Abstract:
A power tool includes a table structure defining a blade slot, a frame supporting the table structure, a blade assembly mounted within the frame, and a carriage assembly. The blade assembly includes a blade positioned within the blade slot and a motor assembly to rotate the blade, in which the carriage assembly supports the motor assembly relative to the table structure. The carriage assembly defines a chamber within which said blade operates and a discharge chute for discharge of dust and debris from the chamber during operation of the blade. The bottom wall of the carriage assembly below said blade defines a plurality of openings that are sized to permit passage of the dust and debris. The openings may be sized to comply with finger probe test safety standards. In certain embodiments, the openings may be provided with a cover that is movable to expose or close the openings.

Description:
TECHNICAL FIELD 
       [0001]    The present disclosure relates generally to power saws, and particularly to power saws having a debris collection system. 
       BACKGROUND 
       [0002]    One type of cutting tool is a power saw that includes an electrical motor mounted below a work surface. Users frequently refer to this type of power saw as a table saw, because the work surface resembles a tabletop. The table has an opening that allows a portion of the cutting tool, such as a saw blade, to extend above the surface of the table. The blade, which is rotatably connected to the electrical motor, is movable relative to the surface of the table to enable a user of the table to make cuts of a particular depth or angle. For example, to adjust the height of the blade, a user may position a workpiece adjacent to the blade and then adjust the height of the blade such that the apex of the blade extends just above the thickest portion of the workpiece. To cut the workpiece, a user positions the workpiece on the table, such that a line representing the cutting path of the blade is aligned with a region of the workpiece to be cut, energizes the motor to rotate the blade, and moves the workpiece toward the rotating blade. As the blade cuts through the workpiece, it generates dust, chips, and other workpiece debris, which may be collected by a debris collection system. 
         [0003]    Table saw debris collection systems, commonly referred to as dust collectors, direct the workpiece debris into a collection receptacle such as a porous bag or other suitable container. Additionally or alternatively, an external negative pressure source, such as a vacuum may be configured to draw the debris from a debris exit port of the table saw into a container. Some users, however, may desire a table saw having a dust collector, which functions effectively without a separate negative pressure source. 
         [0004]    In some cases the user may not apply vacuum to the debris exit port, for example when a vacuum source is unavailable. In this instance, the debris may not be adequately discharged through the exit port while the blade is operating, which can lead to clogging of the debris collection system and even to binding of the blade. The user is then required to turn off the power tool and manually attempt to dislodge the debris through the exit port or disassemble the dust collection system to clean out the debris and dust. Accordingly, further developments in the area of table saw dust collection systems are desirable. 
       SUMMARY 
       [0005]    A power tool includes a table structure defining a blade slot, a frame supporting the table structure, a blade assembly mounted within the frame, and a carriage assembly. The blade assembly includes a blade positioned within the blade slot and a motor assembly to rotate the blade, in which the carriage assembly supports the motor assembly relative to the table structure. The carriage assembly defines a chamber within which said blade operates and a discharge chute for discharge of dust and debris from the chamber during operation of the blade. The bottom wall of the carriage assembly below said blade defines one or more openings that are sized to permit passage of the dust and debris and to comply with finger probe test safety standards. In certain embodiments, the openings may be provided with a cover that is movable to expose or close the openings. The cover may be pivotably, slidably or rotatably mounted to the carriage assembly to move between a position closing the openings and a position in which the openings are exposed for removal of debris therethrough. 
         [0006]    In certain embodiments, the one or more openings include a plurality of elongated slots that extend along a substantial portion of the length of the bottom wall. In embodiments with a cover, the cover may be slidably mounted within certain of the elongated slots. In other embodiments, the openings include a plurality of arc segment openings. In these embodiments, the cover may be rotatably mounted over the openings with arc segment openings that coincide with the openings in the bottom wall when rotated to a certain position. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0007]    Features of the present disclosure should become apparent to those of ordinary skill in the art to which this device pertains from the following description with reference to the figures, in which: 
           [0008]      FIG. 1  is a perspective view of a table saw. 
           [0009]      FIG. 2  is an exploded view of certain components of the table saw of  FIG. 1 . 
           [0010]      FIG. 3  is a side perspective view of the carriage assembly of the saw shown in  FIG. 2 , depicted with the cover removed. 
           [0011]      FIG. 4  is an enlarged view of one embodiment of a dust discharge feature for use with the carriage assembly shown in  FIG. 3 . 
           [0012]      FIG. 5  is an enlarged cross-sectional view of a further embodiment of a dust discharge feature for use with the carriage assembly shown in  FIG. 3 . 
           [0013]      FIG. 6  is an enlarged view of another embodiment of a dust discharge feature for use with the carriage assembly shown in  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    For the purpose of promoting an understanding of the principles of the device described herein, reference is made to the embodiment(s) illustrated in the figures and described in the following written specification. It is understood that no limitation to the scope of the device is thereby intended. It is further understood that the device includes any alterations and modifications to the illustrated embodiment(s) and includes further applications of the principles of the device as would normally occur to one of ordinary skill in the art to which this device pertains. 
         [0015]    As shown in  FIGS. 1 and 2 , a power tool in the form of a table saw  100  includes a blade assembly  101 , a table structure  102  and a frame  104 . The table  102  includes an opening or slot  106  through which a top portion of the blade assembly  101  extends. The table  102  has a generally planar upper surface, which may be referred to as a work surface. The frame  104  is connected to a bottom portion of the table  102  and is configured to define an internal space  105  in which the bottom portion of the blade assembly  101  is positioned. In the embodiment of  FIG. 1 , the table structure  102  and frame  104  may be formed from sheet metal, plastic, aluminum, composite materials, or the like. The table  102  and/or frame  104  may include handles, such as handle  108 , which enable a user to carry the table saw  100  conveniently. 
         [0016]    In certain embodiments, the blade assembly  101  has a fixed position along the longitudinal axis L of the table  102  or along the length of the slot  106 . In other embodiments, the blade assembly  101  may be mounted to a slide assembly (not shown) that enables the blade assembly longitudinally relative to the table  102 , commonly referred to as a “push-pull” saw. 
         [0017]    The blade assembly  101  of the table saw  100  includes an adjustment mechanism  110  for adjusting the angular and vertical position of the blade. The mechanism  110  is adapted to permit rotation of the blade assembly  101  about the longitudinal axis L so that the blade can make an oblique cut in the workpiece. The mechanism may be further adapted to raise and lower the cutting blade relative to the table  102  to adjust the depth of the cut into the workpiece. 
         [0018]    As shown in  FIG. 2 , the blade assembly  101  generally includes a blade  120 , an electrical motor assembly  122 , and a carriage assembly  124  including a cover  126 . The carriage assembly  124  includes a pivot mount  125  that is pivotably mounted to the carriage  104  or to the underside of the table  102  to permit pivoting of the blade assembly, and thus the blade  120 , about the longitudinal axis L ( FIG. 1 ). The motor assembly  122  is supported within a channel  128  in the carriage assembly configured to allow the motor assembly, and therefore the blade  120 , to move up and down relative to the table  102  and slot  106 . The blade  120  may be configured for rotary or reciprocating motion, depending upon the nature of the table saw  100 , and the motor assembly  122  is configured to drive the blade in the rotary or reciprocating motion. 
         [0019]    The adjustment mechanism  110  incorporates a mechanism for controlled pivoting of the carriage assembly  124  relative to the table  102 , and for controlled up and down movement of the motor assembly  122  relative to the table, which ultimately provides for controlled positioning of the cutting blade  120 . It can be appreciated that a variety of adjustment mechanisms may be utilized to provide the angular and up-down adjustments for the blade  120 . For instance, a lead screw mechanism may be provided to move the motor assembly  122 , and thus the blade  120 , up and down relative to the carriage assembly  124  and thus relative to the table  102  and work surface. The angular adjustment mechanism may incorporate a locking pin, such as pin  112 , engaged within a curved slot  113  in a side wall  114  of the frame  104 . Other mechanisms are contemplated provided they are at least capable of adjusting the angle of the blade  120  relative to the table  102  and slot  106 . 
         [0020]    The carriage assembly  124  and cover  126  define a chamber  129  within which the blade  120  rotates when it is mounted to the motor assembly  122 . The chamber  129  includes a discharge chute  130  defined at a lower portion of the chamber to direct dust and debris to an outlet  132 , as shown in  FIGS. 2 and 3 . The chamber and discharge chute are configured to redirect dust and debris propelled by the rotation of the blade  120  in the direction R. Rotation of the blade can generate airflow that helps to further propel the debris along the discharge chute  130  to the outlet  132 . It is also contemplated that suction may be provided at the outlet  132  to assist in clearing the dust and debris from within the chamber  129 . 
         [0021]    The carriage assembly  124  and more particularly the chamber  129  and chute  130 , are configured to contain and convey the majority of the dust and debris when the blade  120  is operated. However, these features have their greatest utility when coupled to a vacuum or suction source at the outlet  132 . In some cases, the user may not apply vacuum, such as when working outdoors or where a vacuum source is not available. While some of the dust and debris may be discharged from the open outlet  132 , dust will typically tend to accumulate within the discharge chute  130 . If the outlet  132  is clogged, the dust will continue to build up within the chamber  129  until the saw blade is impeded. The user must then find some way to remove the built up dust and debris, which involves shutting the power tool down and opening the carriage assembly  124  or poking an instrument through the outlet  132  to scrape out the dust and debris from the discharge chute  130 . It can be appreciated that this method for clearing the carriage assembly can be time consuming and frustrating for the user. 
         [0022]    In accordance with one aspect of the present disclosure, the carriage assembly  124  is provided with openings that allow passage of dust and debris from the carriage assembly while still protecting the user from the blade. Thus, in one embodiment shown in  FIG. 3 , the bottom wall  140  of the carriage assembly  124  includes a number of openings  142  that are sized to at least allow passage of dust generated by operation of the saw blade. The openings  142  are small enough to pass the standard finger probe test (EN 61029 ) to ensure that the user&#39;s fingertips cannot contact the saw blade through the openings. Thus, in one embodiment the openings  142  may be in the form of elongated slots each having a width of less than 0.2 in. The slots may extend along substantially the entire length of the bottom wall  140 . 
         [0023]    The openings  142  may assume various configurations, provided that they have sufficient area to allow passage of at least saw dust and are sufficiently small to pass the finger probe test. In the embodiment shown in  FIG. 3  the openings are elongated linear slots, but the openings could be curved or angled slots, or a series of circular or square perforations. The configuration of the openings may be further affected by the material and method of manufacturing the carriage assembly. For instance, elongated linear slots may be preferable for a molded plastic carriage, while drilled perforations may be preferable for a machined metal carriage. 
         [0024]    In the illustrated embodiment the openings  142  are shown without any closure. Thus, the openings  142  remain open even when vacuum or suction is applied at the outlet  132 . However, it may be desirable to close the openings when suction is used so that all of the dust and debris is ejected through the outlet  132 . The present disclosure thus contemplates the addition of a movable closure for the openings. 
         [0025]    In one embodiment, a movable door  150  is provided that is configured to cover the openings  142 , as shown in  FIG. 4 . In one specific embodiment the cover  150  is mounted to the carriage assembly, such as at the bottom wall  140 , by a hinge  151 . The hinge  151  is configured so that the cover  150  can be pivoted between the position shown in  FIG. 4  to a position covering the opening. The cover may be provided with a lip  152  that is configured to engage the carriage assembly  124  or cover  126  to hold the cover tightly against the openings  142 . Suction applied at the outlet  132  may further help pull the cover against the openings. The cover  150  may be configured with a lip  152  on opposite sides that are configured for press-fit engagement to the carriage assembly, without the need for the hinge  151 . 
         [0026]    In another embodiment, a sliding cover  160  may be provided, as shown in  FIG. 5 . In this embodiment, the cover  160  may be provided with features that engage the carriage assembly that allow the cover to slide from a position blocking the openings  142  to a position substantially clear of the openings. Thus, in one specific embodiment, the cover  160  may be provided with prongs  161  that project into one or more of the slots  142 . The prongs may be provided with lips  162  that engage the inside of the carriage assembly so that the cover is supported with the prongs extending through one or more slots. The prongs  161  may be arranged at one end of the cover  160  so that when the prongs are moved in the direction of the arrow in  FIG. 5  toward one end of the slots  142  the cover  160  is substantially clear of the openings. Sliding the cover in the opposite direction closes the slots. The prongs can be configured for a close running fit between the cover and the openings to maintain as tight a seal as possible when the cover is closed. Again, suction applied through the outlet  132  may help pull the cover against the bottom wall  140  of the carriage assembly. 
         [0027]    As an alternative to engaging within the slots themselves, the prongs  161  of the cover  160  may be arranged to engage grooves in the carriage assembly. For example, grooves may be provided in the side walls of the carriage assembly with the prongs on the cover configured to wrap around the bottom wall  140  to engage the grooves. With this construction, the prongs do not interfere with the openings  142 . The grooves and prongs may be configured to ensure a close running fit between the cover  160  and the openings. 
         [0028]    In a further embodiment, a rotating cover  170  may be provided as shown in  FIG. 6 . In this embodiment, the openings  178  are in the form of circular arc segments. The cover  170  is provided with complementary circular arc segment openings  178  that are sized to generally coincide with the openings  178  in the bottom wall  140  of the carriage assembly. The spaces  179  between the arc segments  178  of the cover  170  are sized to completely cover a respective opening  170 . The cover is rotatably mounted to the bottom wall  140  at a pivot mount  176  so that the cover  175  can be rotated in the direction of the arrows to open or close the openings  170 . A handle  179  may be provided on the cover  175  to facilitate rotation of the cover. The cover  175  and pivot mount  176  may be configured to provide a close running fit between the cover and the bottom wall  140  to ensure as tight a seal over the openings  170  as possible. 
         [0029]    The devices and apparatuses described herein has been illustrated and described in detail in the figures and foregoing description, the same should be considered as illustrative and not restrictive in character. It is understood that only the preferred embodiments have been presented and that all changes, modifications, and further applications that come within the spirit of the device described herein are desired to be protected.