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  Honing guide assembly with camber rollerUSPTO Application #: 20070281594Title: Honing guide assembly with camber roller Abstract: A tool honing guide and an adjustable roller that contacts an abrasive surface during use of the guide facilitates formation of micro bevels, and the roller is barrel-shaped to facilitate honing a curved cutting arris. (end of abstract)
Agent: John S. Pratt Kilpatrick Stockton LLP (l3440) - Atlanta, GA, US Inventors: Steven K. Jones, Robin C. Lee USPTO Applicaton #: 20070281594 - Class: 451367000 (USPTO) Related Patent Categories: Abrading, Work Holder, Clamp, Edge Tool The Patent Description & Claims data below is from USPTO Patent Application 20070281594. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of U.S. Provisional Patent Application No. 60/809,230 filed May 30, 2006. This application is also a continuation in part of U.S. patent application Ser. No. 10/553,592 filed Oct. 17, 2005, which is a 371 U.S. national phase of International Patent Application No. PCT/IB2004/001152 filed Apr. 16, 2004, which claims the benefit of U.S. Provisional Patent Application No. 60/463,484 filed Apr. 17, 2003, the contents of all of which are incorporated herewith. FIELD OF THE INVENTION [0002] This invention relates to honing and sharpening guides used for holding chisels, plane blades and other edge tools and tool blades while grinding, sharpening and honing the tools and blades. BACKGROUND OF THE INVENTION [0003] Honing guides have long been available for holding chisels and plane blades at a predetermined angle relative to a planar abrasive surface, such as the surface of a sharpening stone or a sheet abrasive material affixed to a flat surface such as plate glass. Such commercially available guides generally have wheels or a wide roller that rolls over the abrasive surface or another parallel reference surface and a means for fixing the chisel or plane blade to the guide during use. Some of the prior art guides engage the sides of the chisel or plane blade in a clamping arrangement, and other of the prior guides use a clamping screw to apply force to one face of the chisel or plane blade to force it against guide structure in contact with the other face of the chisel or plane blade. [0004] It is well known in the prior art that a sharp edge can be created more quickly by forming a first bevel on a plane blade or a chisel with a relatively coarse, fast cutting abrasive and then using a finer abrasive, which is therefore slower cutting, to form a micro bevel immediately adjacent to the cutting edge or arris of the blade or chisel at a slightly steeper angle than the principal bevel. This can be accomplished, for instance, by putting a shim under the wheels or roller associated with the honing guide (where the guide separates the roller a substantial distance from the blade bevel) or by adjusting the position of the axis of rotation of the wheels or rollers to slightly lift the guide as taught by U.S. Pat. No. 4,733,501. [0005] While prior honing guides are very useful tools, several aspects of the functionality of these jigs can be improved. [0006] For instance, recent reintroduction of manufacture of number 8 jointer bench planes creates a need for honing jigs able to accommodate the 25/8 inch wide plane blades of such planes, and many currently available honing guides cannot accept blades of that width. [0007] It is also desirable to provide enhanced ability to select bevel angles within the range of such angles typically used, approximately 20 degrees to 40 degrees. It is also desirable to properly locate the entire cutting edge or arris relative to the guide, because some prior guides make it easy for the arris to be located out of square with the guide. [0008] It is desirable to make the honing guide and its blade bevel setting functionality useable with skew chisels. [0009] Many prior art honing guides secure the chisel or plane blade in the guide by reference to the longitudinal tool face surface adjacent to the bevel. This happens, for instance, in a guide where a bench chisel is positioned bevel down and a thumbscrew above the chisel presses against the back face or underside of the chisel, forcing the opposite, top side of the chisel against a guide reference surface. The cutting arris on such a chisel is defined, however, by the intersection of the bevel with the back face of the chisel, against which the thumbscrew presses. The way these prior art honing guides secure the tool being honed is not a problem if the back face and the opposite, front face or top surface are parallel, but they often are not. Additionally, longitudinal bevels on the sides of relatively narrow bench chisels cause this top surface to be quite narrow, which introduces additional difficulty associated with use of it as a reference surface because the chisel may "rock" to one side or the other when it is being secured in the honing guide. [0010] It is desirable to provide a honing guide with enhanced clamping to prevent the tool from skewing while the honing guide is in use. Most existing clamping devices use a single, large screw with a swiveling pad to hold the tool in position. No matter how much pressure is applied to clamp the tool, relatively little force is need to rotate the tool about the axis of the screw. [0011] Another consideration associated with honing guides is the range of bevel angles that can be formed using the guide. Many guides provide a range of angles of approximately 20.degree. to 40.degree., and it is sometimes desirable to be able to hone either smaller or larger angles. [0012] Honing guides with wide rollers provide a stable holder for blades being sharpened so that blade cutting edge or arris remains perfectly straight and square to the blade. While this is desirable for most blades, such perfectly straight cutting edges in larger smoothing planes can produce "plane tracks," which are small steps in the surface of the wood between plane strokes or paths. [0013] To avoid production of such "plane tracks," it is beneficial to add a slight camber or curve to the cutting edge of the plane blade, rather than keep the edge straight. Such a slightly curved-edge plane blade takes a slightly scalloped cut and the resulting surface will be slightly wavy, a feature that is recognized as a hallmark of quality hand woodworking. SUMMARY OF THE INVENTION [0014] The improved honing guide of this invention is an extremely versatile guide useable with a wide range of chisel and blade widths, thicknesses, lengths, and end configurations (square or skewed) to hone a wide range of bevel angles. Associated bevel-setting jigs that couple to the guide makes it easy and quick to position a tool or blade in the guide at a desired bevel angle with the cutting arris properly positioned parallel to the axis of rotation of a guide roller that contacts the planar abrasive surface during use of the guide. A clamping bar contacting the face of the tool or blade adjacent to the bevel securely presses against a reference surface in the guide a surface of the tool or blade that intersects the bevel to form the cutting edge or arris. This reference surface is parallel to the roller axis of rotation. [0015] Consequently, when a plane blade or chisel is secured in the guide, a bevel will be formed that intersects the adjacent tool or blade surface to produce an arris parallel to the axis of rotation of the roller. [0016] In order to minimize the amount of material that needs to be removed during a sharpening operation using the guide of this invention, it is desirable that that the existing arris be positioned parallel to the roller axis of rotation and a distance from that axis of rotation that results in a desired bevel angle. These objectives are achieved by providing a jig or gauge that is temporarily coupled to the honing guide and that has a stop locatable at desired distances from the guide to produce desired bevel angles. One such jig for square end tools provides a reference surface or fence to position a side of the blade or chisel square to the roller so that the bevels formed using the guide will be properly oriented square to the tool. A different positioning jig allows the user to exercise similar control over the positioning of the skew chisels in the jig. It attaches to the honing guide in the same manner, is fitted with an adjustable stop as well, and may include one or two reference fences to contact with the side of a skew chisel or blade. [0017] The tool or blade holding structure of the guide projects beyond the guide roller toward the bevel and grasps the tool relatively near the bevel for better control and so that short tools and blades can be secured in the guide and sharpened. [0018] The roller is positionable in at least two locations relative to the tool holder to facilitate formation on a tool of a primary bevel with the roller in one location and a micro bevel with the roller in a second position that slightly lifts the guide. This may be accomplished as taught in U.S. Pat. No. 4,733,501, which is incorporated herein by this reference. The roller may be moved between the two positions by moving the position of axle on which the roller rotates. The axle may be eccentrically positioned on a shaft that is spring loaded to hold a knob on the end of the shaft against a protrusion on one of the guide body or the knob and one of at least two detents in the other of the guide body or the knob. The knob is pulled axially to disengage the from the detent and rotated to engage another detent. [0019] The honing guide of this invention may also be used as a grinding jig. Structure behind the roller, such as a protruding ledge, enables the guide to rest on a tool rest on a typical motorized bench grinder, belt grinder or other motorized abrasive device. This will allow the user to position a tool to be sharpened once in the guide for both rough grinding and fine honing. Although the guide may not necessarily enable closely controlled, or repeatable grinding angles, by resting the guide on a bench grinder tool rest, such control is not generally required because the angle at which a tool is ground will typically be 2.degree. to 5.degree. less then the honing angle. Such a slightly different grinding angle can typically be judged by eye with very little practice. As is described in detail at page 62 of Leonard Lee's book, The Complete Guide to Sharpening, which book is incorporated herein in its entirety by reference, grinding material from the heel of the bevel at a lower angle will allow much faster honing with less wear on the honing media. Performing both grinding and honing with the tool in the same position in the guide will ensure that the relief grind and the desired cutting arris are parallel--additionally reducing honing time. [0020] The honing guide of this invention may also include concave surface clamp bars to improve the blade-holding ability of the assembly. The concave clamping surface of the clamp bar of this honing guide forces the separation of the regions of contact with the tool being honed and concentrates the clamping force along parallel lines. Continue reading... Full patent description for Honing guide assembly with camber roller Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Honing guide assembly with camber roller patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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