Abstract:
A tool that cuts a hole for a single or double electric gang” switch” box. By having four blades, all cutting at the same time and in the shape of the switch box, a more accurate and appropriately placed hole may be provided. The hole saw may be configured with two centering drills so the tool is guided into the cut. An eccentric drive mechanism converts a rotary drive into reciprocating movement of perpendicularly opposed pairs of blades to cut a rectangular opening.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of priority of U.S. provisional application No. 62/187,879, filed Jul. 2, 2015 the contents of which are herein incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates hole saws, and more particularly to apparatus for cutting a rectangular or square shaped hole. 
         [0003]    Currently in the art, it takes too long to cut out rectangular shaped holes, such as for electrical outlet “gang” boxes. When the rectangular hole is cut, it is not accurate, particularly when the users hand is not steady, resulting in a damaged wall or crooked hole. Other such saws are too slow and take tremendous user concentration to maintain the lines drawn on the wall for the hole&#39;s placement. Many of these saws are not intended to cut holes for electrical boxes, but have been adapted to do so. 
         [0004]    As can be seen, there is a need for an a hole saw having four blades all cutting at the same time in the shape of a square or rectangle, and by using a centering drill but, so the tool is guided into the cut. 
       SUMMARY OF THE INVENTION 
       [0005]    In one aspect of the present invention, a rectangular hole saw is provided having: a housing with a front face, a back face, and at least one sidewall; an eccentric drive mechanism is carried within the housing and is operable to reciprocate a first pair of blade carriers orthogonally relative to a second pair of blade carriers. The eccentric drive mechanism may include a rotary drive shaft having a driven end, proximal to the back face, and a driving end contained within the housing, with an eccentric drive pin carried on the driving end. A first yoke and a second yoke have opposed linear drive ends and an elongate slot defined intermediate the opposed linear drive ends. A first pair of blade slides are reciprocably carried on a first pair of rails disposed in a substantially parallel spaced apart relation. A second pair of blade slides are reciprocably carried on a second pair of rails disposed in a substantially parallel spaced apart relation, orthogonal to the first pair of rails, such that the first pair of blade slides are reciprocably moved by the linear drive ends of the first yoke and the second blade slides are reciprocably moved by the linear drive ends of the second yoke. 
         [0006]    In some embodiments, the rectangular hole saw will have a plurality of blade brackets attached to each of the first pair and second pair of blade slides. A first pair of blades may be removably attached to the blade brackets, attached to the first blade carriers and extending outwardly from the front face of the housing. A second pair of blades are removably attached to the blade brackets, which are attached to the second blade carriers and extend outwardly from the front face of the housing. The first pair of blades are disposed in a substantially parallel, spaced apart relation and the second pair of blades are disposed in a substantially parallel spaced apart relation, orthogonal to the first pair of blades. 
         [0007]    In other aspects of the invention, the rectangular hole saw may also include at least one drill shaft. The drill shaft includes a first end extending through the front face inwardly from the first and second pair of blades and a second end contained within the housing. A, drill gear is coupled to the second end of the rotary drill shaft via; via a drive gear attached to the rotary drive shaft and cooperatively engaged with the drill gear for rotation therewith. The drill shaft may also include a bit holder operatively coupled to the first end of the drill shaft. More preferably, a drill bit is operatively coupled to the bit holder. The rectangular hole saw of the present invention may also include a plurality of drill shafts disposed diagonally across the drive gear. A handle may be attached to the housing and extends outwardly therefrom. 
         [0008]    In yet other aspects of the invention, a rectangular hole saw includes a housing having a front face, a back face, and at least one sidewall; an eccentric drive mechanism is coupled to a rotary drive shaft and is operable to orthogonally reciprocate a first pair of rail mounted blade carriers and a second pair of rail mounted blade carriers. The eccentric drive mechanism includes an eccentric drive pin carried by the rotary drive shaft; and a first yoke and a second yoke each having opposed drive ends and an elongate slot defined intermediate the opposed drive ends; wherein the eccentric drive pin is received in the elongate slot of the first yoke and the second yoke. The first pair of blade slides are reciprocably displaced by the drive ends of the first yoke and the second blade slides are reciprocably displaced by the linear drive ends of the second yoke. 
         [0009]    These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is rear perspective view of rectangular hole saw. 
           [0011]      FIG. 2  is a front perspective view of the rectangular hole saw. 
           [0012]      FIG. 3  is a front perspective view of the rectangular hole saw with multiple components omitted for illustrative clarity of internal components. 
           [0013]      FIG. 4  is a cutaway perspective view of the rectangular hole saw along line  4 - 4  in  FIG. 3 . 
           [0014]      FIG. 5  is a front view of the invention with multiple components omitted for illustrative clarity of internal components and shown item  28  at an exemplary initial orientation. 
           [0015]      FIG. 6  is a front view of the invention with multiple components omitted for illustrative clarity of internal components and shown item  28  at an exemplary secondary orientation (90 degrees relative to  FIG. 5 ). 
           [0016]      FIG. 7  is a front view of the invention with multiple components omitted for illustrative clarity of internal components and shown item  28  at an exemplary tertiary orientation (90 degrees relative to  FIG. 6 ). 
           [0017]      FIG. 8  is a front view of the invention with multiple components omitted for illustrative clarity of internal components and shown item  28  at an exemplary quaternary orientation (90 degrees relative to  FIG. 7 ). 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]    The following detailed description is of the best currently contemplated modes of carrying out exemplary embodiments of the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims. 
         [0019]    Broadly, an embodiment of the present invention provides a hole saw for cutting a rectangular hole in the surface of a substrate material. The hole saw may be operatively coupled to a rotary drive motor, such as a drill, a drill press, a grinder, and the like. 
         [0020]    As seen in reference to  FIGS. 1 and 2 , a rectangular hole saw of the present invention includes a housing having a front face  12 , a back face  10 , and at least one sidewall  14 . A first pair of blades  42  are removably attached to a blade bracket  26  and are oriented in a first direction with the first pair of blades  42  aligned in a substantially parallel relationship. A second pair of blades  42 ′ are removably attached to a blade bracket  26  and are oriented in a second direction, orthogonal to the first direction, with the second pair of blades  42 ′ also aligned in a substantially parallel relationship. The blades  42 ,  42 ′ have a cutting end that extend outwardly from the front face  12  and are generally perpendicular to the front face. The blades  42 ,  42 ′ will also have an attachment end opposite the cutting end. The attachment end may be laterally offset from the cutting end so that, by selection of the length of the offset, a rectangular hole of differing lateral and longitudinal lengths may be cut by the rectangular hole saw. 
         [0021]    The rectangular hole saw is configured to translate a rotary drive input via an input drive shaft  46  to reciprocating action of the first pair of blades  42  and the second pair of blades. The input drive shaft may be coupled to a drill, a drill press, a grinder, or other rotary motor source. The housing may also include a handle  56  extending from the housing to permit the user to hold and stabilize the hole saw when cutting a hole therewith. 
         [0022]    As seen in reference to  FIGS. 3 and 4 , the rectangular hole saw will also include an eccentric drive mechanism carried within the housing. The eccentric drive mechanism is operable to translate the rotary input via input drive shaft  46  to reciprocate a first pair of blade carriers  24  orthogonally relative to a second pair of blade carriers  24 ′. The eccentric drive mechanism includes a rotary drive shaft  46  having a driven end proximal to the back face  10  and a driving end  28  contained within the housing. The drive shaft  46  may be supported by one or more bearings  50  carried in a bearing housing  48 . 
         [0023]    In some embodiments, the eccentric drive mechanism is provided an eccentric drive pin  30  carried on the driving end. The eccentric drive mechanism may also include a first yoke  22  having opposed drive ends  21  and an elongate slot  23  defined intermediate the opposed drive ends  21 . The eccentric drive mechanism may also include a second yoke  22 ′ having opposed drive ends  21 ′ and an elongate slot  23 ′ defined intermediate the opposed drive ends  22 ′. The eccentric drive pin  30  is received in the elongate slot  23 ,  23 ′ of the first yoke and the second yoke. A bushing  32  may also be provided between the eccentric drive pin  30  and the elongate slots  23 ,  23 ′. The first and second yokes  22   22 ′ are oriented in a substantially orthogonal relationship to each other. 
         [0024]    In further reference to  FIG. 3 , a first pair of blade slides  24  are reciprocably carried on a first pair of rails  20  disposed in a substantially parallel spaced apart relation within the housing. A second pair of blade slides  24 ′ are reciprocably carried on a second pair of rails  20 ′, also disposed in a substantially parallel spaced apart relation to each other and orthogonal to the first pair of rails  20 . The first pair of blade slides  24  are reciprocably moved by the drive ends  21  of the first yoke  22  and the second blade slides  24 ′ are reciprocably moved by the drive ends  21 ′ of the second yoke  22 ′. 
         [0025]    A blade bracket  26  is attached to each of the first pair and second pair of blade slides  24 ,  24 ′ to removably attach the blades  42 ,  42 ′ to the blade slides  24 ,  24 ′. As seen in reference to  FIG. 4 , the brackets  26  may be attached to the blade slides  24 ,  24 ′ via a fastener  52  received through aligned apertures in the blade bracket  26  and an attachment end of the blades  42 ,  42 ′. The fastener may be a pin  52  that has a head end may also have a clevis pin  54  to retain the pin  52  in an attaching relationship. Alternatively, the fastener  52  may be a screw or bolt, or similar configuration. 
         [0026]    In other embodiments, the hole saw may also include at least one drill bit  44  to provide a centering orientation of the hole saw when a rectangular hole is being cut with the saw. The drill bit  44  is driven by at least one rotary drill shaft  36  having a first end with a bit holder  40  that may extend through or receive a bit  44  through the front face  12  of the housing. A drill gear  34  is operatively coupled to the second end of the rotary drill shaft  36 . In this case, a drive gear  28  is attached to the rotary drive shaft  46  and cooperatively engaged with the drill gear  34  for rotation therewith. In this case, the eccentric drive pin  30  may extend from a face of the drill gear  34 . In a preferred embodiment, a plurality of drill shafts  36 ,  36 ′ are disposed diagonally across the drive gear  28 . 
         [0027]    Referring now to  FIGS. 5-8 , the operation of the rectangular hole saw is illustrated and described. Beginning with the eccentric drive pin  30  located in a topmost, or 12:00 o&#39;clock position, the first set of blades  42 , carried on their respective blade carriers  24 , through cooperative engagement with the drive ends  21  with the blade carrier  24  will be positioned at a first vertical limit of travel along the rails  20  for the first set of reciprocating blades  42 . The second set of blades  42 ′, carried on their respective blade carriers  24 ′, through cooperative engagement of the drive ends  21 ′ with the blade carrier  24 ′ will be positioned at a center position, intermediate their lateral limits of travel. 
         [0028]    As seen in reference to  FIG. 6 , with rotation of the rotary drive shaft  46  in a counter clockwise direction, the eccentric pin  30  and bushing  32  engage with the elongate slots  23 ,  23 ′ to displace the yokes  22 ,  22 ′ and thereby the blade carriers  24 ,  24 ′ along the rails  20 ,  20 ′. In this instance, the second set of blades  42 ′ will be displaced to a first lateral limit of travel by engagement of the drive ends  21 ′ with the blade carriers  24 ′. The first set of blades  42  will have been displaced from their vertical limit of travel to a centered, intermediate length of travel by the cooperative engagement of the yoke drive ends  21  with the blade carriers  20 . 
         [0029]    As seen in reference to  FIG. 7 , the eccentric drive pin  30  has continued to rotate with the rotary drive shaft  46  in a counter clockwise direction to a 6:00 o&#39;clock position. At the 6:00 o&#39;clock position, the first set of cutting blades  42  have been positioned to a second vertical limit of travel by virtue of the first yoke  22  having been displaced by the eccentric pin  30 . The second yoke  22 ′ has returned to a centered position, intermediate its&#39; lateral limits of travel. 
         [0030]    Proceeding next in reference to  FIG. 8 , continued rotation of the rotary drive shaft  46  in a counter clockwise direction displaces the eccentric drive pin  30  to a 3:00 o&#39;clock position. At this point, the first set of blades  42  have returned to a centered position, intermediate its vertical limits of travel. The second set of blades  42 ′ are not positioned at a second lateral limit of travel. 
         [0031]    In embodiments of the rectangular hole saw with one or more drill bits, the rotary drive shaft  46  is provided with a driving gear  28  for cooperative engagement with a drill gear  34 . As the driving gear  28  rotates, it engages with the drill gear  34  and imparts a rotation in drill shaft  36 . 
         [0032]    It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.