US3885352A

US3885352A - Sharpening machine

Info

Publication number: US3885352A
Application number: US490184A
Authority: US
Inventors: John R Juranitch
Original assignee: John R Juranitch
Current assignee: JURANITCH Inc
Priority date: 1974-07-19
Filing date: 1974-07-19
Publication date: 1975-05-27
Anticipated expiration: 1992-05-27

Abstract

A sharpening machine for guiding the blade of a cutting instrument uniformly across each of a plurality of honing wheels. The sharpening machine includes a frame having at least coarse and fine power driven honing wheels mounted therein, a guide rail adjustably maintained in parallel spaced relation to the circumferences of the honing wheels having parallel grooves along the rail, and an independent carriage for grasping the blade of the cutting instrument. The carriage rides along each groove in said guide rail and positions the blade at a uniform contact angle to the adjacent honing wheel as the blade is drawn across the wheel. The distance between one groove and its adjacent fine honing wheel is greater than the distance between the other groove and its adjacent coarse honing wheel providing a greater angle of contact between the blade and the fine honing wheel relative the coarse honing wheel. Drawing the blade successively across the coarse and fine honing wheels imparts thereon a coarse ground relief surface and a fine ground edge face at the extremity of the relief surface providing a razor-like edge on the cutting instrument blade.

Description

i451 May 27, 1975 SHARPENING MACHINE e d h b e h t g T.m mm m R Tr mm 8 .m h C a 1h 78 UA Inventor: John R. Juranitch, 932 S. Layton Blvd., Milwaukee, Wis. 53215 July 19, 1974 ting instrument uniformly across each of a plurality of [22] Filed:

honing wheels. The sharpening machine includes a Appl. No.: 490,

frame having at least coarse and fine power driven honing wheels mounted therein, a guide rail adjustably maintained in parallel spaced relation to the circum- [52] US. 51/3; 51/92 BS; 5l/l02;

ferences of the honing wheels having parallel grooves 51/218 R B24b 9/00; B24b 3/52;

[51] Im, Cl,, B24b 7/00; along the rail, and an independent carriage for grasp- BZ4b 19/00 ing the blade of the cutting instrument. The carriage 92 R, 92 BS,

[58] Field of Search............. 5l/74 BS, rides along each groove in said guide rail and positions 51/102, 218 R 218 A, 91, 94 the blade at a uniform contact angle to the adjacent honing wheel as the blade is drawn across the wheel.

The distance between one groove and its adjacent fine honing wheel is greater than the distance between the [56] References Cited UNITED STATES PATENTS Drawing the blade successively across the 51 3 coarse and fine honing wheels imparts thereon a 51/92 BS coarse ground relief surface and a time ground edge W0 m mwm m m e m m mm mcw mw ma i JMHBWG 609 33 566777 999999 face at the extremity of the relief surface providing a razor-like edge on the cutting instrument blade.

18 Claims, 17 Drawing Figures Primary Examiner-Othell M. Simpson Attorney, Agent, or Firm-Lockwood, Dewey, Zichert & Alex SHEET 010F4 FIGB SHARPENING MACHINE This invention relates in general to a sharpening machine, and more particularly to a sharpening machine capable of imparting uniformly along a blade mounted therein a cutting edge which includes a coarse ground refief surface and a fine ground edge face at the extremity of the relief surface.

Sharpening machines are well known. Heretofore. existing sharpening machines typically have included a frame. and either a manually or power driven grinding wheel mounted on the frame. Cutting instruments to be sharpened, typically knife blades, were manually moved across the honing or grinding wheel in sharpening. The quality of cutting edge obtained from using the sharpening machines was limited by operator dexterity and experience because the blade was manually moved across the honing wheel at no constant angle. In an effort to obtain more uniformly sharpened blades, an anvil or guide rail was later placed adjacent the grinding wheel to serve as a rest or guide for the manually held cutting instrument. Also, fixtures securing cutting instrument blades have been slidably clamped or fastened to the frame to obtain a uniform edge on a blade secured therein which is passed across the grinding wheel. However, a jig or fixture rigidly and slidably fas tened to a frame does not have the versatility or adjustability to sharpen cutting blades of widely varying shapes and sizes. Also. the cost of manufacturing such a fixture having machined guides and ways is expensive.

The present invention has a flexibility and adaptability not heretofore known in sharpening machines because it utilizes an independent blade holding carriage which is not fastened or clamped but guidably rolled along a groove located on the top surface of the guide rail adjacent each honing wheel. The relative coaction between the guide rail and carriage determines the blade contact angle and is different at each wheel due to a greater spatial relation between one groove and its adjacent fine honing wheel relative the other groove and its adjacent coarse honing wheel. This slight but distinct difference causes a carriage mounted blade drawn across the coarse honing wheel to have a small contact angle therebetween forming a relatively broad relief surface adjacent the cutting edge. A carriage mounted blade drawn across the fine honing wheel has a larger contact angle therebetwecn forming a narrower edge face at the extremity of the relief surface. The finely ground edge is then drawn across a chrome finished hardened steel sharpening bar to remove any burrs.

It is therefore an object of the invention to provide a sharpening machine for commercial use which produces a finer, stronger, more uniform razor-like edge to a wider variety of cutting instrument blades than heretofore obtainable in a machine of comparable cost.

A further object of the invention is to provide a new and improved sharpening machine capable of imparting uniformly along a blade mounted therein a cutting edge which includes a coarse ground relief surface and a fine ground edge face along the extremity of the relief surface producing a razor-like edge on the blade.

Another object of the invention is to provide a sharpening machine including an independent blade holding carriage slidable along a groove in a guide rail adjacent each of a pair of power driven honing wheels mounted in the machine.

Other objects, features. and advantages of the invention will be apparent from the following detailed disclosure, taken in conjunction with the accompanying sheets of drawings. wherein like reference numerals refer to like parts, and in which:

FIG. 1 is a perspective view of the sharpening machine of the invention;

FIG. 2 is a perspective view of the machine, with certain parts broken away for clarity, showing the blade holding carriage riding in the guide rail groove and guiding the knife secured therein across the honing wheel;

FIG. 3 is a cross-sectional view of the guide rail taken substantially along line 33 of FIG. 1;

FIG. 4 is a cross-sectional view like FIG. 3, showing the trailing surface of the groove in front of the coarse honing wheel;

FIG. 5 is a cross-sectional view of the guide rail taken substantially along the line 5-5 of FIG. 1;

FIG. 6 is a cross-sectional view of the guide rail like FIG. 5, showing the trailing surface of the groove in front of the fine honing wheel;

FIG. 7 is a top plan view of'the blade holding carriage as it appears riding in the guide rail;

FIG. 8 is a front elevational view of the blade holding carriage;

FIG. 9 is a side elevational view of the blade holding carriage shown in solid lines with the blade holding jaws open and in phantom with the blade holding jaws closed against a blade mounted therein;

FIG. 10 is a top plan view of the blade holding carriage and attached blade showing the curved blade tip being drawn across a coarse honing wheel;

FIG. 11 is a cross-sectional view taken substantially along line 1111 of FIG. I, but showing the carriage in solid lines guiding the blade across the fine honing wheel and in phantom guiding the blade across the coarse honing wheel;

FIG. 12 is a close-up view of the phantom blade tip in FIG. 11 shown as in contact with the coarse honing wheel;

FIG. 13 is a close-up view of the solid line blade tip in FIG. 11 shown as in contact with the fine honing wheel;

FIG. 14 shows a close-up front elevational view of the triangular blade sharpening bar shown in FIG. 1;

FIG. 15 shows a modification of the sharpening bar shown in FIG. 14;

FIG. 16 shows a modification of the blade holding carriage including a pair of blade holding jaws for gripping the cutting edge of a scissor blade; and

FIG. 17 is a pictorial view of a modification of the invention with certain parts broken away for clarity, showing an added burr removing wheel and the mechanism for adjustably spatially relating the honing wheels and guide rail.

Referring to FIG. 1, the sharpening machine of the invention is shown designated generally by the numeral 20. While the machine is particularly useful for sharpening knives to a razor-like edge, it is also useful for sharpening other cutting instruments such as scissors and the like. The machine includes a rigid frame 21 of steel angle iron sections having vertical leg supports 21a, lower

longitudinal supports

21b and 21c, and upper longitudinal supports 21d. On the lower ends of the leg supports 21a are located casters 22 which enable the frame to be easily moved along the floor. Cross members or

rails

23 and 24 extend between upper supports 21d for mounting a fine honing wheel 25 and a coarse honing wheel 26. The wheels have cylindrical honing surfaces, and are of the same diameter.

Wheels

25 and 26 are carried on a drive shaft 30 which is rotatably mounted in horizontal position in pillow bearing

blocks

31, 31 secured on the

frame cross members

23 and 24, like bearing 31 on members 24 shown in FIG. 2. Drive shaft 30 is drivingly connected to a suitable prime mover which supplies power to rotate the shaft and honing

wheels

25, 26. In this embodiment, an electric motor 32 is mounted in the frame 21 on

cross supports

33, 33 extending between supports 21b and located centrally beneath

cross supports

23, 24. Rotary motion is transferred from electric motor 32 to drive shaft 30 by means of a belt 32a trained over a pulley on the drive shaft and a pulley on the motor shaft. It can be understood that other suitable drive transfer mechanisms can be utilized. A cover 34 surrounds the drive shaft pulley and belt 32a provides a protective shield for the operator.

A guide rail 35 is mounted on frame cross rails 23, 24 so as to be adjustably spatially related parallel to the circumference of the fine and coarse honing

wheels

25, 26. Guide rail 35 includes a horizontal base 36 and an inclined lip 37 extending from its leading edge. A plate 38 is mounted on the inside surface of lip 37 along the lip in front of the fine honing wheel 25. Plate 38 increases the thickness of lip 37 on the front side.

Grooves

40, 41 are defined on the guide rail and located at the juncture of the lip 37 and the base 36 along and adjacent the circumferences of coarse honing wheel 26 and fine honing wheel 25, respectively.

A blade holding carriage 42 more completely shown in FIGS. 7, 8 and 9 secures the blade to be sharpened and coacts with the guide rail 35 to accurately dispose the blade relative the honing wheels during sharpening. More specifically, the carriage 42 includes

jaws

43, 44 which grip a blade 45 wherein the carriage guidingly rides in

grooves

40, 41 as the blade 45 is drawn across, first, the coarse honing wheel 26 and, thereafter, the fine honing wheel 25. After the blade 45 has been drawn across both honing wheels, it is removed from blade holding carriage 42 and drawn across either side of a triangular shaped chrome plated hardened steel sharpening bar 46, shown also in FIG. 14. Bar 46 removes any burrs remaining on the blade providing a razor edge finish thereto.

Upper and lower carriage rolling

support members

64 and 65 are perpendicularly attached to the

blade holding jaws

43, 44, respectively.

Rollers

64a and 65a are carried on the

support members

64 and 65. The rollers enable the blade holding carriage 42 to guidably ride in the respective

guide rail grooves

40, 41. A conventional pressure grip locking mechanism 70 like that well known for wrenches, sold under the trademark Vise-Grip, operates clamped

jaws

43, 44 for selectively securing and releasing a cutting blade 45. The locking mechanism 70 is shown in FIG. 9 in unlocked or open position with the

jaws

43 and 44 open in solid lines and in locked or closed position against blade 45 in phantom. The mechanism 70 may be adjusted by turning bolt 68 and may be unlocked by moving lever 67.

Hand grips 71, 71 placed on either side of the locking mechanism 70 in the plane of the

jaws

44, 45 enable manual manipulation of the blade holding carriage 42. The symmetrical structure of the

jaws

43, 44,

roller support members

64, 65,

rollers

64a, 65a, and hand grips 71, 71 enables the carriage 42 to place either side of the blade 45 in identical proper uniform contact with the respective sharpening

hones

25, 26. The rollers may take any desirable form, such as a ball bearing assembly. The height of the lip 37 is such in relation to the size of the rollers that guiding will be accomplished when sharpening blades with irregularly shaped edges and when raising the rollers above the floop plate 36.

The spatial relationships of the blade 45 and blade holding carriage 42 to the honing

wheels

25, 26 in the dual grinding sharpening machine 20 is illustrated in FIG. 11. The blade 45 is secured in blade holding carriage 42 and rollers 65a attached to the carriage support member 65 ride in groove 40 as shown in FIG. 7 and in dotted lines in FIG. 11 along guide rail 35 adjacent the coarse honing wheel 26. The angular position of blade 45 and blade holding carriage 42 in groove 40 relative the honing wheel is shown in phantom in FIG. 11. The blade holding carriage rollers 650 are restrained by the inside surface of guide rail lip 37, wherein the retention of blade holding carriage 42 in this position causes blade 45 to contact coarse honing wheel 26 at location 51, FIGS. 11 and 12, thereby creating a relatively broad hollow ground relief surface 52 on one side of the blade 45. Turning the carriage and blade about a line essentially perpendicular to the honing wheel surface where rollers 64a engage the guide rail permits rough sharpening the other side of the blade edge.

After the relief surfaces 52, 52 are obtained using the coarse honing wheel 26, carriage 42 and attached blade 45 are moved to groove 41 of guide rail 35 adjacent the fine honing wheel 25. While riding in groove 41 carriage 42 is retained against the inside surface of spacing plate 38 as illustrated in solid lines in FIG. 11. Since groove 41 is located farther from the outside circumference of fine honing wheel 25 than groove 40 is located from the outside circumference of coarse honing wheel 26, the angle of contact between blade 45 and fine honing wheel 25 is greater than the angle of contact between blade 45 and coarse honing wheel 26 as shown in FIGS. 11 and 13. Therefore, blade contact position 53 on fine honing wheel 25 is lower relatively than blade contact position 51 is on coarse honing wheel 26. As shown in FIG. 13, fine honing wheel 25 grinds a

narrower edge face

54, 54 on the extremity of the hollow

ground relief surface

52, 52 as a result of the change in blade contact angle,

The rounded point of a cutting instrument blade 45 being drawn across the coarse honing wheel 26 with the blade holding carriage 42 skewed in relation to the guide rail 35 is shown in FIG. 10. A concave trailing

surface

72, 73 of

grooves

40, 41, respectively, FIGS. 4 and 6, located in portions of guide rail 35 adjacent both honing wheels allows one of the carriage rollers to be skewed in the

grooves

40, 41 without being lifted vertically so the respective blade contact angle with each honing wheel remains constant as the point of the blade is ground.

In FIGS. 1, 11 and 17, a mechanism for adjustably mounting guide rail 35 to frame 21 is shown, whereby the distance between the guide rail and the honing wheels may be changed to adjust the sharpening angle. The mechanism includes a pair of guide rail tracks 55a,

55b attached to the bottom surface of guide rail 35 in parallel spaced relation. Each

guide rail track

55a, 55b is a C-channel member attached to guide rail 35 with the channel webbing located toward the center of the guide rail. The lower arm of each

guide rail track

55a, 55b is matingly received in a

complementary frame track

56a, 56b attached to each frame

upper cross member

23, 24, respectively. In this embodiment,

frame tracks

56a, 56b are L-channel members with the vertical channel portion attached to the

respective cross member

23, 24 so the horizontal channel portion is located in parallel spaced relation with the cross member forming a way 57a (FIGS. 1 and 11), 57b (FIG. 17) in which the lower arm of

guide rail track

55a, 55b is slidably received.

Rounded toe portions

60a, 60b (FIG. 17) are located at the leading edge of the lower arm on each guide rail track which, when inserted in the

ways

57a, 57b of

frame tracks

56a, 56b, limit vertical movement of the leading portion of guide rail track 55a, 5517 while permitting limited pivoting of guide rail 35 and guide rail tracks relative the frame tracks. Rack gear segments 610 (FIG. 1), 61b (FIG. 17) are located with teeth facing upward at the inside front portion of each upper

frame cross member

23, 24. This

rack gear segment

61a, 61b matingly engages a complementary rack gear segment 62a, 62b attached adjacent the trailing edge of each

guide rail track

55a, 55b on the surface of the webbing facing the center of the guide rail 34. Engagement of the meshing comple' mentary rack gears 61a, 61b and 62a, 62b secures the guide rail and its leading edge lip 37 in a specific spatial relation to the outer circumferences of coarse and fine honing

wheels

25, 26, respectively. Since the teeth on the rack gears are identical, the spatial relation of the guide rail 35 to the honing

wheels

25, 26 may be varied by lifting the trailing end of guide rail 34 by means of hand grips 63, 63 located thereon so as to unmesh the rack gears. The

guide rail tracks

55a, 55b then slide along the ways of the

frame rail tracks

56a, 56b until the desired spatial relation is obtained. The trailing end of guide rail 35 is then lowered until the respective track and guide rail rack gears mesh again securing the guide rail 34 in a different position. It can be understood that other devices for maintaining an adjustable spatial relation between the guide rail 35 and respective grinding or honing

wheels

25, 26 may be utilized without departing from the scope of the invention.

The chrome plated hardened steel sharpening bar 46, shown in FIG. 14, is formed in triangular shape with the base as a mounting and the other two sides forming slanted sharpening surfaces for removing burrs from the blade 45 obtained during honing. It is preferably round in cross section but may be formed to merely present an arcuate surface.

In FIG. a modification of the sharpening bar is shown at 74. The modification includes two straight chrome plated hardened

steel sharpening bars

75, 75 of equal length pivoted together at one end and pivoted at their opposite ends to two equal supporting

members

76, 76 which are pivoted together at one end and attached to frame support bracket 77. Accordingly, the angle between the bars 75 may be changed to facilitate deburring action.

In FIG. 17 a further modification of the machine is shown utilizing a deburring wheel 90 rotatably mounted in-line with honing

wheels

25, 26 on an extension 91 of shaft 30. The end of extension 91 is rotatably mounted in a third pillow block 31 attached to an added frame cross member 92 which is parallel to and spatially related to

cross members

23, 24. Deburring wheel 90 is of like circumference to honing

wheels

25, 26 and is made of chrome finished hardened steel. A continuation of groove 41 in guide rail 34 is adjacent wheel 90. After the fine honed edge faces 54, 54 are obtained on blade 45, they are drawn across wheel 90 as carriage 42 is guided in the continuation of groove 41. As with the sharpening bars, drawing the blade across the wheel 90 removes burrs from the blade creating a razor edge. In this modification, the rack gears 61c, 620 are located on frame cross member 92 and its adjacent guide rail track 550 and removed from cross member 23 and track 55a. Operation of the locking gears is the same as discussed previously. Center guide rail track 55a continues to act as a support for guide rail 34.

In FIG. 16 a modification of the blade holding carriage is shown at 80 which is utilized for grinding the cutting edge of a pair of scissors 81. The modified carriage 80 has only one roller supporting member 82 and a pair of rollers 83, one at each end, although only one is shown. Carriage 80 has two sets of combination blade holding jaw and locking

mechanisms

84, 84 mounted in spaced parallel relation along carriage supporting member 82. The locking

mechanisms

84, 84 work substantially identically to locking mechanism found in blade holding carriage 42.

Jaws

85, 86 are shorter than

jaws

43 and 44 of blade holding carriage 42 and are used for grasping and retaining the cutting blade 87 of the pair of scissors 81. The

shorter jaws

85, 86 position the mounted blade 87 farther from honing wheel 25 so a greater angle of contact between the blade and honing wheel is obtained as is proper for a scissors cutting blade. Only one blade 87 is sharpened on a pair of scissors as the second blade 88 is used as an anvil.

It will be understood that variations may be effected without departing from the scope of the novel concepts of the present invention, but it is understood that this application is to be limited only by the scope of the appended claims.

The invention is hereby claimed as follows:

1. A sharpening machine for guiding an edge of a cutting instrument uniformly across a hone to sharpen said edge comprising, a rigid frame, a plurality of power driven honing wheels mounted on said frame, instrument holding means and guide means, said instrument holding means securing said cutting instrument and coacting with said guide means, and said guide means being attached to said frame in spatial relation to said honing wheels and having a plurality of positioning means located thereon coacting with said instrument holding means to position said cutting instrument edge at a plurality of different angles of contact with said honing wheels, whereby said cutting instrument is guided across one of said honing wheels at one angle to form a relief surface thereon and is thereafter guided across another of said honing wheels at another angle forming a finished edge at the extremity of said relief surface.

2. The sharpening machine of claim I, wherein said plurality of power driven honing wheels mounted on said frame further comprises, a shaft rotatably mounted to said frame in horizontal position, a fine honing wheel and a coarse honing wheel of like diameters having honing surfaces along their circumferences and mounted through their centers in spaced relation on said shaft,

3. The sharpening machine of claim 2, further comprising, a deburring wheel of like diameter to said honing wheels having deburring surface along its circumference and mounted through its center in spaced relation to said honing wheels on said shaft.

4. The sharpening machine of claim I, wherein said instrument holding means comprises, a carriage having rollers at its extremities allowing said blade holding means to ride in said guide means, movable coacting jaws attached to said carriage or securing a portion of said cutting instrument therebetween, and a jaw locking mechanism coacting with and maintaining said jaws in a tightly engaging position with said cutting instrument.

5. The sharpening machine of claim 1, wherein said guide means comprises, a guide rail attached to said frame and positioned in perpendicular spaced relation to said honing wheels, means for varying the spaced relation between said guide rail and said honing wheels, and wherein said plurality of positioning means corn prises grooves along the top surface of said guide rail adjacent and parallel the edge of said rail which is closest said honing wheels, said grooves guiding and partially restricting the movement of said carriage riding therein, wherein the distance between each of said grooves and the honing wheel closest thereto determining the angle of contact between a cutting instrument mounted in said carriage and said honing wheel.

6. The guide rail of claim 5, wherein each of said guide rail grooves is located a given distance from said adjacent guide rail leading edge.

7. The guide rail of claim 5, wherein said means for varying the perpendicular spaced relation between said guide rail and said honing wheels comprises, a plurality of tracks located in spaced relation perpendicularly across the bottom side of said rail, and a plurality of mating tracks located in spaced relation on said frame parallel to the plane of said honing wheels, and means attached to said rail facilitating its movement in relation to said honing wheels.

8. A sharpening machine capable of imparting uniformly along a blade mounted therein, a cutting edge which includes a coarse ground relief surface and a fine ground edge face at the extremity of said relief surface comprising, a rigid frame, an electric motor mounted to said frame, a shaft rotatably attached to said frame in horizontal position and drivingly connected to said motor, at least a fine honing wheel and a coarse honing wheel of like diameters having honing surfaces along their circumferences mounted in spaced relation through their. centers to said shaft, a guide rail positioned on said frame parallel to said shaft in adjustable spaced relation to the circumferences of the honing wheels attached thereto, including a pair of grooves in a top surface of said rail adjacent and parallel a leading edge thereof, one of said grooves located along a portion of said rail which, as mounted in said frame, is adjacent said coarse honing wheel, the other of said grooves located at least along a portion of said rail adjacent said fine honing wheel, and the groove adjacent said fine honing wheel being positioned a greater distance from said rail leading edge than said groove adjacent said coarse honing wheel, and a blade holding carriage for coacting with said guide rail in maintaining said blade in substantially fixed angular Contact relations to each of said honing wheels including rollers attached to said carriage for riding in said guide rail grooves. and movable coacting jaws attached to said carriage for securing and locking said blade therebetween, and means for facilitating movement of said carriage relative said grooves and said honing wheels.

9. The guide rail of claim 8, wherein said leading edge further comprises. a lip extending at an incline from said rail. inside surfaces of said lip forming the leading edge surfaces of said grooves, the thickness of said lip adjacent said fine honing wheel being uniformly greater than the thickness of said lip adjacent said coarse honing wheel, and said greater portion of the thickness of said lip extending away from said fine honing wheel.

10. The sharpening machine of claim 8, wherein said guide rail further comprises, a pair of tracks located across the width of the bottom of said rail, a portion of which slidably engages a pair of mating tracks on said frame located in perpendicular relation to said shaft, a locking mechanism for positively locating each rail track with each frame track including a first rack gear connected to each of the tracks on said guide rail which matingly engages a second rack gear connected to each of the tracks on said frame, a rounded pivoting toe at the leading edge of each guide rail, said pivoting toe substantially preventing the vertical movement of the leading edge of said rail track in said frame track, the trailing portion of said frame track being vertically movable for engagement and disengagement of said rack gears, and means for facilitating moving said guide rail in varied spatial relation with the circumference of said honing wheels.

11. The sharpening machine of claim 8, wherein said blade holding carriage further comprises, rollers located at the extremities of said carriage forming a rectangle perpendicularly bisected horizontally by the plane of a blade mounted in said movable jaws, whereby one pair of said rollers on one side of said jaws rides in said guide rail grooves to sharpen one side of a blade mounted in said jaws, and the other pair of said rollers located on the other side of said jaws rides in said guide rail grooves to sharpen the opposite side of a blade mounted in said jaws.

12. The holding carriage of claim 11, further comprising, dual hand grips substantially symmetrically located vertically on said carriage facilitating manual movement of either set of said rollers along said grooves in said guide rail.

13. The blade holding carriage of claim 11, wherein the vertical center of said jaws is offset to one side of the vertical center of said rectangle formed by said carriage rollers.

14. The sharpening machine of claim 8, further comprising a triangularly shaped sharpening steel bar made of hardened steel and mounted on said frame whereby drawing each edge of a sharpened blade across an opposite arm of said bar removes burrs from the edge of said blade.

15. The sharpening machine of claim 8, further comprising, two equal length sharpening steel bars made of hardened steel pivotally mounted together and pivotally attached at their opposite ends to two equal length support rods pivotally connected together and mounted to said frame at one end thereof forming an isosceles quadrilateral figure having an ajustable angle between said sharpening steel rods.

16. The blade holding carriage of claim 8, further comprising two sets of movable coacting jaws located horizontally on said carriage, and said carriage having two of said rollers mounted horizontally at a bottom side thereof for facilitating the mounting and sharpening of scissor blades thereon.

17. The sharpening machine of claim 8, further comprising a deburring wheel of like diameter to said honing wheels made of hardened steel and chrome plated on its outside circumference deburring surface and mounted through its center in spaced relation to said honing wheels on said shaft, and wherein said groove adjacent said fine honing wheel extends along said rail to a position also adjacent said deburring wheel.

18. The elongate guide of claim 8, wherein each of said guide rail grooves further comprise, a concave groove trailing edge surface at the groove located across from and extending away from each of said honing wheels for maintaining a substantially constant pitch angle between the knife edge and honing wheel surface while varying the yaw angle of said blade holding carriage and attached blade in relation to said honing wheel circumference as said carriage is pivoted in yaw on one of said rollers in each of said grooves to sharpen a point of said blade.

Claims

2. The sharpening machine of claim 1, wherein said plurality of power driven honing wheels mounted on said frame further comprises, a shaft rotatably mounted to said frame in horizontal position, a fine honing wheel and a coarse honing wheel of like diameters having honing surfaces along their circumferences and mounted through their centers in spaced relation on said shaft.

4. The sharpening machine of claim 1, wherein said instrument holding means comprises, a carriage having rollers at its extremities allowing said blade holding means to ride in said guide means, movable coacting jaws attached to said carriage or securing a portion of said cutting instrument therebetween, and a jaw locking mechanism coacting with and maintaining said jaws in a tightly engaging position with said cutting instrument.

5. The sharpening machine of claim 1, wherein said guide means comprises, a guide rail attached to said frame and positioned in perpendicular spaced relation to said honing wheels, means for varying the spaced relation between said guide rail and said honing wheels, and wherein said plurality of positioning means comprises grooves along the top surface of said guide rail adjacent and parallel the edge of said rail which is closest said honing wheels, said grooves guiding and paRtially restricting the movement of said carriage riding therein, wherein the distance between each of said grooves and the honing wheel closest thereto determining the angle of contact between a cutting instrument mounted in said carriage and said honing wheel.

8. A sharpening machine capable of imparting uniformly along a blade mounted therein, a cutting edge which includes a coarse ground relief surface and a fine ground edge face at the extremity of said relief surface comprising, a rigid frame, an electric motor mounted to said frame, a shaft rotatably attached to said frame in horizontal position and drivingly connected to said motor, at least a fine honing wheel and a coarse honing wheel of like diameters having honing surfaces along their circumferences mounted in spaced relation through their centers to said shaft, a guide rail positioned on said frame parallel to said shaft in adjustable spaced relation to the circumferences of the honing wheels attached thereto, including a pair of grooves in a top surface of said rail adjacent and parallel a leading edge thereof, one of said grooves located along a portion of said rail which, as mounted in said frame, is adjacent said coarse honing wheel, the other of said grooves located at least along a portion of said rail adjacent said fine honing wheel, and the groove adjacent said fine honing wheel being positioned a greater distance from said rail leading edge than said groove adjacent said coarse honing wheel, and a blade holding carriage for coacting with said guide rail in maintaining said blade in substantially fixed angular contact relations to each of said honing wheels including rollers attached to said carriage for riding in said guide rail grooves, and movable coacting jaws attached to said carriage for securing and locking said blade therebetween, and means for facilitating movement of said carriage relative said grooves and said honing wheels.

9. The guide rail of claim 8, wherein said leading edge further comprises, a lip extending at an incline from said rail, inside surfaces of said lip forming the leading edge surfaces of said grooves, the thickness of said lip adjacent said fine honing wheel being uniformly greater than the thickness of said lip adjacent said coarse honing wheel, and said greater portion of the thickness of said lip extending away from said fine honing wheel.