Abstract:
A rotary cutter lifting apparatus comprising a table plate having an opening and an upper surface, a carriage disposed beneath the table plate and adapted for supporting the rotary cutter, and an adjustment mechanism positioned entirely below the table plate upper surface and operable through the opening. A method of operating a rotary cutter lifting apparatus comprising the steps of positioning the rotary cutter lifting apparatus having a carriage and an adjustment mechanism entirely below a table plate upper surface having an opening, and operating the adjustment mechanism through the opening.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The invention relates generally to an adjustable rotary lift assembly which is mounted to a work table. More particularly, the invention relates to an assembly for raising and lowering a router bit with both a coarse adjustment mechanism and a fine adjustment mechanism. Specifically, the invention relates to an assembly with a handle for rapidly raising and lowering the router for a course adjustment and an easily accessible fine adjustment mechanism built into the rotary lift assembly. 
     2. Background Information 
     Routers can be mounted on a table so that the rotating bit for material removal is help stationary and the work piece is moved into the bit. Since the work piece moves into the bit, the router and bit must be securely held in both the vertical and horizontal orientations. A router is generally only moved in the vertical direction because, once again, the work piece can be moved horizontally about the bit. 
     Movement in the vertical direction is generally accomplished with either coarse adjustment or fine adjustment. Since coarse adjustment is not as accurate, coarse adjustment is used to roughly locate the bit at the desired height. Fine adjustment is then used to precisely locate the bit at the desired height. Traditionally, fine adjustment has been accomplished by locating a tool within a fine adjustment mechanism to rotate a fine adjustment screw. A tool is necessary because the adjustment mechanism needs to be below the table surface so that the work piece can be move about the router bit without interference. Thus, the traditional router lift assembly is plagued with needing additional tools to operate the fine adjustment mechanism which could ultimately be lost or damaged. 
     SUMMARY OF THE INVENTION 
     The present invention broadly comprises a rotary cutter lifting apparatus comprising a table plate having an opening and an upper surface, a carriage disposed beneath the table plate and adapted for supporting the rotary cutter, and an adjustment mechanism positioned entirely below the table plate upper surface and operable through the opening. 
     The present invention also broadly comprises a method of operating a rotary cutter lifting apparatus comprising the steps of positioning the rotary cutter lifting apparatus having a carriage and an adjustment mechanism entirely below a table plate upper surface having an opening, and operating the adjustment mechanism through the opening. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The preferred embodiment of the invention, illustrative of the best mode in which Applicants have contemplated applying the principles of the invention, are set forth in the following description and are shown in the drawings. 
         FIG. 1  is a front view of a router table with portions cut away and a router lift assembly with a lift wheel and a router mounted thereon. 
         FIG. 2  is a top view of a preferred embodiment router lift assembly with a lift wheel taken generally about line  2 - 2  in  FIG. 1 . 
         FIG. 3  is a bottom view of a preferred embodiment router lift assembly with a lift wheel taken generally about line  3 - 3  in  FIG. 1 ; 
         FIG. 4  is a side view of a preferred embodiment router lift assembly with a lift wheel taken generally about line  4 - 4  in  FIG. 1 ; 
         FIG. 5  is a front view of a preferred embodiment lift wheel taken generally about line  5 - 5  in  FIG. 2 ; 
         FIG. 6  is a cross-sectional view of a preferred embodiment lift wheel taken generally about line  6 - 6  in  FIG. 5 ; 
         FIG. 7  is an enlarged top view of the coarse adjustment mechanism of the present invention; 
         FIG. 8  is a sectional view of the coarse adjustment mechanism of the present invention taken generally about line  8 - 8  in  FIG. 7 ; 
         FIG. 9  is a side view of the lift wheel and coarse adjustment mechanism of the present invention with a handle being inserted into the coarse adjustment mechanism; 
         FIG. 10  is the same view as  FIG. 8  with the handle inserted within the coarse adjustment mechanism; 
         FIG. 11  is the same view as  FIG. 10  with the handle being rotated to allow coarse adjustment; 
         FIG. 12  is a side view of a preferred embodiment router lift assembly and the handle being adjusted upwards with the coarse adjustment mechanism; 
         FIG. 13  is a side view of a preferred embodiment router lift assembly with the handle being rotated and removed from the coarse adjustment mechanism; 
         FIG. 14  is a front view of a preferred embodiment router lift assembly with a user operating the lift wheel to provide a fine adjustment and portions of the table plate removed; 
         FIG. 15  is a side view of a preferred embodiment lift wheel being rotated to provide a fine adjustment upwards; 
         FIG. 16  is an enlarged view of the lift wheel being rotated and the fine adjustment mechanism providing a fine adjustment upwards; 
         FIG. 17  is a side view of a preferred embodiment lift wheel being rotated to provide a fine adjustment downwards; 
         FIG. 18  is an enlarged view of the lift wheel being rotated and the fine adjustment mechanism providing a fine adjustment downwards; and, 
         FIG. 19  is a cross-sectional view of a second embodiment coarse adjustment mechanism with annual rings instead of a continuous helical ring. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     At the outset, it should be appreciated that like drawing numbers on different drawing views identify identical, or functionally similar, structural elements of the invention. While the present invention is described with respect to what is presently considered to be the preferred embodiments, it is to be understood that the invention as claimed is not limited to the disclosed aspects. 
     Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this invention belongs. Although any methods, devices or materials similar or equivalent to those described herein can be used in the practice or testing of the invention, the preferred methods, devices, and materials are now described. 
     The router lift assembly of the present invention is indicated generally at  20 , as is particularly shown in  FIGS. 1 through 18 . As particularly shown in  FIG. 1 , a preferred embodiment lift assembly  20  includes an upper plate  22  with an upper surface  23  and is shown mounted on a work table  24  with an upper surface  26  so that upper surfaces  23  and  26  are substantially coplanar and horizontal. Work table  24  also includes a recessed ledge  28  in upper surface  26  which is approximately as deep as the thickness of upper plate  22  so that the upper surfaces form a constant and consistent work surface. Work table  24  further includes a plurality of legs  30  which function to support and raise upper surface  26  so that a router  32  may be located below upper surface  26  and allow a router bit  33  to extend above upper surface  23  as necessary. 
     Lift assembly  20  extends downward from upper surface  23  with a pair of guide posts  34  and  36  and stops  38  and  40  at the lower ends of the guide posts to limit the travel of the lift assembly in the downward direction. The lift assembly includes a carriage assembly  42  with bushings  44  and  46  that are slidably mounted to the pair of guide posts. Carriage assembly  42  is further connected to a coarse threaded rod  48 , which is in turn connected to upper plate  22  through the coarse and fine adjustment mechanisms (described infra). 
     In accordance with one of the main features of the present invention, a fine adjustment mechanism  49  includes a lift wheel  50  disposed completely below upper surface  23  and the majority of upper plate  22 . Lift wheel  50  slides onto a shaft  52  and both rotate together to perform fine adjustments, as detailed below. Shaft  52  extends towards and inside of an adjustment housing  53 , which is enclosed on all six sides, one of which is a removable cover  55 . 
     Referring to  FIG. 2 , upper plate  22  is leveled relative to upper surface  26  with set screws  54 . Guide posts ( FIG. 1 )  34  and  36  are secured to upper plate  22  with bolts  56 . Adjustment housing  53  is secured along the periphery to the bottom side of the upper plate with bolts  58 . Lift wheel  50  is operable from the top through a slot  60  in upper plate  22  which tapers downward from an outer surface  62  to an inner surface  64 . The lift wheel includes a plurality of flats  66  and grooves  68  alternating along the outer surface to provide an improved gripping surface. Lift wheel  50  is secured to shaft  52  with a screw  70  that is inserted through a hole  72  traversing from the outer surface to the center of the lift wheel. 
     Fine adjustment mechanism  49  also includes a gauge  74  extending upward and terminating within upper plate  22  yet still below upper surface  23 . The gauge has a plurality of dashes  76  which may correspond to the pitch of the fine adjustment screw threads or the actual height adjustment as indicated by a reference mark such as a baseline  78 . Since the gauge is connected to the fine adjustment mechanism, the gauge rotates to indicate any height adjustment due to rotation of lift wheel  50 . Further, gauge  74  may be arranged to rotate the fine adjustment mechanism or may be an adjustable scale which cannot rotate the fine adjustment mechanism but is rotated with the fine adjustment mechanism to indicated height adjustments as disclosed in U.S. patent application Ser. No. 11/541,761 by Hummel which is incorporated by reference herein. 
     Upper plate  22  also includes a coarse adjustment hole  80  that allows access to a lift-handle engaging member  82  located on the carriage assembly ( FIG. 7 ). A router plate  84  includes a central hole  86  of a size adapted to allow router bit  33  to pass through and fits within a central hole  88  in upper plate  22 . Central hole  88  in the upper plate includes ledges  90  which the router plate rests on. 
     Referring to  FIGS. 3 and 4 , carriage assembly  42  includes a lift-handle engaging hole  92  and a portion of lift-handle engaging member  82  visible. Further, router  32  is held in place with clamps  94 . The carriage assembly also includes an aperture  96  in the side of the carriage assembly proximate and directed towards coarse threaded rod  48 . A member  98  is located within the aperture to selectively engage and disengage the coarse threaded rod as seen in greater detail in  FIG. 8 . 
       FIGS. 5 and 6  illustrate the details of fine adjustment mechanism  49 . Lift wheel  50  has a diameter D which is larger than slot  60 . In a preferred embodiment, diameter D is in the range of 2 to 5 inches and preferably 3.5 inches, although any diameter D is suitable depending upon the dimensions of upper plate  22  and the desired fine adjustment sensitivity. Further, the lift wheel is located such that the lift wheel outer surface is below outer surface  62  by a gap G. Although gap G may be any suitable distance, the gap is preferably large enough to prevent the lift wheel from interfering with router operation as well as small enough to allow the user to easily operate the lift wheel. 
     In accordance with another main feature of the present invention, fine adjustment mechanism  49  includes a pair of gears  100  and  102  arranged perpendicular to each other. In particular, gear  100  surrounds shaft  52  at an end opposite lift wheel  50  and gear  102  surrounds a central shaft  104  of gauge  74  at an end opposite upper surface  23 . The gears are engaged to their respective shaft with the interaction of splines  106  on the shafts and splines  108  on the inside surface of each gear. Further, gears  100  and  102  each terminate in head portions  110  and  112 , which again have a splined outer surface  114  for rotational engagement with each other. Gears  100  and  102  have an outside diameter A in the range of approximately 0.5 to 1.5 inches and preferably have an outside diameter of approximately 1 inch. Accordingly, the fine adjustment mechanism utilizes a ratio in the range of 1 to 1 and 1 to 5, with a preferred ratio of approximately 1 to 3. Finally, gear  100  is spaced apart, or offset, from lift wheel  50  by a distance in the range of 1.5 to 3.5 inches and preferably 2.5 inches. Although the specific dimensions and ratios listed above correspond to the preferred embodiment, one skilled in the art should immediately recognize that these dimensions are only indicative of one embodiment and that the dimensions and ratios may be varied dramatically for various embodiments without departing from the spirit and scope of the invention as claimed. 
     Both of gears  100  and  102  are contained completely with in a cavity  116  of adjustment housing  53 . A washer  118  is located intermediate cavity  116  and gear  100  and a snap ring  120  is located intermediate cavity  116  and gear  102 . In addition, each shaft ( 52  and  104 ) rotates within a bushing  122  and  124 , respectively. Gauge  74  preferably includes two components which are visible to the user, shaft  104  and a ring  126  which has previously described dashes  76 . Gauge  74  is spaced above bushing  124  by washer  128 , which can be replaced with an o-ring or other suitable ratcheting type mechanism to allow the gauge to rotate upon movement of the fine adjustment mechanism while allowing the gauge to be rotated without any movement of the fine adjustment mechanism as described above. 
     In accordance with yet another main feature of the present invention, a first end of a fine adjustment threaded rod  130  is formed within a stop  132 , which is in turn secured within terminating end  134  of gear  102 . Since fine adjustment threaded rod  130  is fixedly secured to gear  102 , the fine adjustment threaded rod rotates to the same extent terminating end  134  of gear  102  rotates. Thus, rotation of gear  102 , gauge  74 , and fine adjustment threaded rod  130  are equal at all times. Further, since lift wheel  50  is rotationally connected to gear  100 , which is in turn rotationally connected to gear  102 , the rotation in lift wheel  50  and gear  100  are equal to gear  102 , gauge  74 , and fine adjustment threaded rod  130  at all times. 
     A second end, opposite the first end, of fine adjustment threaded rod  130  is arranged to be engaged with coarse threaded rod  48 . Specifically, the fine adjustment threaded rod is threaded into a threaded opening  136  in the top of coarse threaded rod  48 . The threaded opening also has a bottom wall  139 . A stop  138 , which may be a snap-ring or similar device, is located at the upper end of coarse threaded rod  48  and extends radially outward there from. Stop  138  is arranged to limit the travel of the fine adjustment screw by preventing stop  138  from traveling out of cavity  116 . Coarse threaded rod  48  moves through a hole  140  in the bottom of adjustment housing  53  that is large enough for the coarse threaded rod to pass through, but not stop  138 . Thus, the fine adjustment mechanism travel is limited in one direction by contact between stop  138  and cavity  116  and in the opposite direction by contact between stop  132  and coarse threaded rod  48  or contact between fine adjustment threaded rod  130  and bottom wall  139 . 
       FIGS. 7 and 8  are detailed illustrations of the coarse adjustment mechanism. Carriage assembly  42  includes lift-handle engaging hole  92  with a bushing  142  set below lift-handle engaging member  82 . The engaging member is attached to the carriage assembly with a bolt  144  and an edge  146  of the engaging member is arranged to partially block hole  92 . Hole  92  extends downwards past aperture  96  and includes a second bushing  148  below the aperture. The coarse adjustment mechanism essentially includes member  98  with an engagement end  150  and a spring-biased device  152  located in a cavity  154 . Engagement end  150  is preferably threaded to prevent movement of the carriage assembly relative to coarse threaded rod  48 , but may include any suitable connection which prevents relative movement between the rod and the engagement member. Spring-biased device  152  is preferably a pair of springs which force the engagement end of member  98  into engagement with coarse threaded rod  48  in the resting position. The coarse threaded rod also includes a pair of bushings  156 , one on each side of aperture  96  which help to resist horizontal deflection of the coarse threaded rod due to the spring biased device. 
     Referring to  FIG. 9 , a lift-handle  158  is preferably L-shaped with a substantially cylindrical rod  160  and a grip  162  perpendicular to the substantially cylindrical rod and located at the end opposite a lower end  164 . The lower end includes a recessed portion  166  which permits the lift-handle to rotate within engaging hole  92  and is specifically located proximate lift-handle engaging member  82 . The lift-handle also includes an engaging portion  168  with a flat side  170  ( FIG. 11 ) and a rounded side  172 . Since lift-handle engagement member  82  partially blocks engaging hole  92 , flat side  170  must be aligned with edge  146  of the engagement member to allow the lift-handle to be inserted within engaging hole  92 . Thus, the lift handle can only be inserted in one orientation (described above) until recessed portion  166  is even with edge  146  of engagement member  82 . 
     Having described the structure of the preferred embodiment, a preferred method of operation will be described in detail and should be read in light of  FIGS. 1  though  18  and particularly  FIGS. 9 through 18 . 
       FIGS. 9 through 13  illustrate the operation of the coarse adjustment mechanism to provide rapid vertical adjustment of carriage assembly  42 . Lift handle  158  is inserted in the direction associated with arrow  174  through coarse adjustment hole  80  in upper plate  22  and lift-handle engaging hole  92  in carriage assembly  42 . As discussed above, flat side  170  of the lift-handle must be aligned with edge  146  and recessed portion  166  is aligned with edge  146  when the lift handle is completely inserted. 
       FIG. 10  is a view of the lift handle engaging portion being inserted in the direction associated with arrow  174  within engaging hole  92 , and flat side  170  aligned with edge  146  and proximate member  98 . Next,  FIG. 11  illustrates rotation of the lift handle in the direction associated with arrow  176 . When lift handle  158  is rotated, rounded side  172  is located proximate member  98  and the increased radius of the rounded side, in comparison to the flat side, forces member  98  in the direction associated with arrow  178  which compresses spring-biased device  152  and eliminates any contact between engagement end  150  and coarse threaded rod  48 . Thus, anytime that rounded side  172  is in contact with member  98 , the larger radius will disengage engagement end  150  and coarse threaded rod  48  to allow for rapid vertical movement and prevent rapid vertical movement when flat side  170  is proximate member  98 . 
     Next,  FIG. 12  illustrates the rapid vertical movement. In particular, the user pulls grip  162  of handle  158  in the direction associated with arrow  180 . Since, handle  158  has been rotated to allow rapid vertical movement, engaging portion  168  is located below lift-handle engaging member  82  and cylindrical rod  160  is located above the lift-handle engaging member. Further, this arrangement means that any vertical movement of the lift handle is directly imposed on the carriage assembly. Accordingly, movement of handle  158  in the direction associated with arrow  180  a distance B moves carriage assembly  42  in the direction associated with arrow  180  a distance also equal to distance B.  FIG. 13  illustrates the removal of the lift handle after the rapid vertical movement is accomplished. To remove the lift handle, the user rotates the lift handle in the direction associated with arrow  182 , which is opposite of the direction associated with arrow  176 , until flat side  170  is located proximate member  98 . The user then pulls lift handle  158  in the direction associated with arrow  183  to remove the lift handle from lift-handle engaging hole  92  and coarse adjustment hole  80 . 
       FIGS. 14 through 18  illustrate the operation of the fine adjustment mechanism to provide detailed vertical adjustment of carriage assembly  42 .  FIG. 14  illustrates a user&#39;s finger  184  traversing slot  60  and providing a displacement in the directions associated with arrows  186 . The displacement in the directions associated with arrows  186  is translated into a rotation of lift wheel  50  and shaft  52  in the directions associated with arrows  188 .  FIGS. 15 and 16  illustrate movement of the fine adjustment mechanism in the upwards direction. In particular, movement  5  of lift wheel  50  in the direction associated with arrow  190  rotates shaft  52  and gear  100 , which in turn rotates gear  102  and fine adjustment threaded rod  130 . The rotation then imparts a perpendicular rotation of the fine adjustment threaded rod in the direction associated with arrow  192  which, being fixed in the vertical direction and threaded within the coarse threaded rod, forces coarse threaded rod  48 ,  10  carriage assembly  42 , router  32 , and router bit  33  upwards in the direction associated with arrow  194 . The vertical movement of the router bit is smaller than the rapid vertical movement of the coarse adjustment mechanism and is indicated at distance C. 
       FIGS. 17 and 18  illustrate movement of the fine adjustment mechanism in the downwards direction. In particular, movement of lift wheel  50  in the direction associated with arrow  196  rotates shaft  52  and gear  100 , which in turn rotates gear  102  and fine adjustment threaded rod  130 . The rotation then imparts a perpendicular rotation of the fine adjustment threaded rod in the direction associated with arrow  198  (opposite the direction of arrow  192 ) which, being fixed in the vertical  20  direction and threaded within the coarse threaded rod, forces coarse threaded rod  48 , carriage assembly  42 , router  32 , and router bit  33  downwards in the direction associated with arrow  200 . The vertical movement of the router bit is smaller than the rapid vertical movement of the coarse adjustment mechanism and is indicated at distance E. Accordingly, the user can operate the fine adjustment mechanism through the table plate opening free of any additional components or tools. 
     Having described the structure and operation of the first embodiment, only those portions of the second embodiment which are different from the first embodiment are described in detail. Likewise, similar numerals refer to similar parts throughout the various embodiments. 
       FIG. 19  illustrates a second embodiment which replaces threaded rod  48  of the first embodiment with a rod  201  having ribs  202 . Ribs  202  are annular rings arranged parallel to one another along the length of the rod. Similar to the first embodiment, engagement end  150  of member  98  prevents relative movement of carriage assembly  42 . However, in the second embodiment, engagement end  150  prevents relative movement of the carriage assembly by biasing teeth  204  in the direction associated with arrow  206  such that teeth are located between ribs  202 . Since the teeth are located between the ribs and the teeth are vertically locked in place due to their placement within aperture  96 , ribs  202  and rod  201  are also vertically locked in place. Accordingly, the ribbed rod functions identical to the threaded rod without the need for a helical thread throughout the length. 
     Thus, lift assembly  20  provides a mechanism for fine vertical adjustment of a rotary cutter which is also conveniently combined with a fine adjustment gauge and a coarse adjustment mechanism for rapid vertical adjustment. The fine vertical adjustment mechanism is located below upper surface  23  so that it does not interfere with cutter operation, very simple and effective and conveniently ties directly into the coarse adjustment mechanism, thereby producing a very streamlined mechanism. 
     It will be evident to one skilled in the art that a variety of changes can be made that are within the spirit and scope of the present invention. For instance, the fine adjustment mechanism may be configured as an independent unit for use without a coarse adjustment mechanism or configured for use with a different fine adjustment mechanism. 
     Accordingly, the router lift assembly is an effective, safe, inexpensive, and efficient device that achieves all the enumerated objectives of the invention, provides for eliminating difficulties encountered with prior art devices, systems, and methods, and solves problems and obtains new results in the art. 
     In the foregoing description, certain terms have been used for brevity, clearness, and understanding; but no unnecessary limitations are to be implied therefrom beyond the requirement of the prior art, because such terms are used for descriptive purposes and are intended to be broadly construed. 
     Moreover, the description and illustration of the invention is by way of example, and the scope of the invention is not limited to the exact details shown or described. 
     Having now described the features, discoveries, and principles of the invention, the manner in which the router lift assembly is constructed and used, the characteristics of the construction, and the advantageous new and useful results obtained; the new and useful structures, devices, elements, arrangement, parts, and combinations are set forth in the appended claims.