Patent Publication Number: US-2015083275-A1

Title: Cutting shaft for vertical stump grinder

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/882,696, filed Sep. 26, 2013. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates generally to the art of removing tree stumps with a grinding shaft. More particularly, the invention relates to a grinding shaft that rotates. More specifically, the invention relates to a stump grinder that rotates about a vertical axis and includes a replaceable cutting portion and a replaceable grinding tip. 
     2. Background Art 
     The use of a grinding apparatus having an elongated grinding wheel rotatable about a horizontal axis has been very popular in the stump grinding industry for many years. Generally, the grinding wheel that rotates about a horizontal axis removes tree stumps to allow the property owner to remove tree stumps before the tree stump causes damage to people and/or property. For example, a person could trip over the tree stump and/or potentially injure themselves. Further, upon performing general maintenance upon the property, including cutting the grass on the property, equipment may contact the elevated stump causing damage to the equipment or potential injury to people in the vicinity. Additionally, a tree stump may invite unwanted pests that could do damage to the surrounding land and/or surrounding structures. 
     As a result, stump grinders were developed to remove tree stumps before the stumps could become a safety hazard to the property owner and/or others. Further, removal of tree stumps prevents damage to equipment that may be utilized on the property. 
     Generally, prior art stump grinders include a wheel that rotates about a horizontal axis, which is known in the art as a horizontal stump grinder. The wheel is typically powered by a machine. The stump grinder operates by moving through the stump in a direction parallel with the axis of the cutting wheel. In this manner, the drive shaft and the bearings are below the ground level where each component is exposed to dirt and rocks, which may create undesirable wear and/or damage to the components. 
     Additionally, debris from grinding the tree stump and surrounding area may include wood and rocks which may be thrown vertically from the grinding area by a horizontal stump grinder, constituting a safety hazard. Another problem with a horizontal stump grinder is that a wheel with a large diameter is required to grind deep enough to remove the tree stump. The larger diameter wheel requires more power, which further requires more powerful machinery. Further, such a large diameter wheel may have a greater tendency to climb up on the stump being removed during operation, which may disturb the vehicle on which the wheel is mounted. 
     As a result of the issues associated with horizontal stump grinders, prior art vertical stump grinders were developed. A vertical stump grinder includes an elongated grinding shaft that rotates about a vertical axis for drilling into the ground and then moving horizontally into the sides of the stump where the debris and/or rocks are thrown horizontally below ground around the grinding shaft. 
     Similar to a horizontal stump grinder, the prior art vertical stump grinding shaft is attached to a machine that rotates the shaft. Prior art vertical stump grinders include teeth that are welded to the grinder shaft, which facilitate grinding of the tree stump and other debris, including tree roots, rocks, and dirt. A disadvantage of prior art vertical stump grinders is that, upon continued utilization of the grinder, the teeth attached to the vertical stump grinder shaft may become worn out or broken, and/or otherwise require replacement. Further, prior art vertical grinders are limited to replacing the entire grinding shaft, or cutting shaft, when the teeth are worn out and/or broken. In this manner, the entire grinder shaft must be replaced, thus requiring purchasing a potentially costly replacement grinder shaft. Additionally, the installation cost and corresponding amount of time to install the replacement increases the downtime of the prior art vertical stump grinder. 
     Therefore, a need exists in the art for a vertical stump grinder that includes replaceable teeth to minimize the replacement cost and to minimize installation time of worn out and/or broken teeth without replacing the entire cutting shaft or grinding shaft. Additionally, a need exists for a vertical stump grinder that includes a replaceable grinding tip, or puck, that may be removed and replaced. 
     The improved shaft for vertical stump grinder of the present invention solves the problems associated with prior art vertical stump grinder by providing replaceable cutting teeth and a backer, which enable the teeth to be replaced without replacing the entire vertical stump grinder shaft. Additionally, the improved cutting shaft for a vertical stump grinder of the present invention includes a replaceable grinding tip that facilitates removal of tree stumps and corresponding tree roots. 
     SUMMARY OF THE INVENTION 
     An objective of the present invention includes providing an improved cutting shaft for a vertical stump grinder that includes a grinding shaft with replaceable cutting teeth, allowing for the cutting teeth to be replaced without replacing the entire grinding shaft, thereby resulting in decreased down time and decreased maintenance costs. 
     A further objective of the present invention is to provide an improved cutting shaft for a vertical stump grinder that includes a grinding shaft with a replaceable grinding tip that facilitates removal of tree stumps, roots, and other debris, resulting in decreased grinding time and decreased maintenance costs. 
     These objectives and advantages are obtained by an improved cutting shaft for a vertical stump grinder, the cutting shaft including a base portion attached to a drive source, and a grinding shaft attached to and extending downwardly from the base portion. The grinding shaft includes at least one cutting tooth removably attached to the grinding shaft. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       The preferred embodiments of the present invention, illustrative of the best mode in which the Applicants have contemplated applying the principles, are set forth in the following description and are shown in the drawings. 
         FIG. 1  is a side elevational view of a prior art vertical stump grinder mounted on a skid steer loader, showing the prior art vertical grinder in the underground operating position; 
         FIG. 2  is a side elevational view of a prior art vertical stump grinder having a conical end and a cylindrical body, removed from the skid steer loader; 
         FIG. 3  is a perspective side view of first embodiment improved cutting shaft for a vertical stump grinder of the present invention, showing a backer support, a replaceable cutting portion and a replaceable grinding tip; 
         FIG. 4  is a side elevational view of the improved cutting shaft for a vertical stump grinder of the present invention shown in  FIG. 3 ; 
         FIG. 5  is an enlarged perspective view of a backer support shown in  FIG. 3 ; 
         FIG. 6  is an enlarged perspective view of a cutting portion shown in  FIG. 3 ; 
         FIG. 7  is an enlarged perspective view of the grinding tip shown in  FIG. 3 ; 
         FIG. 8  is an exploded perspective view of the attachment of the grinding tip to the improved cutting shaft for a vertical stump grinder shown in  FIG. 7 ; 
         FIG. 9  is another exploded perspective view of the attachment of the grinding tip to the improved cutting shaft shown in  FIG. 7 ; 
         FIG. 10  is a bottom view of another grinding tip for the improved cutting shaft for a vertical stump grinder of the present invention; 
         FIG. 11  is a side elevational view of the grinding tip shown in  FIG. 10 ; 
         FIG. 12  is a bottom view of another grinding tip for the improved cutting shaft for a vertical stump grinder of the present invention; 
         FIG. 13  is a side elevational view of the grinding tip shown in  FIG. 12 ; 
         FIG. 14  is an exploded perspective view of another grinding tip for the improved cutting shaft for a vertical stump grinder of the present invention; 
         FIG. 15  is another exploded perspective view of the attachment of the grinding tip to the improved cutting shaft shown in  FIG. 14 ; 
         FIG. 16  is an exploded perspective view of the improved cutting shaft for a vertical stump grinder of the present invention with weighted rings; 
         FIG. 17  is an isolated exploded perspective view of weighted rings shown in  FIG. 16 ; 
         FIG. 18  is a cross-sectional view of another cutting tooth structure attached to the improved cutting shaft for a vertical stump grinder of the present invention; 
         FIG. 19  is a cross-sectional view of another cutting tooth structure attached to the improved cutting shaft for a vertical stump grinder of the present invention; 
         FIG. 20  is a cross-sectional view of another cutting tooth structure attached to the improved cutting shaft for a vertical stump grinder of the present invention; 
         FIG. 21  is an exploded perspective view of another cutting tooth structure for the improved cutting shaft for a vertical stump grinder of the present invention; 
         FIG. 22  is another exploded perspective view of the cutting tooth structure shown in  FIG. 21 ; and 
         FIG. 23  is a cut-away perspective view of a second embodiment improved cutting shaft for a vertical stump grinder of the present invention. 
     
    
    
     Similar numerals refer to similar parts throughout the drawings. 
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In order to better understand the environment in which the improved cutting shaft for a vertical stump grinder of the present invention is utilized, a prior art vertical stump grinder is indicated generally at reference numeral  10 , is shown in  FIGS. 1-2 , and now will be described in detail. 
     Prior art vertical stump grinder  10  is shown mounted on a skid steer loader  20 . Prior art vertical stump grinder  10  includes a support member or flange  22  mounted on a bucket beam  24  of skid steer loader  20 . Flange  22  may be for a drive source  26 , such as a drive unit or drive shaft, having a hydraulic fluid pressure hose  28  connected to a hydraulic pump in skid steer loader  20 . Prior art vertical stump grinder  10  includes a grinding shaft  12 , or cutting shaft, that is generally cylindrical shaped, tapers at a terminal end  18 , and includes a plurality of cutting teeth  14  mounted on a surface  16  of the grinding shaft. Prior art vertical stump grinder  10  is removably mounted to skid steer  20  which provides sufficient power to rotate grinding shaft  12  about a vertical axis, by bolting a mounting end  15  of the grinding shaft to drive source  26 . 
     Cutting teeth  14  of prior art vertical stump grinder  10  are generally rigidly attached to surface  16  of grinding shaft  12  by means known in the art, such as welding, and typically are made of a steel alloy. Upon continued use of prior art vertical stump grinder  10 , cutting teeth  14  would wear out, and/or break off, as a result of the harsh environment of the stump area S including rocks, wood, soil, and/or other debris above, below, and around ground level G. After a sufficient number of cutting teeth  14  were worn out and/or broken, prior art vertical stump grinder  10  would become less efficient at grinding tree stumps and would require replacement. 
     Replacing prior art vertical stump grinder  10  requires purchasing another grinding shaft  12 , thus requiring additional capital investment cost and lost time to remove the worn prior art vertical stump grinder and install the replacement grinding shaft. The additional capital investment cost and time lost are significant disadvantages associated with prior art vertical stump grinders. 
     Therefore, a need exists in the art for a vertical stump grinder that includes a grinding shaft that includes replaceable cutting teeth such that when individual teeth are worn out and/or broken, the entire grinding shaft does not have to be replaced, thereby minimizing cost and time. Further, there is a need in the art for a vertical stump grinder shaft that includes a grinding tip on the terminal or bottom end of the grinder shaft that may be replaced upon the grinding tip becoming worn out and/or broken. The improved cutting shaft for a vertical stump grinder of the present invention accomplishes these needs, and the structure and installation of the improved cutting shaft is described in detail below. 
     A first embodiment of an improved cutting shaft for vertical stump grinder of the present invention is shown in  FIGS. 3-4 , at reference numeral  100 . First embodiment cutting shaft for vertical stump grinder  100  of the present invention includes a cutting shaft or grinding shaft  102 A, a base portion  104 , and a puck, or grinding tip  108 A. 
     Base portion  104  is generally disk shaped and is formed with a plurality of openings  106 . Fasteners  17  ( FIG. 1 ) are disposed through openings  106  to attached base portion to a vehicle drive source  26  ( FIG. 1 ) of driven equipment, such as skid steer loader  20  ( FIG. 1 ). In this manner, the vehicle provides the power to rotate first embodiment cutting shaft for vertical stump grinder  100 , as will be discussed below. 
     Base portion  104  is generally rigidly attached to grinding shaft  102 A at an intersection  110  by welding, taper lock, or other means known by those in the art. Grinding shaft  102 A includes a plurality of cutting teeth  112 A disposed about the circumference and along the length of the shaft. Grinding shaft  102 A also is formed with a plurality of grooves  114 , each one of which corresponds to one of cutting teeth  112 A. Each cutting tooth  112 A includes a backer support  116  and a cutting portion  118 . Backer support  116  is generally rigidly attached to groove  114  of grinding shaft  102 A by welding or other means known by those in the art. 
     With additional reference to  FIG. 5 , backer support  116  is generally rectangular shaped and formed with an opening  120 . Additionally, backer support  116  includes a tail portion  122 , a pair of side portions  124  (only one shown), a cutting support portion  126 , a base portion  128 , and an angled portion  130 . Tail portion  122  provides an optimum weld location and helps to align backer support  116  with respect to groove  114 . Base portion  128  seats in and is rigidly attached to groove  114  by welding or other means known by those in the art. In addition, tail portion  122  provides additional surface area to attach backer support  116  to grinding shaft  102 A. In this manner, backer support  116  is rigidly attached to grinding shaft  102 A. Preferably, backer support  116  is welded within groove  114  of grinding shaft  102 A. Further, tail portion  122  provides a locating means for correct positioning of backer support  116  within groove  114 . In this manner, backer support  116  is properly positioned upon grinding shaft  102 A and assists the installation of the backer support. 
     A fastener  107  ( FIG. 3 ), such as a bolt, is disposed in opening  120  of backer support  116  to rigidly attach cutting portion  118  to the backer support, as will be described below. 
     Turning to  FIG. 6 , cutting portion  118  is generally rectangular in shape and includes a cutting tip  132  and a cutting tip support  134 . Cutting tip support  134  is formed with an opening  136  and a recess  180  to prevent rotation of the nut (not shown) and to provide protection from abrasive conditions. Cutting tip support  134  includes a pair of side supports  138  (only one shown), a cutting backer portion  140 , a foundation portion  142 , and a fastener portion  144 . Cutting tip support  134  is formed with a notch or cutout feature  135 , which receives cutting tip  132 . 
     Cutting tip  132  seats in notch  135  and is rigidly attached to cutting tip support  134 , preferably by brazing. Cutting tip  132  is generally made of a metal carbide alloy, as known to those skilled in the art, and includes a generally elongated “m-shape”, but other shapes, including a generally “U-shape”, are contemplated. 
     In an important aspect of the present invention, cutting portion  118  is removably attached to backer support  116 . More specifically, once backer support  116  is welded into groove  114  to provide proper alignment for cutting portion  118 , cutting backer portion  140  is abutted against cutting support portion  126  of the backer support. Opening  120  of backer support  116  is aligned with opening  136  of cutting portion  118  and fastener  107  ( FIG. 3 ) is disposed therein. In this manner, cutting portion  118  is removably attached to backer support  116  and may be easily removed if the cutting portion becomes worn out and/or broken or otherwise needs replacement. 
     In addition to utilizing cutting tip  132  of cutting portion  118  to grind and/or cut tree stumps, tree roots and/or other debris, improved cutting shaft for vertical stump grinder  100  includes a grinding tip  108 A connected to the bottom end of the vertical stump grinder. 
     Turning to  FIGS. 7-9 , grinding tip  108 A includes a pair of cutting members  119  with a corresponding cutting tip  133 , a generally rectangular protrusion  154  and a grinding attachment  146 . Protrusion  154  is rigidly attached to grinding tip  108 A, typically by welding and is formed with a pair of openings  158 . Cutting member  119  is typically rigidly attached to grinding tip  108 A by welding. It is contemplated that cutting member  119  may be removably attached to grinding tip  108 A. Grinding attachment  146  is generally disk shaped, generally composed of a metal carbide alloy, and is formed with a pair of openings  148 . Cutting tips  133  are generally located on the outer diameter of grinding tip  108 A and generally opposite of one another. 
     To attach grinding tip  108 A to grinding shaft  102 A, grinding shaft is formed with a slot  152  opposite base portion  104  ( FIG. 3 ). Slot  152  is formed with a pair of openings  156 . Protrusion  154  slides into opening  156  and a fastener  150 , including a bolt, is generally disposed in opening  148 , through opening  158 , and into opening  156  to removably attach grinding tip  108 A to grinding shaft  102 A. In this manner, grinding tip  108 A withstands the harsh underground environment by utilizing multiple connection points including bolts  150  and protrusion  154 . 
     The removable attachment facilitates the replacement of grinding tip  108 A as the grinding tip is exposed to a harsh environment that may include rocks, clay, tree roots, tree stumps, and/or other debris that may damage and/or break the grinding tip. Additionally, the rotation and weight of grinding tip  108 A, grinding shaft  102 A and base portion  104  creates a flywheel effect generating more torque to grind and/or cut tree stumps and other corresponding debris facilitating removal of the tree stump and other debris. Further, it is contemplated that additional weighted rings may be added to provide an increased flywheel effect to grind and/or cut tree stumps and other corresponding debris facilitating removal of the tree stump and other debris, as will be discussed. 
     Improved cutting shaft for vertical stump grinder  100  of the present invention facilitates the easy removal and replacement of individual cutting portion  118  of cutting tooth  112 A upon the cutting portion becoming broken and/or worn out. In this manner, improved cutting shaft for vertical stump grinder  100  reduces down time for use of the vertical stump grinder of the present invention and minimizes costs as a result of simply replacing the worn out and/or broken cutting portion  118 . Further, grinding tip  108 A is removable and replaceable upon becoming worn out and/or damaged as a result of the harsh tree stump grinding environment. It is contemplated that other structures for grinding shaft  102 A, grinding tip  108 A and/or cutting tooth  112 A may be utilized, as will be described. 
     For example, turning to  FIGS. 10-11 , an alternative puck or grinding tip  108 B is shown. Grinding tip  108 B is generally disk shaped and includes a cutting member  218 , a grinding protrusion  210 , and is formed with an at least one opening  212 . Grinding tip  108 B includes grinding protrusions  210  that extends outwardly from the grinding tip. In this manner, grinding protrusion  210  grinds tree stumps, soil, and other debris upon use of grinding tip  108 B. Generally, a fastener (not shown), such as a bolt, is disposed in opening  212  to removably attach grinding tip  108 B to a bottom end of improved cutting shaft for vertical stump grinder  100  of the present invention. 
     Cutting member  218  includes a cutting tip  220  and a cutting support  222 . Cutting tip  220  is generally composed of a metal carbide alloy, and is rigidly attached to cutting support  222 , preferably by brazing. Further, cutting support  222  is rigidly attached to grinding tip  108 B, typically by welding. Cutting members  218  are generally located on the outer diameter of grinding tip  108 B and generally opposite of one another. It is contemplated that cutting support  222  may be removably attached to grinding tip  108 B, using a fastener (not shown), such as a bolt. In this manner, grinding tip  108 B is constructed to withstand the harsh underground grinding environment. 
     Grinding protrusion  210  includes a grinding edge  224  and an edge support  226 . Grinding edge  224  is rigidly attached to edge support  226 , preferably by brazing. As a result of grinding protrusions  210  extending downwardly from grinding tip  108 B, grinding tip  108 B forms a buffer to minimize the interaction of the grinding tip with the underground environment. More specifically, grinding protrusion  210  maintains some spacing between grinding tip  108 B and the underground environment. In this manner, improved cutting shaft for vertical stump grinder  100  will rotate even if grinding tip  108 B comes into contact with the underground environment. This further extends the life of grinding tip  108 B because grinding protrusion  210  limits the amount of contact with the underground environment. 
     Additionally, the removable attachment of grinding tip  108 B to improved cutting shaft for vertical stump grinder  100  facilitates the replacement of the grinding tip as the grinding tip is exposed to a harsh environment that may include rocks, clay, tree roots, and/or tree stumps that may damage and/or break the grinding tip. Further, the rotation and weight of grinding tip  108 B, grinding shaft  102 A, and base portion  104  creates a flywheel effect generating more torque to grind and/or cut tree stumps and other corresponding debris facilitating removal of the tree stump and other debris. Additionally, it is contemplated that additional weighted rings may be added to provide an increased flywheel effect to grind and/or cut tree stumps and other corresponding debris facilitating removal of the tree stump and other debris, as will be discussed. 
     Grinding tip  108 B of improved cutting shaft for vertical stump grinder  100  is a replaceable attachment that includes grinding protrusion  210  and cutting member  218  to facilitate grinding away the harsh environment corresponding to the tree stump and the location surrounding the tree stump. The placement of the grinding protrusion  210  and cutting member  218  allow for grinding in both a horizontal and vertical direction to facilitate faster grinding times of the stump and corresponding area while maintaining a buffer area between grinding tip  108 B and the harsh environment to maintain the rotation of improved cutting shaft for vertical stump grinder  100 . 
     Turning to  FIGS. 12-13 , another example of a grinding tip  108 C for improved cutting shaft for vertical stump grinder  100  is shown. Grinding tip  108 C is generally disk shaped and includes a cutting member  318 , a grinding protrusion  310 , and is formed with an at least one opening  312  to attach the grinding tip to the improved cutting shaft for vertical stump grinder  100 . Grinding tip  108 C includes grinding protrusion  310  that extends downwardly from the grinding tip. In this manner, grinding protrusion  310  grinds tree stumps, soil, and other debris upon use of improved cutting shaft for vertical stump grinder  100 . Additionally, cutting member  318  and grinding protrusion  310  are a single-piece facilitating the replacement of the cutting portion and the grinding protrusion thus minimizing replacement time because of the single-piece. 
     Cutting member  318  and grinding protrusion  310  are removably connected to grinding tip  108 C using a fastener  330 , such as a bolt, disposed in an opening  332 . In this manner, each cutting member  318  and grinding protrusion  310  can be individually removed and replaced from grinding tip  108 C. Additionally, each cutting member  318  and grinding protrusion  310  are located opposite of one another on grinding tip  308  to equalize the weight for when the grinding tip is rotating connected to improved cutting shaft for vertical stump grinder  100 . 
     Cutting member  318  includes a cutting tip  320  and a cutting support  322 . Cutting tip  320  is generally composed of a metal carbide alloy, and is rigidly attached to cutting support  322 , preferably by brazing. Cutting members  318  are generally located on the outer diameter of grinding tip  108 C and generally opposite of one another. 
     Grinding protrusion  310  includes a grinding edge  324  and an edge support  326 . Grinding edge  324  is rigidly connected to edge support  326 , preferably by brazing. As a result of grinding protrusions  310  extending outwardly from grinding tip  108 C, the grinding tip forms a buffer to minimize the interaction of the improved cutting shaft for vertical stump grinder  100  with the environment underground. More specifically, grinding protrusion  310  maintains some spacing between grinding tip  108 C and the underground environment. In this manner, improved cutting shaft for vertical stump grinder  100  will rotate even if grinding tip  108 C comes into contact with the underground environment. This further extends the life of grinding tip  108 C because grinding protrusion  310  limits that amount of contact with the underground environment. 
     Additionally, the removable attachment of grinding tip  108 C to improved cutting shaft for vertical stump grinder  100  facilitates the replacement of the grinding tip as the grinding tip is exposed to a harsh environment that may include rocks, clay, tree roots, and/or tree stumps that may damage and/or break the grinding tip. Further, the rotation and weight of grinding tip  108 C, grinding shaft  102 A, and base portion  104  creates a flywheel effect generating more torque to grind and/or cut tree stumps and other corresponding debris facilitating removal of the tree stump and other debris. Additionally, it is contemplated that additional weighted rings may be added to provide an increased flywheel effect to grind and/or cut tree stumps and other corresponding debris facilitating removal of the tree stump and other debris, as will be discussed. 
     Grinding tip  108 C of improved cutting shaft for vertical stump grinder  100  is a removable attachment that includes grinding protrusion  310  and cutting member  318  to facilitate grinding away the harsh environment corresponding to the tree stump and the location surrounding the tree stump. The placement of the grinding protrusion  310  and cutting member  318  allow for grinding in both a horizontal and vertical direction to facilitate faster grinding times of the stump, and corresponding area, while maintaining a buffer area between grinding tip  108 C and the harsh environment to maintain the rotation of improved cutting shaft for vertical stump grinder  100 . 
     Turning to  FIGS. 14-15 , another example of a grinding tip  108 D for improved cutting shaft for vertical stump grinder  100  is shown. Grinding tip  108 D is generally disk shaped, includes a cutting member  350  and is formed with at least one bolt opening  352  and an at least one pin opening  353 , opposite base portion  104 . Generally, fasteners, including a bolt  354 , and a pin  356  are disposed in opening  352 ,  353 , respectively, to removably attach grinding tip  108 D to a grinding shaft  102 B. Further, grinding shaft  102 B is formed with an at least one pin opening  357  and an at least one bolt opening  358  to receive bolt  354  and pin  356 , respectively. Pins  356  help to locate corresponding openings  357 ,  358  in grinding shaft  102 B to secure grinding tip  108 D to the grinding shift. Additionally, pins  356  provide additional resistance to torque that potentially occurs upon utilization of grinding shaft  102 B and tip  108 D. In this manner, grinding tip  108 D is attached to grinding shaft  102 B and able to withstand the harsh underground grinding environment. 
     Cutting member  350  includes a cutting tip  360  and a cutting support  362 . Cutting tip  360  is generally composed of a metal carbide alloy, and is rigidly attached to cutting support  362 , preferably by brazing. Further, cutting support  362  is rigidly attached to grinding tip  108 D, typically by welding. It is contemplated that cutting support  362  may be removably attached to grinding tip  108 D, using a fastener (not shown), as a bolt. In this manner, grinding tip  108 D is constructed to withstand the harsh underground grinding environment. 
     Additionally, the removable attachment of grinding tip  108 D to improved cutting shaft for vertical stump grinder  100  facilitates the replacement of the grinding tip as the grinding tip is exposed to a harsh environment that may include rocks, clay, tree roots, and/or tree stumps that may damage and/or break the grinding tip. Further, the rotation and weight of grinding tip  108 D, grinding shaft  102 B, and base portion  104  creates a flywheel effect generating more torque to grind and/or cut tree stumps and other corresponding debris facilitating removal of the tree stump and other debris. Additionally, it is contemplated that additional weighted rings may be added to provide an increased flywheel effect to grind and/or cut tree stumps and other corresponding debris facilitating removal of the tree stump and other debris. 
     Turning to  FIGS. 16-17 , a weighted ring  370  that is generally disk shaped is shown. Ring  370  is formed with an at least one base opening  372  and an at least one grinding machine opening  374 . Improved cutting shaft for vertical stump grinder  100  is removably attached to ring  370  utilizing fasteners, such as bolts  376 . Each bolt  376  is disposed through a respective aligned one of openings  106  and through openings  372 . Additional rings  370  may be added to increase the flywheel effect to grind and/or cut tree stumps and other corresponding debris facilitating removal of the tree stump and other debris. 
     Weighted ring  370  is removably attached to a grinder flange  378  utilizing fasteners, including bolts  380 , nuts  382 , and washers  384 . Grinder flange  378  is formed with ring openings  386  and grinder openings  388 . Ring  370  is removably attached utilizing bolts  380 , nuts  382 , and washers  384 , by disposing the bolts through respective aligned one of openings  374  and opening  388  and tightening the respective nut. Additionally to provide a more secured attachment, bolts  376  are disposed through each respective aligned openings  106 , openings  372 , and openings  386 . In this manner, there is a secured attachment of vertical stump grinder  100 , ring  370 , and grinder flange  378  to create a flywheel effect generating increased force to grind and/or cut tree stumps and other corresponding debris facilitating removal of the tree stump and other debris. More specifically, the additional weight of ring  370  at the upper end of grinding shaft  102 B provides an increased flywheel effect as a result of the weight of the ring being near drive source  26  ( FIG. 1 ). Thus, more force is generated and transferred to grinding shaft  102 B. 
     Turning to  FIGS. 18-22 , further examples of attaching a cutting tooth to improved cutting shaft for a vertical stump grinder  100  of the present invention are shown. For example, a cutting tooth  112 B is shown attached to grinding shaft  102 A in  FIG. 18 . 
     Cutting tooth  112 B includes a backer support  416  and a cutting portion  418 . Backer support  416  is generally rigidly attached, preferably by welding, to grinding shaft  102 A, includes a tail portion  422  and is formed with an opening  420 . Tail portion  422  provides additional surface area to weld backer support  416  to grinding shaft  102 A. In this manner, backer support  416  is rigidly attached to grinding shaft  102 A to provide support for cutting portion  418 . 
     Cutting portion  418  is generally rectangular in shape and includes a cutting tip  432  and a cutting tip support  434 . Cutting tip support  434  is rigidly attached to cutting tip  432  and formed with an opening  436 . Cutting tip  432  is rigidly attached to cutting tip support  434 , preferably by brazing. Cutting tip  432  is generally made of a metal carbide alloy, as known to those skilled in the art. 
     In an important aspect of the present invention, cutting portion  418  is removably attached to backer support  416 . More specifically, once backer support  416  is welded to grinding shaft  102 A to provide proper alignment for cutting portion  418 , opening  436  of cutting tip support  434  is aligned with opening  420  of the backer support and a fastener  417  is disposed therein. In this manner, cutting portion  418  is removably attached to backer support  416  and may be removed if the cutting portion becomes worn out and/or broken or otherwise needs replacement. 
     Turning to  FIG. 19 , another example of attaching cutting tooth to improved cutting shaft for a vertical stump grinder  100  of the present invention is shown. A cutting tooth  112 C is shown attached to grinding shaft  102 A in  FIG. 19 . Cutting tooth  112 C includes a backer support  516  and a cutting portion  518 . Backer support  516  is generally rigidly attached to grinding shaft  102 A, and is formed with an opening  520 . Backer support  516  includes an extended curved portion to conform to grinding shaft  102 A and generally extends the length of cutting portion  518  to provide a better rigid attachment to the grinding shaft to provide support for cutting portion. 
     A backer  517  is removably attached adjacent to backer support  516  to secure cutting portion  518  to the backer support, as will be described. Cutting portion  518  is generally rectangular with an extended shaft that includes a cutting tip  532  and a cutting tip support  534 . Cutting tip support  534  extends and is disposed within opening  520  of backer support  516 . Cutting tip  532  is rigidly attached to cutting tip support  534 , preferably by brazing. Cutting tip  532  is generally composed of a metal carbide alloy. 
     In an important aspect of the present invention, cutting portion  518  is removably attached to backer support  516 . More specifically, cutting tip support  534  of cutting portion  518  extends and is disposed within opening  520  of backer support  516 . Backer  517  secures cutting tip portion  534  and the backer is removable if cutting portion  518  becomes worn out and/or broken or otherwise needs replacement. 
     Turning to  FIG. 20 , another example of attaching cutting tooth to improved cutting shaft for a vertical stump grinder  100  of the present invention is shown. A cutting tooth  112 D is shown attached to grinding shaft  102 A. Grinding shaft  102 A is formed with a first opening  601  that passes through the grinding shaft. Grinding shaft  102 A is also formed with a second opening  602  of a larger diameter than first opening  601 , and which aligns with the first opening from the opposite end of the diameter of the grinding shaft. Cutting tooth  112 D includes a cutting tip support  634  and a cutting tip  632 . Cutting tip  632  is generally rigidly attached to cutting tip support  634 , preferably by brazing. Cutting tip  632  is generally made of a metal carbide alloy. Cutting tip support  634  is received in second opening  602 , and in turn is formed with a threaded opening  620 . A fastener  621 , including a bolt, is disposed within first opening  601  and is secured in threaded opening  620  to removably attach cutting tooth  112 D to grinding shaft  102 A. In this manner, fastener  621  removably attaches cutting tooth  112 D to grinding shaft  102 A and the cutting tooth may be removed if it becomes worn out and/or broken or otherwise needs replacement. 
     Turning to  FIG. 21-22 , a cutting tooth  112 E is shown. Cutting tooth  112 E includes a cutting portion  650  and a backer support  652 . Cutting portion  650  is generally rectangular in shape and includes a cutting tip  654  and a cutting tip support  656 . Cutting tip  654  is generally made of a metal carbide alloy, as known to those skilled in the art, and includes a generally elongated “m-shape”, but other shapes, including a generally “U-shape”, are contemplated. Cutting tip support  656  is rigidly connected to cutting tip  654 , preferably by brazing. Cutting tip support  656  is formed with an at least one opening  658  and an at least one opening  660 . 
     Backer support  652  is generally rectangular in shape and formed with an opening  662 , a protrusion  664 , a tail portion  666 , a pair of side portions  668  (only one shown), a cutting support portion  670 , a base portion  672 , and an angled portion  674 . Tail portion  666  provides an optimum weld location and helps to align backer support  652  with respect to groove  114 . Base portion  672  seats in and is rigidly attached to groove  114  by welding or other means known by those in the art. In addition, tail portion  666  provides additional surface area to attach backer support  652  to grinding shaft  102 A. In this manner, backer support  652  is rigidly attached to grinding shaft  102 A. Preferably, backer support  652  is welded within groove  114  of grinding shaft  102 A. Further, tail portion  666  provides a locating means for correct positioning of backer support  652  within groove  114 . In this manner, backer support  652  is preferably positioned upon grinding shaft  102 A and assists the installation of the backer support. 
     In an important aspect, cutting portion  650  is removably attached to backer support  652 . More specifically, once backer support  652  is welded into groove  114  to provide proper alignment for cutting portion  650 , the cutting portion is abutted against cutting support portion  670  of the backer support to align opening  660  to protrusion  664  and opening  658  and opening  662 , respectively. A fastener, including a bolt  676 , is disposed through opening  660  and opening  658 , and a nut  678  is threaded onto the bolt. Nut  678  seats in a recess  680  formed in cutting tip support  656  to prevent rotation of the nut and to provide protection from abrasive conditions. In this manner, protrusion  664  disposed in opening  660  limits the potential movement of cutting portion  650 , providing a consistent removable attachment of the cutting portion and backer support  652 . 
     As discussed above, cutting teeth  112 B,  112 C,  112 D,  112 E provide various attachments to grinding shaft  102 A of improved cutting shaft for a vertical stump grinder  100  of the present invention. Each cutting tooth  112 B,  112 C,  112 D, and  112 E respectively, is removable and replaceable upon becoming worn out and/or broken or otherwise requiring replacement. Additionally, only cutting tooth  112 B,  112 C,  112 D, and  112 E is required to be replaced and not the entire grinding shaft  102 A,  102 B for vertical stump grinder  100  of the present invention. In this manner, replacement cost and downtime are minimized. 
     Turning to  FIG. 23 , a second embodiment of improved cutting shaft for vertical stump grinder of the present invention is indicated generally at  700 . Second embodiment of improved cutting shaft for vertical stump grinder  700  includes a plurality of interlocking segments  702  that are positioned around a vertically-extending central rod  704 . Interlocking segments  702  include a backer support  716 , a cutting portion  718 , and is formed with a plurality of openings  717 . 
     A fastener  705  is disposed within opening  717  to connect terminal end interlocking segments  702  to central rod  704 . Additionally, the fastener may further connect adjacent interlocking segments  702  to strengthen the connection to central rod  704 . Terminal end interlocking segment  702  may include grinding tip  108 A ( FIG. 7 ) to further facilitate grinding away the harsh environment corresponding to the tree stump and the location surrounding the tree stump. Interlocking segments  702  allow for the length of second embodiment of improved cutting shaft for vertical stump grinder  700  to be adjusted according to the size of the tree stump such that additional segments may be added for tree stumps that have roots that are deeper. Further, interlocking segments  702  may be removed from second embodiment of improved cutting shaft for vertical stump grinder  700  thus shortening the length of the cutting shaft for shallower tree stumps. 
     A connected plurality of interlocking segments  702  generally staggers backer support  716  and cutting portion  718  along the vertical length of the connected plurality of interlocking segments. This staggered positioning facilitates more efficient grinding of the tree stump and corresponding area. 
     Backer support  716  is rigidly attached to interlocking segment  702  generally by welding. Backer support  716  includes a curved portion  719  that minimizes contact with the tree stump and corresponding area while second embodiment of improved cutting shaft for vertical stump grinder  700  is rotating. 
     Cutting portion  718  is rigidly attached to backer support  716 , generally by brazing, and is generally composed of a metal carbide alloy. As second embodiment of improved cutting shaft for vertical stump grinder  700  rotates, cutting portion  718  cuts and/or grinds the tree stump and corresponding area. 
     To further cut and/or grind the tree stump and corresponding area, second embodiment of improved cutting shaft for vertical stump grinder  700  includes interlocking segment  702  on a terminal end  703  that includes a protrusion  721 . Protrusion  721  facilitates in grinding and cutting the tree stump and corresponding area and prevents the terminal face of interlocking segment  702  from contacting the ground. By preventing the contact with the ground, the potential reduction of rotational speed of second embodiment of improved cutting shaft for vertical stump grinder  700  is minimized. 
     Upon extensive use and/or requiring replacement, interlocking segment  702  of second embodiment of improved cutting shaft for vertical stump grinder  700  may be removed and replaced by removing the fastener and removing the worn out and/or broken segment. In this manner, second embodiment of improved cutting shaft for vertical stump grinder  700  reduces down time for use of the improved cutting shaft for vertical stump grinder and minimizes costs as a result of replacing the broken and/or worn out interlocking segment  702 . 
     It is to be understood that the above described structure of an improved cutting shaft for vertical stump grinder  100 ,  700 , may be altered without affecting the overall concept or operation of the present invention. For example, any combination of grinding tip  108 A,  108 B,  108 C,  108 D, and cutting tooth  112 A,  112 B,  112 C,  112 D, and  112 E may be utilized. In addition, first and second embodiment improved cutting shaft for vertical stump grinder  100 ,  700  may be rotated about a horizontal axis. Further, cutting tip  132 ,  220 ,  320 ,  432 ,  532 , and  632  and/or grinding edge  224 ,  324  may be constructed out of other materials than an alloy without affecting the overall concept or operation of the invention. Additionally, grinding shaft  102 A,  102 B may be formed without grooves  114  without affecting the overall concept or operation of the invention. Further, weighted ring  370  may be utilized on improved cutting shaft for vertical stump grinder  100 ,  700 . 
     Moreover, any number or combination of cutting teeth  112 A,  112 B,  112 C,  112 D, and  112 E, and/or cutting members  218 ,  318 , and  350 , and cutting portion  718  and/or grinding protrusion  210 ,  310  may be utilized without affecting the overall concept or operation of the invention. Moreover, different shapes and/or configurations of grinding tip  108 A,  108 B,  108 C, and  108 D, backer support  116 ,  416 ,  516 , cutting tooth  112 A,  112 B,  112 C,  112 D, and  112 E, and/or grinding attachment  146  may be utilized on improved cutting shaft for vertical stump grinder  100 ,  700 . 
     Accordingly, the improved cutting shaft for vertical stump grinder is simplified, provides an effective, safe, inexpensive and efficient structure and method which achieves all the enumerated objectives, provides for eliminating difficulties encountered with prior art stump grinder, and solves problems and obtains new results in the art. 
     In the foregoing description, certain terms have been used for brevity, clearness and understanding; but no unnecessary limitations are to be implied therefrom beyond the requirements of the prior art, because such terms are used for descriptive purposes and are intended to be broadly construed. 
     Moreover, the description and illustration of the invention is by way of example, and the scope of the invention is not limited to the exact details shown or described. 
     Having now described the features, discoveries and principles of the invention, the manner in which the improved cutting shaft for vertical stump grinder is used and installed, the characteristics of the construction, arrangement and method steps, and the advantageous, new and useful results obtained; the new and useful structures, devices, elements, arrangements, process, parts and combinations are set forth in the appended claims.