Jan. 7, 1964 C. L. CLARK 3,116,577 KNIFE SHARPENING DEVICE Filed Feb. 7, 1963

FI G-l. Fig. 2. INVENTOR, C.4 o? (2-4 3,116,577 United States Patent Office Patented Jan. 7, 1964 2 tional correcting means is provided to more nearly hold 3,116,577 KNIFE SHARPENING DEVICE the cutting edge at said angie when sharpening this ta Carl L. Clark, 376 Central Pkwy. SE, Warren, Ohio pered end portion of the knife blade. This means con Filed Feb. 7, 1963, Ser. No. 257,813 sists of the outwardly curved ends of support member 3 Claims. (CI. 51-218) 8 as shown in FIG. 3. In FG. 3 the knife is indicated by 9. Projecting the This invention relates to a device adapted for holding position of 9 in FIG. 3 to FIG. 1 it will take the position the blades of knives such as kitchen and butcher knives of 9 shown in FEG. 1 when sharpening the straight por for sharpening. It is designed for use with a sharpen tion of the blade. Imagine now that point 9 drops to ing Stone with flat parallel surfaces. 10 contact the sharpening surface 3, it will take position 8 More specifically, the present invention comprises a in F.G. 1. It is therefore evident that distance 'A' in device for holding a knife blade at a predetermined angle FIG. 1 is the amount of shortening of the distance of in relation to the flat sharpening surface of an oil stone, biade point 9 to the support member 8 in comparison for sharpening such knives as kitchen and butcher knives with the distance of the cutting edge of the straight por having a cutting edge comprising a substantially straight tion of the knife blade to said support member. There portion and a more or less long convex tapered portion fore in sharpening the tapered portion of the blade, terminating in a point. the sharpening angle would change from that for sharp Since the durability of a cutting edge of a knife, aside ening the straight portion of the cutting edge unless a from the quality and temper of the steel, depends on the correction in the angle is made. To make this cor proper sharpening angle, this device will hold the blade 20 rection, the ends of support member 8, as shown in FIG. at the correct angle with reference to the sharpening 3, are bent outward this distance “A.” These bent por Surface of the stone. This angle is generally accepted to tions of 8, in combination with the convex surface of the be about twenty degrees. Support member 8, maintain the sharpening angle closely In the drawings: to the twenty degrees held for sharpening the straight FIG. 1 is a side elevation of the sharpening device and cutting edge of the knife blade. These two elements shows the relative positions of the knife blade, oil stone of the design, namely the convex surface and outwardly and knife holding device during the sharpening operation. bent ends of the support member 8, are important useful FIG. 2 is an end elevation of that portion of the knife and novel features of this knife blade sharpening device. holding device that rests on the flat surface which forms The shape of the convex surface of support member a common Support for this portion of the device and the 30 3, which remains in contact with the flat surface 2 dur oil stone. ing the sharpening operation, as shown in FGS. 2 and FIG. 3 is a plan view showing, the oil stone, and the 4, was chosen after careful experimentation. With this sharpening device with the knife blade clamped in same. convex. Surface, curved as shown, I have proved by ac It also shows the curved ends of that portion of the knife tual tests, with the aid of a sensitive machinist's level holding device that rests on the flat surface which sup 3 5 that the blade of the knife when sharpening the convex ports both the oil stone and the device. tapered portion of the cutting edge will not vary in FIG. 4 is an end elevation of the device showing the angularity to the fiat surface 3 of the sharpening stone required tilting angle so that the extreme point of the by more than one degree from the sharpening angle when knife blade can be sharpened. sharpening the straight portion of the cutting edge. This Referring to the drawings FGS. 1 and 2, the device 40 found to be true even for longer knives with much comprises a bar 6 one end of which is shaped to hold the longer convex tapered cutting edges than that of the short knife blade at twenty degrees to the sharpening surface knife shown in my drawing. En other words, the sharp of the stone by means of a clamping device mounted on ening device of the design shown, will equally well sharpen bar 6, comprising a clamp 5 and a clamping spring 7. both short and icing knife blades and closely maintain At the other end of said bar is a support member 8 the desired sharpening angie, adapted to remain in contact with the flat surface on 45 I have also tested with the level noted in the preceding which the sharpening stone is mounted during the sharp paragraph, a sharpelling device similar to that shown in ening opearition. Bar 6 is usually made so that the dis my drawing, but with the exception that the convex sur tance from the knife blade cutting edge to the support face of support member 8, as shown in FIGURES 2 and 4 member 8 is in the neighborhood of four inches more or is replaced by a straight surface positioned tangent to less. 50 the center of Said convex surface and lengthwise thereto. To cperate the device, the knife blade 4 is clamped It is also straight instead of curved at the ends as Sup as shown in FiG. 3, placed in a horizontal position on the port member 8 is shown in FIG. 3. in these tests i found sharpening stone and is moved about by the operator in that, as tie device was tilted to sharpen the convex ta a rotary motion to sharpen the straight portion of the pered portion of the cutting edge, the inclination of the cutting edge. blade to the sharpening surface changed as much as 6 To sharpen the convex portion of the cutting edge of to 7 degrees from the selected sharpening angle. This the blade, the operator slowly raises the end of the han means a change in the included angle of the cutting dle until the point of the blade engages the surface of edge of 12 to 14 degrees. Therefor, the convex surface the sharpening stone as shown in F.G. 4. During this of support member 8, which is curved both upward and raising of the handle end the rotary sharpening motion 60 outward, makes it possible to sharpen both long and is continued. The above described operation is the pro short blades with equal precision. To obtain this pre cedure to sharpen one side of the knife blade. To sharp cision in sharpening the curved tapered portion of the en the opposite side, the knife is removed from the device, biade cutting edge, the device is purposly clamped so that reversed end for end and reclamped therein. The oper the point of the blade, as shown in plan view, FIG. 3 ator then repeats the above operation to sharpen the op 65 of the drawing, extends beyond the clamping means of posite side. the device to a point approximately in line with the for To maintain the correct sharpening angle while sharp wardly extending tip end of support member 3. ening the tapered convex end portion of the knife blade, ihe clanping means shown in the drawing is subordi the lower edge of support member 8 is contoured to a nate to the two basic elements of the design, namely, the convex shape. This provides a correction to main the 70 convexly curved surface of support member 8, and the cutting angle at or close to twenty degrees. An addi outwardly curved ends of said Support member. Other 3,116,577 3. 4. simple mechanical means for clamping or holding the thereto during the sharpening operation, and at the other knife blade in the device are equally adaptable. This end a Support member, said member having a convex clamping means shown is simply to convey the necessity Surface contacting said flat surface, and also having out of hoiding the knife blade in the device securely and at wardly curved ends which come in contact with said flat the proper sharpening angle. Its function is to hold the surface as the device is tilted for sharpening the convex knife blade in the device at the correct sharpening angle 5 tapered portion of the cutting edge of said knife blade. and prevent slippage or angular movement of the blade 3. In a device designed to hold and maintain the blades in relation to support member 3. of kitchen knives and the like in a selected angular re Having thus described my invention, what i claim lationship to the sharpening surface of a stone, as said as new, and desire to secure by United States Letters 0. knives are moved over and in contact with said stone Patent is: during the sharpening operation, whereby the straight 1. In a device to be used in cornbination with a fiat portion and also the convexly curved portion of the knife surfaced sharpening stone for sharpening the cutting edge blade cutting edge is sharpened to substantially the same of the blades of kitchen knives and the like, when the included cutting edge angle as measured in a plane nor blade is placed in contact with said stone and moved mal to the Straight cutting edge and also in a plane nor over same, said blades having cutting edges with both inal to the tangent to any given point on the curved por straight and convex tapered portions, and said device tion of the cutting edge of said blade, said device com being designed to maintain said knife blade in a selected prising, a bar extending in a direction substantially nor angular relationship with the sharpening surface of said final to said blade and having at one end means for hold stone, said device conprising a bar having at one end 20 ing the blade of said knife in a selected angular relation means for holding said blade in a selected angular rela ship thereto, and at its other end a bar support member tionship thereto, and at the other end a support member being arranged to contact said stone Supporting Surface for supporting said bar and arranged to contact said during the sharpening operation, said bar support mem flat Surface, said Support member comprising a central ber extending on both sides of said bar and the outer portion extending in a substantially parallel direction 25 ends of said bar support member being convexly curved lengthwise to said blade when said blade is held in place outwardly and away from said blade, and the bottom on Said bar, and end portions of Said member being surface of said bar support member where it contacts said curved upwardly and also curved outwardly from the stone supporting surface being convexly curved upwardly cutting blade for contacting said flat surface as the de on each side of said bar, and said bottom surface of vice is tilted for sharpening the convex tapered portion 30 said Support member, at a convexly curved end thereof, of said blade. comes in contact with said stone Supporting surface as the 2. In a device designed to be used in combination device is tilted to sharpen the curved portion of the with a sharpening stone for sharpening the cutting edge cutting edge of said blade. of the blades of kitchen knives and the like, the blades of said knives having cutting edges with both straight 35 References Cited in the file of this patent and convex tapered portions, said sharpening stone being UNITED STATES PATENTS supported on a flat surface so positioned that the sharp 2,741,077 Ayer ------Apr. 10, 1956 ening surface is substantially parallel thereto, and said 2,864,206 Lane et al. ------Dec. 16, 1958 device being designed to maintain the cutting edge of said blades in contact with the sharpening surface of said 40 FOREIGN PATENTS stone and in a selected angular relationship thereto, said 905,102 Germany ------Feb. 25, 1954 device comprising a bar having at one end means for 217,934 Australia ------Oct. 13, 1958 holding said blade in a selected angular relationship