Abstract:
An angle measuring tool for us in combination with a standard framing square. A saddle protractor having a plurality of alignment tabs is engaged with a standard framing square by placing the saddle protractor in fact to face contact with the framing square and in alignment with the alignment tabs. Various incremental indicia on both sides of the saddle protractor depict angular measurements as measured from a pivot point on the saddle protractor. Other alignment tabs and pivot points on the saddle protractor also allow the saddle protractor to be used as a miter layout device to scribe various cutting angles on material having angular cuts.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     This invention relates in general to measuring devices and, more particularly, to an improved device for measuring roof rafter angles or other angles. 
     2. Description of Related Art. 
     Various measuring devices have been invented which provide a means to measure the angles of roof rafters and other types of angles which may occur in the construction industry. While many of those devices perform the required function of determining angles, those devices are normally cumbersome and complex. Such disadvantages are generally the result of designing a measuring device which is intended to work without taking advantage of the assistance that other tools may provide in measuring angles. 
     An example of this disadvantage is found in U. S. Pat. No. 4,712,307 for a rafter angle measuring device. That invention includes components which act as a framing square, ruler, and bubble level, as well as a rafter angle measuring device. Additionally, the invention includes a cumbersome arm which must be used to obtain a measurement of the angle of rafters. When not in use, the invention must be carefully folded and placed in a tool box for storage to ensure that the device is not damaged. The result of these characteristics is an invention which is cumbersome and which provides much more than is needed by a worker who simply wants to measure rafter angles or other types of angles. 
     U.S. Pat. No. 1,083,376 is another example of a measuring instrument that must work by itself to provide the worker with the measurement of rafter angles. This device also includes a number of capabilities other than the simple measurement of various angles and, as a result, the device is much more complex than it needs to be to simply measure angles. 
     Other measurement devices may be less cumbersome and less complex in design, yet fail to allow for the need to have long base lines to ensure that the measured angle is accurate. U.S. Pat. 4,742,619 discloses a roofing speed square for use in laying out and cutting roof rafters. However, the design of the device is intended to depend only upon the short adjacent sides of the device to establish the baseline for the angles being laid out and measured. Additionally, there is no provision for using the tool in conjunction with another device such as a large framing angle, to ensure that the base lines from which the angles are being measured are sufficient to guarantee angular accuracy. As a result, the invention suffers from being unable to provide accurate measurement of roof angles calculated from long base lines. 
     In each of these examples, the design of the measurement tool fails to provide an instrument which will allow the worker to measure rafter angles and other types of angles in a way which would permit the tool to be simple to use and which would allow the tool to be used in conjunction with another tool. Moreover, the designs of these tools do not permit the tools to be used in conjunction with another tool which could provide longer baselines for more accurate determination of angles. 
     Accordingly, it is an object of the invention to provide a measuring tool which is small and simple, and which can used with a standard framing square to allow a worker to measure and layout roof rafter angles and other types of angles. 
     It is yet another object of the invention to provide a measuring tool which, standing alone or in conjunction with a standard framing square, can be used to layout miter angles on materials which require angular cuts. 
     SUMMARY OF THE INVENTION 
     The present invention resides in a saddle protractor which can be used in conjunction with a standard framing square to measure rafter angles and other types of angles. Specifically, the invention discloses an angle measuring tool having angular graduations and which is designed to include various tabs which allow the tool to be securely engaged with the framing square. The saddle protractor includes a pivot pin or pivot tab which allows the device to be used as a miter layout device when used in conjunction with a framing square. One edge of the saddle protractor contains incremental graduations indicating angles in whole degree increments. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an isometric view of the saddle protractor showing one side of the protractor. 
     FIG. 2 is an isometric view of the saddle protractor showing the other side of the protractor. 
     FIG. 3 is an isometric view of the saddle protractor showing use of the protractor with a standard framing square. 
     FIG. 4 is an isometric view of the saddle protractor showing a second embodiment of the protractor. 
     FIG. 4A is an isometric view of an alternate embodiment of the guide pin used on the second embodiment of the saddle protractor. 
     FIG. 5 is an isometric view of the saddle protractor showing a third embodiment of the protractor. 
     FIG. 5B is an isometric view of an alternate embodiment of the guide pin used on the third embodiment of the saddle protractor. 
     FIG. 6 is a plan view of the saddle protractor showing the use of the protractor in measuring angles from the corner of two adjacent walls using the indicia on the top surface of the saddle protractor. 
     FIG. 7 is a plan view of the protractor showing the use of the protractor as a tool for laying out miter cuts using the indicia on the top surface of the saddle protractor. 
     FIG. 8 is a plan view of the saddle protractor showing the use of the protractor to measure the roof rafter angles in a steel beam construction using the indicia on the bottom surface of the protractor. 
    
    
     Corresponding reference numerals indicate corresponding parts throughout the several figures of the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The following detailed description illustrates the invention by way of example and not by way of limitation. The description clearly enables one skilled in the art to make and use the invention, describes several embodiments, adaptations, variations, alternatives, and uses of the invention, including what is presently believed to be the best mode of carrying out the invention. 
     Referring now to FIG. 1, a first embodiment of a saddle protractor  1  is shown. The general shape of the saddle protractor  1  is that of a flat member having a right triangle with the acute corners of the right triangle being truncated. The resulting shape contains a first guide edge  2 , a second guide edge  3 , a first scaled edge  4 , a second scaled edge  5 , a third scaled edge  6 , a top surface  7 , and a bottom surface  8 . The top surface  7  and the bottom surface  8  are generally parallel and generally perpendicular to edges  2 ,  3 ,  4 ,  5 , and  6 . 
     The saddle protractor also includes an alignment tab  9 , an alignment tab  10 , an alignment tab  11 , an alignment tab  12 , and an alignment tab  13 . All alignment tabs  9 ,  10 ,  11 ,  12 , and  13  are perpendicular to the top surface  7  and protrude upwardly from the top surface  7  to a height of about 0.12 inches to about 0.19 inches above the top surface. Each of the alignment tabs  9 ,  10 ,  11 ,  12 , and  13  are generally rectangular in shape. A right triangular orifice  28  is located within the saddle protractor  1  such that the hypotenuse of the right triangle orifice is parallel with the third scaled edge  6 . 
     A standard framing square  18  (FIG. 3) has two legs at right angles and each of the legs of the standard framing square are of different widths. The legs of the standard framing square range from 16.00 inches to 24.00 inches in length. In general, the shorter, narrower leg  19  of the framing square is about 1.50 inches wide and the longer, wider leg  20  of the framing square is about 2.00 inches wide. In the first embodiment of the present invention, the dimension A (FIG. 1) between the inner surface  14  of alignment tab  9  and the inner surface  15  of alignment tab  13  is about 1.50 to allow the shorter, narrower leg  19  of the standard framing square to fit between the inner surfaces  14  and  15 , when the framing square is lying flat against the upper surface  7 . The dimension B between the inner surface  16  of alignment tab  12  and the inner surface  17  of alignment tab  11  is about 2.00 inch to allow the longer, wider leg  20  of the standard framing square to fit between the inner surfaces  16  and  17  when the framing square is lying flat against the upper surface  7 . The dimension A and the dimension B are such that the legs of the standard framing square fit snugly between their respective alignment tabs. 
     While the alignment tabs  9 ,  10 ,  11 ,  12 , and  13  allow for a snug insertion of the standard framing square onto the saddle protractor  1 , other means may also be used to enhance the tightness of the fit of the standard framing square with the saddle protractor. For example, the alignment tabs  9 ,  10 ,  11 ,  12 , and  13  could be made with one or more dimples  42 . The dimples  42  of one tab would be pointed toward the an opposing tab and would allow for a gentle clamping of the standard framing square  18  between the two opposing alignment tabs. It will be appreciated that in lieu of dimples, other means such as small protrusions can also be used to enhance the snugness of the standard framing square between the alignment tabs. Additionally, the alignment tabs could be positioned at an angle other than perpendicular to the tops surface  7  and toward the opposing alignment tab. The slight non-perpendicularity of the alignment tabs would thus act to encapsulate and grip the edges of the standard framing square when the framing square is engaged with the saddle protractor  1 . Various other methods may be used as long as the method selected acts to increase the strength of the engagement between the saddle protractor  1  and the framing square  18 . 
     The top surface  7  near the scaled edge  6 , and between corner  21  and corner  22 , is scribed with indicia  23  to indicate the value of a measured angle. The indicia  23  are in at least one degree angular increments as measured across the edge  6  from the pivot point  24 . The indicia  23  begins with a horizontal mark at the corner  12  indicating 0 degrees and commences with additional marks  24  in at least one degree increments and continuing clockwise toward the corner  22  until the vertical mark indicating 90 degrees is reached. The intersection of the horizontal 0 degree mark and the vertical 90 degree mark of the marking indicia  23  is the angular center point of the marking indicia  23 . 
     Intermingled within the one degree increment indicia  24  are longer indicia marks  25  which are located at every five degree increment. The longer indicia marks  25  are shown onto the top surface  7  by a plurality of first numeric markings  26  which begin with the number  0  at corner  21  and increment in five unit intervals until the value of the first numeric markings reaches 90 at the corner  22 . Just beneath the first numeric markings  26 , a plurality of second numeric markings  27  are also scribed onto the top surface  7 . However, the second numeric markings  27  are opposite in sequence and direction from the first numeric markings such that the second numeric markings begin with the number 0 at the corner  22  and increment in five unit intervals until the value of the second numeric markings reaches 90 at the corner  21 . 
     The saddle protractor  1  includes a right triangular orifice  28  located within the exterior area of the saddle protractor. The right triangular orifice  28  is located within the saddle protractor  1  such that the corner  24  of the right triangular orifice  28  is positioned at the intersection of the 0 degree horizontal mark and 90 degree vertical mark of the marking indicia  23 . 
     A second set of indicia  23 A is similar to the marking indicia  23 , but extends from the inner surface  14  to the inner surface  17 . The second set of indicia  23 A includes numeric markings similar to the first numeric markings  26  and the second numeric markings  27  for marking indicia  23 . 
     A first miter tab  36  protrudes upwardly from the top surface  7  to a height of about 0.50 inches from the top surface. The first miter tab  36  is generally rectangular and is positioned to be perpendicular to the top surface  7 . A second miter tab  37  extends in the opposite direction of the first miter tab  36  and protrudes downwardly from the bottom surface  8  and along the same plane as the first miter tab  36 . The second miter tab  37  is also generally rectangular in shape. 
     In FIG. 2, the surface  8  on the back side of the saddle protractor  1  is also scribed with indicia to indicate the value of a measured angle. However, unlike the numeric markings on the top surface  7 , the indicia  30  are in at least one degree angular increments as measured across the edge  6  from the corner  29  of the saddle protractor. The indicia  30  begins at the corner  31  and commences with additional indicia in at least one degree increments and continuing clockwise toward the corner  32  until the 90 degree increment is reached. Intermingled within the one degree increment indicia  30  are longer indicia marks  33  which are located at every five degree increment. The longer indicia marks  33  are shown on the bottom surface  8  by a plurality of third numeric markings  34  which begin with the number 0 at the corner  31  and increment in five unit intervals until the value of the third numeric markings reaches 90 at the corner  22 . Just beneath the third numeric markings  26 , a plurality of fourth numeric markings  35  are also scribed onto the bottom surface  8 . However, the fourth numeric markings  35  are opposite in sequence and direction from the third numeric markings  34  such that the fourth numeric markings begin with the number 0 at the corner  32  and increment in five unit intervals until the value of the fourth numeric markings reaches 90 at the corner  31 . 
     A second embodiment of the present invention is shown in FIG.  5 . The second embodiment is the same as the first embodiment except the first miter tab  36  and the second miter tab  37  are not used. Additionally, a guide pin  38  is mounted perpendicular to the top surface  7 . The guide pin  38  is located at the pivot point of the indicia  30  which is at the intersection of the vertical indicia of 0 degrees and the horizontal indicia of 90 degrees and extends about 0.50 inches above the top surface  7  and likewise extends about 0.50 inches above the bottom surface  8 . Additionally, the right triangular orifice  28  of the saddle protractor  1  is modified such that the right angle corner of the right triangular orifice is modified to add a gusset  41  into the right angle corner. FIG. 5B shows an alternate construction of the guide pin  38 . 
     The use of guide pin  38  is an alternate embodiment of the saddle protractor because the design of some framing squares prevents the use of first miter tab  36  and second miter tab  37 . One type of framing square  18  is made so that the internal angle of the framing square is simply the intersection of the interior edges of the two legs  19  and  20  of the framing square. In other types there is a circular notch at the intersection point of the interior edges of the framing square. The first and second miter tabs  36  and  37  allow the use of the saddle protractor  1  when there is no notch in the framing square  18 , while the guide pins  38  and  42  of the alternate embodiment of the saddle protractor allow it to be used with a framing square  18  which has the circular notch. 
     A third embodiment of the present invention is shown in FIG.  4 . The third embodiment is also the same as the first embodiment except that the third embodiment does not have a first miter  36  or a second miter tab  37 . Additionally, the third embodiment includes a threaded pivot pin  42  which is mounted perpendicular to the top surface  7  and the bottom surface  8 , and extends above each of those surfaces about 0.75 inches. Two nuts  43  are installed onto the threaded pivot pin  42 , with one nut tightened against the top surface  7  and the other nut tightened against the bottom surface  8 . FIG. 4A shows an alternate construction of the pivot pin  38 . 
     The saddle protractor is intended to be used with a standard framing square  18  as shown in FIG.  3 . To measure the angle of a roof rafter or other type of angle, the standard framing square  18  is engaged with the saddle protractor  1  by placing one face of the standard framing square against the top surface  7  of the saddle protractor. As the standard framing square  18  is placed against the top surface  7 , the inside edges of the framing square and the outside edges of the framing square come into contact with the inner surfaces of the alignment tabs  9 ,  10 ,  11 ,  12 , and  13 . Due to the snug fit, the framing square  18  is held in place between the alignment tabs, and the framing square  18  and the saddle protractor  1  become coupled to function as a single tool. In alternate embodiments of the saddle protractor  1 , the dimples  42  or other types of protrusions on the alignment tabs act to enhance the snugness of the fit between the saddle protractor and the framing square  18 . In yet another embodiment of the saddle protractor  1 , the alignment tabs are bent over at slightly more than a perpendicular angle to position the alignment tabs to embrace the framing square  18 . 
     FIG. 6 shows a method of engaging the saddle protractor  1  with the framing square when the third embodiment of the saddle protractor  1  as shown in FIG. 5 is used. Prior to the coupling of the framing square  18  with the saddle protractor  1 , the nut  43  which is tightened against the top surface  7  is loosened. The framing square  18  is then positioned to allow one face of the framing square to be in contact with the top surface  7 . Once in this position, the framing square  18  is captivated against the saddle protractor  1  by tightening the nut  43  onto the threaded rod  42  so as to clamp the framing square  18  against the saddle protractor  1 . 
     In operation, FIG. 6 shows the method by which the combination of the saddle protractor  1  and framing square  18  can be used to measure an angle set from the corner of a room using the saddle protractor  1 . A first wall  44  and second wall  45  intersect at a corner  46 . After the saddle protractor  1  is engaged with the framing square  18 , the framing square is placed against the wall  45  such that the longer leg  20  of the framing square abuts the surface of the wall. A string line  47  is connected to the corner  46  and the string line is stretched between the corner  46  and a point in the room for which an angle is to be measured. The framing square  18  and saddle protractor  1  are then slid along the surface of the wall  45  until the string line  47  intersects with the pivot point  49  which is at the corner  24  of the saddle protractor. The angle the string line  47  makes with either the wall  45  or the wall  44  is determined by reading the marking indicia  23  on the top surface  7  of the saddle protractor  1 . 
     After the saddle protractor  1  has been engaged with the framing square  18  as described above, FIG. 7 shows how the saddle protractor  1  may be used to lay out miter cuts on building materials such as a board  50 . In this figure, the saddle protractor  1  is used to lay out a miter cut of 45 degrees. The saddle protractor is laid on the surface  51  of the board  50  such that the indicia  23  on the top surface  7  of the saddle protractor  1  is facing away from the surface  51  of the board  50 . The saddle protractor  1  is then positioned on the surface  51  of the board  50  such that the pivot tab  37  located at the corner  24  of the saddle protractor touches the edge  53  of the board  50 . The saddle protractor  1  is then pivoted about the pivot tab  37  until the edge  53  of the board  50  aligns with the indicia  23  that shows an angle of 45 degrees at marking  52 . The miter line  54  is then placed onto the surface  51  by scribing a line onto the surface of the board  50  by running a marking device of some type along the edge  55  of the framing square  18 . As can be seen, this method can be used to lay out angles other than 45 degrees by simply rotating the saddle protractor around the pivot tab  37  until the required angular degree on the indicia  23  aligns with the edge  53  of the board  50 . 
     To layout a miter line on the other side of board  50 , the saddle protractor  1  with the framing square  18  are positioned on the other of the board  50  after the saddle protractor has been flipped over to expose side  7  of the protractor. The indicia  23 A (FIG. 1) are then used to determine the angle to be scribed. It should be noted that when the saddle, protractor  1  uses a guide pin such as guide pin  42  (FIGS. 4 &amp; 4A) or guide pin  38  (FIGS.  5  &amp;  5 B), the post can be position on the saddle protractor  1  such as to eliminate the need to flip the saddle protractor  1  over to layout a miter line on the other side of the board  50 . 
     As another embodiment of the saddle protractor  1 , a removable clip could be use in lieu of the miter tabs  36  and  37 , and the guide pin  38  and  42 . The removable clip would be constructed to slide onto the saddle protractor  1  near the point where the miter tabs  36  and  37  are located. When laying out a miter line from the opposite edge of the board  50 , the removable clip can be removed from the saddle protractor  1 , the removable clip is then rotated 180 degrees and then replaced onto the saddle protractor  1 . Because the protruding tab from the removable clip is now protruding from the other side of the saddle protractor  1 , the removable clip allows the saddle protractor to be pushed against the edge of the board  50  to layout the required miter line. 
     FIG. 8 shows how the saddle protractor  1  can be used to measure the roof rafter angle in a structural steel building construction. After the saddle protractor  1  has been engaged with the framing square  18  as described above, the framing square is placed into the corner  56  at the intersection of I beam  57  and I beam  58 . The edges of the legs  19  and  20  are placed into contact with the edges of the I beams  57  and the I beams  58 . A string line  59  is positioned at the corner  56  of the saddle protractor  1  and the string line is tightened and positioned so that the other end of the string line is located at the point from which the roof angle is to be measured. The roof rafter angle can be found by reading the indicia  23  where the string line  59  crosses the bottom surface  8  of the saddle protractor  1 . 
     In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results are obtained. As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. Additionally, while several methods of angle measurement are described herein, these methods are simply samples of the types of processes by which the saddle protractor is capable of measuring angles in various situations and it will be clear to one skilled in the art that the saddle protractor is capable of measuring angles in any situation where angles must be measured from any flat surface or corner.