Abstract:
A device is provided for measuring the centre of a grinding wheel for use in setting the height of a skate blade. The device has a base, a support extending from the base, a slider block slidable along the neck between the base and a head block secured to an upper end of the neck, a dial indicator supported by the head block for measuring the position of the slider block along the neck, a lower roller, and an upper roller. The lower roller and upper roller are rotatably attached to the slider block and radially aligned with each other such that a portion of each roller protrudes from the slider block, wherein a clockwise tangential force imparted on the upper roller causes the slider block to slide along the neck, and the dial indicator to record the movement of the slider block, which enables the height of an object to be set on the dial indicator with respect to a rest position of the slider block.

Description:
[0001]     This application claims priority from U.S. Provisional Patent Application No. 60/667,689 filed Apr. 4, 2005. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates to devices for measuring, comparing, and setting the height of an object and has particular utility in centring the hollow of a skate blade with respect to the grinding wheel of a skate sharpener.  
       DESCRIPTION OF THE PRIOR ART  
       [0003]     The blade of an ice skate comprises a concave lower surface, providing a pair of edges at terminal ends of the concave surface. This concave surface is generally referred to as the “hollow” of the blade. To maintain the hollow, and thus the pair of edges, the skate is periodically sharpened using a skate sharpening machine.  
         [0004]     A typical skate sharpening machine is generally comprised of a table-top or working surface, and a motor driven grinding wheel mounted on the surface. In order to restore a blade&#39;s hollow, the grinding wheel is oriented substantially parallel to the working surface. Before the grinding wheel is used for sharpening skates, typically it is first “dressed”. Dressing the wheel involves creating a desired convex surface about the periphery of the grinding wheel, which matches the desired hollow of the blade. Once the wheel has been dressed, the skate blade may then be sharpened.  
         [0005]     The technique used for creating and/or restoring a hollow is typically referred to as finish grinding. Finish grinding involves bringing the blade towards the grinding wheel, as it rotates, through a path which is parallel to and aligned with the tangential direction of the rotating grinding wheel. When the blade contacts the rotating grinding wheel, the wheel&#39;s abrasiveness effectively grinds the hollow to its desired concavity, i.e., to match the convexity of the periphery of the grinding wheel.  
         [0006]     It is important for the skate blade to have an even edge (i.e. where the terminal edges of the concave surface intersect a common diameter of the hollow). To ensure an even edge, care should be taken to accurately centre the skate blade with respect to the grinding wheel. The effect of centring the skate blade vertically aligns the length of the blade with the edge of the grinding wheel, enabling an even transfer of curvature from the grinding wheel to the blade. To assist in finish grinding, the ice skate is preferably held in place using a clamping device, known as a skate holder. The skate holder is free to move atop the working surface, and orients the skate blade in the above described position relative to the grinding wheel.  
         [0007]     Many available skate holders permit an operator to adjust the height of the skate blade using a suitable levelling mechanism, enabling the blade to be centred with respect to the grinding wheel. However, this requires that the operator place the skate blade against the grinding wheel (while stopped) and adjust the height of the skate holder until the operator is satisfied that the blade has been adequately centred. Such an operation can be awkward and inaccurate due to the size of the skate sharpening machine and the angle at which the operator would observe the alignment of the blade with respect to the grinding wheel.  
         [0008]     Moreover, if the operator is required to sharpen a number of skates in succession, they would need to perform the above technique for each skate, to ensure that they are satisfied that each skate blade is properly centred before it is sharpened. The downtime between successive sharpenings to center each skate blade, can hinder the productivity of the operator.  
         [0009]     Performing such a technique in the vicinity of the grinding wheel also poses the risk of the grinding wheel inadvertently powering on without warning, creating a hazard for the operator.  
         [0010]     It is therefore an object of the present invention to provide a device that obviates or mitigates at least one of the above-described disadvantages.  
       SUMMARY OF THE INVENTION  
       [0011]     A device for measuring the height of one object for use in setting the height of another object is provided. The device comprises a base, a support extending from the base, a measuring head displaceable relative to the support within a defined range, an indicator for measuring the position of the measuring head relative to the support, and a centering guide engageable with the one object and the another object, wherein the centering guide moves the measuring head relative to the support while locating the height of the one object, and the indicator is operable to capture the height of the one object for use in setting the height of the another object.  
         [0012]     As a preference, a magnetic lock is housed in the base for actuating a magnetic force between the base and a working surface on which the base rests.  
         [0013]     As another preference, a stop collar is included which slides over the support and can be secured thereto for setting a lower limit for the position of the measuring head. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]     An embodiment of the invention will now be described by way of example only with reference to the appended drawings wherein:  
         [0015]      FIG. 1  is a perspective view of a skate sharpening environment.  
         [0016]      FIG. 2  is a perspective view of an embodiment of a height comparator.  
         [0017]      FIG. 3  is an exploded view of the embodiment of  FIG. 2 .  
         [0018]      FIG. 4  is an elevation view of the embodiment of  FIG. 2 .  
         [0019]      FIG. 5  is a perspective view of the embodiment of  FIG. 2  in use.  
         [0020]      FIG. 6  is another perspective view of the embodiment of  FIG. 2  in use.  
         [0021]      FIG. 7  is a pair of perspective views of another embodiment.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0022]     Referring therefore to  FIG. 1 , a typical skate sharpening environment is shown. A table has a working surface  12  that supports a skate sharpening machine  80 . The working surface  12  is preferably made of a material that is attracted to a magnet. The machine  80  is mounted on the surface  12 , and a portion of a grinding wheel  82  protrudes through a slot  84  formed in a shield  86 . The surface  12  also supports a clamping-type skate holder  90 . The holder  90  has a base  92  that rests on the surface  12 . The base  92  supports a levelling plate  94  with a pair of levelling mechanisms  100  (one of them is not shown) having adjustment handles  102 . A skate  200 , having a blade  202 , is clamped between the plate  94  and a jaw  97 . The jaw  97  is part of a clamping mechanism  96 , and is operated by pivoting a handle  98 , which is also part of the clamping mechanism  96 . A device for measuring the height of an object to be used in setting the height of another object is also supported on the surface  12  and is generally denoted by numeral  10 .  
         [0023]     The device  10  is shown in greater detail in  FIGS. 2-4 . The device  10  has a base  14 , which rests on the surface  12 . The base  14 , in this embodiment, is a cylindrical block, which contains a magnetic clamp  18  operated by a switch  16 . The clamp  18  fits into a slot  65 , and upon operating the switch  16 , the base  14  becomes attracted to the surface  12 . The clamp  18  is a well known component in the art. The base  14  also has a vertically oriented bore  66 , for receiving a support, in this example dowel  20 ; and a threaded, horizontally oriented bore  22 , for receiving a set screw  22 . The set screw  22  is used to engage the dowel  20  and secure it to the base  14 .  
         [0024]     A stop collar  26 , is sized to slide over the dowel  20 . The collar  26  has a threaded bore  64  to receive a set screw  28  for engaging the dowel  20 , and to hold the collar  26  at a desired position along the dowel  20 . A measuring head, in this example slide block  30 , has a vertically oriented bore  58 , sized to receive the dowel  20 , enabling the block  30  to slide along the dowel  20  and rest upon the collar  26 . The block  30  has a horizontal channel  39 , and vertical slot  41 .  
         [0025]     The channel  39  is flanked by an upper bore  60 , and a lower bore  62 . The bores  60  and  62  pass through the slot  41  and the width of the block  30 . An upper roller  36  is supported within the slot  41  by an upper dowel pin  35 ; and a lower roller  38  is supported within the slot  41 , below the upper roller  36 , by a lower dowel pin  37 . The dowel pins  35  and  37  are sized to frictionally engage the walls of the upper and lower bores  60  and  62  respectively, in order to hold the rollers  36  and  38  in place. As best shown in  FIG. 3 , a portion of each of the rollers  36  and  38  partially protrudes into the channel  39 , and a portion of each protrudes to the exterior of the block  30  to define convergent surfaces that centre the block on the wheel  82 .  
         [0026]     A head block  32  has a first vertically oriented bore  52 , a second vertically oriented bore  50 , a first horizontally oriented bore  54 , and a second horizontally oriented bore  56 . The bore  52  is sized similar to the bore  58 , enabling the block  32  to slide over the dowel  20 . The bores  54  and  56  are threaded, and sized similar to the bore  22 , such that they may receive set screws  42  and  40  respectively. The set screw  42  engages the dowel  20  to secure the block  32  at a desired position. The bore  50  is sized to receive a stem  44  that extends from a dial indicator  34 . The set screw  40  engages the stem  40  to secure the dial indicator  34  atop the block  32 .  
         [0027]     The dial indicator  34  has a rotatable face  46 . The rotatable face  46  has a set of markings  47  about its circumference, enabling a desired one of the markings  47  to be aligned with a needle  48 . As shown in  FIG. 4 , the stem  44  partially protrudes beyond the lower surface of the head block  32  and is moveable towards the dial indicator  34  when it is pushed from below. The stem  44  is connected to the needle  48 , such that movement of the stem  44  produces a corresponding movement of the needle  48 .  
         [0028]     In order to enable the device  10  to measure the height of an object, the collar  26  should be secured at a particular position, depending on that height. The slide block  30 , and thus the rollers  36  and  38  are intended to have a certain range of travel along the dowel  20 , wherein the typical height of the object being measured should fall within the range of travel of the rollers  36  and  38 . The collar  26  is thus secured to the dowel  20  at a height suitable to inhibit downward movement of the block  30  beyond the lowermost point in its desired range of travel.  
         [0029]     The position of the head block  32  should place the lower surface of the block  32  at the upper limit of the desired range of travel of the block  30 . In this position, the block  32  allows upward movement of the block  30  until the block  30  reaches the upper limit of its range of travel. The stem  44  has a sufficient range of movement to accommodate the movement of the block  32  within the range of travel so that movement of the block  30  will cause a corresponding movement of the needle  48  of the dial indicator  34 .  
         [0030]     The following describes how the device  10  can be used for setting the height of a skate blade for the purpose of sharpening the skate blade, making reference to  FIGS. 5 and 6 .  
         [0031]     The device  10  is first used to measure the “centred” height of the dress of the grinding wheel  82 . Thus, in this example, it will be assumed that the grinding wheel  82  has already been dressed, and is ready to be used to perform a finish grind on a skate blade.  
         [0032]     The range of travel of the block  30 , described above, would be chosen according to the height of the grinding wheel  82  with respect to the surface  12 . A suitable height for the grinding wheel  82  is about 4½″. Since the collar  26  has been secured to the dowel  20  such that the block  30  rests at the lower end of its range of travel, the lower roller  38  would lie below the grinding wheel  82  when the device  10  is not in use. At this point, the needle  48  would be at its rest position.  
         [0033]     To measure the centre of the dress on the grinding wheel  82 , the device  12  is brought towards the grinding wheel  82 , wherein the upper roller  36  would contact the grinding wheel  82  first. The device  10  would then be pushed further towards the grinding wheel  82 , exerting a substantially tangential force on the upper roller  36 . This force would cause the upper roller to move along the curvature of the grinding wheel  82  which in turn causes the block  30  to slide up along the dowel  20  until the lower roller  38  is also in contact with the grinding wheel  82 . The position of the rollers  36  and  38  at this point indicates the center of the dress on the grinding wheel  82 . The upward movement of the block  30 , moves the stem  44 , which in turn rotates the needle  48  a distance that corresponds to the extent to which the stem  44  has moved.  
         [0034]     The face  46  is then rotated to align a “zero” on its dial markings  47  with the position of the needle  38 . This zero marking indicates the required position of the needle  48  (and thus the required position of the slider block  30 ) to replicate the centre of the wheel  82 .  
         [0035]     The device  10  may then be moved away from the machine  80 , along the surface  12 , to an unobtrusive location. Preferably, the device  10  is then firmly locked to the surface  12  by turning the switch  16 , which causes the base  14  to be magnetically attracted to the surface  12 .  
         [0036]     To set the height of the blade  202 , the skate holder  90  having the skate  200  clamped therein, is brought to the device  10 , and the levelling mechanisms  100  are adjusted to place the height of the blade  202  substantially level with the channel  39 . At this point, the skate holder  90  should remain seated on the surface  12  and the blade  202  should be touching at least one of the rollers  36  and  38 .  
         [0037]     The levelling mechanisms  100  can then be used to raise or lower the blade  202 . As the blade  202  is raised, it should be held against the rollers  36  and  38  and maintain contact with at least the upper roller  36 . This will cause the block  30  to slide along the dowel  20  in an upward direction, plunge the stein  44 , and move the needle  48 . The blade  202  should be raised until the needle  48  points to the zero marking on the dial  47 , which was previously set when measuring the height of the grinding wheel  82 . Once this height has been achieved, the blade  202  is now centred. Typically, this operation is performed at each end of the blade  202  to level the blade  202  as well as to adjust its height in order to ensure that the entire length of the blade  202  is centred.  
         [0038]     The skate blade  202  may then be given a finish grind using the grinding wheel  82 , with confidence that the skate blade  202  has been accurately centred, resulting in an even hollow.  
         [0039]     Subsequent skates that are clamped in the holder  90 , can be centred using the device  10 , which is preferably positioned a safe distance from the machine  80 . This can be repeated for each skate  200  that is sharpened, until the grinding wheel  82  is dressed again. This ensures that each time the skate holder  90  is used, its height is accurately set so that the blade  202  receives an even hollow. The skate holder  90  may vary in height since different skate blades  202  can have a different thickness and, moreover, there is no guarantee without measuring that the skate holder  90  has not been readjusted between successive skate sharpening operations.  
         [0040]     In another embodiment shown in  FIG. 7 , a dial lock device  300  is used. A bottom portion  301  of the dial indicator  34  includes a bore  305  that is adapted for receiving a threaded rod  303 . The threaded rod  303  extends from a collar  302  which has a thumbscrew  304  at its other end. The rod  303  is first threaded through a foot  306  until its shoulder engages the foot  306  and is then threaded into the bore  305 . The thumbscrew  304  may be turned by hand to advance the foot  306  along the rod  303  until it presses against the rotatable face  46 . The thumbscrew  304  may then be turned in an opposite manner to release the foot  306 . The lock device  300  may be used to lock the face  46  after it has been set to zero during the procedure explained above. The purpose of locking the face  46  in position is to inhibit accidental movements of the face  46  once it has been set, which can lead to inaccurate height settings.  
         [0041]     Therefore, the device  10  provides a safe, quick, stable, and effective way to center the height of a skate blade  202 , without requiring the operator to adjust the skate holder  90  with respect to the grinding wheel  82  each time a new skate  200  is sharpened, which can be inaccurate and/or dangerous. The device  10  also promotes an efficient skate sharpening routine, since the device  10  can quickly and accurately center successive skate blades  202  without requiring the machine  80  to be turned off causing unnecessary down time.  
         [0042]     Although the invention has been described with reference to certain specific embodiments, various modifications thereof will be apparent to those skilled in the art without departing from the spirit and scope of the invention as outlined in the claims appended hereto.