Abstract:
An improved design for a dust shroud providing an airflow conduit for collecting dust off a work piece and a saw blade is disclosed. The dust shroud is configured with either one or two extending and telescoping lower rigid jaws that are durable and can engage a work piece at different angles. A novel roller is additionally provided for moving along a work piece.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention pertains generally to masonry and carpentry saws. Particularly, the present invention relates to cutting tool devices and methods to maximize containment of dust while cutting cinder block, concrete, brick, clay, stone, tile, wood, and the like. More specifically, the invention pertains to a dust guard configured to a circular saw setting up a conduit for suctioning dust. 
         [0003]    2. Description of the Prior Art 
         [0004]    Devices for grinding or cutting masonry or stone materials have been known for some time. Also known, is a problem of uncontrolled release of and exposure to airborne dust and particulate matter as a by-product from the grinding and cutting. As a result, government agencies such as OSHA have promulgated safety and health requirements for wet and dry cutting. In addition to health issues, the dust by-products present a clean-up challenge, even if all individuals in a contained environment have donned respirators. 
         [0005]    Many prior art solutions have been proposed that specifically employ dry means to control dust. Still other examples specifically provide a dust shroud (or dust guard) configured to a saw blade and forming a conduit for collecting dust off a work piece. One such example was proposed by Loveless et al. entitled “Dust Shroud for Gas Powered Circular Saws,” U.S. Pat. No. 8,011,398, and assigned to Dustless Depot, LLC. In this design, the dust shroud is configured to a leading edge of the circular saw blade. Also, the frontal shroud forms a conduit that leads dust away from a front of the saw. However, this configuration seems less than ideal. For example, a separate vacuum apparatus is needed with a vacuum hose, mobility and portability are restricted. 
         [0006]    Still another related dust shroud was patented by Loveless also assigned to Dustless Depot, LLC, entitled “Universal Dust Collection Shroud for High Speed Gas Powered Saws,” U.S. Pat. No. 8,381,711. In this example, a side exhaust port is coupled to a power saw shroud. Some drawbacks, however, are that the geometry is very asymmetrical and awkward; and it will not retract across a work piece, thereby providing less suction to dust coming off a work piece that can be achieved. 
         [0007]    Yet another similar dust shroud was disclosed by present inventor, Guth entitled “Power Saw Apparatus with Integrated Dust Collector,” U.S. Pub. Pat. App. No. 2011/0079207. This earlier design comprises a flexible bellows (dust guard) framed by a rigid upper shroud ( FIG. 1 ). While the design is a major improvement over previous dust collection devices and methods, there may still remain some drawbacks to that particular solution. Initially, the flexible bellows is relatively difficult to manufacture. Also, the flexible design is prone to deform and may be forced into the blades further damaging the bellows. The dust guard herein seeks to proved strength and longevity to the device. 
         [0008]    In light of the above, it is an object of the present invention to provide a dust guard for circular saws that provides added durability to that particular component. It is an additional object of the present invention to provide lower jaw having a leading edge that may be configured with attachments for cutting at different angles. 
       BRIEF SUMMARY OF THE INVENTION 
       [0009]    The present invention specifically addresses and alleviates the above mentioned deficiencies associated with the prior art. More particularly, the present invention in a first aspect, is dust guard for providing an air flow conduit at a saw blade comprising: an upper shroud surrounding an upper portion of the saw blade providing an air flow conduit as well as housing and providing safety to a saw user; a lower shroud surrounding a rear lower portion of the saw blade the lower shroud comprising a rear exit for dust and air flow; a telescoping jaw rotating about a pivot point with respect to the upper and lower shroud; and a spring coupling the telescoping jaw to the upper shroud configured such that a spring force holds the telescoping jaw fully extended in an open position, wherein further a fully retracted position comprises a force opposite spring force. 
         [0010]    The invention in this aspect is additionally characterized in that the dust guard may have a telescoping jaw with one or two telescoping portions (i.e. a middle jaw telescoping with respect to the lower shroud; and a forward jaw telescoping with respect to the middle jaw). Additionally further, the forward jaw comprises: a roller at a horizontal leading edge of said forward jaw; and a first scoop having a first angled surface removably secured with respect to the forward jaw, the first scoop providing a guide for making angled cuts; and a second scoop removably secured with respect to the forward jaw and interchangeable with respect to the first scoop, the second scoop providing a second angled surface with respect to the first scoop angled surface. 
         [0011]    The dust guard in this aspect in additionally characterized as comprising: a tab at a rear end of the middle jaw; a ridge wall at a junction between the upper shroud and the lower shroud, the ridge wall providing a rear stop against the tab when the middle jaw is fully retracted; and a bump stop coupled to the lower dust shroud, the bump stop contacting the tab and providing a forward stop when the middle jaw is fully extended. 
         [0012]    The dust guard for providing an air flow conduit at a saw blade in this aspect is additionally characterized as further comprising a flange configured between the upper shroud and the lower shroud, the flange concentric to the saw blade. Also, the invention is further defined wherein the spring comprises a helical torsion spring and is configured about the pivot point, and wherein further the spring comprises an arm coupled to a horizontal shoulder screw, the horizontal screw coupled to the telescoping jaw. Further, the horizontal screw is configured though a slot in the upper shroud wherein the horizontal screw slides along a slot length as the telescoping jaw rotates with respect to the upper shroud. 
         [0013]    The slot herein is additionally characterized as a first slot, wherein the telescoping jaw further comprises a forward jaw and a middle jaw, the middle jaw further comprising an inner slot configured within the first slot and having a shorter length, wherein when the horizontal screw travels the length of the inner slot, the horizontal screw contacts an end of said inner slot and further moves the middle jaw a remaining distance along the first slot as the forward jaw and middle jaw fully retract and extend. 
         [0014]    The invention can be better visualized by turning now to the following drawings wherein like elements are referenced by like numerals. 
         [0015]    These, as well as other advantages of the present invention will be more apparent from the following description and drawings. It is understood that changes in the specific structure shown and described may be made within the scope of the claims, without departing from the spirit of the invention. 
         [0016]    While the apparatus and method has or will be described for the sake of grammatical fluidity with functional explanations, it is to be expressly understood that the claims, unless expressly formulated under 35 USC 112, are not to be construed as necessarily limited in any way by the construction of “means” or “steps” limitations, but are to be accorded the full scope of the meaning and equivalents of the definition provided by the claims under the judicial doctrine of equivalents, and in the case where the claims are expressly formulated under 35 USC 112 are to be accorded full statutory equivalents under 35 USC 112. The invention can be better visualized by turning now to the following drawings wherein like elements are referenced by like numerals. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    The novel features of this invention, as well as the invention itself, both as to its structure and its operation, will be best understood from the accompanying drawings, taken in conjunction with the accompanying description, in which similar reference characters refer to similar parts, and in which: 
           [0018]      FIG. 1  is a prior art blade guard device with a flexible retractable bellows configured as a lower jaw to the blade guard device; 
           [0019]      FIG. 2  is a first profile view of the present invention; 
           [0020]      FIG. 3  is a perspective view of the dust guard for circular saws; 
           [0021]      FIG. 4  is top plan view thereof; 
           [0022]      FIG. 5  is a front view of the embodiment; 
           [0023]      FIG. 6  is an additional enlarged profile view of the present invention; 
           [0024]      FIG. 7  is an exploded view thereof showing all components; 
           [0025]      FIG. 8  is an enlarged view of components circumscribed by line  8  in  FIG. 1 ; and 
           [0026]      FIG. 9  and  FIG. 10  are additional profile views illustrating how the lower jaws of the present invention retract. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0027]    Referring initially to the  FIG. 2  and  FIG. 3 , a first improved blade guard  10  (coupled to saw  90 ) is illustrated having a shroud  20  with upper  21  and lower  22  portions generally protecting an upper and rear lower blade  91 . The shroud  20  upper and lower portions are one piece with the lower portion being wider to accommodate retracting and telescoping lower jaws  31 ,  41  as further detailed herein. The telescoping lower jaws  31 ,  41  together provide an enclosure about a lower blade  91 , and importantly provide a dust conduit capable of holding a negative pressure with respect to atmosphere therein. Also as detailed herein, the lower jaws  31 ,  41  rotate about an axis (pivot)  53  slightly above and inward of the circular saw  91  axis  92 . Also, a circular flange  24  at the shroud portion  20  configured to one side or the other for coupling to a fixed portion of the saw  90  via apertures  25  having extra material carved out thereof to accommodate a screw or bolt fastener head. A spring housing  26  further protrudes outwardly from the upper shroud  21  provided to contain a spring  51 , wherein torsion spring force maintains lower jaws  31 ,  41  fully extended. Telescoping herein is essentially defined as forcing into one another in the manner of sliding tubes of a telescope. As claimed herein, the telescoping jaw  31 ,  41  comprises forward jaw  41  and middle jaw  31  telescoping with respect to lower shroud  21 . 
         [0028]    With regard to  FIG. 4 , a top plan view is provided for the dust guard  10 . Here it is revealed that the spring housing protrudes from either side of the device  10 ; and hence, the jaws  31 ,  41  move against the spring  51  force. However, the invention  10  would still function with only one spring  51  to either side. At a rear portion of the lower shroud  22 , a conduit  29  is formed where dust would exit rearwardly to a filter chamber and a dust holding area. At a forward end of the dust guard  10  and at a leading edge of the forward jaw  41 , a roller is configured thereto to roll along a work piece while cuts are being made thereto. Also configured to said leading edge and around the roller, a scoop  63  is removably configured thereto for guiding specific angle cuts to a work piece via angled slope  63   a.  With regard to  FIG. 5 , a front view of the present invention  10  is provided. Herein, alternative views are provided showing the forward jaw  41  having a roller  61  and a scoop  63  configured thereto. 
         [0029]      FIG. 6  provides an additional enlarged profile view of the invention embodiment  10 . As shown, a slot  27  is provided in the upper shroud  21  for movement of a horizontal spring retaining shoulder screw  57  forced upward by the spring  51  force and moving along the slot  27  as pressure is placed on the lower shroud  41  as a leading edge thereof is moved along a work piece. Hence, spring retaining shoulder screw  57  is coupled to the forward jaw  41 . An inner slot  37  is provided to the middle jaw  31 ; however, the inner slot  37  is smaller in length, so that when horizontal screw  57  travels the length of the inner slot  37  it will hit an end of said slot  37  and further move the middle jaw the rest of the way along slot  27  as shown in  FIG. 9  and  FIG. 10 . 
         [0030]    Also with regard to  FIG. 5 ,  FIG. 6  and further  FIG. 7 , a bump stop  28  is coupled to the lower shroud  22  and limits forward motion when the device  10  is fully extended by spring force  53 . Tab  32  provides the extended portion against the bump stop  28 . Conversely at the retracted range of motion, tab  32  will hit ridge wall  23  at the fully retracted position illustrated by  FIG. 11 . 
         [0031]      FIG. 7  provides an exploded view of all components. At the forward end, an aperture  62  is provided to removably secure the scoop  63  having angled surface  63   a  for making specific cuts to a work piece. Circular carve out  35  is configured to middle jaw  31  forward edge to fit around aperture  62  and any screw or bolt configured thereto. As stated, the jaws  31 ,  41  rotate about a pivot  33 ,  43 ,  53  that is above and rearward of saw blade  91  center. Hence, concentric apertures  33 ,  43  are provided overlapping having the spring pin  53  there through.  FIG. 8  is an enlarged view of area bound by line  8  in  FIG. 3 , however from an opposite side since both sides are identical. As shown, spring  51  is coupled to horizontal shoulder screw  57  further being coupled to the forward jaw  41 . The view also provides closer inspection of outer  27  and inner  37  slots. 
         [0032]    Importantly, the invention comprises in alternative embodiments, one telescoping or two telescoping jaws,  31 ,  41  that are rigid and can engage a work piece at different angles  63   a  via different scoops  63 . Tabs  64  and mounting holes  62  are further provided at said leading edge for mounting different scoops  63  thereto. The scoops  63  assist in making cuts from various angles as well as various positions relative to the work piece. 
         [0033]    Also with reference to  FIG. 7 , the forward jaw  41  comprises a roller  61  configured horizontally at a leading edge (or lower portion of the leading edge of jaw  41 ). The roller  61  is configured thereto for rolling across a workpiece while cuts are being made. As stated, the jaws  31 ,  41  are retractable with an opposing force (typically pressing against a work piece) against helical torsion spring  51  force. 
         [0034]    While the particular Dust Guard for Circular Saws as herein shown and disclosed in detail is fully capable of obtaining the objects and providing the advantages herein before stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as described in the appended claims. 
         [0035]    Insubstantial changes from the claimed subject matter as viewed by a person with ordinary skill in the art, now known or later devised, are expressly contemplated as being equivalently within the scope of the claims. Therefore, obvious substitutions now or later known to one with ordinary skill in the art are defined to be within the scope of the defined elements.