Patent Publication Number: US-6990746-B2

Title: Slide calipers

Description:
FIELD OF THE INVENTION 
   This invention relates generally to calipers, and more particularly to slide calipers for accurately measuring the length of structures between one or more theoretical sharp corners. 
   BACKGROUND OF THE INVENTION 
   One of the possible services in the fan and blower industry is to design and manufacture custom fan tray systems. The manufacturing of custom fan tray systems involves sheet metal manufacturing and assembly work. The dimensions to rounded edges (bends) of sheet metal parts are given to the theoretical sharp corners. The location of the theoretical sharp corner is also referred to as mold lines or apexes, and is defined as the location in space where two walls would intersect if they joined at a sharp corner rather than at a rounded edge. Despite the sophisticated equipment available for the manufacture of custom fan trays, there is no adequate handheld tool to measure the lengths of sheet metal walls that are not bent at a right angle. The lengths are most commonly measured to the corner where two walls meet. The corner of two walls that do not meet at right angles is commonly referred to as a “theoretical sharp corner”. Typically during first article inspections the measurement of these walls are skipped since there is no method to easily measure walls with theoretical sharp corners. 
   When a sheet metal design having a theoretical sharp corner is given to a brake press operator for a forming operation, the operator either estimates the length of the wall, or a “custom go/no go” gage is built to check the length. Such gages do not specifically measure values; rather, they merely indicate to the operator whether the part is acceptable. Custom gages have to be designed and built for each application, and can be quite expensive. Moreover, such gages are only useful for one application. 
   In order to solve this measurement problem it has been envisioned to use combination squares to indirectly measure the length of walls with theoretical sharp corners. However, indirect measurement using a combination square can be slow and cumbersome, can rely heavily on operator technique, and can be very inaccurate. It has also been envisioned to use more sophisticated measuring equipment for measuring theoretical sharp corners such as coordinate measuring machines, video capture systems, and optical comparators. However, these are complex, specialized equipment and tend to be quite expensive as compared to a hand held device such as, for example, slide calipers. Such equipment would tend to be maintained in a fixed location such as a quality lab, and therefore those wanting to use the equipment on a shop floor or in design engineering offices would not have timely access to such equipment. Moreover, the sophisticated metrology equipment would require specialized training and dedicated operators. 
   Accordingly, it is an object of the present invention to provide a simple, hand-held and inexpensive apparatus for accurately measuring the length of structures between one or more theoretical sharp corners that overcomes the above-mentioned drawbacks and disadvantages. 
   SUMMARY OF THE INVENTION 
   In a first aspect of the present invention, a slide caliper comprises an elongated shaft defining a gaging surface for abutting against a first surface of an object having a length to be measured. A first jaw is coupled to the shaft and defines a gaging surface for abutting against a second surface of the object. A second jaw is slidably coupled to the shaft and defines a gaging surface for abutting against a third surface of the object. The second jaw is adjustable in position along the shaft between a first position where the gaging surfaces of the jaws generally abut each other to a predetermined second position where the gaging surfaces of the jaws are generally maximally spaced from each other. One of the jaws is adjustably pivotable relative to the shaft about a pivot axis coinciding with an intersection of the gaging surface of the shaft and another axis extending along the associated gaging surface of the adjustably pivotable jaw. 
   In a second aspect of the present invention, a slide caliper comprises an elongated shaft defining a gaging surface for abutting against a first surface of an object having a length to be measured. A first jaw is coupled to the shaft and defines a gaging surface for abutting against a second surface of the object. The first jaw is adjustably pivotable relative to the shaft about a pivot axis coinciding with an intersection of the gaging surface of the shaft and another axis extending along the gaging surface of the first jaw. A second jaw is slidably coupled to the shaft and defines a gaging surface for abutting against a third surface of the object. The second jaw is adjustable in position along the shaft between a first position where the gaging surfaces of the jaws generally abut each other to a predetermined second position where the gaging surfaces of the jaws are generally maximally spaced from each other. The gaging surface of the second jaw is generally perpendicular to the gaging surface of the shaft. 
   In a third aspect of the present invention, a slide caliper comprises an elongated shaft defining a gaging surface for abutting against a first surface of an object having a length to be measured. A first jaw is coupled to the shaft and defines a gaging surface for abutting against a second surface of the object. The first jaw is adjustably pivotable relative to the shaft about a pivot axis coinciding with an intersection of the gaging surface of the shaft and another axis extending along the gaging surface of the first jaw. A second jaw is slidably coupled to the shaft and defines a gaging surface for abutting against a third surface of the object. The second jaw is adjustable in position along the shaft between a first position where the gaging surfaces of the jaws generally abut each other to a predetermined second position where the gaging surfaces of the jaws are generally maximally spaced from each other. The second jaw is adjustably pivotable relative to the shaft about a pivot axis coinciding with an intersection of the gaging surface of the shaft and another axis extending along the gaging surface of the second jaw. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an isometric view of a slide caliper embodying the present invention. 
       FIG. 2  is an exploded isometric view of the slide caliper of  FIG. 1 . 
       FIG. 3  is a top plan view of the slide caliper of  FIG. 1 . 
       FIG. 4  is a side elevation view of the slide caliper of  FIG. 1 . 
       FIG. 5  is a bottom plan view of the slide caliper of  FIG. 1 . 
       FIG. 6  is an end view of the slide caliper of  FIG. 1 . 
       FIG. 7  is a bottom plan view of the slide caliper of  FIG. 1  showing a pivot jaw in a first orientation relative to the shaft of the slide caliper. 
       FIG. 8  is a bottom plan view of the slide caliper of  FIG. 1  showing a pivot jaw in a second orientation relative to the shaft of the slide caliper. 
       FIG. 9  is a bottom plan view of the slide caliper of  FIG. 1  showing a pivot jaw in a third orientation relative to the shaft of the slide caliper. 
       FIG. 10  is a top plan view showing the slide caliper of  FIG. 1  measuring a structure having one theoretical sharp corner. 
       FIG. 11  is an isometric view of a slide caliper in accordance with a second embodiment of the present invention. 
       FIG. 12  is an exploded isometric view of the slide caliper of  FIG. 11 . 
       FIG. 13  is a top plan view of the slide caliper of  FIG. 11 . 
       FIG. 14  is a side elevation view of the slide caliper of  FIG. 11 . 
       FIG. 15  is a bottom plan view of the slide caliper of  FIG. 11 . 
       FIG. 16  is an end view of the slide caliper of  FIG. 11 . 
       FIG. 17  is a top plan view showing the slide caliper of  FIG. 11  measuring a structure having two theoretical sharp corners. 
       FIG. 18  is an isometric view of a slide caliper in accordance with a third embodiment of the present invention. 
       FIG. 19  is an exploded isometric view of the slide caliper of  FIG. 18 . 
       FIG. 20  is a top plan view of the slide caliper of  FIG. 18 . 
       FIG. 21  is a side elevation view of the slide caliper of  FIG. 18 . 
       FIG. 22  is a bottom plan view of the slide caliper of  FIG. 18 . 
       FIG. 23  is an end view of the slide caliper of  FIG. 18 . 
       FIG. 24  is a top plan view showing the slide caliper of  FIG. 18  measuring a structure having two theoretical sharp corners. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   With reference to  FIGS. 1–10 , a slide caliper embodying the present invention is generally indicated by the reference number  10 . The slide caliper  10  is used for measuring the length between two corners of an object wherein one corner might form a theoretical sharp corner (i.e., a non-right angle). 
   The slide caliper  10  comprises an elongated shaft  12  defining a first gaging surface  14 . A first jaw  16  defining a second gaging surface  18  is pivotally coupled to the shaft  12 , preferably adjacent to a first longitudinal end  20  of the shaft. A second jaw  22  defining a third gaging surface  23  is slidably coupled to the shaft  12  for movement therealong. The shaft  12  preferably includes a graduated or linear measuring scale  24  therealong for measuring the distance between two corners of an object to be held between the gaging surface  18  of the first jaw  16  and the gaging surface  23  of the second jaw  22  as will be explained more fully below. The shaft  12  also preferably includes a conventional digital measuring device  26  coupled to and slidable with the second jaw  22  along the shaft for more precisely measuring the distance between two corners of the object to be held between the first and second jaws  16 ,  22 . 
   As best shown in  FIG. 2 , the first jaw  16  includes an arcuate extension  28  defining a semi-circular slot  30  for being pivotally received within a recess  32  defined by an underside of the shaft  12 . The arcuate extension  28  of the first jaw  16  when received within the recess  32  is coupled to and tightened against the shaft  12  with, for example, a thumb screw  34  having two components cooperating with each other to extend through an aperture  36  defined by the shaft and the slot  30  defined by the arcuate extension of the first jaw. 
   As shown in  FIGS. 7–9 , the first jaw  16  is generally continuously adjustably pivotable relative to the shaft  12  about a pivot axis  38  coinciding with an intersection of the gaging surface  14  of the shaft  12  and another axis  40  extending along the gaging surface  18  of the first jaw. Preferably, the pivot axis  38  is a zero distance mark of a measuring scale for generally measuring the distance between two corners of an object to be held between the gaging surface  18  of the first jaw  16  and the gaging surface  23  of the second jaw  22 . More precisely, the slide caliper  10  measures the distance along the shaft  12  between the intersection of the gaging surface  14  of the shaft  12  and the axis  40  extending along the gaging surface  18  of the first jaw  16 , and the intersection of the gaging surface  14  of the shaft  12  and an axis  61  extending along the gaging surface  23  of the second jaw  22 . 
   The first jaw  16  is adjustably pivotable to enable the gaging surface  18  of the first jaw to abut and thereby accommodate an adjacent wall of an object having a corner forming various angles including a right angle and angles that are less than or greater than 90 degrees.  FIG. 7 , for example, shows the first jaw  16  oriented such that the gaging surface  18  of the first jaw forms a 25 degree angle with the gaging surface  14  of the shaft  12 .  FIG. 8 , for example, shows the first jaw  16  in a neutral orientation such that the gaging surface  18  of the first jaw forms a 90 degree angle with the gaging surface  14  of the shaft  12 .  FIG. 9 , for example, shows the first jaw  16  oriented such that the gaging surface  18  of the first jaw forms a 160 degree angle with the gaging surface  14  of the shaft  12 . Accordingly, the first jaw  16  is adjustably pivotable in either direction away from the neutral orientation of 90 degrees in order to accommodate objects having corners either less than 90 degrees or greater than 90 degrees. Moreover, as can be seen in  FIG. 8  the ability of the first jaw  16  to assume a neutral orientation of 90 degrees permits the slide caliper  10  to be employed in a conventional manner. 
   As best shown in  FIG. 2 , the second jaw  22  includes an extension  42  defining a channel  44  for slidably receiving the underside of the shaft  12  to enable movement of the second jaw along the shaft between a first position where the gaging surfaces  18 ,  23  of the jaws  16 ,  22  generally abut each other to a predetermined second position where the gaging surfaces of the jaws are generally maximally spaced from each other. The second jaw  22  is non-pivotally coupled to the shaft  12  such that the gaging surface  23  of the second jaw is oriented perpendicularly to or at right angles with the gaging surface  14  of the shaft. 
   The digital measuring device  26  includes a housing  46  defining a recess  48  on an underside thereof for being received over the shaft  12  and engaging the extension  42  of the second jaw  22  to secure the second jaw to the shaft for movement therealong. The digital measuring device  26  preferably includes a display panel  55 , first switch  50  for toggling between measurements in inches and millimeters, a second switch  52  for turning the device on or off, and a third switch  54  for calibrating the digital measuring device when the gaging surface  18  of the first jaw  16  abuts the gaging surface  23  of the second jaw  22  as shown, for example, in  FIG. 1 . Although the digital measuring device  26  is shown and described by way of example with three switches performing specific functions, it should be understood that the digital measuring device can be embodied in other ways without departing from the scope of the present invention. For example, the second switch  52  for turning the device on or off is not necessary for a solar powered digital measuring device. 
   In operation, the digital measuring device  26  of the slide caliper  10  is turned on by pressing the second switch  52 . The digital measuring device  26  is preferably calibrated/zeroed by moving the second jaw  22  along the shaft  12  until the gaging surface  23  of the second jaw  22  abuts the gaging surface  18  of the first jaw  16 . While the gaging surfaces  18 ,  23  of the first and second jaws  16 ,  22  are abutting each other, the third switch  54  is pressed to calibrate/zero the digital measuring device  26 . The second jaw  22  is then moved along the shaft  12  away from the first jaw  16  in order to accommodate between the jaws an object to be measured such as, for example, a sheet metal wall of a fan tray. 
   As shown by way of example in  FIG. 10 , a fan tray  56  includes a sheet metal wall having a distance to be measured between two corners of the tray. A first corner  58  of the tray  56  is defined as the convergence of a first wall  60  and a second wall  62  of the tray. A second corner  64  of the tray  56  is defined as the convergence of the first wall  60  and a third wall  66 . As can be seen in  FIG. 10 , the first wall  60  and the second wall  62  converging at the first corner  58  cooperate to form a theoretical sharp corner having an angle that is greater than 90 degrees. The first wall  60  and the third wall  66  converging at the second corner  64  cooperate to form an angle of 90 degrees (i.e., right angle). However, it should be understood that the second corner  64  and the third wall  66  can be substituted by a plane edge of the first wall  60  in order to form the right angle. 
   The first wall  60  of the tray  56  is placed against the gaging surface  14  of the shaft  12 . The thumbscrew  34 , as shown in  FIGS. 7–9 , associated with the first jaw  16  is loosened in order to enable the first jaw to pivot relative to the shaft  12 . The second jaw  22  is then moved along the shaft  12  toward the first jaw  16  until the gaging surface  23  of the second jaw abuts the third wall  66  of the tray  56 , and a tip of the gaging surface  18  of the first jaw contacts the second wall  62  of the tray. The contact between the gaging surface  18  of the first jaw  16  and the second wall  62  of the tray  56  as the second jaw  22  is moved along the shaft  12  causes the first jaw to pivot until the gaging surface of the first jaw abuts the second wall of the tray. The thumbscrew  34  associated with the first jaw  16  is then tightened to maintain the first jaw at an orientation relative to the shaft  12  where the gaging surface  18  of the first jaw abuts the second wall  62  of the tray  56 . The distance of the first wall  60  extending between the first corner  58  and the second corner  64  of the tray  56  is then accurately measured using either or both of the scales  24  on the shaft  12  and the digital measuring device  26 . 
   As can be seen in  FIG. 10 , the first jaw  16  preferably includes index marks  29  for determining the angular orientation of the gaging surface  18  of the first jaw relative to the gaging surface  14  of the shaft  12 . However, the angular orientation can be determined in other ways without departing from the scope of the present invention. For example, the angular orientation could be determined by the digital measuring device  26  and shown on the display panel  55 . 
   Referring now to  FIGS. 11–17 , a slide caliper in accordance with a second embodiment of the present invention is generally indicated by the reference number  110 . Like elements with the slide caliper  10  are labelled by like reference numbers preceded by “ 1 ”. The slide caliper  110  is used for measuring the length between two corners of an object wherein both corners might form theoretical sharp corners. 
   The slide caliper  110  comprises an elongated shaft  112  defining a first gaging surface  114 . A first jaw  116  defining a second gaging surface  118  is pivotally coupled to the shaft  112  preferably adjacent to a first longitudinal end  120  of the shaft. A second jaw  122  defining a third gaging surface  123  is pivotally and slidably coupled to the shaft  112  for movement therealong. The shaft  112  preferably includes a graduated or linear measuring scale  124  therealong for measuring the distance between two corners of an object to be held between the gaging surface  118  of the first jaw  116  and the gaging surface  123  of the second jaw  122  as will be explained more fully below. The shaft  112  also preferably includes a conventional digital measuring device  126  coupled to and slidable with the second jaw  122  along the shaft for more precisely measuring the distance between two corners of the object to be held between the first and second jaws  116 ,  122 . 
   As best shown in  FIG. 12 , the first jaw  116  includes an arcuate extension  128  defining a semi-circular slot  130  for being pivotally received within a recess  132  defined by an underside of the shaft  112 . The arcuate extension  128  of the first jaw  116  when received within the recess  132  is coupled to and tightened against the shaft  112  with, for example, a thumb screw  134  having two components cooperating with each other to extend through an aperture  136  defined by the shaft and the slot  130  defined by the arcuate extension of the first jaw. 
   The first jaw  116  is generally continuously adjustably pivotable relative to the shaft  112  about a pivot axis  138  (see  FIG. 17 ) coinciding with an intersection of the gaging surface  114  of the shaft  112  and another axis  140  extending along the gaging surface  118  of the first jaw. Preferably, the pivot axis  138  is a zero distance mark of a measuring scale for generally measuring the distance between two corners of an object to be held between the gaging surface  118  of the first jaw  116  and the gaging surface  123  of the second jaw  122 . The first jaw  116  is adjustably pivotable to enable the gaging surface  118  of the first jaw to abut and thereby accommodate an opposing wall of an object having a corner forming various angles including a right angle and angles that are less than or greater than 90 degrees. 
   As best shown in  FIG. 12 , the slide caliper  110  further comprises a slide member  141  defining a channel  144  along an upper side thereof for slidably receiving an underside of the shaft  112 . An underside of the slide member  141  defines a recess  145  for pivotally receiving an arcuate extension  147  of the second jaw  122  to enable movement of the second jaw along the shaft  112 . The arcuate extension  147  defines a semi-circular slot  149 . The second jaw  122  including the extension  147  is preferably substantially a mirror image, although jogged, of the first jaw  116  including the arcuate extension  128 . The second jaw  122  is pivotally coupled to the shaft  112  via the slide member  141 . The arcuate extension  147  of the second jaw  122  when received within the recess  145  defined by the slide member  141  is coupled to and tightened against the slide member with, for example, a thumb screw  135  having two components cooperating with each other to extend through an aperture  151  defined by the slide member and the slot  149  defined by the arcuate extension of the second jaw. 
   The second jaw  122  is generally continuously adjustably pivotable relative to the shaft  112  about a pivot axis  153  (see  FIG. 17 ) that is movable along with the second jaw  122  along the shaft and coinciding with an intersection of the gaging surface  114  of the shaft  112  and another axis  161  extending along the gaging surface  123  of the second jaw. The second jaw  122  is adjustably pivotable to enable the gaging surface  123  of the second jaw to abut and thereby accommodate an opposing wall of an object having a corner forming various angles including a right angle and angles that are less than or greater than 90 degrees. As can be seen in  FIG. 11 , the ability of the first jaw  116  and the second jaw  122  each to assume a neutral orientation of 90 degrees permits the slide caliper  110  to be employed in a conventional manner. 
   As best shown in  FIG. 12 , the digital measuring device  126  includes a housing  146  defining a recess  148  on an underside thereof for being received over the shaft  112  and engaging the extension  147  of the second jaw  122  via the slide member  141  to secure the second jaw to the shaft for movement therealong. The digital measuring device  126  preferably includes a display panel  155 , first switch  150  for toggling between measurements in inches and millimeters, a second switch  152  for turning the device on or off, and a third switch  154  for calibrating the digital measuring device  126  when the gaging surface  118  of the first jaw  116  abuts the gaging surface  123  of the second jaw  122  as shown, for example, in  FIG. 11 . Although the digital measuring device  126  is shown and described by way of example with three switches performing specific functions, it should be understood that the digital measuring device can be embodied in other ways without departing from the scope of the present invention. For example, the second switch  152  for turning the device on or off is not necessary for a solar powered digital measuring device. 
   In operation, the digital measuring device  126  of the slide caliper  110  is turned on by pressing the second switch  152 . The digital measuring device  126  is preferably calibrated/zeroed by moving the second jaw  122  along the shaft  112  until the gaging surface  123  of the second jaw  122  abuts the gaging surface  118  of the first jaw  116 . While the gaging surfaces  118 ,  123  of the first and second jaws  116 ,  122  are abutting each other, the third switch  154  is pressed to calibrate/zero the digital measuring device  126 . The second jaw  122  is then moved along the shaft  112  away from the first jaw  116  in order to accommodate between the jaws an object to be measured such as, for example, a sheet metal wall of a fan tray. 
   As shown by way of example in  FIG. 17 , a fan tray  156  includes a sheet metal wall having a distance to be measured between two corners of the tray. A first corner  158  of the tray  156  is defined as the convergence of a first wall  160  and a second wall  162  of the tray. A second corner  164  of the tray  156  is defined as the convergence of the first wall  160  and a third wall  166 . As can be seen in  FIG. 17 , the first wall  160  and the second wall  162  converging at the first corner  158  cooperate to form a theoretical sharp corner having an angle that is greater than 90 degrees. The first wall  160  and the third wall  166  converging at the second corner  164  also cooperate to form a theoretical sharp corner having an angle that is greater than 90 degrees. 
   The first wall  160  of the tray  156  is placed against the gaging surface  114  of the shaft  112 . The thumbscrews  134 ,  135  associated with the first and second jaws  116 ,  122  are loosened in order to enable the first and second jaws to pivot relative to the shaft  112 . The second jaw  122  is then moved along the shaft  112  toward the first jaw  116  until a tip of the gaging surface  123  of the second jaw contacts the third wall  166  of the tray  156 , and a tip of the gaging surface  118  of the first jaw contacts the second wall  162  of the tray. The contact between the gaging surface  118  of the first jaw  116  and the second wall  162  of the tray  156  as the second jaw  122  is moved along the shaft  112  causes the first jaw to pivot until the gaging surface of the first jaw abuts the second wall of the tray. Moreover, the contact between the gaging surface  123  of the second jaw  122  and the third wall  166  as the second jaw is moved along the shaft  112  causes the second jaw to pivot until the gaging surface of the second jaw abuts the third wall. The thumbscrews  134 ,  135  associated with the first and second jaws  116 ,  122  are then tightened to maintain the first and second jaws at an orientation relative to the shaft  112  where the gaging surfaces  118 ,  123  of the first and second jaws respectively abut the second and third walls  162 ,  166  of the tray. The distance of the first wall  160  extending between the first corner  158  and the second corner  164  of the tray  156  is then accurately measured using either or both of the scales  124  on the shaft  112  and the digital measuring device  126 . More precisely, the slide caliper  110  measures the distance along the shaft  112  between the intersection of the gaging surface  114  of the shaft  112  and the axis  140  extending along the gaging surface  118  of the first jaw  116 , and the intersection of the gaging surface  114  of the shaft  112  and the axis  161  extending along the gaging surface  123  of the second jaw  122 . 
   As can be seen in  FIG. 17 , the first and second jaws  116 ,  122  preferably include index marks  129  for determining the angular orientation of the gaging surfaces  118 ,  123  of the jaws relative to the gaging surface  114  of the shaft  112 . However, the angular orientation can be determined in other ways without departing from the scope of the present invention. For example, the angular orientation could be determined by the digital measuring device  126  and shown on the display panel  155 . 
   Preferably, one of the shaft  112  and the first jaw  116  defines a detent (not shown) for locking the first jaw into a neutral orientation. Alternatively, other means such as a squareness set block on the gaging surface  114  could be substituted to set square the first jaw  116 . Likewise, the second jaw  122  preferably defines a detent (not shown) for locking the second jaw into a neutral orientation in order to permit the slide caliper  110  to be employed in a conventional manner. Alternatively, other means such as a squareness set block on the gaging surface  114  could be substituted to set square the second jaw  122 . 
   Referring now to  FIGS. 18–24 , a slide caliper in accordance with a third embodiment of the present invention is generally indicated by the reference number  210 . Like elements with the slide calipers  10  and  110  are labelled by like reference numbers preceded by “ 2 ”. The slide caliper  210  is generally the same as the slide caliper  110  shown in  FIGS. 11–17  except that the slide caliper  210  further comprises a pair of additional jaws for measuring inner diameters, and further comprises means for making depth measurements. Accordingly, the slide caliper  210  will be explained only with respect to these additional features. 
   The slide caliper  210  comprises a third jaw  270  defining a fourth gaging surface  272  coupled to the shaft  212  preferably adjacent to the first longitudinal end  220  of the shaft. The third jaw  270  extends outwardly from the shaft  212  in a direction generally opposite to that of the first and second jaws  216 ,  222 . The slide caliper further comprises a fourth jaw  274  defining a fifth gaging surface  276  slidably coupled to the shaft  212  for movement therealong. The fourth jaw  274  also extends outwardly from the shaft  212  in a direction generally opposite to that of the first and second jaws  216 ,  222 . As best shown in  FIG. 19 , the fourth jaw  274  is preferably coupled to the shaft  212  via the slide member  241 . The gaging surface  272  of the third jaw  270  and the gaging surface  276  of the fourth jaw  274  face away from one another when the fourth jaw is moved along the shaft  212  away from the third jaw, thereby permitting the third and fourth jaws to measure inner diameters or otherwise measure distances therebetween. The fourth jaw  274  is disposed slightly below the third jaw  270  relative to the shaft  212  so as to enable the fourth jaw to move under the third jaw and align the gaging surface  276  of the fourth jaw in overlying relationship with the gaging surface  272  of the third jaw (see  FIG. 20 ) when the third and fourth jaws are at the zero distance position relative to each other. Alternatively, the fourth jaw could be modified to be disposed slightly above the third jaw to enable the fourth jaw to move over the third jaw without departing from the scope of the present invention. 
   In operation, the fourth jaw  274  is moved along the shaft  212  away from the third jaw  270  until the gaging surface  272  of the third jaw and the gaging surface  276  of the fourth jaw abut surfaces having an inner diameter or otherwise defining a distance therebetween to be measured. The distance between the gaging surface  272  of the third jaw  270  and the gaging surface  276  of the fourth jaw  274  can be determined from the measuring scale  224  on the shaft  212 , or can be determined from the distance shown on the display panel  255  of the digital measuring device  226 . 
   The slide caliper  210  further comprises means for making depth measurements. As shown in  FIG. 19 , for example, an elongated member  278  for making depth measurements is coupled at a first longitudinal end  280  to the slide member  241 , and is disposed generally within a recess defined by an underside of the shaft  212  (see  FIG. 24 ). When the slide caliper  210  is in the zero distance position, a second longitudinal end  282  of the elongated member  278  is either flush with or extends slightly outwardly from a second longitudinal end  284  of the shaft  212 . 
   In operation, the second longitudinal end  282  of the elongated member  278  is moved away from the second longitudinal end  284  of the shaft  212  a distance corresponding to the depth to be measured. The distance between the second longitudinal end  282  of the elongated member  278  and the second longitudinal end  284  of the shaft  212  can be determined from the measuring scale  224  on the shaft and corresponds generally to the distance between the first and second jaws  216 ,  222 , or can be determined from the distance shown on the display panel  255  of the digital measuring device  226 . 
   Although the slide caliper  210  for measuring inner diameters is shown and described with respect to a slide caliper that can measure two theoretical sharp corners, it should be understood that a slide caliper for measuring inner diameters in accordance with the present invention can be used in a slide caliper that can measure one theoretical sharp corner—similar to the slide caliper  10  shown in FIGS.  1 – 10 —without departing from the scope of the present invention. Moreover, although the third and fourth jaws  270 ,  274  are non-pivoting, it should be understood that one or more of the third and fourth jaws could be substituted with pivotable jaws. 
   As will be recognized by those of ordinary skill in the pertinent art, numerous modifications and substitutions may be made to the above-described embodiments of the present invention without departing from the scope of the invention. Accordingly, the preceding portion of this specification is to be taken in an illustrative, as opposed to a limiting sense.