Patent Application
20100275755
The present invention generally relates to power miter saws and similar power saws.
The design and development of power tools and particularly power saws, such as miter saws, for example, have produced saws that are extremely sophisticated and not only provide reliable and accurate cutting of work pieces, but also are much safer to operate. Such safety considerations have greatly changed the configuration of miter saws over several decades. One of the major changes involves the protection of a user from the rotating saw blade by having not only an upper generally fixed blade guard as part of the design of the motor and blade assembly, but also a swinging lower blade guard that is pivoted out of the way to expose the lower portion or reach of the blade for cutting as the motor and blade assembly is lowered into its operating position to cut a work piece. When the cut is completed and the motor and blade assembly rotated upwardly to return to its normal rest position, the lower blade guard is automatically rotated into position to cover the lower reach of the blade.
As is the case for some known miter saws that are currently marketed, the geometry of the miter saw prevents a lower guard from rolling back away from the saw blade for the purpose of having access to the blade arbor as required when it is desired to change the blade. The actuating link of the lower guard is connected to a frame support and does not normally permit this type of movement. For many designs, it is therefore necessary to at least partially disassemble the saw in order to obtain access to the arbor so that the blade can be changed. The amount of disassembly varies depending upon the particular saw, but is often inconvenient and time consuming.
Embodiments of the present invention permit the lower guard linkage linking mechanism to be easily manipulated to place the lower guard to be rotated out of the way and be temporarily held in a position which exposes the blade and arbor to permit the user to change the blade.
Embodiments of a power miter saw of the type which has an upper fixed blade guard for encasing upper reaches of an installed saw blade without encasing the blade arbor, and a lower swinging blade guard for covering the lower reaches of an installed blade when saw is in its rest position and for exposing the saw blade when moved to its operational position, the saw comprising an elongated linkage mechanism having opposite end portions interconnecting a frame support and the lower blade guard for moving the lower blade guard in response to movement of the saw between the rest and operational positions, such that the lower blade guard covers the lower reaches of the blade when the saw is in its rest position and uncovers the lower reaches of the blade when the saw is moved to its operational position, the linkage mechanism being configured to be selectively detachable from the frame support, thereby enabling the lower blade guard to be placed in at least first and second positions wherein the first position enables normal movement of the saw between its rest and operational positions, and the second position wherein the lower blade guard is raised to expose a blade arbor to facilitate changing of the blade.
One embodiment of the invention has a linkage mechanism that has one end that can be easily detached so that the lower blade guard can be raised to the second position and then reattached to hold it in the second position.
Another embodiment has a linkage mechanism that has one end that can also be easily detached so that the lower blade guard can be raised to the second position and then conveniently uses an opening in the linkage in combination with a necessarily loosened screw to hold the lower blade guard in the second position.
The present invention is particularly suited for use in a power miter saw of the type which has a compound action as well as being adjustable to perform cuts at different miter angles as well as different bevel angles. With the miter saw having a motor and blade assembly that is pivotable along a generally horizontal axis downwardly into contact with a work piece that is placed on a table of the miter saw and wherein the motor and blade assembly includes an upper fixed blade guard as well as a swingable (i.e., rotatable) lower blade guard that is configured to completely encase the blade so that a user cannot contact the blade when the motor and blade assembly is in its upper rest position. However, the present invention includes embodiments that are useful in other types of saws of the type which have a lower blade guard associated with them.
Turning now to the drawings, and particularly
As is typical, the table 14 has a fence 28 which is provided to anchor a work piece that may be placed on the table 14. The frame support 22 has a rearward extension 28 that is preferably integrally formed with the frame support 22. The motor and blade assembly 26 has a handle 30 as well as a carry handle portion 30a. The handle 30 is used by a user to pivot the motor and blade assembly 26 downwardly toward the table 14 for cutting a work piece that is positioned on the table. The motor and blade assembly 26 preferably has an upper blade guard portion that is preferably cast together with other components to include the motor (not shown), a dust collecting portion 34.
A rotatable lower blade guard 36 is shown with the blade 38 being visible, preferably because the lower blade guard 36 is formed of a transparent or nearly transparent plastic material so that a user can see if the blade 38 is moving or not. The lower blade guard 36 has a small roller 40 located on its bottom which acts as a bumper for contacting the top surface of the table 14 when the motor and blade assembly is brought down into cutting position as shown in
The lower blade guard pivots around an axis 42 that is generally concentric with the axis of an arbor 44 (see
The upper post 48 is attached to a flat plate 52 that is generally shaped commensurate with a raised bead 54 outline as shown in
The screw 58 fits within an opening 59 in the upper blade guard 32 as is particularly shown in
As is shown by comparing
As is evident from
The elongated linkage mechanism 60 is preferably fabricated from steel and has an opening 66 (see
The inner component 68 has a number of fingers 84 that are spaced apart from one another and which generally surround the cylindrical post 62, i.e., they have an inside diameter that is approximately equal to the outside diameter of the post 62. The post has an outer free end 86 with a generally flat end surface 88 which preferably has a rounded curved periphery 90 that facilitates matching the snap fit connector onto the post 62. The post also has an annular groove 92 near the outer end surface 88. The groove has sloped sides 94 to facilitate attachment and detachment of the snap fit connection on the post. The fingers 84 have an inwardly directed protrusion 96 with sloped side portions 98 that are preferably angled generally the same as the angle of the sloped side portions of the groove 92 to also facilitate sliding attachment and detachment of the snap fit connector from the post 62. It should be understood that the snap fit connector is fabricated from a plastic or plastic-like material so that the fingers have resilience and are preferably made of polypropylene or similar material.
It should be understood that while the construction of the snap fit connector has inner and outer components that snap together and are more or less permanently retained in the opening 66 of the elongated linkage mechanism 60, it should be understood that alternative constructions for such a snap fit connection can be used, including forming a one piece snap fit connection around the opening 66 and end of the elongated linkage mechanism 60.
The second embodiment of the present invention is shown in
As is typical, the table 114 has a fence 128 which is provided to anchor a work piece that may be placed on the table 114. The motor and blade assembly 126 has a handle 130 which is used by a user to pivot the motor and blade assembly 126 downwardly toward the table 114 for cutting the work piece and is positioned on the table. The motor and blade assembly 126 preferably has an upper blade guard portion that is preferably an aluminum casting that also includes an extension 132 that carries a motor 134.
A rotatable lower blade guard 136 is shown with the blade 138 being visible, preferably because the lower blade guard 136 is formed of a transparent or nearly transparent plastic material so that a user can see if the blade 138 is moving or not. The lower blade guard 136 has a small roller 140 located on its bottom which acts as a bumper for contacting the top surface of the table 114 when the motor and blade assembly 126 is brought down into a cutting position as shown in
The lower blade guard pivots around an axis 142 that is generally concentric with the axis of an arbor 144 (see
The upper post 148 is attached to a flat plate 152 that is generally shaped commensurate with a raised bead 154 outlined which is shown in
The screw 158 is threaded into the upper blade guard 132 and cooperates with a spot 159, the upper blade guard 132 is shown in
As was the case with the embodiment shown in
As is evident from
With regard to the thumb screw 164, it is shown in detail in
While various embodiments of the present invention have been shown and described, it should be understood that other modifications, substitutions and alternatives are apparent to one of ordinary skill in the art. Such modifications, substitutions and alternatives can be made without departing from the spirit and scope of the invention, which should be determined from the appended claims.
Various features of the invention are set forth in the following claims.
