Patent Abstract:
A cutoff saw and filtration system provides convenient multi-stage filtration for a cutoff saw. The filters are effective in capturing the dust and debris created by the saw without becoming clogged. The filters may be easily cleaned and serviced.

Full Description:
PRIORITY 
     The present application claims the benefit of U.S. Provisional Application Ser. No. 61/234,838, filed Aug. 18, 2009, which is herein incorporated by reference in its entirety. 
    
    
     THE FIELD OF THE INVENTION 
     The present invention relates to dust collection. More specifically, the present invention relates to a cutoff saw and stand with an integrated dust collection system. 
     BACKGROUND 
     Dust collection has become increasingly important while cutting materials such as wood, brick or cement, or while performing other similar tasks. Without a dust shroud, debris is typically scattered over a wide area. It is desirable to contain the dust which is created for several reasons. It is desirable to contain the dust and debris to keep the workplace cleaner and to minimize the time necessary to clean up afterwards. While cutting cement or brick, for example, fine dust is often created which is spread over a large distance and can be quite difficult to clean up afterwards. It is also desirable to contain the dust and debris to keep the same from getting into the tool itself, as the fine dust will causing premature failure of the bearings, motor, etc. Additionally, debris such as concrete or brick dust poses a health risk to the machine operator and others who may breathe it. It is thus desirable to collect the dust to minimize any exposure to the dust. 
     Cutoff saws are often used for cutting wood, tile or brick during construction projects. As discussed above, it is desirable to contain the dust to reduce cleanup and tool wear as well as avoiding health issues. Where the tool is used in a finished home or building, such as when performing a repair or a remodel of the location, it is often required to contain the dust so as to avoid damage to the finished building and the items in the building. Cutoff saws, however, have proven difficult to effectively capture the dust. The use of the cutoff saw typically requires that a fairly large portion of the blade is exposed, making dust collection more difficult. The dust collection device can not obscure the blade and interfere with the use of the saw. Additionally, the blade is usually a large diameter and moves at a high speed and tends to forcefully disperse the dust from the tool, making dust collection more difficult. Moreover, the fine dust created when cutting with a cutoff saw has proven a difficulty because the filters are quickly clogged, subsequently reducing the airflow through the dust collector and thereby reducing the effectiveness in capturing the dust. 
     Previous attempts at collecting dust from a cutoff saw have been unsatisfactory. Many of these simply do not adequately collect the dust and debris. Those that initially capture the dust will quickly become clogged with dust and lose effectiveness. 
     Thus there is a need for a cutoff saw which effectively captures the cutting dust and debris. There is a need for a dust collection device which does not interfere with the use of the saw. There is a need for a device which captures dust without quickly losing efficiency, and which has a filter which is easily cleaned or renewed. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an improved cutoff saw and dust collection system. 
     According to one aspect of the invention, a cutoff saw is provided which includes a dust collection system integral to the base of the saw. The dust collection system draws air through the table around the blade and effectively captures the dust which is generated. 
     According to another aspect of the invention, a cutoff saw is provided which has a dust collection system which does not clog quickly. The dust collection system may utilize both a filtration bag and a canister filter, greatly increasing the available filtration surface area. Such a filter arrangement allows the system to capture a significant amount of dust and debris without becoming clogged with dust and experiencing a significant reduction in airflow through the system. 
     According to another aspect of the invention, a cutoff saw is provided which has a dust collection system with easily renewable filters. The system is provided with a filtration bag that is attached to a drawer which forms part of the cutoff saw base. The filtration bag is automatically connected to the dust collection shroud when the drawer is closed. Additionally, a canister filter is provided which further filters the air flowing out of the filter bag. The canister filter is not frequently removed from the base. A spring actuated impact rod is mounted through the base adjacent the canister filter. The rod end outside of the base is pulled by the operator and released, causing the inside end of the rod to hit the canister filter and knock dust off of the filter. This allows a user to renew the filter quickly and without removing the filter from the base. 
     These and other aspects of the present invention are realized in a cutoff saw and dust collection system as shown and described in the following figures and related description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various embodiments of the present invention are shown and described in reference to the numbered drawings wherein: 
         FIG. 1  shows a perspective view of a cutoff saw according to the present invention; 
         FIG. 2  shows a partially disassembled perspective view of the saw of  FIG. 1 ; 
         FIG. 3  shows another partially disassembled perspective view of the saw of  FIG. 1 ; 
         FIG. 4  shows another partially disassembled perspective view of the saw of  FIG. 1 ; 
         FIG. 5  shows another perspective view of the saw of  FIG. 1 ; 
         FIG. 6  shows a perspective view of the rear portion of the table of the saw of  FIG. 1 ; and 
         FIG. 7  shows another perspective view of the rear portion of the table of  FIG. 1 . 
     
    
    
     It will be appreciated that the drawings are illustrative and not limiting of the scope of the invention which is defined by the appended claims. The embodiments shown accomplish various aspects and objects of the invention. It is appreciated that it is not possible to clearly show each element and aspect of the invention in a single figure, and as such, multiple figures are presented to separately illustrate the various details of the invention in greater clarity. Similarly, not every embodiment need accomplish all advantages of the present invention. 
     DETAILED DESCRIPTION 
     The invention and accompanying drawings will now be discussed in reference to the numerals provided therein so as to enable one skilled in the art to practice the present invention. The drawings and descriptions are exemplary of various aspects of the invention and are not intended to narrow the scope of the appended claims. 
     Turning now to  FIG. 1 , a perspective view of a cutoff saw according to the present invention is shown. The saw  10  includes a base  14 , table  18 , a filter drawer  22 , and a saw motor assembly  26  with blade  26   b . The saw motor assembly typically includes an arm extending forwards, a motor, a blade guard, and a blade  26   b . The table  18  is formed with a front section  18   a  and a rear section  18   b . The cutoff saw  10  is modular with respect to the saw motor  26  in that the rear section  18   b  of the table  18  includes a channel  30  which receives a bracket  34  that bolts to the rear section  18   b  of the table  18  and to the saw motor  26 . The bracket  34  forms the pivot for cutting with the saw motor  26 . Various different brackets  34  may be made to accommodate saw motors  26  from different companies and use the same with the saw base  14  as shown. 
     A primary, blade receiving slot  38  is formed in the table  18  (in both halves  18   a  and  18   b  of the table as shown) which receives the saw blade  26   b  when cutting with the saw  10 . Additionally, secondary slots  42  are formed adjacent the sides of the slot  38 . Air flows through the slot  38  and slots  42  and into the base  14  to capture dust created by the saw  10 . 
       FIGS. 2 and 3  show partially exploded views of the saw  10  and illustrate additional aspects of the dust collection system.  FIG. 2  shows a bottom view of the saw  10  and  FIG. 3  shows a top view. A dust collection plenum  46  is located in the base  14  just below the table, and typically seals against the bottom of the table  18  so that air flows into the top of the plenum  46  through the slots  38  and  42 . The plenum  46  captures the dust created when cutting with the saw and directs the dust through a port  50  formed at the bottom of the plenum. The plenum is enclosed except for the open top and the port  50 . The plenum  46  is shallower in the front and deeper in the back in order to help direct dust towards the back and to the port  50 . The front section  18   a  of the table  18  is easily removable to access the plenum  46  to clean or service the plenum. During use of the saw, some pieces of cut material may lodge in the front of the plenum  46  and require that the user remove the front of the table  18   a  and manually remove the debris. 
     A filter drawer  22  fits into an opening  14   a  in the front of the base  14 . A filter bag  54  is secured to the filter drawer  22 . The filter bag  54  is made of a porous filter cloth, such as a spun bonded plastic material, and is enclosed except for an opening in the back that is aligned with the plenum port  50  so that, when the drawer is closed, the filter bag opening seals around the port  50 . The filter bag  54  is typically secured to the filter drawer  22  with screws or clips to hold it in place during use. The drawer  22  is easily removed from or placed into the base  14  to service the filter. 
     Visible in  FIG. 3  is a cylindrical canister filter  58 . The canister filter  58  is typically a pleated filter similar to those used in canister vacuums. The canister filter  58  is attached to an exhaust port  62  on the back wall of the base  14 , but could also be attached to another wall. In use, a vacuum or a lower motor is attached to the exhaust port  62  and draws air through the slots  38 ,  42  and into the plenum  46 , through the plenum port  50 , into the filter bag  54  (where the majority of the dust and debris is captured, through the filter bag, through the canister filter  58 , and out the exhaust port  62  and into the vacuum. Alternatively, the saw  10  may use an integral motor and fan, typically attached to or in place of the exhaust port  62 , to draw air through the table and collect dust in the same manner. In such a situation, the exhaust port  62  would typically be replaced by a motor and fan which draws air through the canister filter  58  and out of the base  14 . Such a motor and fan would typically be synced to the saw motor  26  so that the fan motor starts when the saw motor starts. 
     The base  14  is formed with a filter knock rod  66 . The knock rod  66  is formed with a blunt end  70  placed adjacent the canister filter  58 . The knock rod  66  is spring loaded so that, when the vacuum is off, a user may pull the rod away from the filter  58  and releases the rod, causing the spring to hit the knock rod against the filter  58 . This shakes the filter and causes dust and debris to fall off of the filter. This may be performed periodically when using the saw  10  to prevent the filter from becoming clogged and to prevent against the loss of air flow and corresponding loss of debris collection. The knock rod  66  allows a user to quickly clean the filter  58  without removing the filter; extending the time a user may use the saw without changing or cleaning the filter. 
       FIG. 4  shows the plenum  46  and canister filter  58  in place in the saw  10 , and illustrates the layout of components therein. The plenum  46  is secured to the base  14 , and extends upwardly to seal against the table  18 . According to a preferred embodiment, the drawer  22  and filter bag  54  occupy approximately the lower third or half of the base  14 . The saw blade  26   b  is offset towards the right side of the table  18 , locating the plenum  46  in the right side of the base  14 . The canister filter  58  is located in the left side of the base. When necessary, the filter  58  may be easily changed by removing the front table section  18   a , rear table section  18   b , or the filter drawer  22 . 
       FIG. 5  shows the filter drawer  22  and filter bag  54  in greater detail. Typically, the corners  74  of the filter bag  54  are secured to the drawer  22 . Securing the corners  74  of the filter bag  54  makes it easer to install and remove the drawer  22 , ensures a good seal with the plenum port  50 , and keeps the filter bag  54  in place during operation. The filter bag  54  includes an inlet opening  78  which mates with the plenum port  50 . The inlet opening  78  is typically formed by an inlet plate  82  that is attached to the filter media forming the bag  54  and a rubber seal which extends around the opening  78  to seal against the plenum port  50 . The inlet plate  82  is typically attached to the drawer  22 , such as with a bracket or by attachment with the corner of the filter bag  54 , to hold the inlet plate  82  in place and seal the inlet opening  78  against the plenum port  50  as the drawer  22  is closed. 
     The saw  10  is thus provided with multiple stages of filtration. The filter bag  54  provides a long service life and captures a majority of the debris. The filter bag  54  has a large filter area, and typically does not significantly obstruct flow before the filter bag becomes full. The canister filter  58  captures any fine dust not collected by the filter bag  54 , and may be periodically cleaned with the knock rod  66  without requiring any significant down time. The canister filter does not become quickly clogged and restrict air flow because the filter bag  54  captures a majority of the debris before it reaches the canister filter. The vacuum used to draw air through the saw  10  provides a final filtration stage for any debris that exits the exhaust port  62 . The filter bag  54  and canister filter  58  provide adequate filtration even if the base  14  is used with an integral motor and fan rather than a vacuum. 
       FIG. 6  shows a perspective view of the rear table portion  18   b . The channel  30  for mounting the saw motor bracket  34  can be better seen. Also illustrated is a dust deflector  86 . The dust deflector  86  includes a side plate  86   a  located on the right side of the blade channel  38  (as seen by a saw user) and a curved rear channel  86   b . The curved rear channel  86   b  is formed to curve forward on both sides of the slot  38  and thereby funnel dust and debris which is thrown backwards from the saw blade into the slot  38  for collection. The deflector  86  is pivotably mounted to the table section  18   b  near the front of the deflector and can pivot down into the table as shown by arrow  90 .  FIG. 7  shows the deflector as pivoted in the down position. The deflector  86  is spring biased into the up position shown in  FIG. 6 . 
     Typically, the saw  10  is used in two ways. The saw blade and motor  26  can be pivoted down to cut through wood, brick, or the like. Alternatively, the motor  26  can be locked into the down position and a thin piece of material such as flooring tile may be slid across the table and through the blade to cut the tile similar to a tile saw. When the saw motor  26  is locked down and a tile is moved through the blade to cut, the majority of the dust and debris is carried down through the slot  38  with the blade. The deflector  86  pivots down into the table  18  when a tile or other item slides over the deflector as the tile is being cut. 
     When the saw motor  26  is lowered to cut through a brick or piece of wood, however, the blade is cutting through the top surface of the item being cut and much of the debris is thrown backwards by the blade. The deflector  86  catches the dust and debris which is thrown backwards by the blade and aids in the collection thereof. The curved rear portion  86   b  of the deflector guides the debris to the center of the deflector (which is aligned with the slot  38 ) and downwardly into the slot. The airflow through the slots  38 ,  42  and into the plenum  46  draws the dust and debris into the slots. Thus, the deflector plate  86  improves the collection of dust and debris without interfering with the use of the saw  10 . 
     The saw  10  is advantageous as it provides improved dust filtration as well as extended service life. Cutoff saws have previously proved difficult to achieve effective dust collection because of the large quantity of dust and debris. Prior art collection systems have suffered from poor collection and from filters which become quickly clogged, requiring frequent downtime to remove and replace filters. 
     There is thus disclosed an improved cutoff saw and dust collection system. It will be appreciated that numerous changes may be made to the present invention without departing from the scope of the claims.

Technology Classification (CPC): 8