Abstract:
Disclosed is a method of converting a baseball pitching machine to a lacrosse ball pitching machine by obtaining a baseball pitching machine having a drive wheel and a compression plate spaced by a compression space  3  therefrom, reducing the size of the compression space  3  to an extent effective in propelling a lacrosse ball, and elevating the pitching machine so as to raise the compression space  3  to a height of at least 70 inches above ground level.

Description:
BACKGROUND OF THE DISCLOSURE  
       [0001]     1. Field of the Disclosure  
         [0002]     This invention relates to machines for pitching lacrosse balls.  
         [0003]     2. Description of the Related Art  
         [0004]     Baseball pitching devices are well known in the art. These devices generally utilize a rotating drive wheel and a pressure plate spaced apart a distance smaller than a baseball. A baseball fed into the space between the drive wheel and pressure plate is tightly squeezed between the two and propelled forward.  
         [0005]     Another version of this genre of baseball pitching machines has an additional drive wheel replacing the pressure plate. Because the baseball is driven by two wheels, faster ball speeds are obtained.  
         [0006]     One might simply design a similar device for pitching lacrosse balls, but what is needed is a more economical method that permits a pre-existing baseball pitching device to be converted to a lacrosse ball pitching device, thereby obviating the need for retooling.  
       BRIEF SUMMARY OF THE DISCLOSURE  
       [0007]     Disclosed is a method of converting a baseball pitching machine to a lacrosse ball pitching machine, comprising the steps of obtaining a baseball pitching machine having a drive wheel and a compression plate spaced by a compression space therefrom, reducing the size of the compression space to an extent effective in propelling a lacrosse ball, and elevating the pitching machine so as to raise the compression space to a height of at least 70 inches above ground level.  
         [0008]     Disclosed is a method of converting a baseball pitching machine to a lacrosse ball pitching machine, comprising the steps of obtaining a baseball pitching machine having a drive wheel and a compression plate spaced by a compression space therefrom, and reducing the size of the compression space by about 68%.  
         [0009]     Also disclosed is a conversion kit for converting a baseball pitching machine to a lacrosse ball pitching machine, the kit including a replacement compression plate that, when installed, reduces a compression space between a drive wheel of the pitching machine and a replaced compression plate to an extent effective in propelling a lacrosse ball. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is a front-plan view of the converted baseball pitching machine of the invention.  
         [0011]      FIG. 2  is a rear-plan view of the invention.  
         [0012]      FIG. 3  is a side-plan view of the invention, showing the opening to the feed tube.  
         [0013]      FIG. 4  is a side-plan view of the invention showing where the ball is ejected from. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0014]     Referring to  FIG. 1  in particular and the remaining figures in general, there is shown a lacrosse-modified pitching device  1 , originally designed to pitch baseballs, now modified to pitch lacrosse balls. The basic components include a drive wheel  2  driven about a drive axis  2   b  and having a compressible outer rim  2   a . The compressible outer rim  2   a  is spaced by a compression space  3  from a compression plate  4 , which itself will also generally have a compression pad  4   a . A feed tube  5 , slightly larger than the diameter of the lacrosse ball  6  to be pitched, is utilized to direct the ball into the compression space  3 .  
         [0015]     The compressible outer rim  2   a  and the compression pad  4   a  will typically be made of a resilient material such as rubber or polymer plastic. Note, however, that it is not unusual for the compressible outer rim  2   a  and compression pad  4   a  to be made of different materials and have different resiliencies. Often the compressible out rim  2   a  is made of a harder material than the compression pad  4   a.    
         [0016]     As can be seen, the lacrosse ball  6  is fed into the feed tube  5  causing it to enter the compression space  3 . The drive wheel  2 , rotating rapidly counterclockwise in this view, drives the lacrosse ball  6  through and out the compression space  3 , thereby pitching the lacrosse ball  6 .  
         [0017]     Referring more specifically to  FIG. 2 , additional components include a tripod receptacle  7 , a swivel joint  8  for aiming the assembly horizontally, a tilt joint  9  for aiming the assembly vertically. Levered tightening screws  10  are provided to locking these joints into place. The tripod receptacle  7  is generally three or more hollow pipe members sized to receive supporting legs. As will be more fully explained below, a set of replacement legs  15  will preferably be provided as part of the modification method.  
         [0018]     A drive motor  11  is provided, preferably controlled by a speed controller  12  that has a manual speed control knob  13  or other type of adjustment control. A separate on/off switch may be provided on the speed controller  12 , but generally it is more economical to have an “off” position on the speed control knob  13 .  
         [0019]     Referring again to  FIG. 1  in particular and the remaining figures in general, there is also often provided a carrying handle  14  and a mud flap  17 . The mud flap  17  allows use of the invention  1  in rainy weather by preventing water on the drive wheel  2  from spinning onto the person or device feeding lacrosse balls  6  into the feed tube  5 . A motor shield  18  is also often provided to prevent balls thrown or batted back toward the machine from striking the motor  11  and speed controller  12 .  
         [0020]     The most important modification to the original baseball pitching machine is in the original compression space  3 , which must be reduced to be adapted to the size, friction, and resiliency of a lacrosse ball. The National Collegiate Athletic Association (NCAA) sets standards for equipment used in college sports that are typically followed by their professional counterparts. For a baseball, the diameter is 3 inches and the coefficient of restitution is no more than 0.555. For a lacrosse ball, the diameter is 2.5 inches and the coefficient of restitution is no more than 0.842. Both balls weigh from 5 to 5.25 ounces.  
         [0021]     The coefficient of restitution, c, of a ball is given by:  
       c   =       h   H           
 
 where h is the height to which the ball bounces to when dropped from a height of H. The coefficient of restitution is a measure of the resiliency of the ball. 
 
         [0022]     The problem for the modifier of a baseball machine for use with a lacrosse ball is that the compressibility of the compressible rim  2   a  of the drive wheel  2  and the compressibility of the compression pad  4   a  (if any) of the compression plate  4  will vary among manufacturers and models, therefore the compression space  3  required for a lacrosse ball will vary. However, because compression strength is proportional to compression space  3  to good approximation, we can reasonably rely on the standardization of baseballs and lacrosse balls by the NCAA to determine the modified compression space  3  without undue experimentation. We have found that the original compression space  3  will generally be reduced from 60% to 80%, preferably about 68%, of its original size to modify a baseball pitching machine to pitch lacrosse balls.  
         [0023]     More accurately, the equation for the change in compression space distance is approximated by  
           G   B     -     G   L       ≅         (       D   B     -     D   L       )     ′     +       F   +   ϕ       K   L             
 
 where G B  is the compression space width for the hardball, G L  is the compression space width for the lacrosse ball, D B  is the diameter of the hardball, D L  is the diameter of the lacrosse ball, F is the compression force exerted upon the balls when in the compression space, and K L  is the spring coefficient of the lacrosse ball (wherein F=K L ·ΔD L , where ΔD L  is the change in lacrosse ball diameter caused by force F). The equation assumes the hardball to be incompressible. The factor φ is any additional force that may be desired, such as to compensate for the smoother and lower frictional surface of a lacrosse ball in comparison to a hardball. 
 
         [0024]     Notice from the equation that the difference in compression space distance is independent of the resiliency of the compressible rim  2   a  and compression pad  4   a  and is simply the difference in ball size plus a constant, F/K L , which will generally be from 0.15 to 0.25 or about 0.21. Hence, for any system, one may generally maintain the same compression force in conversion to lacrosse ball use by reducing the compression space by about 0.5+0.21=0.71 inches.  
         [0025]     For example, the modified baseball pitching machine shown in the drawings is sold by Bata Baseball Machines of San Marcos, Calif. under the product model name of BATA-1. The compression space  3  for an NCAA standard hardball baseball is 2.21 inches. Taking 68% of this, we obtain a compression space  3  of 1.5 inches for an NCAA standard lacrosse ball. Alternatively, we could reduce the value of 2.21 inches by 0.71 and obtain the same result of 1.5 inches.  
         [0026]     Hence, for any particular make or model of machine, we need not know the compression strength of the compression pad  4   a  or compressible rim  2   a  and engage in complex calculation or experiment. This is because the manufacturer has already set the original compression space  3  size for us for optimal use with a standardized baseball. We need only take 68% of this value to reasonably adapt to a lacrosse ball. Note that the diameter of an NCAA standard lacrosse ball is only 83% of an NCAA standard hardball, but we must reduce the compression space  3  still further because a lacrosse ball is more resilient and has a less frictional surface than a hardball. Of course, there may be other factors involved, depending on machine design, so that one might wish to take 68% as an initial approximation and then fine-tune the compression space  3  with minimal experimentation.  
         [0027]     How the modification in compression space  3  is made is most simply achieved by either drilling new mounting holes  4   b  in the compression plate  4  supplied with the baseball pitching machine, or by supplying a replacement compression plate  4  with mounting holes that will provide the desired compression space  3  for lacrosse balls. Such a new plate could be supplied as part of a conversion kit, thereby alleviating the need for a customer to machine any parts.  
         [0028]     The next most important modification to the original baseball pitching machine is in the height. Lacrosse balls are mostly thrown high with lacrosse sticks, so the lacrosse-modified pitching machine  1  needs to be much higher. The compression space  3 , where the ball is ejected, is typically about 40 to 50 inches above ground level on the typical baseball pitching machine. For a lacrosse ball, it is preferred that the compression space  3  be at a height above ground of from about 70 to 90 inches, or about 80 inches. To do this, we preferably choose a model of baseball pitching machine that has removable legs and replace them with longer ones. The BATA-1 model shown in the drawings, for example, comes with 34-inch pipe legs that fit into the tripod receptacle  7 , yielding a compression space  3  height of about 48 inches. By replacing these with 68-inch replacement legs  15 , we obtain a compression space  3  height of about 78 inches. Again, these replacement legs  15  may be supplied as part of a conversion kit for the consumer.  
         [0029]     The third most important modification to the original baseball pitching machine is in the feed tube  5 . Depending upon the make and model of the machine this step may or may not be necessary. As can be seen in  FIG. 1 , the original feed tube  16 , shown in dotted outline, on the model BATA-1 is level with an inside diameter large enough to accommodate a 3-inch diameter hardball with room to spare. Further, the tube does not extend very close to the compression space  3 .  
         [0030]     The lacrosse-modified feed tube  5  of the invention has a smaller inside diameter of about three inches to accommodate a 2.5-inch lacrosse ball with half-an-inch to spare. It is preferably tilted downward into the compression space  3  at an angle of from 10° to 20°, preferably about 15°. Note that this angle is in relation to the compression space itself rather than the ground because the device can be tilted. This allows the device to be tilted upward to duplicate the loft normally associated with lacrosse balls when thrown and still permit balls to be fed into the tube without rolling back out. Further, the feed tube  5  is preferably brought in very close to the compression space  3 . Because both the drive wheel  2  and the compression plate  4  obstruct access to the compression space  3 , it is desirable to provide a compression plate clearing cut  5   a  and a drive wheel clearing cut  5   b  on the feed tube  5  so as to permit the feed tube to be extended right into the opening of the compression space  3  as shown. Again, the feed tube  5  of the invention may be provided to the consumer as a replacement part in a conversion kit, requiring only that the original feed tube  16  be discarded and replaced.  
         [0031]     Of course, while this disclosure has been directed to modifying a hardball pitching machine, the parameters therein may be modified to convert a softball pitching machine with little experimentation. Such a conversion would of course require a greater reduction in the compression space.  
         [0032]     While various values, scalar and otherwise, may be disclosed herein, it is to be understood that these are not exact values, but rather to be interpreted as “about” such values, unless explicitly stated otherwise. Further, the use of a modifier such as “about” or “approximately” in this specification with respect to any value is not to imply that the absence of such a modifier with respect to another value indicated the latter to be exact.  
         [0033]     Changes and modifications can be made by those skilled in the art to the embodiments as disclosed herein and such examples, illustrations, and theories are for explanatory purposes and are not intended to limit the scope of the claims. Further, the abstract of this disclosure is provided for the sole purpose of complying with the rules requiring an abstract so as to allow a searcher or other reader to quickly ascertain the subject matter of the disclosures contained herein and is submitted with the express understanding that it will not be used to interpret or to limit the scope or the meaning of the claims.