Abstract:
An adjustment mechanism for selectively tightening the snare wires of a snare drum, having a camming mechanism cooperatively formed by two concentric members with an inherent level of friction that allows it to be reliably set at either extreme position of adjustment of the tightness of the snare wires or at any desired intermediate position of adjustment, thus allowing the musician a full range of choice of the musical tones or effects to be produced by the snare wires.

Description:
PRIORITY CLAIM  
       [0001]     This application claims the priority of our provisional application Ser. No. 60/685,333 filed May 26, 2005. 
     
    
     FIELD OF THE INVENTION  
       [0002]     This invention relates to the field of musical instruments, and particularly snare drums.  
       BACKGROUND OF THE INVENTION  
       [0003]     A typical snare drum has a cylindrical shell with drumheads of flat circular configuration mounted on both its top and bottom ends. Each drumhead is surrounded by a circumferential rim. A group of snare wires extend beneath and across the lower drumhead, in a normally loose configuration. A mechanism which allows the musician to tighten the snare wires causes them to impact the bottom surface of the lower drumhead, generating sounds of a distinctive character, since the vibratory motions of the bottom drumhead are then modified by contact with the snare wires.  
         [0004]     In the presently standard snare drum, at one of their ends the snare wires are supported in abutting relationship to the associated circumferential rim of the bottom drumhead by means of a butt plate and associated clamps which hold the butt plate in rigidly attached relationship to the drum shell. At their other ends the snare wires are attached to a T bracket, which holds them snubbed up against the circumferential bottom rim of the drum. By selectively moving the T bracket up or down the musician selectively tightens or loosens the snare wires to produce a desired musical effect.  
         [0005]     In presently standard snare drums the T bracket is movable between two extreme positions, but the control mechanism is not continuously adjustable to allow the free selection of any intermediate condition of tightness of the wires. The musician must therefore be satisfied with an available position of adjustment and whatever musical sounds the wires then create.  
       SUMMARY OF THE INVENTION  
       [0006]     According to the present invention we control the selective tightening of the snare wires by a camming mechanism that has an inherent level of friction which allows it to be reliably set at an extreme upper position of adjustment of the T bracket, at an extreme lower position, or any desired intermediate position of adjustment. This provides the musician a full range of choice of the musical tones or effects to be created by the snare wires.  
         [0007]     According to the presently preferred form of the invention a vertically extending drive cylinder is supported for free rotation but with its vertical movement inhibited, and an elongated lifting rod is disposed concentrically within the drive cylinder and supported for vertical sliding movement but with its rotational movement inhibited. The drive cylinder has a pair of circumferentially extending sloping grooves on its inner wall surface which are open towards the lifting rod, and a pair of dowel pins carried on opposing sides of the lifting rod slidingly engage the respectively corresponding grooves of the drive cylinder. Each of the grooves extends at least about half the circumference of the drive cylinder and slopes gently throughout its length so that the static friction of the dowel pins resting upon the grooves is sufficient to reliably maintain any rotational position of adjustment of the drive cylinder.  
         [0008]     Further in accordance with the invention a housing member attached to the drum shell supports both the drive cylinder and the lifting rod in their operative positions. 
     
    
     DRAWING SUMMARY  
       [0009]      FIG. 1  is a pictorial representation of a snare drum in which the snare wires, T bracket, and butt plate are shown spaced away from the drum itself;  
         [0010]      FIG. 2  is an exploded perspective view of interior parts of the mechanism of the presently preferred embodiment of our invention;  
         [0011]     FIGS.  3 ( a ) and  3 ( b ) are schematic diagrams which illustrate the friction forces involved in a camming mechanism utilized in accordance with the invention;  
         [0012]      FIG. 4  includes both an elevation view of the presently form of the mechanism, and a cross-sectional view of same; and  
         [0013]      FIG. 5  is another elevation view of the presently form of the mechanism, taken at an angle of ninety degrees relative to the elevation view shown in  FIG. 4 , and with an accompanying cross-sectional view. 
     
    
     DETAILED DESCRIPTION  
     (FIGS.  1 - 5 , inclusive)  
       [0014]     More particularly, according to the presently preferred form of our invention a snare drum  10  has a control housing  20  attached to an outer surface of the drum shell  12  which contains a drive cylinder  30  that extends vertically and is rotatable relative to the housing. Inside the drive cylinder  30  there is a vertically extending lifting rod  40  that is vertically movable within the drive cylinder but does not rotate relative to either the control housing or the drive cylinder. The lower end of the lifting rod  40  is secured to one end of the snare wires  14 , for selectively tightening them when the lifting rod is lifted up.  
         [0015]     A hand-operated camming mechanism is cooperatively formed by the drive cylinder and the lifting rod for selectively raising or lowering the lifting rod within the drive cylinder. The camming mechanism has an inherent level of friction which allows it to reliably set the lifting rod at either an extreme upper position of adjustment, at an extreme lower position, or at any desired intermediate vertical position of adjustment.  
         [0016]     SNARE DRUM. As seen in  FIG. 1 , the snare drum  10  has a shell  12  and snare wires  14  which extend underneath the bottom drumhead, not specifically shown. A T bracket  46  is connected to one end of the snare wires and a butt plate  48  to their other end, as shown in  FIG. 1 . The preferred mechanism of the present invention has a drive cylinder  30  with a radially extending lever or handle  32  attached to its upper end, as shown only in  FIGS. 1, 2 ,  4 , and  5 .  
         [0017]     CONTROL HOUSING. The control housing  20  has a mounting surface  22  for attaching it to the outer vertical surface of drum shell  12 . Threaded holes  24  are provided for a pair of attachment screws  25  which fixedly secure housing  20  to the drum shell. A threaded hole  27  is also provided near the lower end of mounting surface  22  to receive an assembly screw  36 , which is therefore in a fixed relation to the control housing  20 . The function of assembly screw  36  is later described in more detail.  
         [0018]     DRIVE CYLINDER. Drive cylinder  30  is concentrically located inside housing  20  and also concentrically surrounds the lifting rod  40 . Upper and lower O-rings  38  support the drive cylinder  30  within the housing  20 . The lever or handle  32  attached to the drive cylinder upper end permits the musician to selectively rotate the drive cylinder  30  relative to both control housing  20  and lifting rod  40 .  
         [0019]     LIFTING ROD. The lifting rod  40  inside control housing  20  has a vertical slot  42  to receive the inner end of assembly screw  36 . Assembly screw  36  extends into the slot  42 , as further described below. This allows the lifting rod  40  to move vertically relative to control housing  20  and drive cylinder  30  but without rotating relative to either of them.  
         [0020]     ASSEMBLY SCREW. Threaded hole  27  near the lower end of mounting surface  22  of control housing  20  receives the assembly screw  36 , which is therefore held in fixed relation to the control housing  20 . In the lower end of drive cylinder  30  a horizontal slot  34  is provided to receive the assembly screw  36 . Horizontal slot  34  in conjunction with assembly screw  36  therefore maintains a fixed vertical position of the drive cylinder  30  relative to the control housing  20 . The assembly screw  36  extends not only through that horizontal slot  34  but also into the vertical slot  42  in the lifting rod  40 . This allows rotation of the lever  32  on the drive cylinder upper end to raise or lower the lifting rod  40 , and hence to tighten or loosen the snare wires  14 , without rotating the lifting rod itself.  
         [0021]     DETAIL OF LIFTING ROD. Lifting rod  40  is located concentrically within drive cylinder  30  and hence within control housing  20 . Its vertical slot  42  receives the assembly screw  36  in a vertical sliding relationship, allowing an up or down movement of the lifting rod when the tightness of the snare wires is being adjusted. A pair of alignment holes or pin holes  44  are provided in opposing side walls of the lifting rod  40 , which receive the inner ends of respective ones of a pair of lifting pins or dowels  54 . The outer ends of dowels or lifting pins  54  engage respective sloping grooves  52 , for lifting or lowering the lifting rod in response to rotation of the drive cylinder relative to control housing  20 , as will be further described in detail. T bracket  46  is attached, but somewhat indirectly, to the bottom end of lifting rod  40 , to be raised or lowered so as to tighten or loosen the snare wires  14 .  
         [0022]     Thus according to the presently preferred form of the invention a generally cylindrical housing  20  is attached in a fixed position to an outer surface of the drum shell  12 . An elongated drive cylinder  30  is located inside the housing  20  with its longitudinal axis extending vertically, and is rotatable relative to the housing. The drive cylinder  30  is hollow, and a vertically extending lifting rod  40  is vertically movable within the drive cylinder. Horizontal slot  34  in drive cylinder  30  in conjunction with the assembly screw  36  maintains a fixed vertical position of the drive cylinder  30  relative to the control housing  20  when the drive cylinder is rotated. The lower end of lifting rod  40  is secured to T bracket  46  which in turn is secured to one of the ends of the snare wires  14  for controlling their tension.  
         [0023]     CAMMING MECHANISM. A camming mechanism is provided by the cooperative action of the dowels or lifting pins  54 , whose inner ends engage the pin holes  44  in the lifting rod  40  while their outer ends are supported upon the pair of sloping grooves  52  in drive cylinder  30 . The sloping slots or grooves  52  formed in the wall of drive cylinder  30  are inclined uniformly throughout their length to permit complete operator selection of the tightness or looseness of snare wires  14 . The outer end of lever or handle  32  provides for operator rotation of the drive cylinder  30  and hence control of tightness of the snare wires. The lifting pins or dowels are removable, and a careful assembly procedure is therefore needed in order to put all portions of the entire mechanism including the lifting pins  54  into proper operative positions.  
         [0024]     Thus the camming mechanism operates in cooperation with both the drive cylinder  30  and lifting rod  40  for selectively raising or lowering the lifting rod to tighten or loosen the snare wires. It is very important that each of the sloping grooves  54  extends for at least approximately half the circumference of the drive cylinder  30 . In similar fashion, the horizontal slot  34  in the lowermost end of drive cylinder  30  permits the drive cylinder  30  to rotate by at least about 180 degrees relative to the lifting rod  40 . Since the drive cylinder  30  is of larger diameter than the lifting rod  40 , the outer ends of the lifting pins  54  move by a very substantial distance along the length of the respective sloping grooves  52 . It is this rather large distance that makes it possible to have a rather gentle slope of the grooves or cam surfaces  52 , which in turn makes it possible to have a rather high degree of static friction between the lifting pins or dowels  54  and the lower surfaces of grooves  52 .  
         [0025]     FIGS.  3 ( a ) and  3 ( b ) illustrate how the static friction of the camming mechanism serves to hold the snare wires in their selected condition of tightness.  FIG. 3 ( a ) shows that as the rotatable angle of adjustment varies, the snare wire tension to vary the tone and sound quality also varies as a function of the adjustment angle,  
         [0026]      FIG. 3 ( b ) diagrammatically illustrates that because of the slope of the sloping grooves  52 , and the static frictional force of the outer ends of dowel pins  54  resting upon cam surfaces  52 , the force of the static friction always exceeds gravitational force that would tend to make the dowel pins slide downward along the surfaces of the respective sloping grooves  52 . In  FIG. 3  ( b ) the rate of change of the frictional retaining force is represented as dY, while the gravitational force is represented as dX. Thus, the value of dY always exceeds the value of dX. That relationship is still true when the lifting rod is lifted up and the tension of the snare wires adds to the downward force on dowel pins  54 .  
       OPTIONAL FEATURE  
       [0027]     FINE TUNING ADJUSTMENT. In the presently preferred form of the invention the knob head of fine tuning rod  60  always rests upon the top end of the lifting rod  40 . The lower end of rod  60  is threaded (not specifically shown in the drawings) and engages internal threads inside the T bracket  46  (also not shown), thus providing a fine adjustment of the initial or quiescent elevation at which the T bracket is supported relative to the lifting rod. Thus the T bracket  46  is not attached directly to the bottom end of lifting rod  30 , but instead its starting position is established through the fine tuning rod  60 . Inclusion of that fine tuning mechanism, however, is an optional feature of the invention, as the lower end of lifting rod  40  may instead be attached directly to the T bracket  46 , if a fine tuning adjustment is not being used.  
         [0028]     While a particular embodiment of the invention has been disclosed in detail in order to comply with requirements of the patent laws, it will be understood that the scope of the invention is to be determined only in accordance with the appended claims.  
       PARTS LIST  
       [0000]    
       
           10  Snare drum  
           12  shell  
           14  snare wires  
          axis of drum shell (no number)  
          bottom of drumhead (not shown)  
           20  control housing  
           22  the mounting surface of control housing  20   
           24  two threaded holes in  20  for attachment screws  
           25  two attachment screws  
           27  threaded hole in  20  for assembly screw  36   
           30  drive cylinder (inside housing  20  and surrounding rod  40 )  
           32  lever or handle to rotate drive cylinder relative to  20  and  30  (shown in  FIGS. 1, 2 ,  4 , and  5 , only).  
           34  horizontal slot in bottom end of drive cylinder  30  (for assembly screw  36 )  
           36  assembly screw  
           38  upper and lower O-rings supporting  40   
           40  lifting rod (inside drive cylinder  30 )  
           42  vertical slot in lifting rod receiving assembly screw  36   
           44  alignment holes (pin holes) in lifting rod wall receiving dowels  54  to support and lift the lifting rod in response to rotation of the drive cylinder  30   
       
     
         [0047]      46  T bracket attached (indirectly) to bottom of rod  30  through rod  60 , to raise or lower clamp, to tighten or loosen the snare wires  14 . (threaded lower end of  60  engaging threads inside T bracket  46  is not shown) 
     48  butt plate clamped at remote end of snare wires  14 .     camming mechanism has no separate number      52  two sloping grooves in drive cylinder  30  wall      54  lifting pins (dowel pins)      60  Fine tuning rod (its head rides on top of  40 ).