Abstract:
A blade assembly for cutting roots is installed on a hand-carried weed cutter or hand-carried side walk edger. The blade assembly comprises a central blade support that supports a central blade. A plurality of cutting blades are stacked on both sides of the central blade to form a stack of blades. The stack of blades is secured together by fasteners that pass through openings in the blades. The central blade and each of the plurality of cutting blades comprises a plurality of teeth. Outermost blades in the stack of blades are smaller in diameter than the blades directly adjacent to the outermost blades.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
       [0001]    A blade assembly for cutting roots is installed on a hand-held weed cutter/edger. The blade assembly comprises a central blade support that supports a central blade. A plurality of cutting blades are stacked on both sides of the central blade to form a stack of blades. The stack of blades is secured together by fasteners that pass through openings in the blades. The central blade and each of the plurality of cutting blades comprises a plurality of teeth. Outermost blades in the stack of blades are smaller in diameter than the blades directly adjacent to the outermost blades. 
         [0002]    In operation of the device, the cutter is moved in a back and forth motion over a root, left to right, then right to left. The shorter blades on the outside of the stack of blades help to keep the larger blades from getting hung once the blades have begun making resurfacing cuts on the top part of the root. 
         [0003]    For purposes of summarizing the invention, certain aspects, advantages, and novel features of the invention have been described herein. It is to be understood that not necessarily all such advantages may be achieved in accordance with any one particular embodiment of the invention. Thus, the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]    The disclosure can be better understood with reference to the following drawings. The elements of the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the disclosure. Furthermore, like reference numerals designate corresponding parts throughout the several views. 
           [0005]      FIG. 1  is a perspective view of a weed cutter with a root cutting blade shown in exploded view. 
           [0006]      FIG. 2  is an enlarged view of the root cutting blade of  FIG. 1 . 
           [0007]      FIG. 3  is an enlarged perspective view of the blade assembly of  FIG. 1 . 
           [0008]      FIG. 4  is a side plan view of the outermost cutting blades in the blade stack. 
           [0009]      FIG. 4 a    is an enlarged view of an exemplary blade tooth of  FIG. 4 . 
           [0010]      FIG. 5  is a side plan view of the cutting blades adjacent to the outermost cutting blades in the blade stack. 
           [0011]      FIG. 6  is a side plan view of the central blade. 
           [0012]      FIG. 7  is a side plan view of the blade support. 
           [0013]      FIG. 8  is a partially-exploded view of the blade stack according to an embodiment of the present disclosure. 
           [0014]      FIG. 9  is a side view of the blade assembly of  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION 
       [0015]      FIG. 1  is a perspective view of a traditional weed cutter  100 , but with a root cutting blade  101  (shown in exploded view) instead of a traditional weed cutting blade. The weed cutter  100  comprises a support  104  with a motor  106  on an upper end and a cutting end  107  on a lower end. A handle  105  is disposed on the support  104  between the motor  104  and the cutting end  107 . 
         [0016]    The cutting end  107  comprises a blade assembly  101  affixed to the shaft  109  by a nut  103 . A shield  102  protects the user (not shown) from flying debris during operation of the cutter  100 . 
         [0017]      FIG. 2  is an enlarged exploded view of the cutting end  107  of the cutter  100 . The blade assembly  101  comprises an opening  706  that is received by a rotating shaft  109 . The nut  103  that affixes the blade assembly  101  to the shaft  109  is a left handed nut in the illustrated embodiment. A compression washer (not shown) is disposed between the nut  103  and the blade assembly  101  in one embodiment. 
         [0018]      FIG. 3  is an enlarged perspective view of the blade assembly  101  of  FIG. 1 . The blade assembly  101  comprises a central blade support  307 . The blade support comprises the opening  706  that is received by the shaft  109  ( FIG. 2 ). The central blade support  307  is described further herein with respect to  FIG. 7 . 
         [0019]    A plurality of blades  301   a - 301   b ,  302   a - 302   d , and  303  are affixed to the central blade support  307  via a plurality of fasteners  308 . The plurality of blades  301   a - 301   b ,  302   a - 302   d , and  303  are arranged in a “stack”  311 , with blades  301   a  and  301   b  on the outsides (i.e., top and bottom) of the stack. The blades  301   a  and  301   b  comprise substantially identical blades described further herein with respect reference number  301  in  FIG. 4 . 
         [0020]    The blades  302   a - 302   d  comprise substantially identical blades described further herein with respect reference number  302  in  FIG. 5 . Blade  302   a  is the second blade in the stack  311 , blade  302   b  is the third blade in the stack  311 , blade  302   c  is the fifth blade in the stack  311 , and blade  302   d  is the sixth blade in the stack  311 . The blade  303  is described further herein with respect to  FIG. 6 . Blade  303  is in the middle of the stack  311 , i.e., is the fourth blade in the stack. 
         [0021]    Although the blade assembly  101  of  FIG. 3  depicts seven blades  301   a - 301   b ,  302   a - 302   d , and  303  arranged in the stack  311 , in other embodiments there may be more or fewer blades. 
         [0022]      FIG. 4  is a side plan view of the blade  301  (which is referred to as  301   a  and  301   b  to designate the location of the blades in  FIGS. 3, 8 and 9 ). The blade  301  comprises a one piece, flat, unitary roughly disk-shaped blade with a plurality of individual teeth  401  extending outwardly in a radial direction from the center of the blade  301 . The plurality of teeth  401  extend generally equidistantly from the center of the blade  301  to form an outer diameter “d 1 .” In one embodiment, the diameter d 1  is 5.38 inches. In other embodiments, the diameter d 1  may be larger or smaller. 
         [0023]    In the illustrated embodiment, the blade  301  comprises 24 teeth  401  spaced equidistantly apart around the perimeter of the blade  301 . Other embodiments of the blade  301  may comprise more or fewer teeth  401 . 
         [0024]    The blade  301  comprises a central opening  406  and a generally circular inner edge  404 . The opening  406  is between substantially 4.10 and 4.25 inches in one embodiment. A plurality of protrusions  403  extend from the inner edge  404  and comprise openings  405  for receiving fasteners  308  ( FIG. 3 ). The protrusions are generally semi-circular in shape. In the illustrated embodiment, the blade  301  comprises six protrusions  403  for receiving six fasteners  308 . In other embodiments, there may be more or fewer protrusions and more or fewer fasteners. 
         [0025]    The blade  301  is between approximately 0.045-0.050 inches thick and formed from carbide-tipped steel in one embodiment, and may be other thicknesses and formed from other suitable materials in other embodiments. 
         [0026]      FIG. 4 a    is an enlarged view of an exemplary blade tooth  401  of  FIG. 4 . Blade  301 ,  302 , and central blade  303  are categorized as “Rip saw blades” with positive hook angles between 18 degrees to 22 degrees forward from the center line. Blade  301 ,  302 , and central blade  303  each has a top clearance angle of 12 to 13 degrees from the top of the carbide tooth. Blades  302  and  303  have the same amount of teeth (16 teeth) and teeth spacing that ranges from 1.02 inches to 1.07 inches. Blade  301  has 24 teeth with teeth spacing ranging from 0.069 to 0.072 inches. Blade  301 ,  302 , and  303  each has carbide teeth that has kerf ranging from 0.075 inches to 0.11 inches. The tooth configurations for all blades can be either “Alternate Top Bevel”, beveled at 15 degrees on alternating sides on the top of the carbide tips, or “Triple Chip Grind” which is the standard flat top tooth configuration for rip saw blades. 
         [0027]      FIG. 5  is a side plan view of the blade  302  (which is referred to as  302   a - d  to designate the location of the blades in  FIGS. 3, 8 and 9 ). The blade  302  comprises a one piece, flat, unitary roughly disk-shaped blade with a plurality of individual teeth  501  extending outwardly in a radial direction from a center of the blade  302 . The plurality of teeth  501  extend generally equidistantly from the center of the blade  302  to form an outer diameter “d 2 .” In one embodiment, the diameter d 2  is 5.50 inches. In other embodiments, the diameter d 2  may be larger or smaller. 
         [0028]    In the illustrated embodiment, the blade  302  comprises sixteen (16) teeth  501  spaced equidistantly apart around the perimeter of the blade  302 . Other embodiments of the blade  301  may comprise more or fewer teeth  501 . Note that the blade  302  having a smaller number of teeth  501  than the blade  301  means that many of the teeth  401  ( FIG. 4 ) of the blade  301  will be offset from (i.e., not aligned with) the teeth  501  of the blade  302 . This difference in the number of teeth in the blades  301  and  302  improves the root-cutting ability of the blade assembly  101 . 
         [0029]    The blade  302  comprises a central opening  506  and a generally circular inner edge  504 . The opening  506  is substantially 4.10 to 4.25 inches in one embodiment. A plurality of protrusions  503  extend from the inner edge  504  and comprise openings  505  for receiving fasteners  308  ( FIG. 3 ). The protrusions are generally semi-circular in shape. In the illustrated embodiment, the blade  302  comprises six protrusions  503  for receiving six fasteners  308 . In other embodiments, there may be more or fewer protrusions and more or fewer fasteners. 
         [0030]    The blade  302  is approximately 0.045-0.050 inches thick and formed from carbide-tipped steel in one embodiment, and may be other thicknesses and formed from other suitable materials in other embodiments. 
         [0031]    Note that the protrusions  403  ( FIG. 4 ) and openings  405  ( FIG. 4 ) align of the blade  301  align with the protrusions  503  and openings  505  of the blade  302  when the blades are stacked as shown in  FIG. 3  to form the blade assembly  101  ( FIG. 3 ). 
         [0032]      FIG. 6  is a side plan view of the blade  303 , which comprises a one piece, flat, unitary roughly disk-shaped blade with a plurality of individual teeth  601  extending outwardly in a radial direction from a center of the blade  303 . The plurality of teeth  601  extend generally equidistantly from the center of the blade  303  to form an outer diameter “d 3 .” In one embodiment, the diameter d 3  is 5.50 inches. In other embodiments, the diameter d 3  may be larger or smaller. 
         [0033]    In the illustrated embodiment, the blade  303  comprises sixteen (16) teeth  601  spaced equidistantly apart around the perimeter of the blade  303 . Other embodiments of the blade  303  may comprise more or fewer teeth  601 . 
         [0034]    The blade  303  comprises a central opening  606  and a generally circular inner edge  604 . The opening  606  is substantially 4.10 to 4.25 inches in one embodiment. A plurality of protrusions  603  extend from the inner edge  604  and comprise openings  605  for receiving fasteners  308  ( FIG. 3 ). The protrusions  603  are generally semi-circular in shape. In the illustrated embodiment, the blade  303  comprises three protrusions  603  for receiving three fasteners  308 . In other embodiments, there may be more or fewer protrusions and more or fewer fasteners. 
         [0035]    The blade  303  is approximately 045-0.050 inches thick and formed from carbide-tipped steel in one embodiment, and may be other thicknesses and formed from other suitable materials in other embodiments. 
         [0036]    Note that the protrusions  603  and openings  605  align with three of the six protrusions  503  ( FIG. 5 ) and  403  ( FIG. 4 ) and openings  505  ( FIG. 5 ) and openings  405  ( FIG. 4 ) of the blades  301  and  302  when the blades are stacked as shown in  FIG. 3  to form the blade assembly  101  ( FIG. 3 ), as further discussed herein. 
         [0037]    The blade  303  further comprises indentations  609   a ,  609   b , and  609   c , one of each being disposed between adjacent protrusions  603 . The indentations  609   a ,  609   b , and  609   c  comprise a curved surface that receives the blade support  307 , as further described with respect to  FIG. 7  herein. 
         [0038]      FIG. 7  is a side plan view of the blade support  307 . The blade support  307  is roughly triangle shaped with three legs  701   a ,  701   b , and  701   c  extending from a central opening  706  and spaced generally equidistant from one another. The central opening  706  is sized to be installed on the shaft  109  ( FIG. 2 ). 
         [0039]    Curved side  702   a  extends between the leg  701   a  and the leg  702   b ; curved side  702   b  extends between the leg  701   b  and the leg  701   c ; and curved side  702   c  extends between the leg  701   c  and the leg  701   a . The legs  701   a ,  701   b , and  701   c  each comprise a curved surface  703  that joins with the curved surfaces of the indentations  609   a ,  609   b , and  609   c . In other words, the indentation  609   a  receives the leg  701   a ; the indentation  609   b  receives the leg  701   b , and the indentation  609   c  receives the leg  701   c.    
         [0040]    Each leg  701   a ,  701   b , and  701   c  comprises an opening  705  which receives a fastener  308  ( FIG. 3 ). The openings  705  in the legs  701   a ,  701   b , and  701   c  align with alternate openings  505  ( FIG. 5 ) and openings  405  ( FIG. 4 ) of the blades  301  and  302  when the blades are stacked as shown in  FIG. 3  to form the blade assembly  101  ( FIG. 3 ), as further discussed herein. 
         [0041]    The blade support  307  is approximately 0.085-0.092 inches thick and formed from steel in one embodiment, and may be other thicknesses and formed from other suitable materials in other embodiments. 
         [0042]      FIG. 8  is a partially exploded side view of the blade assembly  101  of  FIG. 3 , showing how the blades  301   a - b ,  302   a - d , and  303  are stacked together and joined by fasteners  308 . As discussed herein, the blades  301   a  and  301   b  are on the outer sides of the blade assembly  101 . The blade  302   a  is next to the blade  301   a , followed by the blade  302   b . Next in the stack is the central blade  303 , which fits onto the blade support  307 . The blade  303  and blade support  307  are in the middle of the stack  311  and are sandwiched between the blade  302   b  and blade  302   c . The blade  302   d  is adjacent to the blade  302   c , and the blade  301   b  completes the stack. 
         [0043]    Spacers  310  are disposed between adjacent blades. The spacers  310  are small aluminum washers in the illustrated embodiment. The spacers are 0.32 to 0.37 inches in outside diameter and 0.03-0.06 inches thick in one embodiment. Each spacer  310  comprises a central opening (not shown) to receive the fastener  308 . The fasteners  308  are standard rivets in the illustrated embodiment. 
         [0044]      FIG. 9  is a side view of the blade assembly  101  showing the stack  311 . Note that the diameter d 1  of the blade  301   a  (and  301   b ) is less than the diameter d 2  of the blade  302   a  (and  302   b, c , and  d ). In one embodiment, the diameter of the blades  301   a  and  301   b  are 5.38 inches and the diameter of the blades  302   a - d  and blade  303  are 5.50 inches. The outer blades  301   a  and  301   b  being smaller in diameter than the inner blades  302   a - d  improves the root-cutting action of the blade assembly  101 . The outer blades  301   a  and  301   b  being smaller in diameter than the inner blades  302   a - d  promotes more smooth cutting of roots. This is because in operation of the device, the blade assembly  101  is passed back and forth over the root/stump to be cut. The shorter blades on the outside of the stack  311  help the larger blades on the inside from getting hung up on the roots. 
         [0045]    The diameter d 3  is the same as the diameter d 2  of blades  302   a - d . When fully assembled, the stack  311  is between ¾ inches and one inch thick in one embodiment.