energy therein. 
     The intermediate portion  56  may also have sections or portions removed to reduce the weight of the cam  20 . One or more hook-up posts  62  are formed on the front side of the intermediate portion  56  and are constructed to receive and retain one end of the drawstring  32  looped thereon. If more than one hook-up post  62  is provided, the drawstring  32  may be hooked to any one of the posts  62  to change the effective length of the drawstring  32 . One or more hook-up posts  66  are also formed on the back side of the intermediate portion  56  as shown in FIG.  3 . Each hook-up post  66  is constructed to receive and retain the other end of the drawstring  32  which cooperates with and is received within the track  42  of the first portion  44  of the cam body  40 . Again, a plurality of hook-up posts  66  may be provided to change the location on the cam body  40  where the drawstring  32  is attached to change the effective length of the drawstring  32 . The intermediate portion  56  has a recess  70  to receive the adjustable draw cam  36 . A plurality of holes  72   a-e  are provided in the area of the recess  70  to receive a cap screw  55  or other fastener to releasably mount the draw cam  36  on the cam  20 . A substantial portion of the front side of the intermediate portion  56  is cut away or otherwise removed to define an upper portion  74  of the cam body  40 . 
     The upper portion  74  of the cam body  40  is thin to reduce the weight of the cam  20 , is generally arcuate, and has a third peripheral track  76  adapted to receive a portion of the drawstring  32 . The drawstring  32  is wrapped or trained around the upper portion  74  in the third track  76  when the bow  10  is in its at rest position. As the drawstring  32  is drawn, it is increasingly removed or unwrapped from third track  76  as the cam  20  rotates about the axle  24 . A hole  78  formed through the upper portion  74  adjacent one end of the third track  76  receives the axle  24  therethrough. Other holes  80  through the upper portion  74  are formed to reduce the weight of the cam  20  in general. 
     Thus, the first cam portion  44 , intermediate portion  56  and upper portion  74  of the cam body  40  are preferably integrally formed or machined from a single block of material. Each portion  44 ,  56 ,  74  has a contoured track  42 ,  58 ,  76  formed in its periphery to communicate with either the drawstring  32  or the harness string  26  of the bow  10  to efficiently store and release energy from the bow  10  and to provide efficient, repeatable and accurate performance of the bow  10  in use. 
     As best shown in FIG. 2, pair of adjustment members are provided on the cam body. The first adjustment member being the elongated draw stop arm  34  pivotal about the axle  24  extending through the cam body  40  and mounting the cam  20  on the limb  14 . The second adjustment member being the draw cam  36  mounted on the first portion  44  of the cam body  40 . The draw stop arm  34  or draw cam  36  can be used individually. Both of them preferably have a groove or track formed therein, each adapted to receive a portion of the harness string  26  during the draw of the bow  10  in cooperation with the second track  58  of the intermediate portion  56  of the cam  20 . 
     As best shown in FIGS. 2,  4  and  6 , the draw stop arm  34  is preferably elongated with a groove  82  formed along one side to receive the harness string  26  in cooperation with the draw cam  36  and second track  58 . The harness string  26  engages substantially the entire groove  82  in the draw stop arm  34  and the engagement of the harness string  26  with the draw stop arm  34  limits the maximum draw length of the drawstring  32  or bow  10 . Desirably, to provide a steadier and more controlled stop to the draw, the groove  82  is generally arcuate having a slight radius so that the harness string  26  more gradually engages the draw stop arm  34 , first near one end  84  adjacent to the axle  24  and thereafter increasingly engaging the draw stop arm  34  further from the axle  24  until the harness string  26  is received within substantially the entire groove  82  preventing further rotation of the cam  20  to limit the draw of the drawstring  32 . Alternatively, the groove  82  may be generally flat to provide a less gradual engagement of the harness string  26  and groove  82  to limit the draw of the drawstring  32 . The draw stop arm  34  extends from the axle  24  a distance of less than 2 inches and preferably between 1-1.75 inches. 
     The draw stop arm  34  has a first hole  86  therethrough which receives the axle  24  mounting the cam  20  onto the limb  14  such that the draw stop arm  34  pivots about the axle  24  when it is adjusted. Alternatively, the draw stop arm  34  may be constructed to abut and be held against the axle  24  such as by a recess at end  84  generally complementary to the axle. At the other end  88  of the draw stop arm  34 , one or more openings  90 ,  92  may be formed with each opening  90 ,  92  communicating with the openings  52   a-d ,  53   a-e  extending through the cam  20  to vary the angular position of the draw stop arm  34  on the cam body  40  in desired increments. When an opening  90  or  92  on the draw stop arm  34  is aligned with a corresponding opening  52   a-d  or  53   a-e  on the cam body  40 , a cap screw  55  may be inserted through the openings ( 90  and one of  52   a-d  or  92  and one of  53   a-e ) to releasably retain the position of the draw stop arm  34 . 
     As shown in FIGS. 2 and 5, the draw cam  36  may have a generally circular perimeter with a groove  94  formed therein as shown, and may be mounted about its axis or eccentrically as desired. Alternatively, the draw cam  36  may have an irregular shape with a contoured track or groove adapted to receive the harness string  26  during the draw of the bow  10 . The draw cam  36  is preferably mounted to the cam body  40  by a cap screw  97  received through a bore  95  through the draw cam  36  and one of the plurality of holes  72   a-e  in the cam body  40 . This mounting arrangement enables the position of the draw cam  36  relative to the intermediate portion  56  to vary and correspondingly vary the engagement of the draw cam  36  with the harness string  26  as the drawstring  32  is drawn. As shown in FIG. 5, the draw cam groove  94  is preferably tapered or generally frustoconical along one side  96 . The side  96  may be tapered at an acute included angle of between 20 and 80 degrees. This tapered side  96  provides a smoother engagement of the harness string  26  with the draw cam  36  by gradually centering the harness string  26  in a bottom  98  of the groove  94  if the harness string  26  is slightly misaligned and initially engages the tapered side  96 . Desirably, this reduces friction on the harness string  26  to reduce “thumping” of the string and provide a smoother draw of the bow  10  for the user. This also greatly reduces wear on the harness string  26  to extend its useful life. 
     The draw stop aim  34  and draw cam  36  may be integrally formed and hinged or rotatable about the axle  24  to vary their position relative to the cam  20  as desired. The draw stop arm  34  and draw cam  36  can be individually adjusted to corresponding positions on the cam body  40  to change the draw length and let-off position and magnitude while still providing the optimum feel and consistency of the draw of the bow  10 . Both the draw stop arm  34  and draw cam  36  may be separately adjusted. However, this will have some affect on the draw length of the bow  10  and may provide a less gradual or less smooth draw stop or limit the draw in certain positions. Desirably, when the bow is in its at rest position, no harness string  26  or drawstring  32  acts on or bears on either the draw stop arm  34  or draw cam  36  such that both may be readily adjusted without disassembling the bow  10 . 
     The groove  94  of the draw cam  36  extends along a predetermined radius between about 0.3 and 0.5 inches, nominally 0.40 inches, which provides the desirable break-over radius of the cam  20  to control the let-off near the maximum draw length of the bow  10 . The radius of the draw cam  36  groove remains constant so that even if the draw cam  36  is moved to different positions on the cam  20 , the initiation of the let-off will have essentially the same feel even though the position or location of the let-off during the draw changes as the draw cam  36  is moved to different positions on the cam  20 . A larger radius will initiate let-off more slowly and a smaller radius will initiate let-off more quickly. If an irregularly shaped or non-circular draw cam  36  is provided, it may be possible to change the feel of the initiation of the let-off. As the irregularly shaped draw cam  36  is moved relative to the cam  20 , the portion of the draw cam  36  that defines the break over radius may be changed. A differently shaped break over radius can change the magnitude of the let-off. Desirably, the draw cam  36  can be moved to different positions along an are or radius so that the break over radius portion of the draw cam  36  is at a constant radius relative to the axle  24  to provide consistent performance of the bow  10  when the draw cam  36  is in any of its various positions. Nominally, the radius is less than 1.75 inches and preferably about 1.4 inches in all positions of the draw cam  36 . 
     The draw length of the bow  10  is stopped or limited when the harness string  26  is received in substantially the entire groove  82  of the draw stop arm  34 . The further the cam  20  has to rotate until the harness string  26  engages the free end  88  of the draw stop arm  34 , the greater the draw length of the bow  10 . In some positions, almost the entire length of the track may be engaged all at once or nearly so. Desirably, the draw stop arm  34  may be moved in a plurality of angular positions relative to the cam  20  to change the point in the rotation of the cam  20  wherein the harness string  26  fully engages the draw stop arm  34 . Each position corresponds to a different maximum draw length of the bow  10  and may vary the draw length by substantially any increment from about {fraction (1/16)} of an inch up to 1 inch increments or greater. Alternatively, the draw stop arm  34  may take any shape other than an elongated arm which is suitable to engage at least a ¼ inch length of the harness string  26  to provide a positive, non-spongy stop or limit to the draw length of the bow  10 . Further, the draw stop arm  34  may comprise more than one body, each adjustable on the cam body  40  and that cooperate to engage the harness string  26  along a desired length. In whatever form, the draw stop arm  34  engages at least ¼ of an inch of the harness string  26  at full draw, desirably, at least ½ of an inch and, preferably, between about ½ of an inch to 2 inches. 
     In the embodiment of FIGS. 1-6, the first series of openings  52   a-d  comprises four holes corresponding to four different positions of the draw stop arm  34  and the second series of openings  53   a-e  comprises five holes corresponding to another five positions of the draw stop arm  34 . Thus, the draw stop arm  34  may be disposed in nine different positions corresponding to nine different draw lengths of the bow  10 . By changing the location of the openings  52   a-d ,  53   a-e , or by providing other openings, nearly any increment of change of the draw length can be achieved. Therefore, a single cam assembly can be used to provide a wide range of draw lengths for the bow  10  without having to change the cam  20  or to change or replace differently shaped modules on the cam  20 . 
     Still further, the position of the draw cam  36  also affects the draw length of the bow  10  by changing the amount of rotation of the cam  20  until the draw stop arm  36  engages the harness string  26 . When the draw cam  36  is mounted via hole  72   e , the draw length will be significantly greater than when it is mounted via hole  72   a  for a similar draw stop arm  34  position. 
     As shown, the cam  20  has forty-five different possible settings due to the five possible draw cam  36  positions and nine possible draw stop arm  34  positions. Within the possible settings of the exemplary cam, the draw length can be changed by four inches and the magnitude of the let-off can be changed between over 80% and less than 40% as desired. These ranges are exemplary only and a cam  20  can be designed with a wide range of possible draw lengths and let-offs. 
     In general, the magnitude of the let-off when the bow  10  is fully drawn is at least in part a function of the effective distance of the draw stop arm  34  from the axle  24 . Additionally, the position of the draw cam  36  and its portion defining the break over radius also affects the magnitude of the let-off. Notably, the draw cam  36  rotational distance between the break over radius, where the let-off is initiated, and the draw stop arm  34 , greatly affects the magnitude of the let-off. The greater the rotational distance from the initiation of the let-off to the end of the draw, the greater the magnitude of the let-off and vice versa. 
     A second embodiment of a cam  100  is shown in FIGS. 8-11 which also has a first cam portion  102 , an intermediate portion  56  and an upper portion  74  all preferably integrally formed from a single block or body  107  of material even though they are shown in FIG. 8 in an exploded fashion for case of viewing. The intermediate portion  56  and upper portion  74  are substantially the same as in the first embodiment cam  20  and hence will not be described further. Additionally, the draw stop arm  34  and majority of the first cam portion  102  of the cam  100  are identical to that of the first embodiment cam  20 . The draw cam  108  and its associated section of the first cam portion  102  of the cam  100  are of a different construction than that of the first embodiment cam  20  and will be described in more detail below. 
     As in the first embodiment cam  20  and as shown in FIGS. 8-11, the first cam portion  102  of the cam  100  of the second embodiment has a plurality of holes  72   a-e  spaced from one another, each constructed to receive a fastener to mount the draw cam  108  onto the first cam portion  102  and each corresponding to a different position or location of the draw cam  108  on the cam  100 . The first cam portion  102  of the cam  100  has a raised, contoured boss  112  that cooperates with the draw cam  108  to accurately position the draw cam  108  relative to the cam  100  in each of its various positions to ensure the maximum, efficient performance of the bow  10 . As shown in FIG. 10, a portion of the rear face  114  of the first portion  102  of the cam body  107  has a recess  116  in the area surrounding and including the holes  72   a-e  for mounting the draw cam  108  so that the fastener used to mount the draw cam  108  does not extend beyond the rear face  114  of the first portion of the cam body  107 . 
     The draw cam  108  is not circular, but rather has an irregular, contoured profile with a groove or track  118  formed in a substantial portion of its periphery and adapted to receive the harness string  26  as the bow  10  is drawn. The contoured periphery, and hence, the contoured track  118 , engages the harness string  26  in a predetermined manner to provide more efficient operation of the bow  10 . A plurality of holes  120  may be formed through the draw cam  108  either to reduce its weight or to facilitate mounting the draw cam  108  onto the cam body  107 . At least one hole  121  aligns with the series of holes  72   a-e  through the first portion of the cam body  107  to permit the draw cam  108  to be mounted in the various positions corresponding to the location of the holes  72   a-e . A recess  122  corresponding to the general shape of the boss  112  is formed in the draw cam  108  and is constructed to slidably receive the boss  112  to accurately position the draw cam  108  on the cam body  107  to ensure optimum performance of the bow  10  when the draw cam  108  is in any of its various positions corresponding to the holes  72   a-e . As an alternative, the location of the boss  112  and recess  122  may be reversed, with the draw cam  108  having a boss  112  thereon to be guided for slidable movement relative to the cam body  107  in a complementary recess  122  in the cam body  107 . 
     Desirably, the boss  112  and series of holes  72   a-e  position the draw cam  108  such that the distance from the bottom of its track  118  to the axle  24  which mounts the cam  100  onto the limb  12  ofthe bow  10  is constant in any of the positions of the draw cam  108 . Nominally, this distance is less than 1.75 inches and preferably about 1.4 inches. This provides a consistent mechanical advantage upon engagement with the harness string  26  during the draw of the bow  10  in any position of the draw cam  108  so that the energy stored in the limbs  12 ,  14  provides a consistent and efficient performance of the bow  10 . Each hole  72   a-c  on the cam body  107  corresponds to a different draw length of the bow  10  with a first hole  72   a  defining a shorter draw length and the last hole  72   e  defining a maximum draw length as controlled by the position of the draw cam  108 . Notably, the position of the draw stop arm  34  also effects draw length such that a wide range of draw lengths can be achieved. A maximum draw length of the bow  10  is achieved when the draw stop arm  34  is in its position corresponding to the maximum draw length and the draw cam  108  is also in its position corresponding to the maximum draw length. 
     Instead of a post or anchor, the end of the drawstring adjacent to the track  42  in the first cam portion  102  may be hooked or connected to a finger  124  extending from the cam body  107  spaced from and extending generally perpendicular to the immediately adjacent portion of the groove  42 . 
     In any event, the second embodiment cam  100  functions substantially the same as the first embodiment cam  20  with the intermediate portion  56  of the cam body  107  initially rotated into engagement with the harness string  26  upon drawing of the bow  10 . Upon further drawing of the bow  10 , the draw cam  108  is rotated into engagement with the harness string  26  until the draw stop arm  34  is rotated into engagement with the harness string  26  to prevent further drawing of the bow  10 . Desirably, when the bow  10  is in its at rest position, there is no string acting or bearing on the draw stop arm  34  or the draw cam  108  such that they can be readily adjusted without disassembling the bow  10 , as in the first embodiment cam  20 . 
     For one exemplary embodiment of the invention constructed generally as shown and described herein, the draw length, maximum draw weight or force, and magnitude of the let-off were empirically determined for all forty-five positions of the draw stop arm  34  and draw cam  108  as shown in the following table. 
     
       
         
               
               
               
               
               
             
           
               
                   
               
               
                 Draw 
                 Draw Stop 
                 Draw 
                 Draw 
                   
               
               
                 Cam location 
                 Arm location 
                 Length (in) 
                 Weight (lbs) 
                 % LetOFF 
               
               
                   
               
             
             
               
                 72a 
                 53a 
                 26¾ 
                 70 
                 78.10% 
               
               
                 72a 
                 53b 
                 27½ 
                 70 
                 81.10% 
               
               
                 72a 
                 53c 
                 28⅛ 
                 70 
                 78.40% 
               
               
                 72a 
                 53d 
                 28⅞ 
                 70 
                 79.50% 
               
               
                 72a 
                 53e 
                 29⅞ 
                 70 
                 74.50% 
               
               
                 72a 
                 52a 
                 27⅛ 
                 70 
                 79.70% 
               
               
                 72a 
                 52b 
                 27⅞ 
                 70 
                 80.20% 
               
               
                 72a 
                 52c 
                 28½ 
                 70 
                 78.70% 
               
               
                 72a 
                 52d 
                 29½ 
                 70 
                 78.10% 
               
               
                 72b 
                 53a 
                 27½ 
                 70 
                 67.70% 
               
               
                 72b 
                 53b 
                 27⅞ 
                 70 
                 78.50% 
               
               
                 72b 
                 53c 
                 28½ 
                 70 
                 79.10% 
               
               
                 72b 
                 53d 
                 29⅛ 
                 70 
                 79.10% 
               
               
                 72b 
                 53e 
                 30⅛ 
                 70 
                 75.40% 
               
               
                 72b 
                 52a 
                 27⅝ 
                 70 
                 73.70% 
               
               
                 72b 
                 52b 
                 28¼ 
                 70 
                 80.10% 
               
               
                 72b 
                 52c 
                 28⅞ 
                 70 
                 79.50% 
               
               
                 72b 
                 52d 
                 29⅞ 
                 70 
                 77.40% 
               
               
                 72c 
                 53a 
                 28 
                 70 
                 58.10% 
               
               
                 72c 
                 53b 
                 28⅜ 
                 70 
                 68.80% 
               
               
                 72c 
                 53c 
                 28¾ 
                 70 
                 77.80% 
               
               
                 72c 
                 53d 
                 29¼ 
                 70 
                 78.80% 
               
               
                 72c 
                 53e 
                 30¼ 
                 70 
                 74.00% 
               
               
                 72c 
                 52a 
                 28⅛ 
                 70 
                 63.10% 
               
               
                 72c 
                 52b 
                 28½ 
                 70 
                 74.20% 
               
               
                 72c 
                 52c 
                 29⅛ 
                 70 
                 79.10% 
               
               
                 72c 
                 52d 
                 30⅛ 
                 70 
                 77.70% 
               
               
                 72d 
                 53a 
                 28½ 
                 70 
                 48.70% 
               
               
                 72d 
                 53b 
                 28⅞ 
                 70 
                 58.40% 
               
               
                 72d 
                 53c 
                 29¼ 
                 70 
                 67.00% 
               
               
                 72d 
                 53d 
                 29¾ 
                 70 
                 77.00% 
               
               
                 72d 
                 53e 
                 30¾ 
                 70 
                 75.20% 
               
               
                 72d 
                 52a 
                 25⅝ 
                 70 
                 53.70% 
               
               
                 72d 
                 52b 
                 29 
                 70 
                 63.10% 
               
               
                 72d 
                 52c 
                 29⅜ 
                 70 
                 71.50% 
               
               
                 72d 
                 52d 
                 29½ 
                 70 
                 71.80% 
               
               
                 72e 
                 53a 
                 28⅞ 
                 70 
                 39.50% 
               
               
                 72e 
                 53b 
                 29¼ 
                 70 
                 45.20% 
               
               
                 72e 
                 53c 
                 29¾ 
                 70 
                 52.20% 
               
               
                 72e 
                 53d 
                 30⅛ 
                 70 
                 63.70% 
               
               
                 72e 
                 53e 
                 30¾ 
                 70 
                 74.80% 
               
               
                 72e 
                 52a 
                 29⅛ 
                 70 
                 43.80% 
               
               
                 72e 
                 52b 
                 29½ 
                 70 
                 50.80% 
               
               
                 72e 
                 52c 
                 30 
                 70 
                 58.40% 
               
               
                 72e 
                 52d 
                 30⅝ 
                 70 
                 73.10% 
               
               
                   
               
             
          
         
       
     
     From this data, it is clear that a wide range of draw lengths and let-off magnitudes can be achieved by a user with a single bow  10  having a cam  100  as described. Desirably, the maximum draw force remains essentially constant in all positions to maintain a consistent storage of energy and release of energy from the bow 
     FIGS. 11-12 illustrate a third embodiment of a cam  150  having a modified draw cam  152  and draw stop arm  153  mounted thereon. The draw stop arm  153  is adjustably connected at both ends to the cam  150  such as by fasteners extending through an opening  153   a  in one end  153   b  of the draw stop aim  153  and received in the cam  150  rather than receiving or pivoting about the axle  24 . In any event, the draw stop arm  153  functions in substantially the same manner as the draw stop arm  34 . The remainder of the third embodiment cam  150  is identical to the previous two embodiments of the cam  20 ,  100  except as described below. 
     The draw cam  152  has an irregular, contoured profile with a groove or track  154  formed in a substantial portion of its periphery to receive the harness string  26  upon drawing of the bow  10  as in the other embodiments. The draw cam  152  has a hole  156  therethrough selectively aligned with each of the plurality of holes  72   a-e  through the first portion  158  of the cam  150  to receive a fastener and releasably secure the draw cam  152  in any of the various positions corresponding to the location of the holes  72   a-e . As shown in FIG. 12, the draw cam  152  has a depending finger  160  that is received in a bore  162  in the first portion  158  of the cam  150  to properly position the draw cam  152  on the cam  150 . The draw cam  152  pivots about the finger  160  to accurately position the draw cam  152  on the cam  150  in any of its various positions corresponding to the holes  72   a-e.    
     Desirably, the pivoting of the draw cam  152  about the finger  160  maintains a generally consistent distance of the track  154  of the draw cam  152  relative to the axle  24  to maintain a consistent performance of the bow  10  when the draw cam  152  is in any of its various positions. Desirably, this distance is less than 1.75 inches and is preferably about 1.4 inches. Also, the draw cam  152  preferably has a break over radius of about 0.4 inches as in the previous embodiments. The third embodiment cam  150  functions in the same manner as the previous embodiment in use of the bow  10  with both the draw stop arm  153  and the draw cam  152  being independently adjustable to affect the draw length of the bow  10 , the location of the let-off point and the magnitude of the let-off in the draw. 
     FIG. 13 illustrates a fourth embodiment cam  200  which has a plurality of draw stop bodies  202 , each adjustably carried on the cam  200  via a threaded end (not shown) received in one of a plurality of holes  204  in the cam  200 . The bodies  202  may be arranged to engage a certain length of the harness string  26  at the maximum draw length. Desirably, the bodies engage at least ¼ of an inch of the harness string  26  and preferably, between ½ and 2 inches to provide a controlled, steady limit to the draw. Alternatively, the bodies  202  may be slidably adjustable in elongated or arcuate slots in the body. Further, while shown as a plurality of pegs or the like, the bodies  202  may be elongated with two or more disposed on the cam  200 . In any form, the bodies  202  function in the same general manner as the draw stop arm  34  to provide a controlled, efficient and adjustable limit to the draw of the bow  10 . 
     The invention has been described in an illustrative manner. It is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. 
     Many modifications and variations of the invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the invention may be practiced other than as specifically described.