Patent Abstract:
A manually operable ceiling tile cutting tool has a blade slidably retained in one of several pockets or slots in the tool. Each of the pockets formed by complementary grooves and ridges defines a flat blade receiving surface, is a differing predetermined distance from a bottom of the tool which corresponds to a standard dimension in a ceiling tile relief for a suspended ceiling.

Full Description:
This application claims the priority of provisional application No. 60/903,568, filed Feb. 27, 2007, the contents of which are incorporated herein by reference. 
    
    
     This invention relates to hand tools and, more particularly, to an adjustable ceiling tile relief cutter that utilizes a slidable blade in a housing capable of positioning the blade at a plurality of predetermined distances from a flat surface. 
     BACKGROUND OF THE INVENTION 
     Ceiling tiles for use on suspended ceilings utilized in offices, schools, public and residential buildings and the like, sit on a horizontally oriented framework below a ceiling. Often it is desirable to provide a relief around the edge of ceiling tiles to allow the edge of the tile to nest on the framework with the exposed bottom face of the tile extending below the framework. Hand tools adaptable for cutting such relief in ceiling tiles have been disclosed. However, the adjustable tools have been analog in nature, i.e., adjustable by sliding the blade along a restraint, often having a scale thereon, and affixing that blade anywhere along the restraint. However, in most instances, architectural designs of ceiling tiles have a few set dimensions for such tile reliefs. 
     A need has arisen for a manually usable hand tool capable of cutting ceiling tile reliefs at an easily adjustable multiple of standardized dimensions. 
     It is therefore an object of the present invention, generally stated to provide an improved manually operable ceiling tile relief cutter. 
     Another object of the invention is the provision of an adjustable manually operated ceiling tile relief cutter having a plurality of discrete and distinct operating positions to provide a plurality of differing standardized relief cuts. 
     SUMMARY OF THE INVENTION 
     The invention resides in a tool for manually cutting relief surfaces adjacent ceiling tile edges. The tool comprises: a body assembly including top and bottom members. One of the top and bottom members includes a first groove forming an indent in said one member, having a substantially flat nadir (i.e., bottom surface), and extending across a surface thereof forming an inner surface of the tool. The other of the top and bottom members includes a first rib, forming a detent in the other member, having a substantially flat apex and extending across a surface thereof forming an inner surface of the tool. A blade (also referred to as a knife) is sized to slidably fit on the groove nadir, on one side thereof, and be retained thereon by the apex of the complementary rib on an opposing side thereof. Fastener means hold the top and bottom members together and slidably retain the blade thereon, and a first distance from the blade to a working outer surface of the tool is at least one dimension corresponding to a relief on a ceiling tile. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The invention may best be understood from the following detailed description of currently preferred embodiments thereof taken in conjunction with the accompanying drawings wherein like numerals refer to like parts, and in which: 
         FIG. 1  is a fragmentary perspective view of a ceiling tile, constructed in accordance with a first embodiment of the present invention with the manually operated ceiling tile relief cutter shown positioned on a flat surface and cutting a relief surface. 
         FIG. 2  is a top quarter perspective view of the ceiling tile relief cutter shown in  FIG. 1  constructed for two differing relief cutting dimensions; 
         FIG. 3  is a bottom plan view of a top member of a second embodiment of the ceiling tile relief cutter of the present invention showing four differing slots thereon; 
         FIG. 4  is a front elevational view of the second embodiment top member shown in  FIG. 3 ; 
         FIG. 5  is an end elevational view of the second embodiment top member shown in  FIG. 3 ; 
         FIG. 6  is a top plan view of the bottom member of the second embodiment of the present invention showing a slidable razor, specifically a double-edged knife blade, positioned in one of the slots; 
         FIG. 7  is a front perspective view of the bottom member of the second embodiment shown in  FIG. 6 ; 
         FIG. 8  is an end elevational view of the bottom member of the second embodiment shown in  FIG. 6 ; and 
         FIG. 8   a  is an enlarged fragmentary detail elevational view of the bottom member of the second embodiment showing a hex head bolt molded into the member. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIGS. 1 and 2 ,  FIG. 1  shows a first embodiment of the multiple position adjustable relief cutting tool, generally indicated at  10 , constructed in accordance with the present invention with a blade  11  (not shown) ( FIG. 2 ) sticking into the side of a ceiling tile shown generally at  12 , cutting a second horizontal relief surface  13  on the tile by the manual manipulation of the user generally at  14 . Both the ceiling tile and the adjustable tool are lying on a flat surface. A first cut  15  has already been made with the ceiling tile standing on its end. 
       FIG. 2  is a perspective view of the ceiling tile relief cutter  10  shown in  FIG. 1 . It has been rotated 90 degrees so one can see the commercially obtainable double edged knife blade  11  sticking out of the holder. As noted in  FIG. 2 , the distance (D) of the blade from the bottom of the tool as shown differs from the distance (d) of the blade from the bottom of the tool if the blade was positioned at 90 degrees in the tool to where it is presently. This difference gives the first embodiment of the present invention two differing cutter heights, 0.375 inch (D) and 0.450 inch (d), for creating reliefs of differing sizes, or a relief having one side of one dimension and another relief cut 90 degrees to that side of the second dimension. The bottom member  17  of the generally rectangular tool includes on its top surface two rectangularly cross sectional shaped grooves or slots  20  and  21 , respectively, positioned at 90 degree angles thereto both perpendicular to the tool side surfaces  17   a ,  17   b  (not shown),  17   c  (not shown) and  17   d  and extending across the center of the tool. In the first preferred embodiment  10 , grooves  20 ,  21  are also known as indents and the flat bottom surface of grooves  20 ,  21  is defined as the nadir, respectively, thereof. A bore (not shown in  FIGS. 1 and 2 , but see  122 ,  122   a  in the second embodiment) vertically through the center of the tool keeps the upper  16  and lower  17  pieces (i.e., the to  16  and bottom  17  members) together. A chamfer (also not shown in  FIGS. 1 and 2  but see  123  in the second embodiment) at the bottom of the aperture  122  allows a flathead bolt  24  to be positioned upwardly therethrough and retained therein. The top member  16  is also generally rectangular, preferably 2 5/16×2 5/16 inches and includes a pair of rectangularly cross section shaped ridges or ribs forming detents  25 ,  26  extending from the bottom surface (not shown) thereof positioned at 90 degree angles to each other that matingly engage and fill the complementary rectangular grooves  20 ,  21 , in the bottom member  17  of the tool. The bottom flat surface of ridges or ribs forming detents  25 ,  26  is defined as the apex thereof. The top  16  and bottom  17  members together are preferably 1 inch thick. A wingnut  27  holds the bolt  24  in position and tightens the top against the bottom. The double edged blade  11  has an elongate slot (not shown in  FIG. 2  but see  110   a  in the second embodiment) or aperture centrally therealong which the bolt  24  is positioned through to allow the blade  11  to slide completely into the tool body  10  when not in use. Rotating the wing nut  27  on bolt  24  tightens and loosens the top and bottom members against one another and, depending on how tight the wing nut is turned, selectably slidably retains the knife blade in the tool. 
       FIGS. 3-8  show the insides of the top  160  and bottom  170  pieces or members of a second embodiment  100  of the present invention with the outside surfaces being similar in shape to the first embodiment  10 , that is constructed to place the cutting blade  110  at four differing size heights from the bottom of the tool, the 0.375 and 0.450 slots of the first embodiment plus 0.250 and 0.500 slots. Two of the slots  120 ,  121  are cut at 90 degree angles similarly to the two  20 ,  21  in the first embodiment, although the diagonal sides of the tool of the second embodiment  171 ,  172 ,  173  and  174  are larger than those shown in the first embodiment. Also, the second pair of slots  127 ,  128  in the top member  160  and the bottom member  170  are shown, again at 90 degrees to each other, but oriented 45 degrees from the first two slots  120 ,  121 . 
     The second embodiment  100  is built similarly to the first embodiment  10  with the addition of the two additional slots  127 ,  128 . In order to keep the orientation of the four sets of ridges and grooves, at least one post and in this embodiment, two posts  132 ,  133  are positioned to extend downwardly from the bottom surface of the top member  160  of the tool as locating pins into circular recesses  134 ,  135  in the top surface of the bottom  170  of the tool. The tool may be made of wood, molded plastic, die or sand cast metal, PTFE (Teflon) or the like. 
     Additionally, as shown in  FIGS. 7 and 8 , the chamfer in the bottom of the central hole  122  may be round to accept a flat head bolt, in this case ⅛×1 3/16 inches long, or may also be hexagonal in shape shown at  223  in order to accept a hex head bolt  124  and the hexagonal cut out will maintain that bolt in position to prevent it from rotating in the tool. The hex head bolt may be removable or permanently molded into the tool as shown in  FIG. 8A . 
     Thus, four differing height ceiling relief dimensions are provided in the second embodiment  100  of the tool and the double edged blade  110  may be slidably retained in any of those grooves or indents both wholly within the tool during non-use and slidable positioned party out the side of the tool a set distance and fastened therein by tightening the wing nut on the bolt post, the same as shown in  FIGS. 1 and 2 , to provide a desired depth of cutting relief. The rectangular ridges  140 ,  141 ,  142 ,  143  on the top member  160  of the tool matingly and complementarily engage the rectangular grooves  150 ,  151 ,  152 ,  153  in the bottom member  170  of the tool so as to provide a secure mounting for the blade  110 , in whichever groove the blade is positioned. As shown in all the figures, the nadir or bottom surface of each of the grooves, such as shown at  150 , accommodates the knife  110  to allow slidable mounting and fastening of the knife in each respective groove. As shown in  FIG. 7 , a shim  180 , or shims of varying thicknesses may be utilized in the grooves under a blade to modify the heights of the blade in use. The top  160  and bottom  170  members fit together in ridge in groove fashion similarly to the fit of the top  16  and bottom  17  members of the first embodiment shown most clearly in  FIGS. 1 and 2 . A wing nut and bolt (not shown) identical to wing nut  27  and bolt  24  are utilized to facilitate fastening the members together. As in the first embodiment, tightening the wing nut on the bolt eventually changes the knife mounting from slidable to fixed, as desired by a user. 
     In Operation 
     Further to the explanation in the first paragraph of the detailed Description, in use, the second embodiment  100  of the present invention has exactly the same function as the first embodiment  10  with the exception that the diagonally cut chamfer type sides  171 ,  172 ,  173 ,  174  are larger creating an octagon shape tool  100 . In any case, the face of the tool out of which the blade  110  is extended is positioned flush against the side of the ceiling tile  12  ( FIG. 1 ) with both being positioned on a flat surface. The tool is drawn across the length or width of the ceiling tile, depending upon which surface of the ceiling tile the relief is to be formed. After a single cut such as  13  is made, the ceiling tile is positioned on its end surface perpendicular to the flat surface on which the tool is residing and a second relief cut such as  15  is made, as appropriate to provide a proper size relief for the ceiling tile  12 . 
     While a new and improved manually operable adjustable ceiling tile relief cutting tool has been shown and described, it will be apparent to those skilled in the art that many changes and modifications may be made without departing from the true spirit and scope of the present invention. It is the intent of the appended claims to cover all such changes and modifications which fall within the true spirit and scope of the invention.

Technology Classification (CPC): 4