Patent Application
20080276450
This invention generally relates to saws and more, particularly to tools for changing the circular blade of a saw.
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'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 '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.
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.
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:
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.
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
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
It can be appreciated from
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
With reference to
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.
