Abstract:
A projection apparatus for projecting the axis of a plumbing fixture or an existing opening in a construction member onto a remote member, for locating an opening to be made in the remote member, has a body having at least a first cylindrical portion with a first diameter ending in a shoulder, the first cylindrical portion having an axis, and a laser pointer constrained in a cavity of the body such that the laser, when activated, projects along the axis. The apparatus is useful for projecting a center point from a plumbing fixture onto a remote member, such as for vent installation, and for aligning openings in construction members for pipes and other conduits. In an alternative embodiment the projection apparatus has a vertical-seeking element associated with the laser pointer, so a vertical line may be determined for an upward-facing open pipe that does not point perfectly vertical, but faces generally upward.

Description:
FIELD OF THE INVENTION 
     The present invention is in the field of hand-held plumbing tools, and has particular application in providing an improved method and apparatus for projecting a center point from one surface to another for providing alignment. 
     BACKGROUND OF THE INVENTION 
     The construction of a new home or other building that is to have running water and or sewage fixtures, or the remodeling of an existing structure where an additional fixture will be installed for water or sewage, requires installation of all the various pipes necessary to carry water from the water supply to the fixtures, and subsequently drain the used water from the fixtures, as well as vent lines and pipes from waste apparatus. The matter of containing and controlling the water supply as it flows through the home or other structure is known in the art as plumbing. In a typical plumbing configuration for a home for example, pressurized water enters the home through a main supply line, usually passing through a water meter, and a portion of the incoming water is then branched off to enter a water heater. The heated water and remaining cold water are then piped to the various fixtures throughout the home. For each fixture within the home to which there is a water supply there must also be water drainage. The used cold or hot water, once passing through the fixture is typically drained into drainage pipes below the fixture, first passing through an S-shaped portion of pipe known as a trap that prevents sewer gas from drifting up through the drain. The used water than drains down, flowing by gravity, into the final sewer line where it is carried away from the home. 
     The drainage pipe attached to each fixture within the home or other structure must also be connected to a ventilation pipe in order to draw air from outside the home or structure to allow for proper gravity-fed drainage of the used water. In a typical plumbing configuration ventilation pipes for several fixtures are interconnected through an array of pipes to a main ventilation pipe, known in the art as a waste and vent stack. The waste and vent stack, connected to the main sewer line, usually extends from below ground level, vertically up through the structure and ultimately through a hole cut in the roof. In the case of buildings or structures with multiple floor levels, it is necessary for the waste and vent stack contained within or behind the walls, to first pass through the floor of each level, up through holes cut into the flooring material and horizontal members of the wooden framing, ultimately passing up through the roof of the structure. The portion of the waste and vent stack that penetrates the roof is known as a roof vent and can be fitted with an air filter, screen, rain shield or some other attachment. 
     In most buildings with running water all of the pipes used to carry water into, through, and away from the building are contained within the framework of the structure, and have a need to run in a vertical or horizontal direction in relation to the framework. The pipes are contained within the framework so that when sheet rock or other wall-covering material is applied to the framework to create walls, the plumbing pipes are hidden within the covered walls and away from view. For a drainage pipe running in a horizontal direction a slope rate, typically ⅛ inch or ¼ inch for each foot of the pipe&#39;s length is incorporated to allow for gravity flow of the drainage water. Vertical vent, supply and drainage pipes typically have no slope rate and run within the walls parallel to the vertical members of the framework. 
     A plumber in conventional art is faced with a cumbersome task when attempting to determine the center point of the holes to be drilled in the framework and other materials of a structure to accommodate all of the various pipes involved. A plumber is required to manually transpose the position of a center point of a fixture where the waste and vent pipe begins, upward through multiple floors if needed, marking the, center point of the new location and making the hole through each surface. In the case of a residential structure the last horizontal portion of framework that a waste and vent pipe needs to travel through before reaching the roof is known in the art as a top-plate, and the plumbing phase that involves marking and cutting the necessary holes and extending the waste and vent pipe up through the top-plate, extending the pipe through the roof is known in the art as the top-out phase. In order to accurately place the center point for holes to be drilled or cut into members of the framework and the roof during the top-out phase, a plumber needs to first determine the center point of the line that the ventilation pipe will follow, the center point of a hole already cut into the top-plate for example, then gain access to the attic using a ladder or some other object. A plumber then needs to hold a plumb line, which is a cord or string with a lead bob or some other weighted material attached to the other end, to the underside of the roof where the new hole is to be drilled or cut in order to determine perpendicularity between the reference center point in the top-plate and the center point of the new hole to be drilled or cut into the roof. 
     When working with vertical drainage or vent pipes, particularly the repair or replacement of existing pipes or fixtures, the starting center point for a vertical line to be projected is typically the center of the insertion hole of a plumbing fixture, such as an elbow section for example, into which the threaded end of a newly installed vertical pipe will be inserted. A problem often encountered when plumbing vertical pipes is the top horizontal edge of the insertion hole of a plumbing fixture such as described is not always exactly perpendicular in relation to the desired vertical line to be projected. For example, to avoid installing a vertical pipe at an undesirable angle, a plumber is required to compensate for the undesirable angle of the plumbing fixture used as the starting reference point. In this example the starting reference point is the center point of the insertion hole into which a vertical pipe will be installed. After manually projecting the desired vertical line from the center point utilizing methods previously described, a plumber must then detach the fixture from any other pipes it may be attached to, correct the undesirable angle by changing the angle of the fixture or attached pipes, and then reattach the fixture at the correct angle so as to allow for the installation of the vertical pipe which follows the desired vertical projected line. 
     A plumber is also required to make holes through the framework of a structure to accommodate all of the horizontal pipes in the plumbing configuration. Projecting the center point of a horizontal plumbing line from one surface to another where holes are to be drilled or cut is also a cumbersome and time-consuming task using conventional methods and apparatus. Since a plumb line cannot be used in this instance, the reference center point where the line begins, the center point of an existing hole or fixture for example, must be manually transposed to new surface by first taking measurements between the starting center point and nearby objects and applying those measurements to the new surface. As previously mentioned all horizontal drainage pipes require a slope to be incorporated into the horizontal path they will follow, adding another complicated step and exacerbating the problem of manually transposing measurements from one surface to another. Other methods of projecting a horizontal line from one surface to another involve the use of vertical or horizontal carpenter&#39;s levels, strings, tape measures, etc., methods that are also cumbersome and time-consuming in conventional art. 
     The methods used to project a vertical or horizontal line from one surface to another has changed little over many years in the art of plumbing, and needs to be greatly simplified for the professional plumber or layman. Much time and money can be saved by such a process that enables a user to quickly and accurately project a center point using less time, effort and tools. 
     What is clearly needed is an improved method and apparatus for projecting a center point that enables the utilization of an existing common plumbing fixture or an existing hole&#39;s center point to provide a starting reference center point, and quickly and accurately projects that center point to another surface for marking. What is also clearly needed is a method and apparatus using center point projectors that compensates for undesirable slopes or angles of holes or plumbing fixtures, thus allowing for easier and more accurate projection of exactly vertical center lines from the starting reference point. Such a method and apparatus in a preferred embodiment should be compatible for use with different standard sizes of plumbing pipe fittings, pipe dimensions, as well as other tools and practices commonly known in the art. It is to these objects and others that the present invention is dedicated, and apparatus and methods are taught herein in enabling detail for accomplishing these ends. 
     SUMMARY OF THE INVENTION 
     In a preferred embodiment of the present invention, a center-point projector for determining location for alignment is provided, comprising a body having at least a first cylindrical portion with a first diameter ending in a shoulder, the first cylindrical portion having an axis; and laser pointer constrained in a cavity of the body such that the laser, when activated, projects along the axis. In some embodiments there is a switch for activating the laser pointer, and the switch may be a push-button switch, normally off. In some embodiments the switch further comprises a flexible, sealable cover. 
     In some embodiments there is a second cylindrical portion sharing the axis of the first cylindrical portion, the second cylindrical portion having a second diameter greater than the first diameter, which allows the device to be used with openings of differing diameters. 
     In another aspect of the invention, in a construction process involving plural members of an assembly, a method for projecting the axis of an opening in a first member onto a second member is provided, comprising steps of (a) positioning a laser projector having a first cylindrical portion with a first diameter ending in a shoulder, the first cylindrical portion having an axis, the laser projector having also a laser pointer constrained in a cavity of the body such that the laser, when activated, projects along the axis, into a cylindrical cavity of the first member; (b) activating the laser pointer so that the laser projects along the axis of the opening of the first member onto a remote member; and (c) marking the position of the laser projecting on the remote member. 
     In some embodiments of the method the first member is a plumbing fixture, and in others the first member is a construction member having a circular opening. The laser pointer may be activated by an on-off switch, which may be a push-button switch, normally off. The switch can be protected by a flexible, sealable cover. 
     In some embodiments the laser projector further comprises at least a second cylindrical portion sharing the axis of the first cylindrical portion, the second cylindrical portion having a second diameter greater than the first diameter, and there may be a level-indicator, with the method further comprising a step for consulting the level-indicator. 
     In yet another aspect of the invention a center-point projector for determining location for alignment is provided, comprising a body having at least a first cylindrical portion with a first diameter ending in a shoulder, a vertical-seeking mechanism mounted in the body, and a laser pointer mounted in the vertical-seeking mechanism. In this aspect the vertical-seeking mechanism causes the laser pointer, when activated, to seek to point vertically in the direction of action of gravity. In preferred embodiments the vertical-seeking mechanism is a weighted gimbal mechanism. 
     In embodiments of the invention disclosed herein in enabling detail, for the first time a projector is provided that makes the job of aligning openings in separate construction members relatively easy. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 a  is an elevation view of a center point projector according to an embodiment of the present convention. 
     FIG. 1 b  is a bottom view of the center point projector of FIG. 1 a.    
     FIG. 1 c  is a top view of the center point projector of FIG. 1 a.    
     FIG. 2 a  is an elevation view of the center point projector of FIG. 1 a  and a standard plumbing pipe fixture. 
     FIG. 2 b  is an elevation view of the components of FIG. 2 a  assembled according to an embodiment of the present invention. 
     FIG. 2 c  is an elevation view of the center point projector of FIG. 1 a  fitted with another standard plumbing pipe fixture according to another embodiment of the present invention. 
     FIG. 3 is a broken view of the center point projector of FIG. 1 a  used in the framework of a building according to an embodiment of present invention. 
     FIG. 4 is a broken view showing the center point projector of FIG. 1 a  inserted into a framing member according to an embodiment of the present invention. 
     FIG. 5 is an elevation view showing an expanded application of the components of FIG. 3 used according to a preferred embodiment of the present invention. 
     FIG. 6 a  is elevation view of a gimbal base according to an embodiment of the present invention. 
     FIG. 6 b  is a top view of the gimbal base of FIG. 6 a.    
     FIG. 7 a  is an elevation view of an inner gimbal ring according to an embodiment of the present invention. 
     FIG. 7 b  is an elevation view of the inner gimbal ring of FIG. 7 a  rotated 90 degrees. 
     FIG. 7 c  is a top view of the inner gimbal ring of FIG. 7 b.    
     FIG. 8 a  is an elevation view of an outer gimbal ring according to an embodiment of the present invention. 
     FIG. 8 b  is an elevation view of the outer gimbal ring of FIG. 8 a  rotated 90 degrees. 
     FIG. 8 c  is a top view of the outer gimbal ring of FIG. 8 b.    
     FIG. 9 is elevation view of the center point projector of FIG. 1 a  and the inner gimbal ring of FIG. 7 a.    
     FIG.  10 . is elevation view of the assembled center point projector and inner gimbal ring of FIG.  9  and the outer gimbal ring of FIG. 8 a  according to an embodiment of the present invention. 
     FIG. 11 is an elevation view of the components of FIG. 10 assembled according to a preferred embodiment of the present invention, and gimbal base  601  of FIG. 6 a  rotated 90 degrees. 
     FIG. 12 is elevation view of the components of FIG. 11 assembled according to a preferred embodiment of the present invention, and the plumbing fixture of FIG. 2 a.    
     FIG. 13 is an elevation view of plumbing fixture  205  of FIG. 2 c , and a gimbal assembly with center point projector  101  of FIG. 1 a  according to another embodiment of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 a  is an elevation view of a center point projector according to an embodiment of the present convention. Projector  101  is provided having three portions, each cylindrical in shape and having a separate height and circumference. Cylinder  102 , having the largest circumference, is positioned at the top of projector  101 , cylinder  106  having the smallest circumference is positioned at the bottom of projector  101  and cylinder  104  having a circumference in between that of cylinders  102  and  106  is positioned in between cylinders  102  and  106 . Shoulders  121  and  123  are provided in this embodiment by the positioning of the three separate cylinders of different circumference. The purpose of the different circumference is in positioning of cylinders  102 ,  104  and  106  will be explained further in greater detail. In a preferred embodiment the body of projector  101  is manufactured using a high-strength, high-impact plastic material such as ABS, but in alternative embodiments may be manufactured using a variety of materials such as wood or wood polymer, lightweight metals such as aluminum or magnesium alloy, or other material having similar strong, high-impact and resilient properties. Projector  101  has a circular hole  105  drilled, bored, or fashioned by some other means into the top center of the upper portion of projector:  101 , extending down into the body of projector  101  to a depth sufficient to hold a standard laser pointer device, such as laser pointer  103 , so that the top edge of such a laser pointer device when fully inserted into hole  105  is somewhat flush with the top edge of the upper portion of projector  101 , and a laser beam when emitted from laser pointer  103  points directly upward in a straight line. In alternative embodiments of the present invention hole  105  can be of various depth and circumference to accommodate a variety of standard laser pointer devices. Laser pointer  103  in this embodiment has a lens  107  through which a laser beam is emitted, and is connected to and powered by a battery  113  contained within the lower portion of projector  101 . In various embodiments battery  113  can be of many different types, such as rechargeable nickel-cadmium or long-life lithium types, and can be of many different shapes and sizes in alternative embodiments. 
     Battery compartment  115  is provided in this embodiment to contain a battery such as battery  113 , being cut, bored, or fashioned by some other means into the body of the bottom portion of projector  101 . Battery  113  is secured within compartment  115  by a removable battery cover plate  117  and screws  119  fastened to the bottom portion of the body of projector  101 . In other embodiments battery access may be enabled by some other means such as a hinged battery door with a latch, a circular lid having threaded edges screwed into the bottom of the body of projector  101 , or some other method. Laser pointer  103  in a preferred embodiment is actuated by an on-off switch  111  being of push button type and protected from the elements with a flexible rubber covering, half-spherical in shape. In other alternative embodiments however, switch  111  can be of a variety of types without departing from the overall scope and spirit of the present invention. For example, a sliding switch or toggle switch may be used, and a protective covering may or may not be used. Projector  101  has an overall height of dimension D 1 , equal to approximately two inches in this embodiment. The vertical height of the middle cylinder of projector  101  is represented as dimension D 2 , equal to approximately one inch in this embodiment. The vertical height of the lower cylinder in this embodiment is represented as dimension D 3 , in a preferred embodiment being no longer than ¾ inch overall. The vertical height of the upper cylinder of projector  101  represented as dimension D 4  is approximately ¼ to ⅜ of an inch. All of the dimensions above can vary slightly in other embodiments, and their use and significance will be explained and depicted later in enabling detail. 
     FIG. 1 b  is a bottom view of projector  101  of FIG. 1 a . In this view cover plate  117  and screws  119  can be clearly seen as can the circular shape of cylinders  102 ,  104  and  106 . In a preferred embodiment of the present invention the bottom cylinder  106  has a diameter D 5  equal to approximately 1½ inches so that when projector  101  is inserted into the opening or hub of a standard plumbing fixture having an inner diameter approximately equal to or slightly greater than that of diameter D 5  a snug, but not tight fit is achieved. The middle cylinder  104  has a diameter D 6  that is equal to approximately 2 inches in order to, when fully inserted into the hub of a plumbing fixture having a standard inner diameter of approximately 2 inches or slightly greater, provide a snug fit similarly to that achieved by cylinder  106 . In a preferred embodiment upper cylinder  102  has a diameter D 7  that is proportionately larger, in this case approximately 3 inches, than that of middle cylinder  104 . Unlike the diameters of cylinders  104  and  106  in a preferred embodiment, diameter D 7  of cylinder  102  can vary slightly in alternative embodiments since there is not a requirement for this cylinder to fit into any plumbing fixture or hole. 
     FIG. 1 c  is a top view of projector  101  of FIG. 1 a . In this view laser pointer  103  with lens  107  can be seen seated within hole  105 , as can the positioning of switch  111  in this embodiment. 
     FIG. 2 a  is an elevation view of the center point projector of FIG. 1 a  and a standard plumbing pipe fixture. Fixture  201  has a hub  203  with an inner diameter of approximately 1½ inches as referenced previously. When projector  101  is fully inserted down, in the direction indicated, into the opening provided by hub  203 , shoulder  121  of projector  101  rests upon the upper edge of hub  203 , cylinder  106  fitting snugly within the opening of hub  203 . In this manner, once fully seated within fixture  201 , projector  101  is positioned in line with the lengthwise orientation of fixture  201 , therefore providing a means for laser pointer  103 , when actuated, to project a laser beam in straight line in relation to fixture  201 . The fit of the cylinder into the plumbing fixture assures that the laser beam will project substantially along the center line of the axis of the pipe of the plumbing fixture. 
     FIG. 2 b  is an elevation view of the components of FIG. 2 a  assembled according to an embodiment of the present invention: In this view projector  101  can be seen fully inserted into fixture  201 , shoulder  121  resting upon the upper edge of hub  203  as previously described. 
     FIG. 2 c  is an elevation view of projector  101  fitted with another standard plumbing pipe fixture according to an alternative embodiment of the present invention. Projector  101  can be seen in this view fully inserted into a plumbing fixture  205 , fixture  205  having a hub  206  with an inner diameter of approximately 2 inches, a diameter standard in the art. In this case, middle cylinder  104 , having a greater diameter than that of cylinder  106 , fits snugly within the larger hub  206  when fully inserted, shoulder  123  resting upon the upper edge of hub  206  as in FIG. 2 b.    
     FIG. 3 is a broken view showing an example of an application wherein projector  101  is used to project a center point to a new surface according to a preferred embodiment of the present invention. Projector  101  can be seen in this view inserted into standard plumbing fixture  303 , fixture  303  connected to a drainage pipe  305  and a drainage pipe  306 . Drainage pipe  305  can be seen extending down through a hole within horizontal framing member  307 , with drainage pipe  306  extending horizontally through a hole within vertical framing member  309 . As previously mentioned all drainage pipes in a standard plumbing configuration within any building supplied with running water must be ultimately connected to a vent pipe to allow outside air to be drawn into the system when drainage occurs, thus allowing for proper drainage of the used water. In order for a plumber to properly install and align a vent pipe, additional holes need to be cut or drilled through various framing members within the structure to accommodate the passage of the vent pipe, and a center point of the new hole needs to be projected from the starting reference center point and marked on the new surface, in the case of FIG. 3 a  top-plate  311 . Line A in this view represents the center point to be projected, Line A correlating with the direction of a laser beam emitted from projector  101  once projector  101  is properly seated within fixture  303  and the laser beam is actuated. Once the center point is established on the new surface, a hole such as hole  313  can be accurately cut or drilled through the new&#39;surface at the proper location. In the case of a residential structure the last horizontal portion of framework that a vent pipe needs to travel through before reaching the roof is known in the art as a top-plate, and the plumbing phase that involves marking and cutting the necessary holes and extending the vent pipe up through the top-plate, and ultimately through the roof is known in the art as the top-out phase. 
     FIG. 4 is a broken view showing projector  101  inserted into a framing member according to an embodiment of the present invention. In this view an application of the present invention during a top-out phase is shown wherein projector  101 , inserted into top-plate  311  using hole  313  is in the correct position to accurately project the center point to the new surface once the laser pointer within projector  101  is actuated and the laser beam is emitted. Vertical framing members  309  are also shown in this view for reference. 
     FIG. 5 is an elevation view showing an additional application of the components of FIG. 3 used according to a preferred embodiment of the present invention. Plumbing fixture  303  can be seen connected to drainage pipes  305  and  306  running both horizontally and vertically. Line A, in this view, is shown as it was projected by projector  101  from the original starting reference point as in FIG.  3 . Aligned with line A, projector  101  in this embodiment is now inserted into hole  313  of top-plate  31  and fully seated as previously described. Once the laser beam is actuated and emitted from projector  101  within hole  313 , the new center point for hole  501  in roof  503  can be marked for drilling or cutting, thus eliminating the cumbersome process of projecting this new hole using conventional methods as previously described. 
     A projector such as projector  101  can be used to project a center point either vertically or horizontally using the same methods as previously described for a preferred embodiment. In an alternative embodiment of the present invention, in order to accurately project a line allowing for a gradual slope such as for a horizontal drainage pipe as previously mentioned, a center point projector may have a built-in level or some other integrated method and apparatus to project such a sloped line. In another alternative embodiment a center point projector may have a sonar system or some other similar apparatus integrated within to allow the user to easily determine the distance between the starting reference center point and the new surface onto which the new projected center point will be marked. In yet another alternative embodiment of present invention a center point projector may have an apparatus allowing a user to attach the projector to a board, truss, plank or some other surface to allow drilling of consecutive or parallel boards. Such an apparatus may incorporate the use of a standard screw, nut and bolt or some other fastening device. In other alternative embodiments the diameters of the cylinder portions of a projector such as projector  101  can vary slightly without departing from the scope and spirit of the invention. It is the purpose of these diameters to allow for fitting of the projector snugly into the all of the standard dimensions of common pipe fixtures and holes used for the passage of plumbing pipes of standard circumference known in the art, so that when fully inserted the laser beam emitted from the projector is aligned as desired. 
     FIG. 6 a  is elevation view of gimbal base according to an embodiment of the present invention. Gimbal base  601  is provided having an upper portion  613  of a cylindrical shape similar to that of a cup or drinking glass, with a vertical rigid wall encompassing a cylindrical void within. Gimbal base  601  in a preferred embodiment is manufactured of a light weight, rigid material such as high-impact plastic or a metal alloy for example, and can be made using a variety of manufacturing methods. Protrusions  608 , only one of which is shown in this view, are provided in this embodiment located slightly under the upper rim of upper portion  613 , extending outward from the inner wall of upper portion  613 . Protrusions  608  are located at exact opposite points on the circumference of upper portion  613 . Protrusions  608  can be attached or formed into the inner wall of upper portion  613  by welding, bonding, molding, or a variety of other methods known in the art. 
     Each of protrusions  608  has a small, concave recess  609  formed into the upper surface near the edge facing inward. Cylinder  604  and cylinder  606  can be seen in this view extending downward from the underside of upper portion  613  and in a center location. The radius of cylinders  604  and  606  in this embodiment is equal to that of cylinders  104  and  106  respectively, of center point projector  101  of FIG. 1 a . The height of cylinders  604  and  606  in this embodiment is also roughly equal to the cylinders of center point projector  101  of FIG. 1 a , but can vary in other embodiments. The radius of cylinders  604  in  606 , as well as those of cylinders  104  and  106  or those of other preferred embodiments, have been determined by the inventors, as previously mentioned, to be compatible with diameter dimensions standard in the industry allowing for a snug fit when inserted into a hole or opening of a plumbing fixture. 
     FIG. 6 b  is a top view of gimbal base  601  of FIG. 6 a . The cylindrical shape of upper portion  613  and cylinders  604  and  606  can be better seen in this view, as can the placement of protrusions  608  in relation to each other, and the location of recesses  609  within upper surfaces of protrusions  608 . 
     FIG. 7 a  is an elevation view of an inner gimbal ring according to an embodiment of the present invention. Inner gimbal ring  701  is provided in this embodiment having a ring-shaped upper portion  704  with the inner edge having a radius nearly equal to but slightly larger than that of cylinder  104  of center point projector  101  of FIG. 1 a . Upper portion  704  is designed providing a snug but not tight fit when center point projector  101  is inserted down through upper portion  704  to the resting position. A hidden line indicating the inner wall of ring  704  can be seen in this view illustrating the somewhat narrow thickness of the ring-shaped upper portion  704 . Pins  707 , extending slightly outward from the outer edge of upper portion  704  have a spherical tip on the outer end of each, and are located 180 degrees opposite to each other similarly to protrusions  608  of FIG. 6 b.    
     In various embodiments of the present invention pins  707  may be screwed into a threaded hole drilled or bored into the outer edge of upper portion  704 , having a threaded self-tapping tip for example, or may be inserted into a pre-drilled hole similar to a dowel and spot welded or secured by some other means that allows secured pins  707  to have collective rigidity to independently support the entire weight of gimbal ring  701 . Supports  712 , each side secured to the underside of upper portion  704  and located 180 degrees opposite each other directly below pins  707 , extend downward and curve inward towards each other eventually meeting at the center. A weight  715  is attached to the underside of support  712  and, in a preferred embodiment is of a magnitude significantly greater than that of the combined weight of the remaining components of inner gimbal ring  701 . Weight  715  is square shaped and of lesser height than width in this embodiment, but in alternative embodiments the size, shape, weight, or method of attachment of a weight such as weight  715  can vary significantly, as can the various attributes of a support such as support  712  such as the curvature the lower end for the method of attachment to upper portion  704 . 
     It is an object of the invention as depicted in embodiments described herein, to have a weight such as weight  715  heavy enough in relation to the combined weight of the remaining components of inner ring  701  and positioned low enough in relation to the pivot points of pins  707 , so that when a weight equal to that of center point projector  101  of FIG. 1 a  is added to the overall weight of inner ring  701  a vertical position is maintained by the heavier bottom weight  715  and its low center of gravity, when all of the components are supported only by the spherical tips of pins  707 . For reasons stated the type and size of weights used as well as the type of weight support mechanism utilized can vary in different embodiments without departing from the scope and spirit of the present invention. As is true for components previously described the materials and methods used in the composition of, or manufacture of new embodiments described herein may also vary in different alternative embodiments. 
     FIG. 7 b  is elevation view of inner gimbal ring  701  of FIG. 7 a  rotated 90 degrees. In this view the thickness of supports  712  can be seen and a direct view of pin  707  is provided. 
     FIG. 7 c  is a top view of inner gimbal ring  701  of FIG. 7 b . Inner wall  705  can be clearly seen here as can the ring-like shape of upper portion  704  and the square shape of weight  715  in its centered position. The two sides of supports  712  are again depicted in this view to illustrate their alignment with pins  707  and weight  115 . 
     FIG. 8 a  is an elevation view of an outer gimbal ring according to an embodiment of the present invention. Outer gimbal ring  801  is provided in this embodiment as being similar in basic shape to inner gimbal ring  701  of FIG. 7 a . Upper portion  804  is provided having a ring-like shape also similar to that of upper portion  704  of inner gimbal ring  701 , but having a diameter slightly larger than upper portion  704 . Pins  807 , identical to pins  707  of FIG. 7 a  are also located in a similar position 180 degrees opposite from each other and attached to upper portion  804  using means and method similar to those of pins  707  of FIG. 7 a . Support  812  has two sides extending down from upper portion  804 , curving inward and connected at the bottom with a weight  815  attached, attributes also similar to inner gimbal ring  701 . Being similar in overall structure and having similar physical properties to inner gimbal ring  701 , the relationship between the total weight of the components of outer gimbal ring  801 , and that of weight  815  is also similar therefore providing similar preferred actions where carrying significant additional weight while being suspended solely by pins  807 . The significance of these relationships will become more apparent as explained and depicted later in greater enabling detail. Protrusions  810  are provided in this embodiment identical to protrusions  608  of gimbal base  601  of FIG. 6 a , and are attached to inner wall  805  using various means and methods previously described. Protrusions  810  are also located on inner wall  805  in 180 degrees opposite position similar to protrusions  608  of gimbal base  601 . Recesses  811  are also provided being identical to recesses  609  of FIG. 6 a.    
     FIG. 8 b  is an elevation view of outer gimbal ring  801  of FIG. 8 a  rotated 90 degrees. In this view the thickness of supports.  812  can be seen and a direct view of pin  807  is provided. 
     FIG. 8 c  is a top view of outer gimbal ring  801  of FIG. 8 b . Inner wall  805  can be clearly seen here as can the ring-like shape of upper portion  804  and the square shape of weight  815  and its centered position in relation to upper portion  804 . An improved view of protrusions  810  extending out from inner wall  805 , with concave recesses  811  on their upper surface, is also provided here. The two sides of supports  712  are again depicted in this view to illustrate their alignment with pins  807  and weight  815  in identical fashion to that of inner gimbal ring  701  of FIG. 7 a.    
     FIG. 9 is elevation view of center point projector  101  of FIG. 1 a  and inner gimbal ring  701  of FIG. 7 a . As previously described, the radius of inner wall  705 , referenced in this embodiment as been dimension D 1 , of upper portion  704  is slightly larger, approximately {fraction (1/64)} inch in a preferred embodiment, than a radius of cylinder  104 , referenced as dimension D 2 , of center point projector  101 . The difference in dimensions D 1  and D 2  previously referenced as {fraction (1/64)} inch is somewhat arbitrary and can vary slightly in alternative embodiments. Inner gimbal ring  701  is designed as a resting base for center point projector  101  inserted in the downward direction as indicated completely through ring-shape upper portion  704 , surface  123  of center point projector  101  coming to rest upon the upper surface of upper portion  704 . It is the intention of the design of inner gimbal ring  701  to allow a user to easily slide a center point projector such as center point projector  101  in and out of the upper portion  704  of inner gimbal ring  701  while maintaining a somewhat snug fit when a center point projector is fully inserted, thus stabilizing the center point projector in its seated position. 
     FIG. 10 is elevation view of assembled center point projector  101  and inner gimbal ring  701  of FIG.  9  and the outer gimbal ring of FIG. 8 a  according to an embodiment of the present invention. In this embodiment the distance between the centers of the spherical tips of pins  707  is identical to the distance between the centers of the concave recesses  811  of protrusions  810 . Center point projector  101 , inserted and fully seated within inner gimbal ring  701  according to a preferred embodiment, is lowered downward as an assembly in the direction indicated, through upper portion  804  of outer gimbal ring  801  until both spherical tips of pins  707  of inner gimbal ring  701  rest neatly within the concave recesses  811  regions  810  of upper portion  804 . The combined weight of seated center point projector  101  and inner gimbal ring  701  is supported solely by the spherical tips of pins  707  seated within recesses  811 , providing a pivot point allowing the assembled center point projector  101  and inner gimbal ring  701  to swing freely from side to side. 
     FIG. 11 is an elevation view of the components of FIG. 10 assembled according to a preferred embodiment of the present invention, and gimbal base  601  of FIG. 6 a  rotated 90 degrees. As shown here, center point projector  101  is firmly seated within inner gimbal ring  701 , the assembly supported by the spherical tips of pins  707  of inner gimbal ring  701  well resting within recesses of protrusions  810  of outer gimbal ring  801 . As described earlier and more clearly seen here, the assembled center point projector  101  and inner gimbal ring  701  is allowed by its design to swing freely side to side, but maintains a perfectly vertical position within outer gimbal ring  801  when motion subsides and the effect of gravity acts upon weight  715  of inner gimbal ring  701 . As is true with pins  707  of inner gimbal ring  701  and notches  811  of outer gimbal ring  801 , the distance between the center points of the spherical tips of pins  807  and the concave recesses  608  of protrusions  609  of gimbal base  601  are exactly identical. The assembled outer gimbal ring  801 , inner gimbal ring  701  and seated center point projector  101  is by design able to be lowered down into the cylindrical void within gimbal base  601 , supported fully by only the spherical tips of pins  807  resting within recesses  609 , with sufficient room within gimbal base  601  to allow for substantial front to back movement pivoting on pins  807 . 
     FIG. 12 is elevation view of the components of FIG. 11 assembled according to a preferred embodiment of the present invention, and the plumbing fixture of FIG. 2 a . A section view of gimbal base  601 , taken along section line A—A of FIG. 6 b , is provided to enable a better view of the assembled components within. Gimbal base  601  is shown in this view rotated 90 degrees from its position in FIG. 11 providing a direct view of protrusions  608  and pins  807 , on which the combined weight of center point projector  101 , inner gimbal ring  701  and outer gimbal ring  801  is supported. Center point projector  101 , when seated within inner gimbal ring  701  and pivoting within outer gimbal ring  801  is allowed free movement in any direction when lowered into gimbal base  601 , supported by and pivoting on pins  807  resting upon protrusions  608  of gimbal base  601 . Plumbing fixture  201  of FIG. 2 a , into which the gimbal assembly is lowered as indicated, is shown here for the purpose of illustrating a starting reference point from which a vertical line will be projected in a preferred embodiment of present invention. 
     The design and dimensions of cylinders  604  and  606 , similar to those of center point projector  101  of FIG. 1 a  as previously described, enable a secure fit into the opening of a standard plumbing fixture such as fixture  201 , bottom surface  605  resting upon the upper edge of the opening of fixture  201 . Alternative embodiments however may provide a gimbal base with cylinders of different sizes to accommodate a variety of applications and different sizes of holes or plumbing fixture openings. In other alternative embodiments a gimbal base may be provided with removable and interchangeable cylinders which may be attached to the bottom of the gimbal base using a variety of methods, allowing a user to quickly and easily adapt to different situations requiring vertical lines to be projected from holes or plumbing fixtures of varying dimensions. 
     FIG. 13 is an elevation view of plumbing fixture  205  of FIG. 2 c , and a gimbal assembly with center point projector  101  of FIG. 1 a  according to another embodiment of the present invention. Plumbing fixture  205  of FIG. 2 a , into which the gimbal assembly is fully inserted suspending a freely moving center point projector  101 , is shown for the purpose of illustrating a starting reference point from which a vertical line will be projected in a preferred embodiment of present invention. As previously described plumbing fixture  205  has an opening of a larger size, standard in the industry, than that of plumbing fixture  201  of FIG. 12. A secure fit between the gimbal assembly and opening of plumbing fixture  205  is provided by the larger cylinder  604 , being the cylinder now used for insertion into the opening, surface  614  resting upon the top edge of plumbing fixture  205 . Plumbing fixture  205  the shown in this view tilted approximately two degrees counterclockwise, the center line represented as line  920 , to illustrate in enabling detail an application of a preferred embodiment with the intention of projecting a vertical center line from the opening of a plumbing fixture that is slightly off angle. With gimbal base  601  fully seated within and aligned with plumbing fixture  205 , the vertical center line can be projected with the fully&#39;seated center point projector  101 , the vertical line represented as line  921  in this view, by the centering actions of weights  715  and  815  of the freely pivoting inner and outer gimbal rings. 
     It will be apparent to a person of ordinary skill that there are many alterations that may be made in the embodiments described herein without departing from the overall spirit and scope of the present invention. For these reasons the invention should be afforded the broadest possible scope limited only by the language of the claims that follow.