Abstract:
A floating bench saw guide for guiding a portable circular saw along a workpiece while sawing the workpiece, has a cradle for retaining a portable circular saw, a saw plane across the cradle, and a guide lip movably affixed to the cradle. A pair of gage blocks are affixed to the cradle along the saw plane. The gage blocks are advantageous for allowing the use of a straight edge for easily positioning the blade of a circular saw along the saw plane. In another feature of the invention, a pair of spaced-apart parallel rails are affixed to the cradle. The guide lip is movably affixed to the rails and is reversible relative to the saw plane. The guide lip overhangs its mountings to the rails such that it is positional relative to the saw plane over a distance which is longer than the length of the rails.

Description:
FIELD OF THE INVENTION 
     This invention pertains to portable circular saw guides and more particularly it pertains to circular saw guides which have universal saw mounting cradles, reversible guiding edges and rulers. 
     BACKGROUND OF THE INVENTION 
     It can be difficult for a carpenter to carry a conventional table saw from one job site to another. This can be particularly difficult when the project involves the working on a roof or on other parts of a building requiring the transport of tools in stairs, in ladders or on scaffolding. This inconvenience with conventional table saws has created a need for a portable device that is compact, lightweight and that can be used to perform substantially the same work as can be done on a conventional table saw. 
     In the past, several circular saw guides have been developed and used with varying degrees of success. The known circular saw guides belong to two groups wherein the devices in each group have common characteristics. The main feature of the saw guides in the first group consists of an anchor device which attaches to the skid plate of a portable circular saw. A guiding edge is mounted on a stem which is telescopically movable in a socket mounted to the anchor device. The circular saw is used in a conventional manner but with the guiding edge following the straight edge on the panel being sawn. Examples of circular saw guides belonging to the first group are described and illustrated in the following documents: 
     U.S. Pat. No. 4,128,940, issued on Dec. 12, 1978 to José K. Ong; 
     U.S. Pat. No. 4,397,089, issued on Aug. 9, 1983 to Mason E. Pease; 
     U.S. Pat. No. 4,628,608, issued on Dec. 16, 1986 to Gerhard Kuhlmann et al.; 
     U.S. Pat. No. 5,035,061, issued on Jul. 30, 1991 to Timothy Bradbury et al.; 
     U.S. Pat. No. 5,815,931, issued on Oct. 6, 1998 to Todd Cleveland, and 
     U.S. Pat. No. 5,901,450, issued on May 11, 1999 to Thomas P. James. 
     The second group of circular saw guides of the prior art is characterized by the mounting of the portable saw in a cradle which is movably supported or fixedly attached to a pair of rails. A guiding edge or the saw itself is movable along the rails so that the relative positions of the guiding edge and the saw are adjustable, for sawing a panel or a board at selected places. Examples of saw guides of the second group are illustrated and described in the following documents: 
     U.S. Pat. No. 3,434,514, issued on Mar. 25, 1969 to Charles E. McManama; 
     U.S. Pat. No. 4,016,649, issued on Apr. 12, 1977 to James R. Kloster; 
     U.S. Pat. No. 4,135,419, issued on Jan. 23, 1979 to Everett E. Chapin; 
     U.S. Pat. No. 4,237,762, issued on Dec. 9, 1980 to Kevin J. Winter; 
     U.S. Pat. No. 4,852,257, issued on Aug. 1, 1989 to Kenneth D. Moore; 
     U.S. Pat. No. 4,909,111, issued on Mar. 20, 1990 to Walter E. Noble; 
     U.S. Pat. No. 5,080,152, issued on Jan. 14, 1992 to Michael Collins et al.; 
     U.S. Pat. No. 5,107,736, issued on Apr. 28, 1992 to James O. Albrecht, and 
     U.S. Pat. No. 5,921,161, issued on Jul. 13, 1999 to Robert M. Newell. 
     Although the circular saw guides of the prior art deserve undeniable merits, these devices are believed to be deficient in at least the features of being capable of accommodating various makes and models of circular saws, and being readily adjustable for use without having to measure the position of the saw blade relative to the guiding edge. Such lack of instant positioning means can lead to errors in sawing and can cause irreparable damage to expensive wood boards or panels. 
     As such, it will be appreciated that there continues to be a need for a new and improved circular saw guide which is readily usable with various models of saws, without having to measure using a measuring tape and laboriously adjust the position of the saw blade relative to the guiding edge. 
     SUMMARY OF THE INVENTION 
     The present invention provides a floating bench saw guide which has a compact configuration and a saw cradle in which the portable saw is readily positional for use without subjective measurement using a measuring tape. 
     Broadly, in accordance with one feature of the present invention, there is provided a floating bench saw guide for guiding a portable circular saw along a workpiece while sawing the workpiece. The floating bench saw guide comprises a cradle for retaining a portable circular saw, a saw plane across the cradle, and a guide lip movably affixed to the cradle. A pair of gage blocks are affixed to the cradle or to a structure adjacent the cradle. The gage blocks have a certain thickness and are positioned along the saw plane. The gage blocks define the saw plane. The provision of the gage blocks on the cradle is particularly advantageous for allowing the use of a straight edge such as a carpenter square for easily positioning the blade of a circular saw along the saw plane without having to use a measuring tape to measure the position of the saw blade within the cradle. 
     In accordance with another feature of the present invention, a pair of spaced-apart parallel rails are affixed to the cradle. The rails have a common length of about thirty six inches and extend away from the saw plane. The guide lip is movably affixed to the rails and is reversible relative to the saw plane. Moreover, the guide lip overhangs its mountings to the rails such that it is positional relative to the saw plane over a distance ranging from about zero inch to about forty-eight inches from the saw plane. The floating bench saw guide is thereby relatively compact in size when the guide lip is positioned in a forward orientation nearest to the saw plane. 
     In accordance with yet another feature of the present invention, each rail has a ruler affixed thereto. A pointer is affixed to the guide lip and overhangs one of the rulers. The ruler on one rail has a graduation set which is a continuation of the graduation set on the other ruler. The pointer indicates the position of the guide lip relative to the saw plane whether the guide lip is positioned in a forward or reverse orientation. 
     In accordance with a further feature of the present invention, the guide lip is mounted to an intermediate position along the rails, and a router support member is removably mounted to the far ends of the rails relative to the saw plane. The router support member has a structure which allows its mounting over the cradle. The router support member has clamping means to retain a router over the cradle in place of a circular saw, such that the floating bench saw guide is usable with several carpentry tools. 
     Still another feature of the floating bench saw guide according to the present invention is that it is susceptible of a low cost of manufacture with regard to both materials and labor, and which accordingly is then susceptible of low prices of sale to the consumer, thereby making such floating bench saw guide economically available to the public. 
     Other advantages and novel features of the present invention will become apparent from the following detailed description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     One embodiment of this invention is illustrated in the accompanying drawings, in which like numerals denote like parts throughout the several views, and in which: 
     FIG. 1 is a perspective side and top view of the preferred configuration of the floating bench saw guide according to the present invention; 
     FIG. 2 is a plan view of the floating bench saw guide; 
     FIG. 3 is a plan view of the base frame of the floating bench saw guide; 
     FIG. 4 is the bottom view of the base frame of the floating bench saw guide; 
     FIG. 5 is a cross-section view of the base frame, as seen along line  5 — 5  in FIG. 3; 
     FIG. 6 is a cross-section view of one of the rails in the floating bench saw guide, as seen along line  6  in FIG. 2; 
     FIG. 7 is a plan view of the saw holding plate in the floating bench saw guide; 
     FIG. 8 is an end view of the saw holding plate; 
     FIG. 9 is an enlarged side view of the toggle clamp mounted on the saw holding plate; 
     FIG. 10 is a plan view of the movable guide member comprised in the preferred floating bench saw guide; 
     FIG. 11 is a cross-section view through the movable guide member as seen along line  11 — 11  in FIG. 10; 
     FIG. 12 is an enlarged top view of a slide block comprised in the movable guide member; 
     FIG. 13 is an end view of the slide block shown in FIG. 12; 
     FIG. 14 is a plan view of the sight glass affixed to the movable guide member; 
     FIG. 15 is another plan view of the floating bench saw guide showing specific reference dimensions, and showing the movable guide member mounted in a forward orientation nearest to the saw plane; 
     FIG. 16 is yet another plan view of the floating bench saw guide wherein the movable guide member is mounted in a reverse orientation farthest from the saw plane; 
     FIG. 17 is a side view of the floating bench saw guide with the movable guide member mounted in a forward orientation; 
     FIG. 18 shows a plan view of the router support member which is optionally comprised with the preferred floating bench saw guide; 
     FIG. 19 is an end view of the router support member; 
     FIG. 20 is a cross-section view through the router support member as seen along line  20 — 20  in FIG. 18; 
     FIG. 21 is another cross-section view through the router support member, as seen along line  21  in FIG. 18; 
     FIG. 22 is a side view of the floating bench saw guide with a router in place of a circular saw; 
     FIG. 23 illustrates a method, using the floating bench saw guide with a circular saw mounted therein, for sawing a wedge-shaped shim; 
     FIG. 24 illustrates a method, using the floating bench saw guide with a router mounted therein, for making book case ends; 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     While this invention is susceptible of embodiments in many different forms, there is shown in the drawings and will be described in details herein a specific embodiment, with the understanding that the present disclosure is to be considered as an example of the principles of the invention and is not intended to limit the invention to the embodiment illustrated and described. 
     Referring firstly to FIG. 1 the major components of the floating bench saw guide according to the preferred embodiment comprises a saw cradle  30 , a base frame  32 , comprising a base plate  34  and a pair of rails  36 ,  38  extending from the base plate  34 . A movable guide member  40  is engaged with, and movable along the rails  36 ,  38 . A router support member  42  is removably engaged into the far ends of the rails  36 ,  38  and is optionally mountable over the saw cradle  30  for supporting a router in place of a circular saw  44 . 
     The structural details of the base frame  32  will now be described with reference to FIGS. 1-6. The base plate  34  is affixed to the near ends of the rails  36 ,  38 , flush with or slightly raised from the bottom of the rails as seen in FIG.  5 . The preferred base plate  34  is about ¼ of a inch thick and the rails  36 ,  38  are preferably made of aluminum tubing 1 inch by 1 inch square by 0.120 inch wall thickness. A rectangular opening  50  in the base plate  34  allows the passage of a saw blade and a saw blade guard on a circular saw  44 . This rectangular opening  50  is at the near end of the base frame  32 . A circular indentation  52  is provided in the rectangular opening for clearance around the chuck of a router (not shown), as will be understood from the following description of the preferred embodiment. An array of threaded holes  54  is provided in the base plate  34  to retain the saw holding plate thereto as will also be explained later. A central hole  56  through the base plate  34  is usable to retain the router support member  42  to the base plate  34 . Each of the holes  54 ,  56  in the base plate as well as in the other parts of the preferred floating bench saw guide is reinforced with a threaded insert  58  known in the field of machine design as a PEM™ fasteners or a NUTSERT™. 
     Each of the rails  36 ,  38  has a longitudinal slot in the inside wall thereof, such that it forms a C-shaped configuration as best illustrated in FIGS. 5 and 6. The slide blocks along the saw holding plate and the movable guide member are movably engaged inside this C-shaped configuration as seen in FIG.  6 . Each rail also has a ruler printed thereon or affixed thereto. The ruler  60  on the right side rail  36  is graduated from 0-24 inches. The ruler  62  on the left side rail  38  is graduated from 24-48 inches. 
     Most importantly, there are two gage blocks  64 ,  66  affixed to the upper walls of the rails, at the near ends of the rails. These gage blocks  64 ,  66  define a saw plane  68  against which the saw blade of the circular saw  44  is positioned in the saw cradle  30 , and from which both rulers  60 ,  62  are referenced. The utility of these gage blocks will be further explained when making reference to FIG.  15 . 
     Transverse slots  70  are provided through the underside walls of both rails near the far edge of the base plate  34 , for evacuating sawdust which may accumulate inside the rails during use of the floating bench saw guide. If not removed, the sawdust can hinder the movement of the movable guide member  40 . 
     The saw cradle  30  consists of the base plate  34  and the saw holding plate  80  mounted over and overlapping the base plate  34 . The saw holding plate has a C-shaped configuration and a pair of sliding block  82 ,  84  mounted along the edges thereof. The slide blocks are dimensioned to slide precisely but freely inside the rails  36 ,  38  as illustrated in FIG.  6 . The saw holding plate  80  has a thickness of about ⅛ of an inch, and the rectangular opening  90  therein has dimensions to partly enclose the skid plate of a circular saw  44 . On the forward side of the saw holding plate, there is provided a clamp bar  92  which is affixed to the saw holding plate  80  by screws  94 . The saw holding plate  80  is retained to the base plate  34  by means of two thumb screws  96 ,  98  through adjustment slots  100 ,  102  in the saw holding plate, and through two of the series of holes  54  in the base plate  34 . The slots  100 ,  102  and the series of holes  54  provide adjustment to accommodate the holding of various models and sizes of circular saws in the cradle  30 . 
     In use, the skid plate of a circular saw  44 , is placed over in the base plate  34  of the floating bench saw guide and inside the rectangular opening  90  of the saw holding plate  80 . The forward edge of the skid plate is inserted under the clamp bar  92 , and is clamped down against the base plate  34  using the thumb screw  104  through the clamp bar  92 . The rear end of the skid plate  110  of the circular saw  44  is held down against the base plate  34 , by a toggle clamp  112  on the saw holding plate, near the rear end of the saw holding plate  90 . This type of toggle clamp  112  is available from Carr-Lane Manufacturing Co., a company from St. Louis, Mo., USA. A wing nut  114  is provided on the bumper  116  of the toggle clamp, for easy height adjustment of the bumper  116  to accommodate various thicknesses of skid plates  110 . 
     Also as illustrated in FIG. 7, a slot  124  is provided in the clamp bar  92 . In use, the slot  124  is positioned to coincide with any raised deformation that may be present on the skid plate  110  of a portable saw  44 . 
     The movable guide edge  40  will now be described with reference to FIGS. 10-17. The movable guide edge  40  comprises a guide lip  130  formed on the edge of an guide-carrier plate  132 . A channel-like member  134  is affixed to the top side of the guide-carrier plate  132  and encloses a pair of slider blocks  136 ,  138 . These slider blocks have dimensions for sliding freely but precisely inside the rails  36 ,  38 . The guide-carrier plate  132 , is held below the slider blocks  136 ,  138 , such that it moves under both rails  36 ,  38  as shown in FIG. 17, under the base plate  34  and under the router support member  42 . 
     A handle  140  is provided on the channel-like member  134  to facilitate the adjustment of the movable guide member and to support the preferred floating bench saw guide in use. 
     Each of the slider blocks  136 ,  138  has a slider portion  150  which has a similar cross-section as the inside dimensions of one of the rails, and an anchor portion  152  which has dimensions for precise insertion inside one end of the channel-like member  134 , and attachment to the channel-like member. The slider portion  150  is retained to the anchor portion  152  by a thin portion  154  having substantially a same thickness as the width of the slot in each of the rails. There is further provided in each of the slider blocks  136 ,  138 , a quarter-turn lock nut  156 ,  158 , each having a stem extending through the slider portion  150  of each slider block. These lock nuts are used to selectively clamp the wall of the rails between the slider portion  150  and a washer  160  under each lock nut, for the purpose of locking the movable guide member  40  to the rails  36 ,  38 . The quarter-turn lock nut  156  on the right side of the preferred floating bench saw guide has a clockwise thread, and the quarter-turn lock nut  158  on the left side has a counter-clockwise thread as represented by arrows  162  and  164  respectively in FIG.  10 . These lock nuts are thereby easily loosened and tightened in a common direction for adjusting the position of the movable guide edge member  40  along the rails  36 ,  38 . 
     The exact position of the movable guide edge  40  along the rails  36 ,  38  is easily confirmable by means of a sight glass  170  affixed to the channel-like member  134  and extending above one of the rulers  60 ,  62  on the rails of the preferred floating bench saw guide. A first hairline  172  indicates the position of the guide lip  130  relative to the saw plane  68 . A second hairline  174  indicates the position of the guide lip  130  relative to the position of the tool bit when a router is used in place of the saw  44 . The second hairline  174  indicated the position of the guide lip  130  relative to the center of the circular indentation  52  in the base plate  34 . 
     Referring back to FIG. 10, there are two threaded holes  176 , for optionally retaining the thumb screws  96 ,  98  and preventing these screws from becoming lost when the saw holding plate  80  is removed from the base plate  34 . 
     Reference is now made to FIGS. 1,  15  and  16  to explain some of the most important features of the floating bench saw guide according to the preferred embodiment. The mounting of a portable circular saw  44  in the saw cradle  30  is preferably effected while using a carpenter square  180  laid against the gage blocks  64 ,  66  as illustrated in FIG.  15 . The saw guard of the circular saw  44  is moved up, and the saw blade  182  is moved against the carpenter square  180 . Then the skid plate  110  of the circular saw is clamped down against the base plate  34  as previously explained. This procedure ensure that the outside face of the saw blade  182  is aligned with the saw plane  68 . 
     Although a carpenter square  180  has been suggested for adjusting the position of the saw blade along the saw plane  68 , it will be appreciated that any straight edge such as a piece of molding or a piece of board can also be used to obtain the same result. 
     The right side ruler  60  is positioned such that the distance ‘A’ between the zero mark on the ruler and the saw plane  68  is a same distance as the measurement ‘B’ between the guide lip  130  and the left hairline  172  on the sight glass  170 . Therefore the actual distance ‘C’ between the guide lip  130  and the saw plane  68  is read under the hairline  172 . 
     The guide-carrier plate  132  has a substantial length measured along the rails, to provide the option of bringing the guide lip  130  close to the saw plane  68  if required. When the movable guide member  40  is in the forward orientation as illustrated in FIGS. 15 and 17, the guide lip  130  is movable to a distance ‘D’ of about ⅛ inch or less from the saw plane  68 . 
     Both slide blocks  136 ,  138  on the movable guide member  40  are symmetrical and parallel, such that the movable guide member is reversible in its mounting inside the rails  36 , 38  as shown in FIG.  16 . When the movable guide member  40  is mounted in this position, referred to herein as the reverse orientation, the distance ‘E’ between the near side of the guide lip  30  and the saw plane  68  is a same distance as read on the left side ruler  62  under the hairline  172 . For this reason, the zero mark on the left side ruler  62  is set at a distance ‘F’ from the saw plane  68  which corresponds to the distance ‘A’ plus the thickness of the guide lip  130 . 
     The structure of the router support member  42  is illustrated in FIGS. 18-22. The router support member  42  comprises a thick plate  190  made of plastic material for example, and has a hole  192  through its center. The hole  192  may have a shoulder  194  to conform to the shape of a router body. The plate  190  is made in two pieces which are joined together by a pair of clasps  196  extending over a tongue-and-groove parting line  198 . The hole  192  has dimensions to provide a tight fit over a router body, such that a router body may be retained to the plate  190  when the clasps  196  are closed. A handle  200  is also provided to assist in operating the preferred floating bench saw guide with a router in place of a circular saw. 
     Each of the side edges  202  of the thick plate  190  has a shape and a groove on its upper surface to mount into one of the slotted rails  36 ,  38 . The lower surface of the thick plate  190  is planar and smooth such that it can be inserted into the near ends of the rails and over the base plate  34 , in place of the saw holding plate  80 . When not used, the router support member  42  is preferably inserted in the far ends of the rails and left there to keep the rails in parallel alignment and to prevent damage to the far ends of the rails in use. 
     A level gage blade  204  is affixed to the front edge of the thick plate  190  and is used when a router  210  is installed in the preferred floating bench saw guide in place of a circular saw. The level gage blade  204  is adjustable up and down relative to a working position of the router support member, by means of a pair of slots  206  and two wing nuts  208 . The level gage blade  204  is advantageous for leveling the preferred floating bench saw guide along a workpiece when the guide lip  130  is made to slide in a router-made shallow groove for example, and to ensure that the next groove will be truly perpendicular to the surface of the workpiece. The utility of the level gage blade  204  will be further explained when making reference to FIG.  24 . 
     The router support member  42  is adjusted and retained to the base plate  34  by means of a thumb screw  212  mating into the threaded hole  56  in the base plate  34 . The position of the screw  212  and the hole  56  in the base plate  34  are calibrated with the number sets on the rulers  60 ,  62  such that the center of the router bit  214  relative to the guide lip  130  is indicated on one of the rulers, under the hairline  174  on the sight glass  170 . 
     As may be understood from the foregoing detailed description, the preferred floating bench saw guide is used while holding the circular saw  44  in one hand and the handle  140  of the movable guide member in the other hand. The guide lip  130  is brought against a straight edge of the workpiece and the saw is driven through the workpiece to cut the workpiece at the exact measurement from the guide lip  130  as is indicated on one of the rulers under the hairline  172 . 
     While a right-handed circular saw  44  has been illustrated, it may be appreciated that the all the components of the preferred floating bench saw guide are symmetrical and can be reversed to accommodate a left-handed circular saw. Similarly, braille rulers may also be used to accommodate the visually impaired users of the floating bench saw guide according to the preferred embodiment. 
     The floating bench saw guide according to the preferred embodiment of the present invention can also be used to perform non-conventional work such as sawing a workpiece along an acute angle for example, as illustrated in FIG.  23 . In this case, the work is performed on a table  220  or on carpenter benches. A piece of lumber  222  is temporarily affixed to the table  220  or to the benches. The workpiece  224  to be sawn is placed against the piece of lumber  222  with the largest finished end  226  of the workpiece resting against the piece of lumber. A saw mark  228  indicating the width ‘G’ at smallest finished end of the workpiece  224  is moved away from the piece of lumber  222  a distance ‘H’ equal to the finished width of the workpiece at the large finished end  226 . The workpiece  224  is then temporarily affixed to the table  220 . The cut is then effected with the preferred floating bench saw guide as explained before, that is with the guide lip  130  sliding against the piece of lumber  222 . 
     A second application of the preferred floating bench saw guide is illustrated in FIG.  24 . In this application, a router  210  and router support member  42  are used in place of a circular saw. The preferred floating bench saw guide is used to cut shelving seat grooves in a pair of bookcase ends. The first groove  232  is effected while manipulating the preferred floating bench saw guide as previously explained, that is with the guide lip  130  sliding against the ends  234  of the bookcase ends. The second and subsequent grooves  236  are effected while sliding the guide lip  130  into the adjacent groove  232 . Depending upon the depth at which the grooves are made, the level gage blade  204  may be adjusted to maintain the rails  36 ,  38  parallel with the surface of the workpiece and to maintain the second and subsequent grooves true with the surface of the bookcase ends. 
     Reference may be made again to FIG. 22 to better understand the adjustment of the level gage blade  204 . In the case of the bookcase ends  230  as just explained, the level gage blade  204  is set higher than the bottom edge of the guide lip  130  by a dimension ‘J’ which is equivalent to the depth at which the first groove has been made. 
     It will be appreciated from the examples illustrated in FIGS. 23 and 24 that the applications of the floating bench saw guide according to the preferred embodiment in carpentry work are limited only by the imagination of the users. As such, it is believed that further explanation relative to the manner of usage and operation of the floating bench saw guide according to the present invention would be considered repetitious and is not provided. 
     While only one embodiment of the present invention has been illustrated in the accompanying drawings and described herein above, it will be appreciated by those skilled in the art that various modifications, alternate constructions and equivalents may be employed without departing from the true spirit and scope of the invention. Therefore, the above description and the illustrations should not be construed as limiting the scope of the invention, which is defined by the appended claims.