Patent Publication Number: US-2023134361-A1

Title: Tool-less re-zero adjustment knob for aiming devices, and methods of zeroing an aiming device

Description:
RELATED APPLICATIONS 
     This application is a continuation-in-part under 35 U.S.C. § 120 of U.S. patent application Ser. No. 16/803,881, filed Feb. 27, 2020, which claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application No. 62/811,022, filed Feb. 27, 2019, both of which are incorporated by reference herein. 
    
    
     TECHNICAL FIELD 
     The present disclosure generally relates to aiming devices such as rifle scopes and other weapon aiming devices, and more particularly, adjustment turret knobs for aiming devices that can be re-zeroed without the use of tools, and to aiming devices including such adjustment knobs. 
     BACKGROUND 
     An optical aiming scope for a projectile weapon such as a firearm may require adjustment when targeted on an object. For example, because a bullet may fall or otherwise have its course changed by environmental factors as it travels, the aim of the scope may be adjusted vertically and/or horizontally to compensate for such effects and increase the likelihood that an object located in crosshairs of the scope will be impacted by the bullet. Vertical adjustment of the scope&#39;s aim is known as elevation adjustment because it compensates for a bullet&#39;s elevation change (e.g., falling), and horizontal adjustment of the scope&#39;s aim is known as windage adjustment because it compensates for sideways movement of a bullet, which is often caused by wind. 
     The horizontal and vertical adjustment of the aim can be accomplished by manually rotating turret knobs on the scope that adjust the position of lenses or other optical elements inside the scope. An indicator scale comprising a set of markings on the outside of the knob provides a visual indication of the amount of rotation of the knob. In some adjustment knobs, the position of the indicator scale can be adjusted relative to the setting of the knob by using a hex key to loosen a grub screw coupling a dial of the knob to a rotatable threaded member inside of the knob, as is taught for example in patent No. U.S. Pat. No. 9,170,068 of Crispin, which is incorporated herein by reference. After the grub screw is loosened, the dial can be rotated to the desired position to adjust a zero setting of the knob, then the grub screw is re-tightened to fix the dial to the threaded member for co-rotation. By “zeroing” the elevation and/or windage knob in this manner, the shooter may ensure that the scope is properly calibrated (or “sighted-in”) for aiming the firearm at an object at a particular distance. Sighting-in a riflescope at a known distance facilitates accurate aiming adjustments for other distances or environmental conditions, relative to the calibrated setting. 
     Patent Nos. U.S. Pat. No. 6,279,259 of Otteman and U.S. Pat. No. 5,513,440 of Murg disclose riflescope adjustment mechanisms that can be re-zeroed without the use of tools. In each case, a dial portion of the adjustment mechanism is movable axially relative to inner threaded member. When the dial portion is pushed axially inward into engagement with the threaded member, the dial and threaded member rotate together to accomplish aiming adjustments. When the dial portion is pulled axially outward it can be rotated relative to the threaded member to re-set a zero setting of an indicator scale of the adjustment mechanism. 
     The present inventor has recognized the need for improved systems and methods for re-zeroing optical scope adjustment mechanisms. 
     Additional aspects and advantages will be apparent from the following detailed description of preferred embodiments, which proceeds with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a partial cross-sectional view of a riflescope along a longitudinal axis showing an adjustment knob in a disengaged position. 
         FIG.  2    is an exploded isometric view of the adjustment knob of  FIG.  1   . 
         FIG.  3    is an enlarged isometric cross-sectional view of the adjustment knob of  FIG.  1    showing a dial of the knob disengaged from a rotating member of the knob. 
         FIG.  4    is an enlarged, isolated side view of the rotating member of  FIG.  3    showing details of dial retention features of the rotating member. 
         FIG.  5    is an enlarged cross-sectional view of the riflescope and adjustment knob of  FIG.  1    showing the dial engaged with the rotating member. 
         FIGS.  6 A and  6 B  show exterior isometric views of a riflescope having the adjustment knob of  FIG.  1    used as an elevation adjustment knob and a windage adjustment knob, where  FIG.  6 A  shows the elevation adjustment knob in an engaged position and the windage adjustment knob in a disengaged position, and  FIG.  6 B  shows the opposite situation. 
         FIG.  7    is a cross-section view showing an adjustment knob according to a second embodiment, showing a clutch of the adjustment knob in an engaged position. 
         FIG.  8    is an exploded view of the adjustment knob of  FIG.  7   . 
         FIG.  9    is an oblique section view of the adjustment knob of  FIG.  7   , showing a clutch of the adjustment knob in a disengaged position. 
         FIG.  10    is a pictorial view of a rotating member of the adjustment knob of  FIG.  7   . 
         FIG.  11    is a pictorial view of a gripper element of the clutch of the adjustment knob of  FIG.  7   . 
         FIG.  12    is a cross-section view showing an adjustment knob according to a third embodiment. 
         FIG.  13    is a pictorial view of a gripper element of a clutch of the adjustment knob of  FIG.  12   . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       FIG.  1    Illustrates a cross-sectional view of a riflescope  100  along a longitudinal axis having a housing  102  (sometimes referred to as the “maintube”) and an image-inverting erector system  104  pivotably mounted within the housing  102 , where erector system  104  provides an image of a point of aim. An adjustment knob  106  protrudes from housing  102  and is rotatable about an axis  108  extending transversely to a longitudinal axis of the housing  102 . In some embodiments, adjustment knob  106  is press fit onto housing  102 . In other embodiments, adjustment knob is threaded onto housing  102 . Although a presently preferred embodiment of a weapon aiming device is described herein as riflescope  100 , adjustment knobs consistent with the present disclosure may also be used with other types of optical aiming devices, such as red-dot sights, reflex sights, holographic aiming sights, iron sights, and other devices for aiming weapons and other devices, and particularly those devices for which a user may wish to adjust a zero or home position of the aiming device. 
     With reference to  FIGS.  1 - 3   , in the embodiment shown, adjustment knob  106  includes a dial  110  configured to engage and disengage with a rotating member  112  (which is also rotatable about axis  108 ). When in an engaged position (as illustrated in  FIG.  5   ), dial  110  is engaged with rotating member  112 . When in a disengaged position (as illustrated in  FIG.  3   ), dial  110  is disengaged with rotating member  112 . In some embodiments, rotating member  112  may be configured as a rotating adjustment nut or spindle that includes a hub  172 . When there is engagement between dial  110  and rotating member  112 , a setting of riflescope  100  can be changed. In the example illustrated, an adjustment screw (or threaded plunger)  114  is coupled (e.g., threaded) to an interior threaded cavity of the rotating member  112  and rotationally constrained in a slot in housing  102  so that rotation of dial  110  and rotating member  112  causes responsive movement of adjustment screw  114  along axis  108 , and driving pivoting movement of erector system  104 , illustrated by arrows  116 , which effects a point of aim shift either vertically (elevation) or horizontally (windage) depending on the position of the adjustment knob  106  on the housing  102 . In other embodiments (not illustrated), the rotating member  112  may be an externally threaded screw that is threaded into a threaded hole fixed on housing  102 , so that the screw moves axially as it rotates to effect changes in the point of aim or other setting of riflescope  100 . The shift in the point of aim of riflescope  100  is typically accomplished through cooperation between lenses or other optical elements within erector system  104  and a reticle  118  within housing  102 . A spring  120  biases erector system  104  relative to housing  102  to press erector system  104  against screw  114 . In  FIG.  1   , adjustment knob  106  is shown disengaged with rotating member  112 . While  FIG.  1    shows a single adjustment knob  106 , it should be understood that a second adjustment knob (not visible) may be coupled to housing  102  orthogonally relative to adjustment knob  106 , where adjustment knob  106  is one of an elevation adjustment knob which effects a point of aim shift vertically or a windage adjustment knob which effects a point of aim shift horizontally and the second adjustment knob is the other of the elevation adjustment knob or windage adjustment knob. 
     As shown in  FIG.  2   , adjustment knob  106  includes a retainer device  122 . In some embodiments, retainer device  122  is seated in a different groove (explained with respect to  FIGS.  3 - 5   ) of rotating member  112  depending on when adjustment knob  106  is in the engaged or disengaged position. In some embodiments, retainer device  122  is a spring, such as a spring snap ring, for example, and the ring may encircle rotating member  112  fully or partially. In other embodiments, the retainer device may be omitted, or retention may be accomplished through different structures for features. 
     In some embodiments, adjustment knob  106  further includes a locking mechanism  123  which may include a lock release  125  and a guideway ring  130 . In the embodiment illustrated, lock release  125  comprises a depressible button  124  located on a side of dial  110  and accessible from outside of dial  110 . Button  124  includes one or more springs  126  that bias button  124  radially outward and a pin  128 , guide tab, or other protrusion, movable with button  124  radially relative to axis  108  when button  124  is pressed and released. The button  124  is movable relative to dial  110  and rotating member  112  to release locking mechanism  123  and allow dial  110  and rotating member  112  to be co-rotated to adjust a setting of riflescope  100 . Guideway ring  130  is affixed to housing  102  of riflescope  100 , for example by press-fitting guideway ring  130  onto a threaded flange  140  that has been threadably secured to housing  102 . In this manner, a channel  132  or other guideway of guideway ring  130  is fixed relative to housing  102 . In the embodiment shown, when adjustment knob  106  is in the disengaged position as illustrated in  FIG.  3   , pin  128  is retracted axially from channel  132  of guideway ring  130 , but when adjustment knob  106  is in the engaged position as illustrated in  FIG.  5   , pin  128  (or guide tab or other protrusion) is received in channel  132  and travels within channel  132  or otherwise ride along the channel  132  or other guideway as dial  110  is rotated. Pin  128  (or guide tab or other protrusion) is biased into a notch  133  ( FIG.  2   ) formed in the guideway of the guideway ring  130  at a zero location of the dial  110  to lock adjustment knob  106  at the zero location, as is described in greater detail in patent No. U.S. Pat. No. 9,170,068, which is incorporated herein by reference. When the button  124  or other lock release  125  is depressed or otherwise actuated, it moves the pin  128  (or other guide tab or protrusion) out of notch  133  to release the locking mechanism  123  and allow the dial  110  to be rotated away from the zero location. In some embodiments, locking mechanism  123  does not lock at any rotational position of dial  110  other than the zero location. In other embodiments locking mechanism  123  may lock at multiple rotational positions of dial  110 . In yet other embodiments, locking mechanism  123  may comprise any of various different adjustment knob locking mechanisms, particularly those locking mechanisms including a lock release accessible from outside the dial  110 , and/or those including a lock release carried by the dial  110  for rotation therewith about the axis  108 , such as lock release button located on a side of the dial  110  that is depressible in a radial direction toward the axis  108  to release the locking mechanism. Locking mechanisms that are lockable electronically or by other means are also envisioned. 
     In the embodiment shown, an o-ring  134  is seated within a groove  136  of rotating member  112  (shown in  FIG.  3   ), and a washer  138  is seated within a groove  142  of threaded flange  140  (shown in  FIG.  2   ). 
     In some embodiments, adjustment knob  106  includes a click mechanism to provide tactile and/or audible feedback to the user when adjustment knob  106  is rotated. For example, in the embodiment shown, a click ring  144  is interposed between a shoulder  150  of the lower base portion  148  of rotating member  112  and threaded flange  140 . Click ring  144  includes a grooved surface  146  facing rotating member  112 . Grooved surface  146  includes regularly spaced apart features, which, for example, include splines or a series of evenly spaced vertical grooves or ridges. Other engagement features may include a series of detents, indentations, apertures, or other suitable features. The click mechanism further includes a click pin  152  with a ramped surface configured to engage the regularly spaced apart features of grooved surface  146 . Click pin  152  is housed within a bore  156  in rotating member  112  that has an open end facing grooved surface  146 . A spring  154  or other biasing element urges click pin  152  to extend outwardly from within bore  156  and engage grooved surface  146 . In operation, rotational movement of adjustment knob  106  about axis  108  causes click pin  152  to move out of contact with one groove and into a neighboring groove, thereby producing a click that is either audible, tactile, or both. Each click may coincide with an adjustment amount to alert the user about the extent of an adjustment being made. 
       FIG.  3    is an enlarged isometric cross-sectional view of adjustment knob  106  of  FIG.  1   , showing dial  110  disengaged with rotating member  112  (meaning that rotation of dial  110  will not cause rotation of rotating member  112  or any change to the setting of riflescope  100  by movement of internal optical components within housing  102  or otherwise). In the embodiment shown, a retainer device  122  is at least partially housed by and carried by a retainer groove  158  formed in dial  110  such that retainer device  122  is axially moveable relative to rotating member  112  with dial  110 , but is not axially movable relative to dial  110 . In some embodiments, retainer groove  158  is sized such that it allows free expansion of retainer device  122  within it. 
     With reference to  FIG.  3    and  FIG.  4   , in the embodiment shown, rotating member  112  includes a disengagement ridge  160 , a disengagement groove  162 , a ridge  164 , and an engagement groove  166 , where disengagement groove  162  and engagement groove  166  are spaced apart and ridge  164  is formed between grooves  162  and  166 . In some embodiments, ridges  160  and  164  and grooves  162  and  166  are formed in hub  172  of rotating member  112 . In some embodiments, disengagement groove  162  and engagement groove  166  are spaced apart on hub  172  and ridge  164  is formed between grooves  162  and  166  on hub  172 . Items  160 - 166  are discussed further below. In other embodiments, grooves  162 ,  166  and ridges  160 ,  164  may be formed on a shaft, shank, or shoulder of an adjustment screw. 
     Adjustment knob  106  may include a clutch  167  that selectively couples dial  110  to rotating member  112  for co-rotation. In the embodiment shown, clutch  167  includes a dial clutch surface  168  on dial  110  and a rotating member clutch surface  170  on rotating member  112 . Dial  110  is illustrated in  FIG.  3    in a disengaged position with dial clutch surface  168  moved axially outward and disengaged from rotating member clutch surface  170 . In the disengaged position, the clutch  167  is said to be disengaged or released, whereas in the engaged position the clutch  167  is engaged. In some embodiments, one of dial clutch surface  168  and rotating member clutch surface  170  may have at least one male spline, and the other of dial clutch surface  168  and rotating member clutch surface  170  may have at least one female spline. Either of dial clutch surface  168  and rotating member clutch surface  170  may have male or female splines formed thereon at the same or different pitches. In some embodiments, dial clutch surface  168  may include a spline ring in the form of a plurality of splines that fully or partially encircle an interior cavity  218  of dial  110 , and rotating member clutch surface  170  may include a spline ring in the form of a plurality of splines that fully or partially encircle an outer surface of rotating member  112 . In some embodiments, dial clutch surface  168  and rotating member clutch surface  170  have the same number of splines, while in other embodiments, dial clutch surface  168  and/or rotating member clutch surface  170  have a different number of splines or no splines at all. It should be noted that dial clutch surface  168  and rotating member clutch surface  170  need not have the same arrangement of splines. For example, one of dial clutch surface  168  and rotating member clutch surface  170  may include one or more splines arranged such that the splines fully encircle interior cavity  218  or an outer surface of rotating member  112 , while the other of dial clutch surface  168  and rotating member clutch surface  170  may include only a single spline or a plurality of splines that only partially encircle interior cavity  218  or an outer surface of rotating member  112 . It should be noted that dial clutch surface  168  and rotating member clutch surface  170  need not use the same type of engaging components. For example, one of dial clutch surface  168  and rotating member clutch surface  170  may include one or more splines, while the other of dial clutch surface  168  and rotating member clutch surface  170  may include one or more keys or one or more ridges. In another example (not illustrated), dial clutch surface  168  and rotating member clutch surface  170  may each have at least one tooth and form a Hirth joint when dial clutch surface  168  and rotating member clutch surface  170  are engaged. Alternative push-button style clutches are described below with reference to  FIGS.  7 - 13   . Many other designs for clutches are also envisioned, including conical clutches, plate clutches, rotary-actuated clutches, electronically actuated clutches, etc. 
     In some embodiments (not illustrated), the splines of dial clutch surface  168  or rotating member clutch surface  170  may be axially elongated so they can be used both as an element of clutch  167  and as a detent ring for the click mechanism of adjustment knob  106 , eliminating the need for a separate detent ring  144 . 
     With reference to  FIG.  3   , dial  110  is illustrated in a disengaged position, where retainer device  122  is seated in disengagement groove  162 , abutting disengagement ridge  160 , and substantially housed by retainer groove  158 . It should be noted that dial  110  may also be in a disengagement position when retainer device  122  is seated in disengagement groove  162  but not abutting disengagement ridge  160 . 
     With reference to  FIGS.  3 - 5   , in the embodiment shown, dial  110  is moveable to an engaged position by pushing dial  110  toward housing  102  ( FIGS.  1  and  5   ) such that retainer device  122  moves over ridge  164  to engagement groove  166  and dial  110  is in an engaged position having dial clutch surface  168  and rotating member clutch surface  170  engaged with each other.  FIG.  5    is an enlarged cross-sectional view of adjustment knob  106  showing dial  110  in the engaged position. In the engaged position, rotation of dial  110  will rotate rotating member  112  and change a setting of riflescope  100 , e.g., by moving erector system  104  within housing  102 . 
     In some embodiments, when retainer device  122  is seated in the disengagement groove  162 , retainer device  122  is substantially housed by retainer groove  158 . For example, substantially housed means that about 50% or more of a diameter of retainer device  122  is received in retainer groove  158 . In some embodiments, when retainer device  122  is seated in the engagement groove  166 , retainer device  122  is only partially housed by retainer groove  158 . For example, partially housed means that less than about 50% of a diameter of retainer device  122  is housed by retainer groove  158 . It should be noted that in some embodiments, retainer device  122  may be partially housed or substantially housed by retainer groove  158  when it is seated in one or both of disengagement groove  162  or engagement groove  166 . 
     In some embodiments, when dial  110  is moved from a disengaged position to an engaged position (and vice versa), retainer device  122  is moved between disengagement groove  162  and engagement groove  166  and rides over a ridge  164  when moving between grooves  162  and  166 . In some embodiments, when retainer device  122  moves or rides over ridge  164  when traveling from engagement groove  166  to disengagement groove  162 , retainer device  122  expands into retainer groove  158  such that a greater portion of retainer device  122  is housed by retainer groove  158  when retainer device  122  is seated in the disengagement groove  162  relative to when retainer device  122  is seated in the engagement groove  166 . In some embodiments, when retainer device  122  moves or rides over ridge  164  when traveling from disengagement groove  162  to engagement groove  166 , retainer device  122  collapses out of retainer groove  158  such that a smaller portion of retainer device  122  is housed by retainer groove  158  when retainer device  122  is seated in the engagement groove  166  relative to when retainer device  122  is seated in the disengagement groove  162 . 
     Retainer device  122  can be configured such that it limits or reduces total travel from the engaged position to the disengaged position (and vice-versa). For example, retainer device  122  can apply constant or substantially constant friction to rotating member  112  such that free movement of retainer device  122  is limited or reduced. In some embodiments, the snap ring or other spring of retainer device  122  may be sized and selected to cooperate with ridge  164  for requiring a minimum pull force to move dial  110  from the engaged position to the disengaged position. The minimum pull force can be a value in the range from about 1 lb. to about 10 lbs, or between about 2 lbs. and 10 lbs. Disengagement ridge  160  is preferably sized larger than engagement ridge  164  to require a pull force preferably exceeding 10 lbs., or exceeding 14 lbs., to remove dial  110  from rotating member  112 . In some embodiments, the push force required for moving dial  110  from the disengaged position to the engaged position is about 2 lbs. or less or less than about 1 lb. 
     It should be noted that while  FIGS.  1 - 5    illustrate embodiments where disengagement groove  162  and engagement groove  166  are formed on rotating member  112  and retainer groove  158  is formed on dial  110 , embodiments having other configurations are encompassed by this disclosure. For example, in some embodiments, dial  110  may have a plug configured to insert into a receiving cavity formed in hub  172  of rotating member  112 , and the plug may have a disengagement groove and an engagement groove formed thereon substantially similar to grooves  162  and  166 . In some embodiments, the receiving cavity of hub  172  may have a retainer groove formed therein substantially similar to retainer groove  158 . In such embodiments, retainer device  122  may partially or fully encircle the plug. In such embodiments, retainer device  122  is at least partially housed by and carried by the retainer groove of the receiving cavity such that retainer device  122  is axially moveable relative to dial  110  but not axially movable relative to rotating member  112 . In still other embodiments, disengagement groove, engagement groove, and retainer device may be omitted, as illustrated in  FIGS.  7 - 13   . Retainer device may also be integrally formed with one or both of dial  110  and rotating member  112 , or in other components of adjustment knob  106 . In other embodiments, retention may be provided by suction or vacuum through the use of an airtight seal between dial  110  and rotating member  112 . Such an airtight seal may be accomplished through the use of a precise mechanical fit, or by o-rings or other seals, while a desired range of movement may be provided through the use of a bladder or flexible diaphragm contained within the adjustment knob and in communication with the sealed space between the dial  110  and rotating member  112 . To achieve suction or vacuum, the assembly of such a device may involve bleeding off air from the enclosed space through a vent in the side of the dial  110  as the dial  110  is fitted onto rotating member  112 , then sealing the vent after the assembly of dial  110  is complete. 
       FIG.  4    is an enlarged, isolated view of rotating member  112  of adjustment knob  106 . As illustrated in  FIG.  4    and discussed above, in some embodiments, rotating member  112  includes disengagement ridge  160 , disengagement groove  162 , ridge  164 , and engagement groove  166  formed in a hub  172  of rotating member  112 . In some embodiments, hub  172  also includes a top rib  174  and a bottom rib  178 . Engagement groove  166  can also be referred to as a first circumferential step, disengagement groove  162  can also be referred to as a second circumferential step, top rib  174  can also be referred to as a third circumferential step, and bottom rib  178  can also be referred to as a fourth circumferential step. For example, the first circumferential step may be formed by a first circumference of rotating member  112  and the second circumferential step may be formed by a second circumference of rotating member  112 , wherein the first circumference is less than the second circumference. For example, the third circumferential step may be formed by a third circumference of rotating member  112  and the fourth circumferential step may be formed by a fourth circumference of rotating member  112 , wherein the third circumference is greater than the second circumference, and the third circumference is less than the fourth circumference. For example, the third circumference and fourth circumference may be equal. Moreover, in some embodiments, disengagement groove  162  is formed by a first diameter of rotating member  112  and the engagement groove  166  is formed by a second diameter of rotating member  112 , where the first diameter is larger than the second diameter such that the engagement groove  166  is deeper than the disengagement groove  162  relative to an outer circumferential surface of hub  172 . 
     Disengagement ridge  160  and ridge  164  can also each be referred to as a chamfer, for example. For example, a top ridge  180  may be formed on top rib  174 , and may also be referred to as a chamfer. In some embodiments, one or more of ridges  160 ,  164 , and  180  are sloped or inclined. 
     In the embodiment shown in  FIG.  4   , ridge  160  forms a retention angle θ 1  with a vertical axis  184  around rotating member  112  which is parallel to axis  108  ( FIG.  1   ). Retention angle θ 1  is sized and chosen to cooperate with retainer device  122  to inhibit dial  110  from being detached from rotating member  112 . In some embodiments, angle θ 1  is about 45 degrees. In some embodiments, angle θ 1  can range from about 30 degrees to about 60 degrees. In the embodiment shown, ridge  164  forms a retention angle θ 2  with a vertical axis  186  around rotating member  112  which is parallel to axis  108  ( FIG.  1   ). In some embodiments, angle θ 2  is about 17 degrees. In some embodiments, angle θ 2  can range from about 10 degrees to about 30 degrees. In some embodiments, top ridge  180  also forms an angle θ 3  with a vertical axis  188  around rotating member  112 . In some embodiments, angle θ 3  is about 30 degrees. In some embodiments, angle θ 3  can range from about 10 degrees to about 45 degrees. In some embodiments, angle θ 3  is selected such that installation of retainer device  122  on rotating member  112  will limit or avoid or reduce damage on hub  172  and/or retainer device  122  from incidence with a surface of rotating member  112 , such as a surface of top rib  174  (which may have the largest diameter of hub  172  that retainer device  122  rides over). 
     In some embodiments, a distance between ridge  160  and ridge  164 , forming a length of disengagement groove  162 , is about 0.09 inches. In some embodiments, a distance between ridge  164  and a lip  182  of bottom rib  178 , forming a length of engagement groove  166  is about 0.08 inches. In some embodiments, a distance between ridge  160  and top ridge  180 , forming a length of top rib  174 , is about 0.09 inches. In some embodiments, the length of disengagement groove  162  and engagement groove  166  is selected such that there is enough clearance for pin  128  of button  124  (shown in  FIG.  3   ) to extend into and retract out of a channel  132 . In some embodiments, the ratio of lengths between all or a subset of disengagement groove  162 , engagement groove  166 , and top rib  174  is selected to reduce or limit the overall assembled height of adjustment knob  106  and/or reduce or limit the freedom of movement of adjustment knob  106  to improve ergonomics of engagement and/or disengagement. 
       FIG.  6 A  illustrates a riflescope  200  having adjustment knob  106  used as an elevation knob  202  and a windage knob  204 . As shown in  FIG.  6 A , elevation knob  202  is in an engaged position such that its dial is engaged with a rotating member ( 112  in  FIGS.  1 - 5   ) of the elevation knob  202 , and windage knob  204  is in a disengaged position such that its dial is disengaged with a rotating member ( 112  in  FIGS.  1 - 5   ) of the windage knob  204 . A user may have pushed elevation knob  202  toward housing  206  to place elevation knob  202  in its engaged position. In the engaged position, the user may rotate the elevation knob  202  such that optical components of riflescope  200  are adjusted to reflect a particular elevation. The user may then pull elevation knob  202  away from housing  206  to place elevation knob  202  in the disengaged position (as illustrated in  FIG.  6 B ) and then rotate elevation knob  202  until zero mark  208  is aligned with reference mark  210  that is fixed. The user may thereafter push elevation knob  202  back toward housing  206  to place elevation knob  202  in the engaged position, where elevation knob  202  is now zeroed. In  FIG.  6 A , rotation of windage knob  204  will not cause adjustment of the optical components because windage knob  204  is in a disengaged position.  FIG.  6 B  illustrates an opposite situation to that shown in  FIG.  6 A  where riflescope  200  has elevation knob  202  in a disengaged position and windage knob  204  in an engaged position. When windage knob  204  is in the engaged position illustrated in  FIG.  6 B , it may be used to adjust optical components of riflescope  200  as discussed above with respect to elevation knob  202  in  FIG.  6 A . 
       FIGS.  7 - 11    illustrate an adjustment knob  106 ′ according to another embodiment, and  FIGS.  12 - 13    illustrate an adjustment knob  106 ″ according to yet another embodiment. In  FIGS.  7 - 13   , parts of adjustment knobs  106 ′ and  106 ″ that are identical, very similar, and/or functionally equivalent to parts having the same name in the embodiments of  FIGS.  1 - 6    are identified by the same reference numeral followed by a prime symbol (′) in the case of the embodiment of  FIGS.  7 - 11   , or a double prime symbol (″) in the case of the embodiment of  FIGS.  12 - 13   , and may not be otherwise described or discussed herein. For example, a guideway ring  130 ′ of a locking mechanism  123 ′ of adjustment knob  106 ′ is identical to guideway ring  130  illustrated in  FIGS.  2 ,  3  and  5   , operates in the same manner, and is not otherwise discussed herein. 
       FIG.  7    is a cross-sectional view of adjustment knob  106 ′ mounted on a riflescope  100 ′ with a clutch  167 ′ (described below) of adjustment knob  106 ′ shown in an engaged position.  FIG.  8    is an exploded view of adjustment knob  106 ′. And  FIG.  9    is an oblique section view of adjustment knob  106 ′ with its clutch  167 ′ illustrated in a disengaged position. With reference to  FIGS.  7 - 9   , clutch  167 ′ is a push-button style clutch that is actuated by depressing a clutch release button  710  along the axis of rotation  108 ′. Clutch release button  710  is carried by dial  110 ′ in a counterbore  712  formed in an axial outward end  714  of dial  110 ′ and is accessible from outside of dial  110 ′ at the axial outward end  714 . Clutch release button  710  is retained on dial  110 ′ by a retainer ring  716  that is fitted into a groove  718  circumscribing counterbore  712  near axial outward end  714 . Retainer ring  716  is received in a circumferential channel  720  in clutch release button  710  that is sized to allow a range of axial movement of clutch release button  710  along axis of rotation  108 ′. In an alternative embodiment (not illustrated), the retainer ring  716  may be carried in a narrower slot on clutch release button  710  and the groove  718  may be wider to allow retainer ring  716  to move axially therein. Other structures and devices for retaining button  710  on dial  110 ′ may also be utilized. A wave spring  726  is positioned in counterbore  712  between dial  110 ′ and clutch release button  710  to bias clutch release button  710  axially outwardly away from housing  102 ′ of riflescope  100 ′ so as to urge clutch  167 ′ toward the engaged position. Clutch release button  710  is illustrated as being relatively large and extending beyond dial  110 ′ when clutch  167 ′ is in the engaged position, but to prevent accidental release of clutch  167 ′ the clutch release button  710  may alternatively be made smaller and/or sit flush or recessed relative to outward end  714  of dial  110 ′ when clutch  167 ′ is in the engaged position. 
     A gripper  730  of clutch  167 ′ is attached to clutch release button  710  and extends axially away from an underside of clutch release button  710  toward housing  102 ′. Gripper  730 , which is best illustrated in  FIG.  11   , includes a mounting ring portion  732  that is coupled to clutch release button  710  via a snap ring  736 , and one or more resilient arms  740  extending away from mounting ring portion  732  toward housing  102 ′. A wedge-shaped gripper shoe  744  is provided near a terminal distal end of each resilient arm  740 . In the embodiment illustrated, gripper  730  includes a balanced arrangement of three arms  740  each terminating in a wedge-shaped gripper shoe  744 . Each of the arms  740  may extend through bore  746  ( FIG.  8   ) of dial  110 ′ and are received in a lobe  748  of an opening formed in a shoulder portion  752  of dial  110 ′ at the outer end of bore  746 . The entirety of gripper  730 , including mounting ring portion  732 , arms  740 , and gripper shoes  744 , are preferably formed together in a unitary one-piece construction, such as by molding or by machining from a solid block of metal or other material. 
     With reference to  FIG.  11   , each of the gripper shoes  744  may include one or more gripper splines  750 , or another type of high-friction surface, on an inner face thereof. Gripper splines  750  face toward and engage a spline ring  760  ( FIG.  10   ) or other rotating member clutch surface  170 ′ of rotating member  112 ′ when clutch  167 ′ is in the engaged condition/position. An outer surface  764  of each gripper shoe  744  on an opposite side of gripper shoe  744  from gripper splines  750  is shaped to wedge into a conical surface  770  or chamfer circumscribing an axially-inner opening of bore  746  ( FIG.  8   ) and forming a dial clutch surface thereof. Outer surface  764  may be smooth (as illustrated) to facilitate smooth actuation of clutch  167 ′, or may textured. As illustrated in  FIGS.  7 - 10   , spline ring  760  circumscribes hub  172 ′ of rotating member  112 ′ and gripper splines  750  are formed on a radially-inner surface of each of gripper shoes  744  and facing spline ring  760 . However, in an alternative embodiment the gripper splines  750  may be formed on the opposite sides of gripper shoes  744  and spline ring  760  (or other high-friction surface) may circumscribe the axially-inner opening of bore  746 , which may or may not be conical or chamfered. In such alternative embodiments, the radially-inner surface of each gripper shoe  744  may be smooth or textured, and optionally inclined or wedge-shaped relative to arms  740 , so as to wedge into and grip a complementary rotating member clutch surface on hub  172 ′. 
       FIG.  9    illustrates adjustment knob  106 ′ with clutch release button  710  depressed to move gripper  730  axially inward to a disengaged position whereat clutch  167 ′ is disengaged so as to allow dial  110 ′ to be rotated relative to rotating member  112 ′ for zeroing the adjustment knob  106 ′ without changing the elevation or other setting of riflescope  100 ′. 
       FIGS.  12  and  13    illustrate an alternative embodiment of an adjustment knob  106 ″ including a push-button style clutch  167 ″ similar to the push-button clutch  167 ′ of  FIGS.  7 - 11   , but in which gripper shoes  744 ″ lack splines on either side. Gripper shoes  744 ″ may be smooth or roughened. The inner gripping surface  780  of gripper shoes  744 ″ may be raised to provide optimal engagement or gripping with rotating member clutch surface  170 ″. Similarly, the embodiment of  FIGS.  12  and  13   , omits splines from the dial clutch surface  168 ″ and rotating member clutch surface  170 ″. Although rotating member clutch surface  170 ″ is illustrated as merely being a cylindrical side surface of hub  172 ″, the rotating member clutch surface  170 ″ may be roughened to improve grip, or may include a ridge or detent (not illustrated) to improve grip and retention when clutch  167 ″ is engaged. 
     In accordance with a method of use of an aiming device, an adjustment knob  106  of the aiming device of the kind including a dial and a rotating member rotatable about an axis of rotation  108  to change a setting of the aiming device, is zeroed following initially sighting-in the aiming device. The process of sighting-in an aiming device such as a riflescope, is well known, and typically involves shooting a weapon to which the aiming device is attached and observing deviation of the point of impact of the bullet or other projectile on a target at a known range, such as 100 yards, or 200 yards, or 100 meters (m), or 200 m. The deviation of the point of impact relative to the point of aim of the riflescope or aiming device indicates how much adjustment must be made to the aiming device—in terms of elevation (vertical) adjustment and windage (lateral) adjustment—in order for the scope to be “sighted-in” at that range. The step of “sighted-in” then involves releasing a locking mechanism  123  of the adjustment knob, for example by manually depressing a lock release button  124  located on the dial  110  or by otherwise moving a lock release  125  relative to the dial  110  and the rotating member  112 ; and, while the locking mechanism  123  is released, rotating the dial  110 , whereby the rotating member  112  co-rotates with the dial  110  to adjust an aim of the aiming device, until the aiming device is accurately targeting a point of impact of a firearm or other weapon (not illustrated) to which the aiming device is attached. Once the aiming device has been sighted-in, the method next involves disengaging a clutch  167  of the adjustment knob  106  that selectively couples the dial  110  to the rotating member  112 ; and, while the clutch  167  is disengaged, rotating a dial  110  of the adjustment knob  106  about the axis of rotation  108 , relative to the rotating member  112 , until the dial  110  is at its zero position, then engaging the clutch  167  to couple the dial  110  to the rotating member  112  for co-rotation therewith about the axis of rotation  108  for adjusting the aim of the aiming device. In some embodiments the lock release button  124  is located on a side of the dial  110  and releasing the lock mechanism  123  includes manually depressing the button  124  in a radial direction toward the axis of rotation  108 . In some embodiments, disengaging the clutch  167  may involve moving at least a portion of the dial  110  axially relative to the rotating member  112 . 
     If sighting-in requires a downward adjustment of the aiming device from its locked position, the method may further include prior to completing the sighting-in process, releasing the locking mechanism  123  and adjusting the adjustment mechanism  106  in a positive direction to clear a zero locked position of the locking mechanism  123 , then disengaging the clutch and rotating the dial  110  in the same direction (positive direction) relative to the rotating member  112  while the clutch  167  is disengaged, and then re-engaging the clutch  167  after rotating the dial  110  relative to the rotating member  112 . Thereafter a shot is taken with the weapon and the sight adjusted until it is sighted-in, and the remainder of the method described above is then completed to zero the dial. 
     It will be apparent to those having skill in the art that many changes may be made to the details of the above-described embodiments without departing from the underlying principles of the invention. The scope of the present invention should, therefore, be determined only by the following claims.