Patent Description:
Ice skates engage the surface of the ice on a pair of edges. Over time, the edges can become dull or nicked and, in such conditions, the performance of the ice skates is less than optimal. To restore the performance of the ice skates, the skate blades can be sharpened.

While the frequency of ice skate blade sharpening differs depending upon the individual, the recommended frequency for most serious skaters is one sharpening for every three to five hours of ice time. When it is time for the sharpening, few people have the equipment necessary to sharpen the skates and, for that reason, the skates need to be dropped off at a local skate shop or ice rink for sharpening. The frequent trips for sharpening can become an annoyance and many skaters will skate on less than optimal skate blades simply to avoid the extra trips or time in line at the skate shop or rink. Even if people had access to the equipment, few people have the training or skills necessary to sharpen their own skates.

Document <CIT> discloses a skate sharpening system allowing access to the base but not with the convenience of the invention.

A need exists for skate sharpening machines that are simple to use and cost effective enough for home use. Certain features, aspects and advantages of the present invention address a myriad of challenges encountered when designing a portable skate sharpening machine that is cost effective and easy to use. The systems, methods and devices described herein have innovative aspects, no single one of which is indispensable or solely responsible for their desirable attributes. Without limiting the scope of the claims, some of the advantageous features will now be summarized.

In accordance with claim <NUM>, a skate sharpening system includes an operative unit and a base, the operative unit comprising a central body, the central body comprising a skate receiving slot, a skate clamp being positioned adjacent to the skate receiving slot such that a skate can be secured within the skate receiving slot for a sharpening operation, the operative unit further comprising a grinding unit, the grinding unit being configured to translate along a length of the slot such that the grinding unit can conduct the sharpening operation on the skate that is secured within the skate receiving slot, the operative unit being positioned over at least a portion of the base, the base comprising a swarf-receiving cavity, the operative unit and the base being pivotably connected.

In some embodiments, the base comprises a first side wall and a second side wall, the operative unit being pivotably connected to the first and second side walls.

In some embodiments, the base comprises a bucket.

In some embodiments, the bucket has a height, a width and a depth, the width being greater than the height and the depth.

In some embodiments, the bucket comprises a bottom surface, the bottom surface being supported by a plurality of feet and the bottom surface comprising a reflective region.

In some embodiments, a biasing assembly interacts between the operative unit and the base to resist closure of the operative unit relative to the base.

In some embodiments, the first side wall comprises a first mount and the second side wall comprises a second mount, the operative unit being connected to the first mount and the second mount.

In some embodiments, each of the first mount and the second mount is defined by a saddle shape.

In some embodiments, the operative unit comprises a first biasing assembly that is received within the first mount and a second biasing assembly that is received within the second mount.

In some embodiments, the first and second biasing assemblies each comprises a torsion spring that opposes pivotal movement of the operative unit toward a closed position against the base.

In some embodiments, the biasing assemblies and the mounts comprise a protuberance that is received within a pocket, the protuberances and the pockets cooperating to resist pivoting movement of the first and second biasing assemblies relative to the first and second mounts.

In accordance with claim <NUM>, the system includes a position lock that secures the operative unit against movement relative to the base.

In some embodiments, the position lock comprises at least a first rod that translates relative to the operative unit.

In some embodiments, the first rod engages with at least one corresponding recess.

In some embodiments, the operative unit is locked against pivotal movement relative to the base when the first rod is engaged with at least one corresponding recess.

In some embodiments, the system includes a first actuator that is operatively connected to the first rod.

In some embodiments, the base is a molded resin-based component.

In some embodiments, the resin-based component is optically translucent, optically transparent, or optically clear.

In accordance with certain features, aspects and advantages of at least another one of the embodiments disclosed herein, a skate blade sharpening system includes a clamp configured to retain a skate blade in a sharpening position, a centerline of the sharpening position having a first predetermined location; a motor-driven rotating shaft, the shaft having a wheel-mounting location at which a grinding wheel is mounted to rotate with the shaft and contact the skate blade in the sharpening position during a sharpening operation; and an adjustment mechanism comprising: an alignment shaft; a bushing positioned on a longitudinal portion of the alignment shaft; a compression mechanism applying pressure to the bushing, wherein the pressure is applied to the alignment shaft, wherein the pressure is configured to substantially eliminate unintentional rotational movement of the alignment shaft; and an adjustment member configured to rotate the alignment shaft, wherein rotation of the alignment shaft is configured to vary a position of the grinding wheel relative to the centerline of the sharpening position.

In some embodiments, the bushing is a threaded bushing and the threaded bushing is threaded onto a threaded portion of the alignment shaft or the bushing is a through hole bushing positioned on an unthreaded portion of the alignment shaft.

In some embodiments, the bushing is a threaded bushing threaded onto a threaded portion of the alignment shaft and the adjustment mechanism further comprises a through hole bushing, and wherein the alignment shaft comprises an unthreaded portion, wherein the through hole bushing is positioned on the unthreaded portion of the alignment shaft.

In some embodiments, the through hole bushing is reamed and has an interference fit with the unthreaded portion of the alignment shaft.

In some embodiments, the alignment shaft comprises a detent portion having a plurality of detents circumferentially disposed about a circumference of the alignment shaft, wherein the adjustment mechanism further comprises a spring pin configured to ride within a detent.

In some embodiments, manipulation of the adjustment member is configured to move the alignment shaft relative to the spring pin such that the movement of each detent past the spring pin results in at least one of an auditory or tactile indication of movement and a defined amount of linear movement of the grinding wheel.

In some embodiments, the defined amount of linear movement is between <NUM> and <NUM> of a mm per detent.

In some embodiments, the bushing is formed from a polymer.

In some embodiments, the adjustment member is adjustable by a user, wherein a diameter of adjustment member is greater than a diameter of the alignment shaft.

In some embodiments, the system includes a controller configured to control a motor, wherein the adjustment member is adjustable by the motor.

In some embodiments, the threaded bushing includes tabs extending radially from a body of the bushing to prevent rotation of the threaded bushing during rotation of the alignment shaft.

In some embodiments, the pressure on the bushing is sufficient to substantially prevent hysteresis based on movement of the alignment shaft not caused by intentional movement of the adjustment member.

In accordance with certain features, aspects and advantages of at least another one of the embodiments disclosed herein, a skate blade sharpening system includes a blade retention mechanism configured to securely hold a blade to be sharpened in a sharpening operation within a skate blade opening of the skate blade sharpening system; a rotating shaft driven by a grinding motor and configured to have a grinding wheel mounted thereon, the grinding wheel contacting the blade during the sharpening operation; an arbor on the rotating shaft, the arbor having a heat-conducting mating with the grinding wheel when the grinding wheel is mounted on the rotating shaft, and heat dissipation features extending a portion of the width of the arbor; and an arbor shroud preventing access to the heat dissipation features through the skate blade opening of the skate blade sharpening system.

In some embodiments, the arbor shroud covers at least the portion of the width of the heat dissipation features.

In some embodiments, the arbor shroud further comprises a sidewall that forms an opening in the arbor shroud, wherein the arbor is disposed at least partially within the opening, the opening extending about at least a circumferential portion of the arbor, wherein the arbor shroud is fixed in a stationary position relative to the rotation of the rotating shaft, wherein a gap is formed between the sidewall and the arbor such that the arbor does not contact the sidewall when rotating.

In some embodiments, the arbor shroud has an opening on its circumference configured to direct airflow.

In some embodiments, the opening is up to one half the circumference of the arbor.

In some embodiments, a carriage moves with grinding wheel during the sharpening operation.

In some embodiments, the arbor shroud is coupled to the spindle assembly.

In some embodiments, the arbor shroud includes at least one retention feature.

In some embodiments, arbor shroud is coupled to the spindle assembly by at least one fastener.

In some embodiments, the arbor shroud includes a plurality of openings in a back wall of the shroud configured to direct airflow.

In some embodiments, the arbor shroud includes at least one vertical displacement member on at least one side of the shroud that is configured to vertically displace the grinding wheel relative to the skate blade opening.

In some embodiments, the vertical displacement members extend distally from shroud.

In some embodiments, the at least one vertical displacement member is configured to prevent the grinding wheel from contacting jaws of a skate blade retentions system during a sharpening operation.

In some embodiments, the heat dissipation features are a set of vanes.

In some embodiments, the arbor shroud moves transversely along the skate blade with the arbor during the sharpening operation.

Throughout the drawings, reference numbers can be reused to indicate general correspondence between reference elements. The drawings are provided to illustrate example embodiments described herein and are not intended to limit the scope of the disclosure.

<FIG> is a perspective view of a skate sharpening system <NUM> used to sharpen the blades of ice skates. As illustrated, the skate sharpening system <NUM> is designed and configured to provide a safe, clean, and automated skate sharpening system. The skate sharpening system <NUM> allows users to sharpen skates at home, on their own schedule, and with professional quality results. Operation of the skate sharpening system <NUM> generally can be as described in <CIT> and which published as <CIT>.

<FIG> also shows a coordinate system for references to spatial directions within this disclosure. The X direction is left-to-right, the Y direction back-to-front, and the Z direction bottom-to-top with respect to the skate sharpener <NUM> in the upright, front-facing orientation of <FIG>. This coordinate system also defines an X-Y plane (horizontal), X-Z plane (vertical and left-to-right), and Y-Z plane (vertical and front-to-back).

The illustrated skate sharpening system <NUM> comprises an operative unit <NUM> and a base <NUM>. As will be described below, the illustrated operative unit <NUM> contains blade retention assemblies for gripping an ice skate blade, grinding assemblies for sharpening the skate blade, and control arrangements for controlling the skate sharpener <NUM>. An ice skate blade can by inserted into the skate slot <NUM> and secured by blade retention jaws <NUM>. Slot covers <NUM> overly at least a portion of the skate slot <NUM>. The slot covers <NUM> can be moved along a portion of the length of the slot <NUM> to abut the ends of the skate blades that are secured by the blade retention jaws <NUM>.

The base <NUM> supports the operative unit <NUM> during operation. In the illustrated configuration, the base <NUM> provides a receptacle for capturing the swarf and collecting the dust resulting from a sharpening operation. In some configurations, the operative unit <NUM> can be removed from the base <NUM>. In the illustrated configuration, the operative unit <NUM> is configured to pivot open relative to the base <NUM> and the operative unit <NUM> is configured to be completely removed from the base <NUM> as desired.

The base <NUM> can have any suitable configuration and can be formed of any suitable material. In the illustrated configuration, the base <NUM> is molded of a resin-based material. In some such configurations, the base <NUM> is formed from an optically translucent or an optically transparent material. To improve monitoring of operation of the skate sharpening system <NUM>, the base <NUM> can be formed from an optically clear material. Some desired materials from which the base <NUM> can be formed include, but are not limited to, polycarbonate, polystyrene, PET, or PETG.

In some embodiments, the base <NUM> can comprise a plastic or metal structure and a clear or translucent window. The window can be positioned along any portion of the base. In some configurations, the window can be positioned on the front of the base such that the base <NUM> can provide structure and rigidity while maintaining a portion for viewing operation of the skate sharpening system.

With reference to <FIG>, the base <NUM> can be configured as a shallow bucket. As used herein, the term "bucket" is intended to mean an open container or a container with an opening. The bucket forms a shallow enclosure or a shallow tray in the illustrated configuration. The bucket can have one or more side wall and a bottom wall. The illustrated base <NUM> is defined by a bucket that comprises a bottom wall <NUM> and four side walls. The bottom wall <NUM> can be bounded by a right side wall <NUM>, a left side wall <NUM>, a front wall <NUM>, and a rear wall <NUM>.

With reference to <FIG>, the bottom wall <NUM> can include feet <NUM>. In the illustrated configuration, the bottom wall <NUM> includes four feet <NUM>. While the feet <NUM> can be adjustable in some configurations to provide a small degree of leveling, the illustrated feet <NUM> are non-adjustable rubber feet. The nonadjustable rubber feet <NUM> can be adhered within features that are integrally molded into the base <NUM>. The features are integrally molded into the bottom wall <NUM> in the illustrated configuration. In some embodiments, the feet are protuberances that are integrally molded into the bottom wall <NUM>. Given the material of the base <NUM>, the base <NUM> is capable of flexing sufficiently to accommodate minor irregularities in any surface upon which the base is placed. For example, it has been found that the base <NUM> is capable of flexing a sufficient degree to accommodate an offset between any two feet <NUM> of up to <NUM> over a span of <NUM>.

The illustrated base <NUM> has a height H, a width W, and a depth D. The width W exceeds the depth D and the height H. The width W is large enough to underlie an adult or senior skate supported in the operative unit <NUM> for a sharpening operation. The height H is less than the depth D. In some configurations, the height H is just large enough to accommodate moving components of the operative unit <NUM>. In some such configurations, the height H is just enough to provide access to a grinding wheel of the operative unit <NUM> and a filter assembly of the operative unit <NUM>. In one configuration, the height is <NUM>, the depth is <NUM>, and the width is <NUM>. Given that the skate sharpening system <NUM> can be used in a home, the base <NUM> is configured to have a footprint of less than <NUM><NUM>. In some configurations, the width is about twice the depth. In some configurations, the footprint is less than <NUM><NUM> with a width that is about twice the depth. Such a small footprint and configuration is difficult to achieve while accommodating senior skates and the movement of sharpening components of the operative unit <NUM> while providing a skate sharpening system that can sit on a countertop.

With reference to <FIG>, in the illustrated configuration, a reflective surface <NUM> can be provided on at least a portion of the bottom wall <NUM> of the base <NUM>. The reflective surface <NUM> can be positioned under a path of the moving components of the operative unit <NUM>. In particular, the reflective surface <NUM> can be positioned such that the reflective surface <NUM> can aid during an alignment process. In some configurations, the reflective surface is provided by a reflective sticker that is secured in position using adhesive. Other configurations can be used keeping in mind a desire to have the reflective surface properly positioned after cleaning of the base <NUM> following a series of sharpening operations. In other words, the reflective surface desirably does not become dislodged as a result of routine operation of the device, including cleaning of the base <NUM>.

At least one of the right side wall <NUM> and/or the left sidewall <NUM> can carry a magnet <NUM>. As described above, the operative unit <NUM> and the base <NUM> can be connected such that the operative unit <NUM> pivots relative to the base <NUM>. In one configuration, the magnet <NUM> aligns with a sensor such that operation of the sharpening assembly of the operative unit <NUM> can be prevented unless the operative unit <NUM> is closed against the base <NUM>. The position of the operative unit <NUM> relative to the base <NUM> can be indicated by the sensor depending upon the placement of the sensor relative to the magnet <NUM>. In some configurations, the magnet <NUM> cooperates with a reed switch that tells the operative unit <NUM> whether the operative unit <NUM> is in an open position or a closed position. Other configurations may include the use of different switches or sensors to determine the position of the operative unit <NUM> relative to the base <NUM>. For example, position detection can be performed by sensing means that include one or more of an optical switch, a mechanical switch, angle sensors, accelerometers, or other types of switches and sensors.

The front wall <NUM> can comprise at least one cut out <NUM>. In the illustrated configuration, the front wall <NUM> includes a cut out <NUM> at each end of the front wall <NUM>. As will be described, the cut-outs <NUM> accommodate portions of the operative unit <NUM>. The cut-outs <NUM> can have any suitable configuration. In the illustrated configuration, however, the cut-outs <NUM> closely align with corresponding surfaces of the operative unit <NUM>.

The rear wall <NUM> can include a vent feature <NUM>. In the illustrated configuration, the vent feature <NUM> comprises a u-shaped opening. The vent feature <NUM> can be sized and configure to accommodate the placement of an airflow outlet from the operative unit <NUM>. The vent feature <NUM> aligns with the airflow outlet from the operative unit <NUM> when the operative unit <NUM> and the base <NUM> are connected together and when the operative unit <NUM> is in position for a sharpening operation. The illustrated vent feature comprises a u-shaped or c-shaped recess that extends downward from an uppermost edge of the rear wall.

The right side wall <NUM> can include a right mount <NUM> and the left side wall <NUM> can include a left mount <NUM>. The mounts <NUM>, <NUM> can be configured in any suitable manner keeping in mind a desire to support the operative unit <NUM> using the base <NUM>. In the illustrated configuration, the mounts <NUM>, <NUM> define saddles. The saddles have generally C-shaped ledges <NUM>, <NUM> with outer walls <NUM>, <NUM>. The ledges <NUM>, <NUM> extend laterally outward from the right side wall <NUM> and the left side wall <NUM> of the base <NUM>. The ledges <NUM>, <NUM> in the illustrated configuration extend between the walls <NUM>, <NUM> and the walls <NUM>, <NUM> respectively.

As discussed above, the operative unit <NUM> includes assemblies for gripping an ice skate blade, for sharpening the skate blade, and for controlling the skate sharpener <NUM>. The illustrated operative unit <NUM> generally comprises a central body <NUM>, a right end cap <NUM> and a left end cap <NUM>. The end caps <NUM>, <NUM> can be secured to the central body <NUM> in any suitable manner. In the illustrated configuration, the end caps <NUM>, <NUM> are secured to the central body using threaded fasteners.

The central body <NUM> comprises a forward shelf <NUM> and a rear housing <NUM>. The forward shelf <NUM> can be secured to the rear housing <NUM> in any suitable manner. In the illustrated configuration, the rear housing <NUM> has a lip that overlies a rear portion of the forward shelf <NUM> and the two <NUM>, <NUM> are secured together with threaded fasteners from the bottom. In some configurations, the forward shelf <NUM> is formed as an extrusion that can be cut to length in serial production. In some configurations, the rear housing <NUM> is formed as an extrusion that can be cut to length in serial production. The end caps <NUM>, <NUM> span the juncture between the forward shelf <NUM> and the rear housing <NUM>.

The illustrated operative unit <NUM> comprises a pair of biasing assemblies <NUM>, <NUM>. The illustrated biasing assemblies <NUM>, <NUM> protrude outward from the end caps <NUM>, <NUM>. The biasing assemblies <NUM>, <NUM> and the mounts <NUM>, <NUM> of the base <NUM> are sized and configured such that the biasing assemblies <NUM>, <NUM> can be received within and supported by the mounts <NUM>, <NUM>. At least a portion of the biasing assemblies <NUM>, <NUM> and the mounts <NUM>, <NUM> are secured against significant relative rotation. In the illustrated configuration, each of the mounts <NUM>, <NUM> includes a respective pocket <NUM>, <NUM>. Each of the biasing assemblies <NUM>, <NUM> incorporates a protuberance <NUM>, <NUM>. The protuberances <NUM>, <NUM> are received within the respective pockets <NUM>, <NUM>. The interaction between the protuberances <NUM>, <NUM> and the pockets <NUM>, <NUM> limits relative rotation between at least those portions. In some configurations, the protuberances can be formed along the mounts and the biasing assemblies incorporate a pocket. Other configurations also can be used to limit the relative rotation between at least those portions.

With reference now to <FIG>, the biasing assemblies <NUM>, <NUM> will be described with reference to the right biasing assembly <NUM>. In the illustrated configuration, the left biasing assembly <NUM> is a mirror image of the right biasing assembly <NUM> and includes the same components. Moreover, while the illustrated biasing assemblies are mounted to the operative unit and locked to the base, it is possible to reverse this configuration such that the biasing assemblies are mounted to the base and locked to operative unit. The biasing assemblies exert a biasing force between the base and the operative unit. The biasing assemblies exert a pivotal biasing force in some configurations.

The illustrated biasing assembly includes a cover <NUM>. The cover <NUM> includes the protuberance <NUM>. The cover <NUM> has a cup shape that accommodates a torsion spring <NUM>. The torsion spring <NUM> includes a first leg <NUM> that is received within a hole <NUM> formed in the cover <NUM>. The torsion spring <NUM> also includes a second leg <NUM> that is received within a hole <NUM> formed in the right end cap <NUM>. A hub <NUM> extends outward from the right end cap <NUM> and the torsion spring <NUM> surrounds at least a portion of the hub <NUM>. The cover <NUM> is secured to the right end cap <NUM> by a threaded fastener <NUM> but the right end cap <NUM> is capable of pivoting movement relative to the cover <NUM>.

When the biasing assembly <NUM> is received within the mount <NUM>, a thumbscrew <NUM> extends through an opening in the ledge <NUM> and engages with a threaded opening formed in the cover <NUM>. In this way, the biasing assembly <NUM> is secured to the base <NUM>. The cover <NUM> does not pivot relative to the base <NUM>. The operative unit <NUM>, including the right end cap <NUM>, pivots relative to the cover <NUM>. The torsion spring <NUM> unloads a biasing force as the operative unit <NUM> is pivoted into an opened position and the torsion spring <NUM> loads a biasing force as the operative unit <NUM> is pivoted into a closed position. The torsion spring <NUM> helps to control a rate of descent of the operative unit <NUM> as the operative unit <NUM> moves between the open position and the closed position. In some configurations, the torsion spring <NUM> provides a sufficient biasing force to oppose final closure of the operative unit <NUM> against the base <NUM> without a force input by a user. In some configurations, the torsion spring <NUM> provides less resistive force such that the operative unit <NUM> will fully close against the base <NUM> without a force input by a user but the torsion spring <NUM> provides at least some opposition to the closure.

In some configurations, a prop rod can provide means for securing the operative unit <NUM> in an open position. The prop rod can hold the operative unit <NUM> in one or more open orientations relative to the base <NUM>. The prop rod may be in addition to the biasing assembly or the prop rod may be an alternative to the biasing assembly. In some configurations, the cover <NUM> (or an analog for the cover <NUM>) can be formed to have a hexagonal shape, for example but without limitation, while the corresponding mount <NUM> can have a complementary shape such that the operative unit <NUM> can be lifted from the base <NUM>, pivoted and then returned to the base at a different angle. In such a configuration, there is no need for the biasing assembly, for example. In such a configuration, the operative unit <NUM> may not be secured to the base <NUM> to oppose relative vertical movement between the two components <NUM>, <NUM>.

Another possible configuration that allows for the removal of the biasing assembly is adjusting the pivot location such that the pivot location is near a center of gravity of the operative unit. If the pivot location was moved closer to the center of the side walls of the base <NUM>, then the bucket height would need to increase but lighter springs could be used. Such a configuration, however, may not be a desired tradeoff. In some configurations, the pivot location can intersect with the rear wall or a structure that extends from the rear wall. The illustrated pivot location was designed to facilitate a low profile for the base (and the overall system). As shown in <FIG>, there is a curvature along the sides of the base <NUM>. The operative unit <NUM> has a complementary curved shape. These curves follow the center of rotation such that, when the operative unit <NUM> is in a closed position, a minimal amount of clearance exists between the base <NUM> and the operative unit <NUM>.

Reduced clearance between the walls reduces the likelihood of bypassed airflow, which allows increased airflow through the slot <NUM> that receives the skate (such that more of the swarf and dust can be pulled into the base <NUM>). The system operates under vacuum; the fan pulls air into the base <NUM> and then exhausts that air through the back of the operative unit. The air is replaced primarily by air flowing in through the skate slot <NUM>. This flow of air will capture the swarf/dust from the grinding. While seals could be used to seal the gaps between the base <NUM> and the operative unit <NUM>, the variety of environments in which the system <NUM> may be used, such as those with a wide operating temperature swings, can make seal optimization difficult. Such seals also may increase friction and would increase costs.

With reference to <FIG>, <FIG>, and <FIG>, the operative unit <NUM> and the base <NUM> are pivotally connected. To adjust the grinding wheel, to replace an air filter, or to remove the dust collected during sharpening operations, the operative unit <NUM> can be pivoted to an open position, such as shown in <FIG> and <FIG>. The operative unit <NUM> exceeds <NUM>,<NUM> (<NUM> pounds) in weight in the illustrated configuration. As discussed directly above, a biasing assembly can be used to assist with the raising and lowering of the operative unit <NUM> relative to the base <NUM>. In some configurations, means for securing the operative unit <NUM> in an open position can be provided. As discussed above, the means for securing can include a prop rod that holds the operative unit <NUM> in a particular open orientation relative to the base <NUM>, a biasing assembly that supplies sufficient biasing force to maintain the operative unit <NUM> in an open orientation relative to the base <NUM>, or a mechanical locking configuration that provides physical stops to secure the operative unit <NUM> in one or more particular open orientations relative to the base <NUM>, for example but without limitation.

A mechanical locking configuration <NUM> is shown in <FIG>. While only the right side mechanical locking configuration <NUM> will be shown, a mirror image of the illustrated mechanical locking configuration <NUM> can be used on the left side. In some configurations, only one side has the locking configuration.

The illustrated mechanical locking configuration <NUM> comprises a trigger <NUM>. In some embodiments, another suitable mechanism, such as a button, latch, slide, switch, knob, pin, or other mechanism can be used to replace the trigger to actuate the mechanical locking configuration <NUM>. The trigger <NUM> can include one or more grip locations <NUM>. The grip locations <NUM> can be configured to receive one or more fingers of the user. A thumb pad <NUM> can extend a short distance along a front of the system <NUM>. The short thumb pad <NUM> reduces any impact on visibility into the system <NUM>; if an elongated thumb pad <NUM> extended a full length of the front of the operative unit <NUM>, the height of the overall system <NUM> may need to be increased to provide a desired level of access and vision. As shown in <FIG>, in the illustrated configuration, the thumb pad <NUM> extends less than <NUM>/<NUM> of the full length of the operative unit <NUM>. In some configurations, the thumb pad extends to less than or equal to one half of the full length of the operative unit <NUM>. In some configurations, the thumb pad <NUM> is integrally formed with the end caps <NUM>, <NUM>. Such configurations advantageously facilitate forming the central body <NUM> of extrusions.

Together with the thumb pad <NUM> that is located forward of the trigger <NUM> and lower than the trigger <NUM>, the grip locations <NUM> can guide a user to a desired placement of their hand while operating the mechanical locking configuration <NUM>. In some configurations, as discussed above, two mechanical locking configurations <NUM> are provided such that both of the mechanical locking configurations <NUM> must be operated at the same time to pivot the operative unit <NUM> relative to the base <NUM>. Such configurations help to reduce pinching risks in an advantageous manner.

With reference again to <FIG>, a rod <NUM> connects to the trigger <NUM>. In the illustrated configuration, the rod <NUM> has a threaded end <NUM> that engages with threads of the trigger <NUM>. A circlip <NUM> and a spring <NUM> provide a return force that opposes unlocking movement of the trigger. The spring <NUM> is captured between an internal surface of the end cap <NUM> and the circlip <NUM>. Other configurations are possible to provide the biasing force to the mechanical locking configuration <NUM>. In some less desired configurations, the biasing force is omitted.

In the illustrated configuration, an engagement tip <NUM> of the rod <NUM> extends beyond the end cap <NUM> to engage a recess <NUM> formed in the base <NUM>. The base <NUM> can comprise one or more recess <NUM> that correlates to the one or more positions of the operative unit <NUM> relative to the base <NUM> that is desired to be maintained. In the illustrated configuration, the operative unit <NUM> can be secured in any of three positions relative to the base <NUM> and, accordingly, three recesses <NUM> correlated to those positions. In the illustrated configuration, the first recess <NUM> corresponds to a closed position, the second recess <NUM> corresponds to the position shown in <FIG>, and the third recess <NUM> corresponds to the position shown in <FIG>. The position in <FIG> allows for access to the grinding wheel and for adjustment of the position of the grinding wheel. The position in <FIG> allows for more complete access to the interior of the base <NUM> for cleaning and allows for improved access to a filter assembly for replacement of the filter.

The biasing elements on the rod/trigger assembly could be omitted and a pin or the rod could simply be inserted into the recess such that the operative unit can be pivoted and secured in a desired position (e.g., pin and overlapping hole assemblies). Other locking arrangements (e.g., interference components, frictional components, adjustable friction components, adjustable interference components) also are possible to allow the operative unit to be secured in different pivotal positions relative to the base. In some configurations, the operative unit <NUM> may be configured to lock in position relative to the base <NUM> by tightening the end caps and locking the unit at any height position. In other words, the endcap <NUM> could be tightened down by the user and, as the endcap gets tighter, friction locks-out rotation of the operative unit <NUM> relative to the base <NUM>.

<FIG> and <FIG> show an embodiment of the grinding wheel and spindle assembly <NUM>. The grinding wheel <NUM> includes a metal grinding ring <NUM> disposed on a rigid hub <NUM>. The grinding wheel <NUM> is mounted to an axle <NUM> of the spindle <NUM> by a retention nut <NUM> that urges the grinding wheel <NUM> against a metal arbor <NUM> that forms part of the spindle <NUM>. The grinding ring <NUM> has an abrasive outer surface for removing material from a skate blade during a sharpening operation.

As shown, both the arbor <NUM> and hub <NUM> have shaped outer edges which mate with respective edges of the grinding ring <NUM>. The mating between the arbor <NUM> and wheel <NUM> is a sliding contact mating that permits mounting and dismounting of the grinding wheel <NUM> while also providing for heat transfer between the grinding ring <NUM> and the arbor <NUM>. The heat transfer helps dissipate frictional heat generated in the grinding ring <NUM> as it rotates against a skate blade in operation. Specifically, this mating is between a portion of an inner annular surface of the grinding ring <NUM> and an annular outer rim of the arbor <NUM>. Both the hub <NUM> and arbor <NUM> have notches or shoulders on which respective portions of the grinding ring <NUM> rest. Thus the shoulder portion of the hub <NUM> extends only partway into the grinding ring <NUM>, so that a remaining part of the grinding ring <NUM> extends beyond the arbor-facing end of the hub <NUM> and mates with the shoulder portion of the arbor <NUM>.

The arbor <NUM> can include vanes <NUM> or other features to increase its surface area and/or enhance air flow for a desired cooling effect, further promoting heat dissipation and helping to maintain a desired operating temperature of the grinding ring <NUM> in operation. The vanes can provide a conductive and convective cooling effect. One challenge of the geometry and size of the grinding ring <NUM> is heat removal, and this can be addressed in part by the heat-conducting mating with the arbor <NUM> and heat-dissipating features of the arbor <NUM>.

The arbor shroud <NUM> is further illustrated in <FIG>. In the illustrated embodiment, the arbor shroud <NUM> includes a body portion <NUM>, a sidewall <NUM> defining a shroud opening, a front wall <NUM> defining jaw protection features <NUM>, a lower opening <NUM>, fastener openings <NUM>, back wall <NUM>, and recessed walls <NUM>.

The body <NUM> extends distally from the front wall <NUM>. The body <NUM> is configured to be mounted on the spindle <NUM>. The body <NUM> comprises leg portions that extend distally from the front wall <NUM> and are configured to be secured to the spindle <NUM>. Each leg portions extends circumferentially about a portion the spindle. In the illustrated embodiment, the body <NUM> includes fastener openings <NUM> configured for attaching the shroud to the spindle <NUM> using fasteners <NUM>. In the illustrated embodiment, the legs are substantially symmetric with offset fastener openings <NUM>. The fastener openings <NUM> are offset from each other in elevation to stabilize the shroud <NUM> when secured to the spindle <NUM>. The shroud is configured to remain stationary with the spindle and does not rotate with the grinding wheel or arbor <NUM>. In some embodiments, the body may be formed as a single leg that extends about a portion of the circumference of the spindle <NUM>. In some embodiments, the shroud may be secured in place by a single fastener and a protuberance or other feature to help secure the position and prevent rotation. In some embodiments, the shroud may include members that snap into corresponding positions on the spindle. In some embodiments, the shroud <NUM> may be mounted on a different portion of the carriage assembly that remains stationary relative to the rotation of the arbor <NUM> and grinding wheel <NUM>. The recessed walls <NUM> can provide structural rigidity and help prevent the lower portion of the shroud <NUM> from contacting the arbor <NUM>. In some embodiments, the shroud <NUM> may be formed as part of the spindle <NUM>.

In the illustrated embodiment, the shroud <NUM> is formed as a single molded part. In some embodiments, the shroud may be formed from two or more separate pieces. The shroud may be coupled to the spindle using other means known in the art. Some desired materials from which the shroud <NUM> can be formed include, but are not limited to, Nylon, Glass-filled nylon, or POM.

The sidewall <NUM> and back wall <NUM> form a shroud opening in the front wall <NUM> that is configured to cover at least the vanes <NUM> of the arbor <NUM>. The shroud opening can be concentric with the arbor <NUM> when coupled to the spindle <NUM>. The shroud <NUM> is configured such that it can be installed on the spindle <NUM> before or after the installation of the arbor <NUM>. The shroud opening is configured to be larger than the diameter of the arbor <NUM> so that the arbor can freely rotate without contacting the sidewall <NUM>. The shroud opening can have a diameter that is greater than the diameter of the arbor <NUM>. When the shroud <NUM> installed, a gap <NUM> is formed between the sidewall <NUM> and shoulder portion <NUM> and vanes <NUM> of the arbor <NUM>. The width of the side wall <NUM> can cover at least a portion of the vanes <NUM>. The width of the side wall <NUM> can be as wide as or greater than the width of the vanes <NUM> of the arbor <NUM>. The width of the front wall <NUM> can be substantially the same as the width of the sidewall <NUM>. The width of the front wall <NUM> of the shroud <NUM> is configured so that, when installed, it can fit between within the opening of the skate slot <NUM> with the grinding wheel <NUM> and arbor <NUM> (such as illustrated in <FIG>). In some configurations, the width of the front wall <NUM> can be between <NUM> and <NUM>. The shroud can include a back wall <NUM> configured to be separated from the vanes <NUM> during operation. In the illustrated embodiment, the back wall <NUM> has a flat portion and angled portions that extend distally away and downward. The back wall <NUM> can be configured to help direct the airflow from the arbor <NUM> during operation. The side wall <NUM> forms the lower opening <NUM>. In some configurations, the lower opening <NUM> can be up to <NUM>% of the circumference of the opening. The opening <NUM> is configured to allow sufficient air to flow through and away from the arbor <NUM>. In combination with the shape of the back wall <NUM>, air can be directed downward and away from the arbor <NUM> and grinding wheel <NUM>. The configuration of the lower opening <NUM> can help to effectively dissipate heat for cooling of the grinding wheel <NUM> during operation. In some configurations, the back wall <NUM> can include one or more openings to provide additional airflow for heat dissipation. In some configurations, the sidewall <NUM> can form an opening having a different shape, for example, the shroud opening may have a U-shape or other shaped opening. The gap between may not be uniform between the side wall and the arbor. In some embodiments, the shroud may be formed using a screen or fence-like construction. In such an embodiment, the screen can provide the same functionality of the walls of the shroud. The screen can provide airflow through the arbor, while also preventing access by the user with arbor during operation of the skate sharpener.

The shroud <NUM> provides a protective cover over at least a portion of the arbor <NUM>. The shroud can cover at least a portion of the vanes <NUM> of the arbor <NUM>. In some configurations, the shroud <NUM> may cover the width of the vanes or may be wider and extend over a larger portion of the arbor. In some configurations, the shroud can extend up to the thickness of the arbor <NUM>, to the extent that the shroud <NUM> does not interfere with the grinding operation. The grinding wheel <NUM> and arbor <NUM> can be accessed from the topside of the sharpening unit and are sized to fit between with the walls of the skate slot <NUM> (such as illustrated in <FIG>). The positioning of the shroud <NUM> is configured to prevent human interaction with the arbor <NUM>, such as with the vanes of the arbor <NUM>, during operation of the skate sharpener. The shroud <NUM> helps to prevent accidental or intentional interaction with the arbor <NUM> during operation. Additionally, the shroud can help to prevent sparks and swarf from escaping upwards during the sharpening operation and instead be captured by and within the base <NUM>.

With additional reference to <FIG>, the functionality of lobes <NUM> is illustrated. The front wall <NUM> forms lobes <NUM> on both sides of shroud <NUM>. If the sharpener were to operate without a skate between the jaws, the grinding wheel <NUM> could potentially grind a portion of the jaws. The lobes <NUM> are configured to prevent the grinding wheel <NUM> from contacting components of the skate sharpener when it is operated without a skate blade inserted in the blade slot <NUM> and secured by blade retention jaws <NUM>. The lobes <NUM> are configured to act as a ramp when the carriage moves laterally in the x direction during operation. When the lobes contact a lower surface of the jaws <NUM> (<FIG>), the grinding wheel is displaced downward in the z direction (<FIG>). The downward displacement prevents contact between the grinding wheel <NUM> and the jaws <NUM>. The lobes are disposed on both sides of the shroud <NUM> so that the ramp will function while the grinding wheel is operating in either direction during the sharpening operation. The upper wall of the shroud may include a portion that is substantially flat, the flat portion is configured to slide along the lower surface of the jaws, as illustrated in <FIG>. In the illustrated embodiment, the jaw protection features <NUM> are illustrated as triangular lobes on the shroud <NUM>. In other embodiments, the jaw protection features <NUM> may have a different shape or appearance. In some embodiments, the jaw protection feature is included on a single side.

<FIG> illustrate aspects of the grinding wheel alignment system. Specifically, the alignment system positions the grinding wheel relative to the position of a skate blade inserted within blade slot <NUM>. The alignment system provides for the movement of the grinding ring along the y axis without backlash. Backlash is a common and undesired mechanical problem inherent in threaded or geared mechanisms. <FIG> is a perspective view of the grinding wheel assembly <NUM> and carriage assembly <NUM>. <FIG> illustrates a partial section view at the location of the alignment shaft <NUM>. <FIG> illustrates an exploded view of components of the carriage assembly <NUM>.

The alignment shaft <NUM> is secured at each end to the carriage <NUM>. Shown on the left, the shaft <NUM> is secured in place by the end fastener <NUM> having screw threading corresponding to threading on an internal opening of the shaft <NUM>. The end fastener <NUM> secures an adjustment knob <NUM>, and bearing <NUM> in place on the left side of the carriage <NUM>. Shown on the right is a nut <NUM> having screw threading engaging corresponding screw threading on the alignment shaft <NUM>. Arranged between the nut <NUM> and the shaft is a bearing <NUM>. The alignment shaft <NUM> includes a threaded portion <NUM>, a detents portion <NUM>, and an unthreaded portion <NUM>. The detents portion <NUM> includes a plurality of detents disposed circumferentially about the shaft. The detents of the shaft extend along a longitudinal portion of the shaft between the threaded portion <NUM> and the unthreaded portion <NUM>. The detents are sized and configured to engage the spring pin <NUM>. The spring pin <NUM> has a fixed position and rides in the series of detents or recesses in the outer diameter of the shaft <NUM>. As the adjustment knob <NUM> is manipulated, each movement of the detents relative to the spring pin <NUM> corresponds to a single tactile and/or audible click of the adjustment wheel <NUM>. In some embodiments, the spring pin may be replaced by a ball and plunger or any spring-like feature that can provide audible and/or tactile feedback of the adjustment wheel <NUM>. In some embodiments, detents can be molded into the backside of knob <NUM> and a spring pin or ball plunger can be provided on the body of the carriage <NUM>. The detent mechanism can be effectively implemented by using two surfaces in the assembly that rotate relative to each other when the adjustment knob <NUM> is manipulated. Each detent is sized and configured to correspond to a defined amount of movement of the grinding wheel along the y-axis with each click of the adjustment wheel <NUM>. In some configurations, each click can correspond to of an adjustment between <NUM> and <NUM> of a mm of the y-position of the grinding wheel. In one embodiment, a click is <NUM>/<NUM>th of a mm adjustment of the y-position of the grinding wheel. The adjustment mechanism will be further described below.

The alignment shaft <NUM> is further secured in place within the carriage <NUM> by the mounting bracket <NUM>. The mounting bracket <NUM> includes compression brackets <NUM>. The mounting bracket <NUM> is secured to the carriage by fasteners <NUM>. The mounting bracket includes an axial path for the shaft <NUM>. The threaded bushing <NUM> and the through hole bushing <NUM> are positioned within the axial path. The through hole bushing <NUM> is positioned at least partially within the axial opening formed in compression bracket 428A. The threaded bushing <NUM> is positioned at least partially within the axial opening formed in compression bracket 428B. The threaded portion <NUM> of the shaft <NUM> includes threading that corresponds to threading of the threaded bushing <NUM>. The through hole bushing <NUM> can have a reamed diameter that is substantially the same as the diameter of the unthreaded portion <NUM> of the shaft <NUM>. Reaming the through hole bushing can result in a more accurate fit. The through hole bushing <NUM> can be configured to have an interference fit with the unthreaded portion of the shaft <NUM>. In some embodiments, only a single bushing may be used. The bushing may be a threaded bushing or a through hole bushing.

The bushings <NUM>, <NUM> can include tabs <NUM> that are configured to longitudinally space the bushings along the axial path and prevent the bushings from rotating during operation. The shaft <NUM> is positioned within the axial path of the mounting bracket <NUM>. The threaded bushing <NUM> is threaded onto the threaded portion <NUM> of the shaft <NUM> and positioned within the axial opening of compression bracket 428B. The through hole bushing <NUM> is positioned on the unthreaded portion <NUM> of the shaft <NUM> and positioned within the axial opening of compression bracket 428A. The through hole bushing <NUM> is a follower. The bushings <NUM>, <NUM> can be formed from any suitable material but a polymer is used in this embodiment. Some desired polymers from which the bushings <NUM>, <NUM> can be formed include, but are not limited to, POM (acetal), UHMW polyethylene, or Nylon.

The spacing bracket <NUM> is positioned between bushings <NUM> and <NUM>. With respect to the shaft <NUM>, the spacing bracket <NUM> is configured to be positioned over the detent portion <NUM>. The spacing bracket <NUM> includes a recess <NUM> sized and configured to receive the spring pin <NUM>. As described above, the spring pin <NUM> is configured to engage the detents in the shaft <NUM>. The longitudinal positions of the bushings <NUM>, <NUM> are secured between the spacing bracket <NUM> and compression brackets 428A-B by tabs <NUM>.

The compression brackets 428A-B are configured to tighten and secure the position of the shaft <NUM> relative to the bushings <NUM>, <NUM> When the compression brackets are secured, they cause the bushings <NUM>, <NUM> to contract on the corresponding portion of the shaft <NUM> and secure the shaft in place. Tabs <NUM> on the bushings <NUM>, <NUM> prevent the bushings from rotating during operation. The bushings <NUM>, <NUM> apply a force on the shaft that is sufficient to prevent undesired rotation of the shaft <NUM>, such as during a sharpening operation. However, the lubricity of the polymer material of the bushings allows the shaft <NUM> to rotate without binding when the adjustment knob <NUM> is manipulated. The compression of the bushings on the shaft <NUM> additionally secures the position of the shaft such that there is substantially no hysteresis, backlash, or uncertainty of location caused by rotation of the adjustment knob <NUM>. The shaft <NUM> can rotate from forward to backward and visa-versa without backlash when the adjustment knob <NUM> is manipulated, regardless of the y-position of the grinding wheel. By compressing the polymer bushings, any undesired rotation is prevented. Additionally, any desired rotation is not inhibited.

In the illustrated embodiment, the adjustment knob <NUM> can be manipulated by a user in order to adjust the rotation of the shaft <NUM>. In some embodiments, the adjustment knob may be configured to be manipulated by an electronically controlled alignment system. For example, the shaft may be rotated by a motor, such as a stepper or servo motor. The system may utilize a machine vision system or encoder to determine alignment. The components can be controlled by a controller.

The grinding ring is adjustable in the transverse or Y-direction. The motor arm pivots on bearing <NUM> and bearing <NUM>. In some embodiments, the system can use bushings in place of bearings. The threaded shaft <NUM> moves the assembly in and out in the Y-direction. The Y-position of the grinding wheel assembly <NUM> is varied by user rotation of the adjustment knob <NUM>. As described above, the detents <NUM> and spring pin <NUM> are co-configured to form a detent mechanism providing several detent locations for a rotation of the adjustment knob during the adjustment process. Each click of the adjustment knob provides for alignment of the grinding wheel assembly <NUM> by a defined adjustment amount (e.g., <NUM>/<NUM>th of a mm per click) of the grinding wheel position in the y direction.

As the adjustment knob <NUM> rotates, the screw action causes the carriage assembly <NUM> to move transversely in the Y direction along the alignment shaft <NUM>, and move the grinding wheel assembly <NUM> transversely along with it. The alignment system is configured to reduce or eliminate undesired transverse movement of the grinding wheel assembly <NUM> during an alignment operation. Additionally, the alignment system prevents undesirable transverse movement resulting from a sharpening operation.

The detent system can also help to prevent undesirable movement and facilitate desirable movement. As the adjustment knob <NUM> is rotated, the shaft <NUM> is rotated and the spring pin <NUM> moves from one detent to the next, requiring a small force to push the spring pin <NUM> sufficiently out of the first detent and into the next.

Additionally, the configuration of the alignment shaft <NUM> and bushings <NUM> components prevent undesirable movement during alignment or operation. The compression of the bushings <NUM>, <NUM> on the shaft <NUM> increases the force required to rotate the shaft. This has the effect of fixing the position of the shaft such that there is no movement or play in the rotation of the adjustment knob <NUM>. When a user rotates the adjustment knob <NUM> forward or backward there is substantially no hysteresis or backlash regardless of the y-position of the grinding wheel assembly.

The force to move the shaft <NUM> through the detent positions is easily generated by the rotation of the adjustment knob <NUM>. However, vibration or other mechanical forces occurring during sharpening operation do not have the force to cause the rotation of the shaft between detent position.

Conditional language used herein, such as, among others, "can," "could," "might," "may," "e.g.," and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or states. Thus, such conditional language is not generally intended to imply that features, elements and/or states are in any way required for one or more embodiments or that one or more embodiments necessarily include these features, elements and/or states.

While the above detailed description may have shown, described, and pointed out novel features as applied to various embodiments, it may be understood that various omissions, substitutions, and/or changes in the form and details of any particular embodiment may be made and that the invention is defined by the claims. As may be recognized, certain embodiments may be embodied within a form that does not provide all of the features and benefits set forth herein, as some features may be used or practiced separately from others.

Additionally, features described in connection with one embodiment can be incorporated into another of the disclosed embodiments, even if not expressly discussed herein, and embodiments having the combination of features still fall within the scope of the disclosure. For example, features described above in connection with one embodiment can be used with a different embodiment described herein and the combination still fall within the scope of the disclosure.

It should be understood that various features and aspects of the disclosed embodiments can be combined with, or substituted for, one another in order to form varying modes of the embodiments of the disclosure. Thus, it is intended that the scope of the disclosure herein should not be limited by the particular embodiments described above. Accordingly, unless otherwise stated, or unless clearly incompatible, each embodiment of this disclosure may comprise, additional to its essential features described herein, one or more features as described herein from each other embodiment disclosed herein.

Features, materials, characteristics, or groups described in conjunction with a particular aspect, embodiment, or example are to be understood to be applicable to any other aspect, embodiment or example described in this section or elsewhere in this specification unless incompatible therewith. The protection is not restricted to the details of any foregoing embodiments. The protection extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Furthermore, certain features that are described in this disclosure in the context of separate implementations can also be implemented in combination in a single implementation. Moreover, although features may be described above as acting in certain combinations, one or more features from a claimed combination can, in some cases, be excised from the combination, and the combination may be claimed as a subcombination or variation of a subcombination.

As another example, in certain embodiments, the terms "generally parallel" and "substantially parallel" refer to a value, amount, or characteristic that departs from exactly parallel by less than or equal to <NUM> degrees, <NUM> degrees, <NUM> degrees, <NUM> degrees, <NUM> degree, <NUM> degree, or otherwise.

The scope of the present disclosure is not intended to be limited by the specific disclosures of preferred embodiments in this section or elsewhere in this specification, and may be defined by claims as presented in this section or elsewhere in this specification or as presented in the future. The language of the claims is to be interpreted broadly based on the language employed in the claims and not limited to the examples described in the present specification or during the prosecution of the application, which examples are to be construed as non-exclusive.

Reference to any prior art in this description is not, and should not be taken as, an acknowledgement or any form of suggestion that that prior art forms part of the common general knowledge in the field of endeavor in any country in the world.

The invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the description of the application, individually or collectively, in any or all combinations of two or more of said parts, elements or features.

Where, in the foregoing description, reference has been made to integers or components having known equivalents thereof, those integers are herein incorporated as if individually set forth. In addition, where the term "substantially" or any of its variants have been used as a word of approximation adjacent to a numerical value or range, it is intended to provide sufficient flexibility in the adjacent numerical value or range that encompasses standard manufacturing tolerances and/or rounding to the next significant figure, whichever is greater.

Claim 1:
A skate sharpening system (<NUM>) comprising an operative unit (<NUM>) and a base (<NUM>), the operative unit (<NUM>) comprising a central body (<NUM>), the central body (<NUM>) comprising a skate receiving slot, a skate clamp being positioned adjacent to the skate receiving slot such that a skate can be secured within the skate receiving slot for a sharpening operation, the operative unit (<NUM>) further comprising a grinding unit, (<NUM>,<NUM>), the grinding unit being configured to translate along a length of the slot such that the grinding unit can conduct the sharpening operation on the skate that is secured within the skate receiving slot, the operative unit (<NUM>) being positioned over at least a portion of the base (<NUM>), the base (<NUM>) comprising a swarf-receiving cavity, the operative unit (<NUM>) and the base (<NUM>) being pivotably connected, characterised in that the skate sharpening system (<NUM>) further comprises a position lock (<NUM>, <NUM>) that secures the operative unit (<NUM>) against movement relative to the base (<NUM>).