US2938311A - Plane blade grinding jig - Google Patents

Description

y 1960 T. R. CHAMBERS 2,938,311

PLANE BLADE GRINDING JIG Filed March 24, 1958 Fig.1

Thomas R. Chambers 1N VEN TOR.

United States Patent O PLANE BLADE GRINDING J IG Thomas R. Chambers, 4616 N. Ozanam Ave., Norridge 31, 111.

This invention relates generally'to a jig and more particularly involves a novel and improved construction in a jig particularly designed for properly positioning plane blades adjacent a grinding wheel.

The home hobbyist or busy workman generally sharpens a plane blade or properly establishes a hollow ground on the blade by simply holding the blade against a moving grinding wheel and feeling his way to a proper ground. Most often this method is satisfactory for. general purposes but, however, sometimes an inexperienced person or an inattentive person may perhaps ruin the blade edge by shotty grinding. The prior art of course shows the development of many blade grinding jig devices but most of these are not adaptable to home use in that they are somewhat complex and-expensive. Therefore, the development of a simple, inexpensive, and reliable jig would be most welcome by individuals concerned with this art. It is therefore the principal object of this invention to provide a novel and improved blade grinding jig which is particularly characterized by its simplicity, low expense and reliability.

A further object of this invention is to provide a blade grinding jig which lends itself to easy and rapid utilization.

It is a still further object of this invention to provide a blade grinding jig for properly positioning a blade for establishing a good hollow ground surface.

In accordance with the above stated objects, below are particularly disclosed the details of construction for a blade grinding jig particularly designed to properly position a wood plane blade proximate a grinding wheel for establishing a good hollow ground surface on the blade. The jig includes an elongated angle member which is adapted to be held on a conventional tool rest. A projecting member is transversely fixed to the elongated member and a pair of threaded aligned apertures pass therethrough. The projecting member is adapted to be slidably accommodated in a slot conventionally formed in a plane blade. The projecting member guides or aligns the blade properly relative to the grinding wheel while a winged or locking screw carrying a washer passes through the slot, projecting member, and angle member for selectively locking the blade relative to the projecting member and angle member.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

Figure 1 is a perspective view of the component jig elements and plane blade;

Figure 2 is a side elevational view illustrating the jig comprising this invention in operating position;

Figure 3 is an elevational front view of the jig, blade, and grinding wheel; and

2,938,311 Patented M y 9 ice Figure 4 is a perspective view illustrating the hollow ground of the blade.

With continuing reference to the drawings and initial reference to Figure 2, the numeral 10 generally represents a conventional grinder having a grinding wheel 12 adapted to rotate about an axle 14 driven by the motor 16 of Figure 3. The motor and grinding wheel are generally supported on a base as shown at 18 which further carries an arcuate tool rest 20 which is aligned with the driving wheel 12 and has a flat upper surface 22 which approximates the level of the horizontal diameter of the grinding wheel 12.

In order to properly establish a hollow ground as shown at 24 on the blade 26, the 'blade 26 is generally held adjacent the grinding wheel 12. "To properly grind the blade 26, however, it is necessarysto maintain the leading edge 28 of the blade 26 horizontal or transverse to the motion of the grinding wheel 12. .The elements comprising the jig forming this invention aid in maintaining the proper relationship'between the leading edge 28 and the grinding wheel 12. The jig includes an elongated angle member 30 having a transverse projecting member 32 fixed thereon as by welding. The elongated member 30 includes two- leg portions 34 and 36. The projecting member 32 may be fixedto leg 34 and project therebe yond. A pair of aligned apertures 38 and 40 extend through the, projecting member 32 and the leg 34. aligned apertures38, and'40 are threaded to threadedly receive a'winged lock screw 42.

The blade 26 has a longitudinal slotted portion 44 adapted to slidably receive the projecting member 32 therein. A washer 46, having an outer diameter greater than the slot width, is accommodated on the wing screw 42 over the blade 26. By tightening the winged screw or locking screw 42 in the threaded apertures 38 and 40, the washer 46 is brought-to bear on the blade 26 so as to selectively lock the blade 26 in a desired position relative to the projecting member 32 and the angle member 30. The blade 26 and leading edge 28 describe a sliding path prescribed by the projecting member 32 which is fixed transversely to the leg 34. Therefore, the leading edge 28 will necessarily remain parallel to the vertex line formed by the angle created at the jointure of the legs 34 and 36 of the angle member 30. Likewise, the free ends of the legs 34 and 36 will also be the vertex line and the leading edge 28.

In the utilization of the jig comprising this invention, the jig elements and the blade are assembled'as indicated in Figure 1. That is, the slot 44 of blade 26 slidably receives and is aligned by projecting member 32. The winged or locking screw 42 carrying the washer 46 is threadedly engaged by the apertures 38 and 40. By screwing the screw 42 tightly, the washer 46 locks the blade 26 relative to the projecting member 32 and angle member 30. The legs 36 and 34 are then placed on the flat portion 22 of the tool rest 20 in the manner indicated in Figure 2. The motor 16 is then actuated to turn grinding wheel 12 to establish the proper hollow ground surface 24 on blade 26. The blade 26 and jig are properly moved reciprocally transverse to the wheel motion for establishing the proper hollow ground on the entire width of the leading edge 28. The proper reciprocal motion is indicated by the arrows and at 50 and 52 in Figure 3. The operator of course, should be aware that the blade requires frequently cooling to prevent burning of the steel due to the tremendous friction of the grind ing wheel 12 relative to the blade 26. v

After grinding the blade, it is possible that a feathered edge will be developed which can be removed with a few strokes of a fine stone.

parallel to 3 V a The foregoing is considered as illustrative only of the principles of the'invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to theexact construction and operation shown and described and accordingly, all suitable modifications .and

equivalents may be resorted to, falling within the scope of the invention as claimed.

What is claimed as new is as follows:

1. A.plane blade grinding jig for properly positioning a plane blade proximate a grinding wheel for establishing a good hollow ground comprisingan elongated angle member, said angle member including a pair of identical-rectangular legs, guide means carried by said angle member for aligning a plane blade transversely of said angle member exterior to the angle betweensaid legs, means cooperating with said angle member for retaining said plane blade adjacent said angle member, said guide means including a flat rectangular projecting member fixed to one leg of said angle member, and aligned apertures in said projecting member and said angle member.

2. In combination with a plane blade having a longitudinal slot therein, a grinding jig for properly positioning said blade proximate a grinding wheel comprising an elongated angle member, said angle member including a pair of identical rectangular legs, a flat rectangular projecting member transversely fi xed to one leg of said .angle member-exterior to the angle between said legs, said projecting member adapted to slidably fit within said longitudinal slot whereby said blade is prevented from rotating relative to said projecting member, and locking means ior selectively locking said plane blade. relative to said angle member and projecting member.

' 3. In combination with a plane blade having a longitudinal slot therein, a grinding jig for properly positioning said blade proximate a grinding wheel comprising an elongated angle member, said angle member including a pair of identical rectangular legs, a flat rectangular projecting member transversely fixed to one leg of said angle member exterior to the angle between said legs, said projecting member adapted to slidably fit within said longitudinal slot whereby said blade is prevented from rotating relative to said projecting member, and locking means for selectively locking said plane blade relative to said angle member and projecting member, said locking means including a lock screw and a washer, aligned apertures in said projecting member and said angle member, said apertures adapted to accommodate said screw to carry said Washer bearingly against said blade for locking said blade relative to said le me ber a d prdesiine m References Cited'in the file of this patent UNITED STATES PATENTS 147,297 White Feb. 10, 1874 277,958 Strong et'al. May 22, 1883 470,196 Jacobson et al. Mar. 8, 1,892 2,060,927 Cristiani Nov. v17', .1936 2,362,711 Mo0re Nov. 14,1944 2,764,187 Zerm owski Sept. 25 195.6 FOREIGN PATENTS 21,355 .G eatBrit p on. 11. 1898- 695.333

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