Abstract:
A panel cutting apparatus is disclosed. The apparatus comprises a bench and a rail mounted to the bench, and adapted to guide a saw along the rail. A bench aligner displays a visual indication of a desired cut line of said workpiece. A positioning guide allows for convenient repositioning of a workpiece, allowing a user to make accurate, repeatable cuts in a workpiece, such as a panel material or sheet of plywood.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to the field of hand-operated construction equipment, and more particularly to a method and apparatus for cutting building material. 
       BACKGROUND 
       [0002]    During the construction of wooden structures, it is often necessary to use a relatively large amount of lumber or other panel material. For example, lumber may be typically used to form both interior and exterior walls of buildings and houses, and may also be used to fabricate forms which are used when pouring concrete foundations. In addition, lumber is used in siding, wooden decks or porches, wooden floors, and cabinets. Because lumber is typically purchased in predetermined lengths, it is often necessary to repeatedly cut lumber to form one of the aforementioned structures. 
         [0003]    Because lumber is relatively heavy and bulky, it is often difficult to uniformly cut the lumber such that the cut is straight and in a direction which is substantially perpendicular to the length of the lumber. The reason for this difficulty is that a relatively large effort is required to repeatedly position an often long piece of lumber each time a cut is to be made. In addition, it is often difficult to position and secure a piece of lumber with one hand, and accurately position a hand-held electrically operated circular saw with the other hand. These problems are compounded by the fact that circular saws are relatively difficult to control with one hand while lumber is being cut. Furthermore, certain types of woodworking, such as cabinetmaking, require very precise cuts which can be difficult to achieve with a hand-held saw. 
         [0004]    While the use of table saws and panel saws may overcome some of these problems, they are often of little use to the craftsman who may find it virtually impossible to repeatedly transport these heavy pieces of equipment to different job sites. These saws typically require a considerable amount of floor space, since the panels are moved against a stationary saw blade. Accordingly, there is a need for a relatively portable and compact device which enables the craftsman to conveniently make precise, uniform cuts in panel material. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention addresses the aforementioned problems by adapting a hand-held saw to travel in a linear path on a bench, constrained by a guide means. An alignment system allows a workpiece (e.g. a sheet of plywood) to be aligned with the saw along a desired cut line. A clamping mechanism secures the workpiece to a bench. An adjustable positioning guide allows the workpiece to be quickly moved to a new position for subsequent “repetitive” cuts, facilitating an efficient way to cut a workpiece into multiple pieces, each of approximately the same dimensions. For example, an 4×8 foot sheet of plywood could be quickly cut into 8 strips, each strip being 6 inches wide and 8 feet long. The present invention provides a way to accurately and conveniently make precise, uniform cuts in panel material. It also allows for large panels to be cut in a relatively confined area such as a basement or garage of a residential home. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  shows a side view of an exemplary embodiment of the present invention. 
           [0007]      FIG. 2  shows a top view of an exemplary embodiment of the present invention. 
           [0008]      FIG. 3  shows another side view of an exemplary embodiment of the present invention, indicating the positioning guide. 
           [0009]      FIG. 4  shows detail of a tensioning mechanism used in an embodiment of the present invention. 
           [0010]      FIG. 5  shows detail of a saw and guide used in an embodiment of the present invention. 
           [0011]      FIG. 6  shows a cross section of a guide bushing used in an embodiment of the present invention. 
           [0012]      FIGS. 7A-7D  show a method of calibrating and using an exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]      FIG. 1  shows a side view of an exemplary embodiment of a panel cutting apparatus  100  of the present invention. This embodiment comprises a bench  102  which is supported by a plurality of main legs ( 106 A and  106 B are visible in this drawing), and a plurality of rear support legs ( 104 A is visible in this drawing). Two horizontal supports  108 A and  108 B provide additional stability to the panel saw apparatus  100 . A saw  110  travels in a linear fashion along a rail  118 . In an exemplary embodiment, the saw is a circular saw. However, other types of saw may be used, such as a jig saw with a reciprocating blade. The saw  110  has an alignment device  112 , which may be an optical alignment device, such as a laser device, or other device capable of producing a thin, visible line, such as a beam of light, or a shadow. Alignment device  112  is also referred to as the saw alignment device. In an alternative embodiment, the alignment device  112  may be a visible mark on the saw  110  that is disposed along the cut line of the saw. 
         [0014]    The rail  118  is suspended by rear rail mount  114  and front rail mount  116 . The height of the rail  118  above bench  102  is adjustable to accommodate panels of various thicknesses. A second alignment device  120  is mounted on the apparatus  100 . Alignment device  120  is also referred to as the bench aligner. The position of alignment device  120  is adjustable, and as part of the initial setup of the apparatus, is adjusted to project a visual indication (such as a laser beam) along the cutting path of saw  110 . In this particular embodiment, second alignment device is mounted on the front rail mount  116 . A positioning guide  122  may optionally be used to aid in positioning a workpiece on the apparatus  100  in order to be cut. 
         [0015]      FIG. 2  shows a top view of the embodiment of  FIG. 1 . In this drawing, a workpiece  208  (also referred to as a “panel”) is shown in phantom lines to indicate how a panel is placed on the panel saw apparatus  100 . The panel saw has clamping means  212  and  213  to help secure the workpiece  208  prior to cutting it. 
         [0016]      FIG. 3  shows another side view of an exemplary embodiment of the present invention, indicating the positioning guide. For clarity, not all parts are illustrated in this drawing. In this view, the positioning guide  122  of this embodiment is shown as a generally L-shaped part mounted underneath bench  102 . The highest part of positioning guide  122  exceeds the level of the bench, thereby serving to guide a workpiece to a desired position to be cut. It is used to aid in positioning the workpiece prior to cutting it. 
         [0017]      FIG. 4  shows detail of a tensioning mechanism used with front rail mount  116  used in an embodiment of the present invention. Rail  118  traverses block  404 A and is attached to block  404 B. Threaded shaft  410  traverses block  404 B, and is connected to knob  408 . When knob  408  is turned in a clockwise direction, it forces threaded shaft  410  against block  404 A, thereby inducing tension in rail  118 . This improves the accuracy of the cuts, as it reduces the amount of free play of the saw  110  ( FIG. 1 ) during a cut. The tension allows rail  118  to have a smaller diameter and still be effective. In a preferred embodiment, the rail diameter is in the range from about 1 inch to about 2 inches. 
         [0018]    Block  404 A has post  406  that inserts into shaft  417 . Shaft  417  is mounted to support  108 A. The post and shaft arrangement provides a mechanism for adjusting the height of rail  118  above bench  102  ( FIG. 1 ). Preferably, post  406  is sized such that it forms a “friction fit” with shaft  417 . That is, there is sufficient friction such that the shaft will remain at the position to which it is inserted, allowing it to be securely fastened in place with a bolt or other fastener (not shown). Rear rail mount  114  also has a similar post and shaft mechanism to also be adjusted to the appropriate height. 
         [0019]    In this embodiment, alignment bracket  412  supports alignment device  120 . In one embodiment, alignment device  120  is a STRAIT-LINE LASER LEVEL, marketed by NEWELL RUBBERMAID, INC, of Freeport, Ill. 
         [0020]      FIG. 5  shows detail of a saw and guide used in an embodiment of the present invention. Saw  110  is comprised of a motor portion  510 , and blade assembly  518 . Alignment device  112  is mounted on the blade assembly  518 . Motor portion  510  and blade assembly  518  are affixed to base  526 . In this embodiment, rail  118  is cylindrical, and resembles a segment of pipe. Base  526  is secured to rail  118  via bushings  522 A and  522 B. Bushings  522 A and  522 B keep the saw  110  attached to rail  118  while still allowing travel along the elongated direction of the rail. It is also contemplated that the rail may have other embodiments, such as a track with integrated bearings. 
         [0021]      FIG. 6  shows a cross section of a guide bushing  522  used in an embodiment of the present invention having a cylindrical rail such as described previously. The guide bushing  522  is comprised of an inner ring  534  circumscribed by outer ring  536 . Inner ring  534  is preferably elliptical in shape, whereas outer ring  536  is substantially circular. The narrower part of the inner ring  534  is oriented such that it is positioned above rail  118 . The inventor has found that this arrangement, combined with the tensioning mechanism described in  FIG. 4 , provides for reduced play of the saw  110  as it travels along rail  118 . 
         [0022]      FIGS. 7A-7D  show a method of calibrating and using an exemplary embodiment of the present invention.  FIGS. 7A-7D  are all top views.  FIGS. 7A and 7B  show calibration steps. A workpiece  208  is inserted into the apparatus  100  and secured via clamping means  212  and  213 . The workpiece is optionally marked with at least two points ( 717 A and  717 B) lying along the desired cut line (not shown), using a pencil, or other suitable marking device. 
         [0023]    The saw  110  is moved to a first position P 1  which is relatively close to alignment device  120 . In one embodiment, alignment device  112  on saw  110  produces a visible indication  704  (e.g. a laser line), and alignment device  120  produces visible indication  708  which may be another laser line. Indications  704  and  708  should line up as shown in  FIG. 7A , and also align with the point  717 B marked along the desired cut line of workpiece  208 . This process is repeated at position P 2  (see  FIG. 7B ) where P 2  is further away from alignment device  120  than position P 1 , and is checked against point  717 A. This ensures that the path of the saw aligns with the desired cut line on the workpiece  208 , and that the visible indication from alignment device  120  is aligned with both points ( 717 A and  717 B), and hence, aligned with the desired cut line. 
         [0024]      FIGS. 7C and 7D  show a method of using the present invention. In  FIG. 7C , workpiece  208  is cut by moving saw  110  to a starting position, and operating the saw  110  in the direction D 1 , as indicated by the referenced arrow until the saw reaches a finishing position, at which point the cut is complete. The workpiece is secured adjacent to positioning guide  122 . When the cut is complete, the workpiece is moved so it once again is adjacent to positioning guide  122 .  FIG. 7D  indicates the second cut, where the workpiece has been moved in direction D 2  after completion of the previous cut. Subsequent cuts of similar dimensions can be easily made by continuing to move the workpiece in the direction D 2  after the completion of a cut, and then moving the saw in direction D 1  to complete the next cut. 
         [0025]    It will be understood that the present invention may have various other embodiments. Furthermore, while the form of the invention herein shown and described constitutes a preferred embodiment of the invention, it is not intended to illustrate all possible forms thereof. It will also be understood that the words used are words of description rather than limitation, and that various changes may be made without departing from the spirit and scope of the invention disclosed. Thus, the scope of the invention should be determined by the appended claims and their legal equivalents, rather than solely by the examples given.