Patent Abstract:
A blade changing tool for changing a blade for saws, particular table saws, is provided. The tool includes a body having a face that includes at least one recess for receiving and engaging a saw blade. Typically, the face will include a plurality of axially offset recesses resulting in a stepped face. A blade face abutment surface and a riser extending therefrom combine to form the recesses. The risers may be concave in shape giving the recesses a circular segment shape. The body also includes at least one blade engaging catch that engages teeth of the blade to prevent rotational movement of the blade while it is being loosened or tightened. The tool may be free of undercuts to facilitate straight-pull molding. Also, the stepped face may be an external face to facilitate visually inspecting the engagement between the blade and the tool.

Full Description:
FIELD OF THE INVENTION 
     This invention generally relates to saws and more, particularly to tools for changing the circular blade of a saw. 
     BACKGROUND OF THE INVENTION 
     Saws are used for cutting stock material such as wood, plastic, metal and the like to a desired shape and/or size. After extensive use, the blade of the saw may become worn and need replacing. Alternatively, a saw operator may switch from working with one material to another or may desire to alter the cutting action of the saw, and therefore may be similarly required to change the blade or the orientation of the blade of the saw. 
     Typically, saws that use a circular saw blade use a nut to mount the blade on a shaft that is rotated by the saw to rotate the blade. Typically, the blade is secured to the shaft by a nut. When the blade needs to be replaced or otherwise removed, the nut must be loosened and removed from the shaft to release the blade. However, the shaft typically freely rotates within the saw when power is not provided to the saw. As such, application of torque to the nut to remove the nut from the shaft will cause the shaft and blade to rotate unless the blade and/or shaft is prevented from rotating. 
     In the past, the operator would use an additional tool to stop the blade from rotating while torque is applied to the nut. In many instances, the second tool was a block of wood. Many operators would unplug the saw and engage a block of wood with the teeth of the saw blade to prevent it from rotating. With the saw blade engaging the block of wood, the operator could use a wrench to apply torque to the nut and loosen it. However, as the blade was uncovered, if the wrench were to slip from the nut, the exposed teeth of the saw blade provided the potential for minor cuts or injuries to the operator. Further, to attain leverage for loosening the nut, the operator may position his free hand against the block of wood. As such, should the wood or wrench slip, the operator&#39;s other hand could also potentially contact the blade and become injured. 
     U.S. Pat. No. 5,983,480 to Fontaine et al. has attempted to prevent these problems by providing a blade changing tool that uses an arcuate guard that engages a blade that includes a slot having two sidewalls and a bottom. The tool also includes two feet that project from one sidewall to abut the table of the saw to prevent the blade from rotating. However, the present inventors identified what they believe to be several drawbacks of the &#39;486 patent as will be further evident from the present disclosure including (1) the tool provides only a single size arcuate slot which is only closely sized for a single size blade; (2) the tool includes a complex design such that it includes undercuts, which prevent the device from being manufactured from a straight-pull mold thereby increasing manufacturing costs; (3) as the engagement between the teeth of the blade and the tool is hidden within the slot and behind the two parallel sides, it can be difficult to determine if the tool has properly been engaged with the tool. 
     There exists, therefore, a need in the art for an improved blade changing tool that facilitates removal of the blade, but makes it easier to determine if the tool is properly engaging the blade, can be manufactured more efficiently, and/or can easily accommodate multiple blade sizes. 
     BRIEF SUMMARY OF THE INVENTION 
     The invention provides an improved tool for assisting with changing the blade of a saw that can accommodate multiple blade sizes while being less complex to manufacture, and/or provides improved visibility for inspecting the engagement between a saw blade and the tool. 
     In some forms of the invention, the tool includes a body having a stepped face that provides a plurality of steps. The steps may be provided by recesses sized to receive different sized saw blades. The recesses may have a blade face abutment surface that is positioned proximate a face of the blade during use and a riser extending axially outward from the blade face abutment surface that is proximate the teeth of the blade during use. The tool further includes a tooth engaging catch for engaging the blade to control the blade and prevent its rotation during tightening or loosening of a nut holding the blade to the saw. 
     In some forms of the invention, the body of the tool is formed free of undercuts such that the body may be formed using a straight-pull mold that includes only two shells. In such a form, the body may be formed using injection molding and using plastic material. 
     In some forms of the invention, the body includes a handle for the operator to control the position and prevent movement of the tool during use. The handle may or may not be formed as one piece with the body. 
     The body may include feet that extend axially outward from a rear face of the body that is on the opposite side as the stepped face. The feet may be used to traverse any slot in the table of the saw and prevent the tool from rotating with the blade while loosening or tightening. Further, the feet can help stabilize the body while using the tool. 
     In some forms of the invention, the face that includes the blade receiving recesses, or even a single blade receiving recess, i.e. the stepped face, may be open such that the face is an external face. This configuration can simplify the tool as well as improve visual inspection of the engagement between the tool and the saw blade. In another forms of the invention, the stepped face may be hidden behind a plate or wall that extends downward in front of at least part of the recesses. 
     Other aspects, objectives and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention and, together with the description, serve to explain the principles of the invention. In the drawings: 
         FIG. 1  is a perspective bottom view of an exemplary embodiment of a blade changing tool in accordance with the teachings of the present invention; 
         FIG. 2  is a front profile view of the blade changing tool of  FIG. 1 ; 
         FIG. 3  is a cross-sectional view of the blade changing tool of  FIG. 1  about line  3 - 3  of  FIG. 2 ; 
         FIG. 4  is an exploded top perspective view of the blade changing tool of  FIG. 1 ; 
         FIG. 5  is an elevation view of the blade changing tool of  FIG. 1  positioned adjacent to a saw and a saw blade such as during operation; and 
         FIG. 6  is a top plan view of the blade changing tool positioned adjacent to the saw blade of  FIG. 5 . 
     
    
    
     While the invention will be described in connection with certain preferred embodiments, there is no intent to limit it to those embodiments. On the contrary, the intent is to cover all alternatives, modifications and equivalents as included within the spirit and scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  illustrates an exemplary embodiment of a blade changing tool  10  according to the teachings of the present invention for assisting changing the blade  212  of a circular saw especially a table saw  200  (see  FIGS. 6 and 7 ). The illustrated blade changing tool  10  generally includes a body  12  and a handle  13 . The body  12  generally includes a stepped face  14  and a plurality of blade engaging catches illustrated in the form of protrusions  16   
     The stepped face  14  of the illustrated embodiment defines or otherwise includes a plurality of steps illustrated in the form of arcuate recesses  20 - 24  that are recesses for receiving blades. The recesses  20 - 24  are generally concentric and axially offset from one another. A blade face abutment surface  28 - 32  cooperates with a corresponding riser  36 - 40  that extends axially outward from the blade face abutment surface  28 - 32  to form each recess  20 - 24 , respectively. Due to the arcuate shape of the risers  36 - 40  of the illustrated embodiment, each recess  20 - 24  can be viewed as a minor segment of a circle bordered or defined by a riser  36 - 40  and the bottom edge of the body  12 . 
     The blade face abutment surfaces  28 - 32  are axially offset from one another by the risers  36 - 40 . In use, the blade face abutment surfaces  28 - 32  axially position the blade changing tool  10  relative to a saw blade  212 . More particularly, one of the blade face abutment surfaces  28 - 32  is positioned axially proximate a face or side of the saw blade during the changing process. 
     Each riser  36 - 40  extends axially outward from a corresponding blade face abutment surface  28 - 32  to define the radially outer periphery of each recess  20 - 24 , respectively. In use, the blade changing tool  10  is generally radially positioned relative to the edge of the saw blade  212  defined by the teeth  208  of the saw blade  212  such that one of the risers  36 - 40  is positioned radially against or proximate the teeth  208  of the saw blade  212 . As illustrated in  FIGS. 5 and 6 , riser  40 , the radially outermost riser, is illustrated as bordering a the exposed teeth  208  of the saw blade  212 . As such, an operator is protected from the teeth  208  by the blade changing tool  10 . With reference to  FIGS. 1 and 2 , the risers  36 - 40  are illustrated as concave surfaces opening towards the bottom edge  42  of the body  12 . During blade changing operations, the saw blade  212  will be raised relative to the top  204  of the table  202  to the same height as the inner surface of the corresponding riser  36 - 40 . 
     The risers  36 - 40  are generally concentric minor arcs having differing radii. As the risers  36 - 40  are concentric and the recesses  20 - 24  are centered about the width W of the body  12 , the midpoint of each riser  36 - 40  aligns at the center of the width W of the body  12 . The bottom edge  42  of the body  12  forms the cord that defines the ends of the individual risers  36 - 40 . 
     The concave shape of each riser  36 - 40  is closely sized to the respective blade size that the individual recess  20 - 24  is designed to receive. Preferably, the blade changing tool  10  includes at least three recesses configured to receive standard sized saw blades having diametrical sizes of seven and one-quarter inch (7¼″), eight inch (8″) and ten inch (10″), respectively. However, saw blade changing tools  10  according to the teachings of the present invention can be sized for other saw blade sizes. 
     Risers  36 ,  38  between recesses  20  and  22  and recesses  22  and  24 , respectively, offset the adjacent recesses  20 ,  22  and  22 ,  24  from one another. These offsets provide the stepped configuration of the face  14 . Further, lending to the stepped configuration is riser  40  positioned between abutment face  32  of recess  24  and an outer rim  44  of the body  12 . 
     The protrusions  16  are used to engage individual teeth  208  of the saw blade  212  to prevent the saw blade  212  from rotating while torque is operatively applied to the nut  216  securing the saw blade  212  while releasing or tightening. The illustrated protrusions  16  are positioned proximate to and are unitarily formed with the risers  36 - 40 . A protrusion  16  may extend the same distance outward from the blade abutment surface as the riser of its respective recess such as the protrusions  16  proximate risers  36  and  38 . Alternatively, a protrusion may extend axially outward a shorter distance than the riser of its respective recess such as illustrated with protrusion  16  of recess  24  proximate riser  40 . 
     The protrusions  16  are one form of an engaging catch for engaging the teeth  708  of a saw blade  212  that can be incorporated when practicing the present invention. As illustrated in  FIG. 2 , the protrusions include a tooth engaging face  50  that engages a tooth  208 . The tooth engaging face  50 , as illustrated, extends radially inward from its respective riser  36 - 40 . It is preferred that the tooth engaging face  50  forms an angle with a riser  36 - 40  that is equal to or less than 90 degrees to prevent the tooth  208  from slipping relative to the protrusion  16 . While the protrusions  16  are all illustrated as having the tooth engaging face  50  on the same side, other blade changing tools can have symmetric protrusions where both sides of the protrusions are configured to engage the cutting edge of a tooth. 
     It can be appreciated from  FIGS. 1 through 3  that the stepped face  14  of the body  12  is an open face that is fully exposed. In other words, the recesses  20 - 24  and protrusions  16  are not positioned between the body  12  and a separate wall or plate. This configuration facilitates improved visibility for determining the engagement between the teeth  208  of the blade  212  and the blade changing tool  10 . 
     However, in alternative embodiments, the blade changing tool could include a separate wall or plate (not shown) attached or integrally formed to the rim  44  of the body  12 . In such a configuration, the wall or plate would cover the entire stepped face  14  or only a portion of the stepped face  14 . In this configuration, the stepped face  14  would be an internal or inner face internal to the cavity formed between the body  12  and the additional plate or wall. The saw blades  212  would be received between the body  12  and the plate or wall at least partially in a radial direction. Such a wall or plate could provide additional safety for the operator. 
     The body  12  also includes two feet  60 ,  62  extending axially outward from a rear face  64  of the body. With reference to  FIG. 1 , the feet  60 ,  62  align with the bottom edge  42  of the body  12  and have a generally flat or planar bottom surface. With reference to  FIG. 7 , the feet  60 , 62  function to abut against the top  204  of the table  202  of the table saw  200  as the saw blade  212  is being torqued during tightening or loosening of the saw blade  212 . More particularly, as the table  202  includes a slot  211  through which the saw blade  212  extends, the feet  60 ,  62  function to extend across the slot  211 . Depending on the direction of rotation, one of the feet  60 , 62  will be biased into the top  204  of the table  202  to stop rotation of the saw blade  212  as the nut  216  is being torqued. 
     With reference to  FIG. 1 , it can be seen that the primary features of body  12  of the blade changing tool  10  are formed such that the body  12  is generally free of undercuts. An undercut would occur when it is impossible to form a two shell or two piece mold to define all of the structures of the body  12 . As the body  12  is free of undercuts, the body  12  can be generally formed by a straight-pull mold using an injection molding process. More particularly, the body  12  can be formed using only two mold shells. The mold shells move relative to one another along a mold pull axis. In the illustrated embodiment, the mold pull axis is generally horizontal or parallel to the extension of the protrusions  16  from the blade face abutment surfaces  28 - 32  and generally perpendicular to the blade face abutment surfaces  28 - 32 . Typically, the body  12  will be injection molded from a plastic material to form a one-piece body. 
     The handle  13  preferably extends at an angle α relative to body  12 . The handle  13  permits the operator to control the blade changing tool  10  while tightening or loosening the saw blade  212 . The angled orientation permits the operator to easily apply radial and axial loading to the blade changing tool  10 . By being able to apply loads in both directions, the operator can more securely engage the saw blade  212  with the blade changing tool  10 . Further, the feet  60 ,  62  prevent the blade changing tool  10  from tipping away from the saw blade  212  so that the blade changing tool  10  does not disengage the saw blade  212 . 
     The angled handle configuration may generate undercuts if the handle  13  was formed as one piece with body  12  preventing a straight-pull mold from being employed to injection mold the body  12 . As such, the handle  13  is formed as a second piece that is attached to the rear face  64  of the body  12  rather than having the body  12  and handle  13  formed as one-piece. However, other embodiments could form the handle  13  and body  12  as a one-piece body. Further, the handle  13  could only extend axially or radially to more easily facilitate straight-pull molding. 
     Depending on the cutting operation to occur after a saw blade  212  has been mounted to the saw  200 , the operator may desire to adjust the height at which the blade extends above the top  204  of the table  202  of the saw  200 . As such, the blade changing tool  10  may include blade height indicators  74  so that the operator can quickly, and without the assistance of other tools, adjust the blade height to a desired working level. The blade height indicators  74  are indentations formed in the blade face abutment surfaces  28 - 32  of the individual recesses  20 - 24 . The blade height indicators  74  are preferably spaced apart at equal increments. As illustrated, the blade height indicators  74  are centered along the width W of the body  12 . 
     All references, including publications, patent applications, and patents cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein. 
     The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) is to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention. 
     Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.

Technology Classification (CPC): 1