1. Technical Field
This disclosure is directed to a stand for holding a bench stone, and in particular, for holding a bench stone at a selected angle, greater than zero degrees.
2. Description of the Related Art
The knife is one of the most common and widely used of all tools. Knives are employed in many different industries and crafts, and are available in innumerable configurations and designs. Most adults are familiar with knives, and a typical home includes several knives. Knives are especially common in home and commercial kitchens, for use in preparing food.
Generally, the cutting edges of “western” style knives are symmetrical, with respect to a central plane A, as described below with reference to
The angle B of the secondary bevel 110, relative to the central plane A, is of particular importance to the proper operation of the knife 100. A manufacturer selects the angle B on the basis of a number of factors, including the intended use of the knife 100, and the hardness, i.e., resistance to dents or scratches, and toughness, i.e., resistance to breaking, of the steel from which the blade is made. From the standpoint of cutting efficiency, the smaller the angle B, the better. A small-angle blade cuts more easily and with less force than a large-angle blade. However, as angle B is reduced, the amount of metal supporting the edge 106 diminishes, making the edge weaker than one with a larger angle. The blade will tend to dull more quickly, and require more frequent sharpening. A practical limit is therefore imposed by how frequently a typical user is willing to resharpen a blade. This limit will vary, depending on the intended use. If the knife is to be used to cut relatively softer materials, the blade will not wear as fast, and can therefore be made with a smaller angle.
A hard steel will hold an edge longer than a relatively softer steel, and so, a blade made from the harder steel can be sharpened to a smaller angle. However, typically, as a given steel is made harder, it also loses toughness, becoming progressively more brittle. Such a blade has a greater tendency to chip or break. Additionally, a blade of harder steel is usually more difficult to sharpen, so when such a knife becomes dull, it requires more time and effort to sharpen. Thus, another practical limit is imposed by how hard a steel can be made before it becomes too brittle for its intended use, or too difficult to sharpen. Typically, Asian style knives, whether beveled on one side or both, are ground to a smaller angle than western style knives, and are made from harder steel. This results in a more efficient cutting edge than comparable western knives, but that are more fragile, and require more maintenance. Manufacturers typically provide what they consider the appropriate angle for a given knife, as determined by the material of the blade, the advertised use of the knife, and the perceived consumer expectation, with regard to maintenance and edge retention.
Given the steel formulations that have been available to manufacturers over recent decades, and referring to western knives in particular, a range of about 20-22 degrees has been commonly regarded as an optimum angle for knives made for use in food preparation, and sometimes larger angles for general and outdoor use. However, in recent years, with the development of a number of new steel formulations for blades that can be hardened to a higher degree while retaining toughness, some knives are available for which the sharpening angle recommended by the manufacturer is at 16 degrees or less. Thus, depending on the style, intended use, dimensions, and material of a given knife, the critical angle can vary from as small as about 10 degrees to as high as around 35 degrees, but most are between about 15 degrees and 25 degrees.
Even though most adults regularly use knives, few actually understand some of the most basic technical elements that influence their design and maintenance, like those briefly discussed above. Consequently, it is quite common for a person to buy an expensive knife, and after sharpening the knife a few times, to find that it no longer cuts as well as it did when it was new.
Alternatively, the user may sharpen the knife at the primary bevel angle 108, which is also less then optimum because, unless a large amount of material is removed, the actual edge of the blade will not be sharpened, so the knife will remain dull, in spite of much time and effort by the user.
The problem is that once the angle B has been changed, either increased or decreased by even a few degrees, sharpening at the correct angle will have no immediate effect at the cutting edge, and sharpening at the new angle B1 will never produce an edge that cuts as well as the knife did at the original angle B.
There are many sharpening systems that can assist a user in sharpening a knife at a selected angle, but they are often expensive, some are impractical, and most require specialized stones or abrasive rods that are themselves expensive and not easily adaptable for use in other applications.
According to an embodiment, a knife sharpening system is provided, which includes a substantially planar bed defining a first plane, and a support base rigidly coupled to the bed and defining a second plane lying at a selected angle with respect to the first plane. First and second end rails are rigidly coupled to respective ends of the bed and extend outward therefrom, and define a bed surface. A reference surface is provided on an end of the second end rail, defining a plane that lies parallel to the second plane. A bench stone is received on the bed, and supported thereby so that a surface of the bench stone is parallel to the bed, and lies at the selected angle, relative to the second plane. Apertures formed in the first and second end rails form a cradle configured to receive a sharpening steel, and support the sharpening steel at the selected angle, relative to the second plane.
The sharpening steel 206 comprises a handle 207, a rod 208, and a guard 209. According to one embodiment, the sharpening steel 206 is a general-purpose steel such as is commonly manufactured for use with cutlery. According to another embodiment, the sharpening steel 206 is manufactured for use with knives of a specific type, grade of steel, or manufacturer. In use, typically, a user holds the steel in one hand and a knife in the other, and strokes the cutting edge of the knife across the rod of the sharpening steel while holding the blade at approximately the critical angle, with respect to the longitudinal axis of the rod. This action can realign a wire edge or micro-teeth along the blade, and burnish the final bevel, to restore the cutting edge. In some cases, depending on the design of the sharpening steel, a small amount of material is removed from the blade, to restore the final bevel.
The bench stone 204 includes a first surface 232 having an abrasive whose hardness and grit are selected to impart a desired acuity to a knife blade. According to an embodiment, the stone includes a second side of a coarser grit, for preliminary sharpening of a knife. The bench stone 204 can be a standard size bench stone, such as is available from many manufacturers, or can be made to a specific, non-standard size to fit the stand 202.
Referring jointly to
The cradle 224 is defined by first and second apertures 220, 222 formed, respectively, in the first and second end rails 213, 215. The first and second apertures 220, 222 comprise respective semi-cylindrical terminations that lie coaxial to each other, and that are sized to receive the rod 208 of the sharpening steel 206. The reference face 218 comprises a planar surface formed on the second end rail 215. In the embodiment shown, the second aperture 222 extends through the reference face 218, dividing the face into two surfaces lying in a common plane.
Turning now to
A bottom face of the bench stone 204 is in face-to-face contact with the bed 210, and so lies at the same angle D, relative to the base plane C. Opposing faces of the bench stone 204 are parallel to each other, so the upper face 232 lies parallel to the bed 210, and at the same angle D with respect to the base plane C. When a knife blade 104 is placed with one side 105 in face-to-face contact with the reference face 218, the angle E of the central plane A of the blade, relative to the face 232 of the bench stone 204, is equal to the angle D.
According to one embodiment, the angle D is selected to be equal to a selected critical angle B of the edge 106 of the knife blade 104. In operation, the user places the knife 100 with the blade 104 resting against the reference face 218, as shown in
It has been found that most people are able to hold an object such as a knife at a substantially horizontal position with a relatively high degree of accuracy and repeatability. This is especially true when a reference is provided, such as the reference face 218, by which the user can periodically confirm the proper position as being exactly horizontal while sharpening a blade. In contrast, it is generally very difficult to consistently maintain an object at a specific angle that is neither horizontal nor vertical, through many repetitions of movement. In contrast, if the stone 204 is positioned on a flat surface, the user must hold the knife at the correct angle to properly sharpen the blade. If the correct angle is, for example, 22.5 degrees, the user must hold the knife edge exactly or very nearly at 22.5 degrees for the entire sharpening stroke and also for repeated sharpening strokes. If the knife tips slightly, for example, to 25 degrees, then the angle B is changed and the problems described in the background occur, and, if the angle is too shallow, for example, 20 degrees, the knife if not sharpened and the movement on the stone has no affect on sharpening the cutting edge. It is very difficult for a person to hold a knife edge at exactly 22.5 degrees, as compared to 20 degrees or 25 degrees. The inventors have realized, however, that nearly all users have the skill to hold and move a knife blade at very nearly 0 degrees. This is especially true if assisted by a reference surface 108 that is exactly horizontal, at 0 degrees. A person can more easily move the knife exactly horizontal to within, e.g., 0.5 degrees of tolerance as compared to moving the knife at exactly 22.5 degrees within the same 0.5 degrees of tolerance.
Referring again to
It is sometimes desirable to limit the force that the user will apply when sharpening a knife because there can be a tendency to change the angle of the blade against the stone when one is pressing down with excessive force. This can result in the user inadvertently changing the critical angle of the blade.
When the stand 202 is positioned on support 201, such as a table or counter top, the amount of static friction that is generated between the base 211 and the underlying support 201 is a function of the mass of the device, and the vector and degree of force applied, as well as the coefficient of friction between the base 211 and the upper face of support 201. When the static friction is overcome, the stand 204 will begin to slide across the surface of support 201. Thus, the user is compelled to limit the force applied to avoid exceeding the static friction so that the stand remains stationary.
In operation, the user first places the knife edge against the face 232 of the bench stone 204, using the reference face 218 to establish the angle, then applies a force against the blade in a forward and slightly downward direction to slide the knife along the stone. The force of the blade against the angled surface 232 of the stone creates a vector of force in the downward direction, pressing the base 211 with more force into the underlying support 201. The downward force effectively increases the apparent mass of the stand on the underlying surface, as well as of the knife against the stone. The coefficient of friction between the blade and the stone is higher than that between the base of the stand and the underlying surface, so as the user increases the downward force, friction between the blade and stone increases faster than between the base and the underlying surface. Thus, the user must find a balance between the forces that will permit the blade to slide on the stone and be sharpened, while the stand remains stationary and does not move with respect to support 201. If the user applies too much downward force, static friction between the blade and the stone will rise beyond that between the stand and the surface, so that the friction at the base 202 with the support 201 is overcome first, and the base slides. A larger surface area of the base will produce a greater increase of friction as downward force increases, meaning that greater downward force can be applied without overcoming the friction at the base. Thus, by selecting the surface area of the base 211, and the material of the base, the maximum force a user is permitted to apply when sharpening the knife can be selected, at least to an approximate amount. Of course, the actual maximum value will also depend on the material and texture of the underlying surface 201, which will vary. On a hard, smooth surface, such as ceramic tile, the maximum force will be relatively smaller, while on an unfinished wood bench top, it will be relatively greater, but even at these extremes, the difference is not great, and the maximum value can be approximated to a sufficient degree.
Turning now to
The sharpening system 200 of the embodiment of
In the embodiment disclosed with reference to
According to an embodiment, a manufacturer provides a sharpening system with the angle D set to the specific critical angle of particular set of knives. This can be indicated by an indicia, writing or marking on the bed 210 that clearly states the angle D to which the bed is set, the type knife, or even the brand and style of knife to be sharpened on that particular stand. In this embodiment, an angle D is set by the maker of the stand 202 for a particular set of knives, with both often made or distributed by the same company.
Additionally, according to an embodiment, the material and grade of the stone 204 are selected according to the material of the knives to be sharpened. For example, where a knife is made from a particularly hard steel, some commercially available bench stones may be too soft to effectively sharpen the knife. In other cases, a knife intended for a particular purpose might require a particularly fine edge, so that a stone of a commonly available grade would be too coarse to properly sharpen the knife. In such cases, the knife manufacturer provides a sharpening system that includes a stone with a material and grade that are selected to provide the desired edge on the knife.
According to an embodiment, the dimensions of the bed 210 are selected to be incompatible with most commercially available bench stones, i.e., slightly shorter or narrower than typical stones of about the same size range. Of course, the bench stone 204 provided by the manufacturer, which is designed and formulated to meet the requirements of the knives for which it was intended, is sized to properly fit the bed 210. Thus, a user is encouraged to obtain replacement stones from the manufacturer or other authorized sources, and discouraged from replacing the stone 204 with another commercially available stone, which might be incapable of sharpening the knives for which it was designed, or, worse, might damage them. As noted above, even if the bench stone 204 is specifically designed for optimal performance with a particular line of knives, it will still remain widely useful for many unrelated tasks in a shop or kitchen.
Turning to
As noted with respect to
According to an alternate embodiment, blind apertures are provided on the surface 210 of the bed, at each end. When it is necessary to change the sharpening angle, pegs of the appropriate length are placed in the apertures at one end of the bed, to raise that end of the stone a desired distance. This is one acceptable way to change the angle instead of using a shim. There are other ways that the sharpening angle can be changed besides pegs and shims, for example, steps or ledges may be provided in the end walls or other structure provided that will permit a user to easily modify the angle D as needed for a particular sharpening need.
In describing the embodiments illustrated in the drawings, directional references, such as right, left, top, bottom, etc., are used to refer to elements or movements as they are appear in the figures. Such terms are used to simplify the description and are not to be construed as limiting the claims in any way.
The term sharp, and related terms, do not refer to the critical angle of a cutting edge, but instead to the degree to which the final bevels of both sides of the blade meet at a straight and smooth line. Likewise, a blade is not made dull by changing the critical angle of the blade, but by rounding or deforming the edge. To resharpen the blade, material from the sides is removed until the rounded edge is eliminated and the edges meet at a straight lines from their respective beveled edges.
Ordinal numbers are used in the specification and claims to distinguish between elements so referenced. There is no necessary significance to the value of a number assigned to one element with respect to other numbered elements. Furthermore, an ordinal number used to refer to an element in the claims does not necessarily correlate to a number used to refer to an element in the specification on which the claim reads.
Where a claim limitation recites a structure as an object of the limitation, that structure itself is not an element of the claim, but is a modifier of the subject. For example, in a limitation that recites “a plurality of probe pins configured to make contact with respective terminals of a wafer of semiconductor material,” the wafer is not an element of the claim, but instead serves to define the scope of the term probe pins. Additionally, subsequent limitations or claims that recite or characterize additional elements relative to the wafer do not render the wafer an element of the claim.
The abstract of the present disclosure is provided as a brief outline of some of the principles of the invention according to one embodiment, and is not intended as a complete or definitive description of any embodiment thereof, nor should it be relied upon to define terms used in the specification or claims. The abstract does not limit the scope of the claims.
Elements of the various embodiments described above can be combined, and further modifications can be made, to provide further embodiments without deviating from the spirit and scope of the invention. All of the U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications and non-patent publications referred to in this specification and/or listed in the Application Data Sheet, are incorporated herein by reference, in their entirety. Aspects of the embodiments can be modified, if necessary to employ concepts of the various patents, applications and publications to provide yet further embodiments.
These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.
Number | Date | Country | |
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61318109 | Mar 2010 | US |