You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
CROSS REFERENCE TO RELATED APPLICATIONS 
     Not applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     FIELD OF THE INVENTION 
     The present invention relates to a device for leveling and spacing tiles. 
     BACKGROUND OF THE INVENTION 
     It is a problem in the art, when laying tiles on a surface, to equally level the tiles to be coplanar and space the tiles. This is applicable to laying tiles on surfaces in general, including floors, walls, ceilings, and on other surfaces which can support tiles. The term tiles should be understood as including panels, sheets, boards, paving stones, and other materials capable of being laid out in a pattern. 
     SUMMARY OF THE INVENTION 
     From the foregoing, it is seen that it is a problem in the art to provide a device meeting the above requirements. According to the present invention, a device is provided which meets the aforementioned requirements and needs in the prior art. Specifically, the device according to the present invention provides a device for leveling and spacing tiles. 
     The present invention provides a two part device for use in leveling and spacing tiles. The device includes two parts, a rotatable portion and a fixed portion. The rotatable portion referred to hereinafter as a knob-cam includes two helical diametral opposed frontal action cams, a domed knob portion, a central opening, a knurled or ribbed portion and an annular surface portion. The fixed portion referred to hereinafter as a hook-base includes a base with flat surfaces for seating the tiles and ribs for spacing and separating tiles, a neck portion extending through a slot in the knob-cam and double blades which will engage with the double cam. The installation does not require tools. 
     In use, the base portion is inserted from the side underneath the tiles and spaced by the ribs in between the tiles. After insertion of the base portion will be installed all surrounding tiles, and then the knob-cam will be inserted. The neck portion extends upwardly above the tiles, and is adapted to be broken away after the adhesive sets upon application of sufficient upward force or sideways force. The knob-cam is placed against the tiles such that the neck extends through the key opening. The knob-cam includes two diametral opposed frontal action cam surfaces that engage the blades when the knob-cam is rotated. The knob-cam is rotated until the tiles are temporarily secured between the knob-cam and the base. Adhesive is used to permanently secure the tiles on the surface. The device evenly holds the tiles in correct position during the curing process. When the adhesive is set, the neck and hook portions can be removed by breaking them away from the base portion. Clamping is provided from opposite directions, fastening the tiles in such a way that the upper surface of the tiles will be coplanar, having correct reciprocal positions. Optionally the device may be used in conjunction with regular spacers, wider than the ribs and the device is providing just clamping force. 
     Other objects and advantages of the present invention will be more readily apparent from the following detailed description when read in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a device for use in leveling and spacing tiles, the device having a knob-cam portion and a hook-base portion shown separated prior to assembly, and with some tiles in place with the hook-base portion. 
         FIG. 2 a    is a perspective view of the device of  FIG. 1 , showing an assembly step. 
         FIG. 2 b    is a perspective view of the device of  FIG. 1 , showing another assembly step. 
         FIG. 2 c    is a perspective view of the device of  FIG. 1 , showing an assembled configuration. 
         FIG. 3 a    is a perspective section view of the device in the position shown in  FIG. 2 b    wherein the hook from the hook-base portion is inserted through a key opening of the knob-cam portion. 
         FIG. 3 b    is a view similar to  FIG. 3 a   , and wherein the knob-cam portion has been rotated and locked into place with the hook-base portion, consequently clamping tiles. 
         FIG. 4 a    is a perspective view of the knob-cam portion and the hook-base portion of  FIG. 1 , prior to assembly, and with the tiles omitted for the sake of clarity. 
         FIG. 4 b    is a perspective view of the device having the knob-cam portion and the hook-base portion of  FIG. 4 a   , following assembly and tightening, and with the tiles omitted for the sake of clarity. 
         FIG. 5 a    is a front elevational view of the hook-base portion. 
         FIG. 5 b    is a top elevational view of the hook-base portion shown in  FIG. 5   a.    
         FIG. 5 c    is a right side elevational view of the hook-base portion of  FIG. 5   a.    
         FIG. 6 a    is a perspective view of the hook-base portion of  FIG. 5 a   , for use with four tiles. 
         FIG. 6 b    is a perspective view of a second embodiment of the hook-base portion, for use with three tiles. 
         FIG. 6 c    is a perspective view of a third embodiment of the hook-base portion, for use with two tiles. 
         FIG. 7 a    is a front elevational view of the knob-cam portion of  FIG. 1 . The radial valleys have been omitted for the sake of clarity 
         FIG. 7 b    is a top elevational view of the knob-cam portion of  FIG. 7 a   . The radial valleys have been omitted for the sake of clarity 
         FIG. 7 c    is a side elevational view of the knob-cam portion of  FIG. 7 a    as viewed from the right of  FIG. 7 a   . The radial valleys have been omitted for the sake of clarity 
         FIG. 8 a    is a perspective view of the knob-cam portion of  FIG. 1  showing a knurled portion. The radial valleys have been omitted for the sake of clarity 
         FIG. 8 b    is a perspective view of another embodiment of the knob-cam portion, having a plurality of separated rib portions for manual gripping and turning. The radial valleys have been omitted for the sake of clarity 
         FIG. 9 a    is a side elevational view of a further embodiment of a knob-cam portion, having a pair of cams, and pairs of radial valleys. 
         FIG. 9 b    is a top elevational view of the knob-cam portion of  FIG. 9A , showing the pair of cams, together with the pairs of radial valleys. 
         FIG. 9 c    is an enlarged section of a portion of one of the cams, showing a close-up view of the radial valleys and teethed stepped profile. 
         FIG. 9 d    is an enlarged section view of an assembly formed by a blade and a cam, showing a close-up view of a blade engaging with one of the radial valleys. 
         FIG. 10  is a perspective view of a further embodiment of a knob-cam portion which can be used in the device of  FIG. 1 , wherein the cams have textured or smooth surfaces instead of teethed stepped surfaces. 
         FIG. 11  is a perspective view of a further embodiment of a knob-cam portion which can be used in the device of  FIG. 1 , wherein the cams are shown, as well as a plurality of spaced ribs for facilitating manual gripping and turning. 
         FIG. 12 a    is a side sectional view showing a hook-base portion shown sliding under the tile which is previously disposed on adhesive, and a floor which is covered by the adhesive. 
         FIG. 12 b    is an enlarged sectional view of the downward oriented chamfer of the hook-base, wherein for the sake of clarity the hatching has been removed. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A device  1000  according to the present invention is shown in  FIG. 1 , depicting a knob-cam portion  2000  and a hook-base portion  3000 . The hook-base portion  3000  includes a hook  3100  and a base  3200 . Three tiles  4100  are shown mounted against the base  3200  of the base portion  3000 , and the tiles  4100  are shown as having side walls  4130 . There is room for a fourth tile  4100  against the base portion  3200 , which has been omitted for the sake of illustration. The device  1000  is provided for use in leveling and spacing tiles. The knob-cam portion  2000  is shown separated from the hook-base portion  3000 , prior to assembly. 
     As shown in  FIG. 1  and in  FIGS. 4-6 , the knob-cam portion  2000  has a domed knob shape  2300  and includes a pair of frontal cams  2100  (including a left cam  2110  and a right cam  2120 , the left cam  2110  having an engaging edge  2111 , a helical teethed and stepped cam profile  2112 , an uppermost edge  2117 , and an outer wall  2118 . The right frontal cam  2120  has an engaging edge  2121 , a helical teethed and stepped cam profile  2122 , an uppermost edge  2127 , a central opening  2200 , a central key hole  2210 , a central key slot  2220 , an outer wall  2128 , a knurling  2330  formed by alternating raised portions  2331  and recesses  2332 , a surface  2310 , a surface  2320 , and an annular seating bottom surface  2350 . 
     The hook-base portion  3000  is formed by a hook  3100  and a base  3200 . The hook  3100  has a rounded key  3130  formed by a tongue  3133  which has a central hole  3131  with a chamfer  3132 , a pair of engaging blades  3110  and  3120 , and a neck  3140  which has two side surfaces  3141  and  3142 . The neck  3140  is connected to the base  3200  by breakable portions  3150 , consisting in the edge  3151  and the corners  3152  which are disposed at a bottom region of the neck  3140 . The base  3200  has a supporting flat wall  3210 , a plurality of ribs  3220 , each of the ribs  3220  respectively including a slanted portion  3222  and a top portion  3221 , and a plurality of flat portions  3211 . The plurality of flat portions  3211  respectively receive bottom corner portions of the tiles  4100  which are to be separated by the ribs  3220 . The flat portions  3211  are provided between adjacent ones of the ribs  3220 . 
       FIG. 2 a    is a perspective view of the device of  FIG. 1 , showing an assembly step in which the knob-cam portion  2000  is brought toward the upper surfaces  4110  of the tiles  4100  in the direction shown by the dashed arrow D 1 . 
       FIG. 2 b    is a perspective view of the device of  FIG. 1 , showing the next assembly step in which the hook  3100  of the hook-base portion  3000  extends through the key opening  2200  of the knob-cam portion  2000  and the blades  3110  and  3120  extend above the cams  2110  and  2120  such that the engaging edges  2111  and  2121  of the cams are below the blades portions  3110  and  3120 . The annular surface  2350  is touching the upper portion of tiles  4110 . The knob-cam portion  2000  is about to be rotated in the direction shown by the dashed arrow R 1 , the shown mechanism is unlocked and does not provide residual force. 
       FIG. 2 c    is a perspective view of the device of  FIG. 1 , the shown assembly mechanism is locked. By rotating the knob-cam  2000 , the frontal cams act as circular wedges and will provide the clamping residual force between the knob-cam  2000  and the tiles  4100 . When the knob-cam is rotated beyond the first engaging position, the blades  3110  and  3120  will start climbing on the cams&#39; teethed and stepped profiles  2112  and  2122 , generating click sounds which can quantify the residual force necessary for proper clamping. It is important that the rotation is stopped after few clicks, to prevent breakage of the neck  3140  along the breakable portions  3151  and  3152 . The clamping effect will self level the upper surfaces of the tiles  4110  until they all touch the annular surface  2350  which creates a datum plane for leveling. The clamping effect is similar to the force provided by the jaws from a vice. The self-leveling effect propagates to all adjacent tiles found under the knob-cam  2000 . When the adhesive securing the tiles  4100  has been sufficiently set, the hook  3100  is adapted to be broken by fracture and can be removed, either by further rotation of the knob-cam portion  2000  or by striking of the hook  3100  in a sideways direction. The breaking edges  3152  and  3151  will be below the upper surface of tiles  4110  and will be covered later with grout and hidden. The hook portion  3100  can then be removed and the knob-cam portion  2000  can be reused. 
       FIG. 3 a    is a perspective section view of the device  1000  in the position shown in  FIG. 2 b    wherein the hook  3100  of the hook-base portion  3000  is inserted through the key opening  2200  of the knob-cam portion  2000 . The mechanism is shown unlocked. Also in this view, the base portion  3200  has a bottom seating wall  3210 . The remaining parts are as numbered and described in the foregoing. 
       FIG. 3 b    is a view similar to  FIG. 3 a   , and wherein the knob-cam portion  2000  has been rotated and locked into place between the blades portion  3110  and  3120  and radial valleys  2115  and  2125 , consequently clamping surrounding tiles  4100  in place. The mechanism is shown locked. 
       FIG. 4 a    is a perspective view of the device  1000  with the knob-cam portion  2000  and the hook-base portion  3000  of  FIG. 1 , prior to assembly, and with the tiles  4100  omitted for the sake of clarity. The mechanism is shown unlocked. The remaining parts are as numbered and described in the foregoing. 
       FIG. 4 b    is a perspective view of the device  1000  having the knob-cam portion  2000  and the hook-base portion  3000  of  FIG. 4 a   , following assembly and tightening. The mechanism is shown locked. Here the tiles  4100  have been omitted for the sake of clarity. 
       FIG. 5 a    is a front elevational view of the hook-base portion  3000 , showing the hook  3100 , the neck  3140 , and the base  3200 . Here, the base  3200  is shown having a chamfer  3212  and a seating surface  3211 . The central neck  3140  is perpendicular to the base&#39;s flat seating surfaces  3211 . The tongue portion  3130  from the key  3100  is suitable for gripping by the user during the rotation of knob-cam  2000 . The ribs  3220  from the base  3200  have continuous material with no gaps in between. The ribs  3220  provide equidistant spacing between adjacent tiles and can be made in a plurality of colors, each color representing a different spacing distance between tiles. The remaining parts are as numbered and described in the foregoing. 
       FIG. 5 b    is a top elevational view of the hook-base portion  3000  having the seatings surfaces  3211  of the base  3200  as shown in  FIG. 5 a   . The remaining parts are as numbered and described in the foregoing.  FIG. 5 c    is a right side elevational view of the hook-base portion  3000  having the base  3200  shown in  FIG. 5 a   . The remaining parts are as numbered and described in the foregoing. 
       FIG. 6 a    is a perspective view of the hook-base portion  3000  having the base  3200  shown in  FIG. 5 a   , for use with four tiles. 
       FIG. 6 b    is a perspective view of a second embodiment of the hook-base portion  3000  having the base  3200 , for use with three tiles. 
       FIG. 6 c    is a perspective view of a third embodiment of the hook-base portion  3000  having the base  3200 , for use with two tiles. 
       FIG. 7 a    is a front elevational view of the knob-cam portion  2000  of  FIG. 1 , having an annular bottom surface  2350 . Here, the cam  2120  is shown having respective engaging edge  2121  and uppermost edge  2127 . In this view, the cams are shown with smooth surfaces, for the sake of clarity. By providing clamping force, the tiles will self level guided by the datum plane created by the bottom annular portion  2350  of the knob-cam. The knob-cam  2000  can be reused. The remaining parts are as numbered and described in the foregoing. 
       FIG. 7 b    is a top elevational view of the knob-cam portion  2000  of  FIG. 7 a   . In this view, the cams are shown with smooth surfaces, for the sake of clarity. Here, the central key opening  2200  is shown having a central key hole  2210 , a central key slot  2220  and two wing-shaped key slot ends  2221  and  2222 . The central key hole  2210  has a diameter sufficient to accommodate and guide during rotation the neck portions  3141  and  3142  of hook-base  3000 . The two wing-shaped slot ends  2221  and  2222  are sufficiently wide to accommodate passage of the entire width of the hook  3100  of the hook-base portion  3000 . 
       FIG. 7 c    is a side elevational view of the knob-cam portion of  FIG. 7 a    as viewed from the right of  FIG. 7 a   . In this view, the cams are shown with smooth surfaces, for the sake of clarity. 
       FIG. 8 a    is a perspective view of the knob-cam portion  2000  of  FIG. 1  showing a knurled portion  2330 . The remaining parts are as described in the foregoing. 
       FIG. 8 b    is a perspective view of another embodiment of the knob-cam portion  2000 , having a plurality of separated rib portions  2340  for ease of gripping and rotating. The remaining parts are as described in the foregoing. 
       FIG. 9 a    is a side elevational view of a further embodiment of a knob-cam portion  2000  of  FIG. 1 , having an annular bottom surface  2350 . Here, the cam  2120  is shown having respective engaging edge  2121  and uppermost edge  2127 . By providing clamping force, the tiles will self level guided by the datum plane created by the bottom annular portion  2350  of the knob-cam. The knob-cam  2000  can be reused. The remaining parts are as numbered and described in the foregoing. 
       FIG. 9 b    is a top elevational view of the knob-cam portion  2000  of  FIG. 9A , showing the cam  2110  and the cam  2120 , together with the pairs of radial valleys  2115  and  2125 . The pairs of radial valleys facilitate seating and locking of the blade portions  3110  and  3120  during operation. 
       FIG. 9 c    is an enlarged frontal section of a portion of the cam  2120 , showing a close-up view of the teethed stepped radial valleys  2125 . Each of the radial valleys  2125  has a generally scalloped shape, and includes the edges  2121  which prevents the blade portion  3110  and blade portion  3120  from unlocking itself; a valley portion  2124  which cooperates with the edge  2121  to prevent the blade portion  3110  and blade portion  3120  from unlocking itself; and a hill portion  2126  which allows a smooth transition to the next edge  2121  and provide residual force. Each of the radial valleys  2125  has an axial pitch h 1 , measured vertically between two consecutive edges  2121 , and a depth h 1   a  of the valley (which determines the key&#39;s sound pitch intensity during turning). Each of the radial valleys  2125  also has a total blade travel h 1   b  from the bottom of a valley to the next edge  2121 . Each of the radial valleys  2125  has a perimeter pitch p 1  (e.g., a length p 1 ), a distance p 1   a  between and edge  2121  and the bottom of a valley, and a hill p 1   b  which is a distance between the bottom of the valley to the next edge  2121 , measured transversely. As seen in  FIG. 9 c   , the radial valley  2125  has a concave portion  2124  where the locking ramp of the valley is located and a convex portion  2126  which leads smoothly to the next edge  2121 . The cams have axial and frontal action, and the orientation of the edges  2121  from the teethed and stepped profile is in opposite direction from the tiles. 
       FIG. 9 d    is an enlarged section view of an assembly formed by a blade  3120  which looks like a V-Notch and the cam teethed and stepped profile  2122 . The tip edge  3122  and two adjacent sidewalls  3121  seats and engages with the locking valley portions  2124  wherein the edge  2121  and the locking ramp  2124  prevent the tip blades  3122  from unlocking themselves. Upon further urging of the blade portion  3110  during rotation of the knob-cam portion  2000 , the tip  3122  slides upwardly along the hill portion  2126  which forms a smooth transition to the next edge  2121  whereupon the tip  3122  can slide into the next radial valley portion  2125 . In this preferred embodiment, this sharp and central V shape is very effective in engaging with the teethed stepped profile on cams. Because the teeth have a radial pattern, i.e. are radially disposed, the blades  3110 ,  3120  have to engage in a substantially exactly radial manner, and this determines that the sharp blades tips  3122  will be substantially exactly in the middle of the radial valleys  2125  and  2115 . 
       FIG. 10  is a perspective view of a further embodiment of a knob-cam portion  2000  which can be used in the device of  FIG. 1 , wherein the cams  2110  and  2120  have smooth or textured surfaces instead of teethed and stepped surfaces. 
       FIG. 11  is a perspective view of a further embodiment of a knob-cam portion  2000  which can be used in the device of  FIG. 1 , wherein the cams  2110  and  2120  have smooth or textured surfaces instead of teethed and stepped surfaces as well as a plurality of ribs  2340  for facilitating manual gripping and turning. 
     In the foregoing description, the frontal cams have specified surfaces. It is contemplated as being within the scope of the present invention that the frontal surfaces of helical cams can have any of: teethed and stepped surfaces; textured surfaces; or smooth surfaces. This includes teethed stepped surfaces as described above. 
       FIG. 12 a    is a frontal sectional view showing a base portion  3200 , shown sliding into engagement from the side under the tile  4100  in the direction indicated by an arrow D 2 . The tile  4100  is disposed on the adhesive  4200  which is covering the floor  4300 . 
       FIG. 12 b    is an enlarged view of the chamfer  3212  portion. In this view the seating wall  3210  through the seating surface  3211  of the base  3200  is supporting a tile  4100 . The leading edge of the wall  3100  has the downward oriented chamfer  3212 , wherein the chamfer  3212  assists in penetrating the adhesive A along with an arrow labeled D 2  showing a direction of insertion or movement. That is, the chamfer  3212  in this process will push down the adhesive  4200  so as to help rub and clean the lower seating surface  4120  of tile  4100  from the adhesive  4200  in the location adjacent to the base  3200 . In this view, an arrow labeled D 3  shows a direction in which the adhesive A is pushed down by the chamfer  3212 , such that adhesive is cleaned from underneath the tile  4100 , providing a clean supporting surface. 
     The invention being thus described, it will be evident that the same may be varied in many ways by a routineer in the applicable arts. Such variations are not to be regarded as a departure from the spirit and scope of the invention and all such modifications are intended to be included within the scope of the claims. 
     The invention has several preferred embodiments but they are not exclusive. The invention is susceptible of many embodiments, all of which are within the scope of the appended claims. All the details may be substituted by other equivalent elements.

Summary:
A two part device is used in leveling and spacing tiles. The device includes two parts, a rotatable portion called a knob-cam and a fixed portion called hook-base. The hook-base includes ribs for spacing and separating tiles, and a neck portion extending through a slot opening in the knob-cam. In use, the hook-base portion is set down and tiles are laid down and spaced by the ribs of the base portion. The neck portion extends upwardly above the tiles, and is adapted to be broken away upon application of sufficient upward force or sideways force. The knob-cam includes two diametral opposed frontal action cam surfaces that engage portions of the hook when the knob-cam is rotated. The knob-cam is rotated until the tiles are secured between the knob-cam and the hook-base. This clamps the corners or edges of the tiles, making coplanar upper surfaces.