US2160979A - Knife rest for sharpening knives - Google Patents

Description

June 6, 1939. M v MQELLER 2,160,979

KNIFE BEST FOR SHARPENING KNIVES Filed Dec. 30, 1935 Mueller, flee mi-2e); Qdhebn used,

ZhM W i/ WITNESSES; fiwm Patented June 6, 1939 UNITED STATES PATENT OFFICE KNIFE BEST FOR SHARPENING KNIVES Tempelhof, Germany Application December 30, 1935, Serial No. 56,744 In Denmark January 4, 1935 3 Claims.

This invention relates to a knife-rest, having a grinding face on which a knife can be ground for sharpening. The knife has to be uniformly held at a predetermined angle to the grinding face in order that the correct cutting angle is given to the cutting edge from both sides. It is, however, extremely difficult, to correctly and uniformly maintain this angle when the knife is held in the free hand, so that the knife is generally not only not sharpened correctly but scratched on its side faces, this being very inconvenient especially for chromed knives polished to brilliant polish.

These inconveniences are obviated, according to the invention, when grinding knives or the like on the knife-rest, in that in front of the grinding face a guide groove for the knife back is arranged. Consequently it is not longer necessary to preserve the sharpening angle with the free hand, as, by insertion of the knife back into the guide groove'the correct angle for the sharpening is automatically adjusted and uniformly preserved, so that any unskilled person can accurately grind a knife on the knife rest. Scratching of the side faces of the knife is also excluded. The sharpening is automatically effected only at the cutting edge so that the chrome side faces of a knife are not injured by the sharpening. The bottom of the guide groove or the side face of the guide groove facing the grinding face is preferably domed, for instance bulged outwards at the middle, in order that the knife back, even if it is curved, bears during the grinding, at one point and can be easier moved to and fro. The knife, when moving over the bulged portion, is further slightly lifted and lowered, so that it moves over several portions of the grinding face adjusted at the same height, and the grinding stone or the like wears more uniformly. The grinding face may consist for instance of grind stone or of a support of wood or other suitable material covered with carborundum or a similar substance. The grinding face may be, if desired, mounted so that it can rock about an axle, in order that it can be adjusted at difierent angles to thereby alter the grinding angle or to adapt the same to special conditions. In order that the grinding angle remains as uniformly as possible, the same for wide and for narrow knives, the grinding face may be bulged according to the radius of a circle or according to a certain curve, the curve of the logarithmic spiral being preferably employed. Two grinding faces, lying back to back may be preferably arranged mutually symmetrical, each one having a guide groove in front of it, whereby a knife rest is produced on which on the right hand side the one side face and on the left hand side the other side face of a knife can be sharpened. Or both grinding faces each with its guide groove are arranged symmetrically opposite, a free upwardly projecting rib being provided as separating partition. Grinding faces may further be arranged one at either side of a single guide groove. An especially simple arrangement is obtained if guide grooves are arranged, one at either side of a grinding face. The grinding faces may be removable in order that they can be interchanged or reversed or adjusted in the longitudinal and transverse directions. With this object in view a holding bar, or a bar adapted to be inserted either below or above the grinding stone is for instance provided, enabling especially adjusting in vertical direction. A holding face may be arranged at the side of the grinding face on one side or on both sides of the same, by means of which the knife-rest can be held in one hand or fixed on the table top by screws.

Several embodiments of the invention are illustrated by way of example in the accompanying drawing in which:

Fig. 1 shows in end view, partly in section a knife-rest with grinding face and. guide groove for the knife back in front of the grinding face.

Fig. 2 shows in end view partly in section a knife-rest, the grinding face of which is oscillatably mounted.

Fig. 3 shows in end view partly' in section a knife-rest having a concave grinding face and adapted to be combined with a second knife-rest as indicated in dash lines and in dot-dash lines respectively.

Fig. 4 is a section on line A-B of Fig. 3.

Fig. 5 shows in end View a knife-rest with two grinding faces and a common guide-groove between the grinding faces.

Fig. 6 shows in end View, partly in section a knife-rest with one grinding face and two guidegrooves, one on each longitudinal edge of the grinding face.

Fig. 7 shows in end view partly in section a knife rest with two grinding faces, one guide groove being arranged in front of each grinding face and a holding face on one side.

Fig. 8 shows in top plan View part of the knife rest shown in Fig. 7.

A knife-rest of simple form of construction consists of a vertical back wall I, recessed on the front side so that a box-shaped bed for a grind stone 2 is formed as shown in Fig. 1. The back wall I has at the top a top bar 6 and on the bottom a socle 3 with guide groove 5-. The socle 3 is fixed on a base plate 8 which is so long that it projects from the socle 3 at one side or at both sides and can be securely held with a hand or be fixed on a table top by screws.

The back wall i of the knife-rest shown in Fig. 2 is oscillatably mounted on a horizontal axle 5 so that, to alter the grinding angle, the a grinding surface can be adjusted at any desired angle.

In order to preserve the same grinding angle, independently on the width of the knife to be sharpened, the grinding face i (Fig. 3) is concave and curved according to a logarithmic spiral. In order that the knife back, even if it is curved, bears as far as the possible and is guided only at one point, the bottom 3 of the guide groove is domed, as shown in Figs. 3 and 4. Owing to the bulged surface of the bottom of the guide groove the knife is lowered and lifted during the grinding and the grinding face is. more uniformly worn. All the parts of the knife-rest shown in Fig. 3 may be repeated symmetrically to the line aa so that (as indicated in dash lines) the grinding face It, a guide groove ii and a socle 9 are added. In this instance a knife-rest is produced on which on the right the left side of the knife edge and on the left the right side of the knife edge can be sharpened. If, however, all parts of the knife rest shown in Fig. 3 are again repeated symmetrically to the dash-dot line b-b, a grinding face l3, guide groove Hi and socle l2 are added, and it is possible to sharpen with this device also both sides of a knife edge. In this instance, a guide rib 15 projects between the two guide grooves 3 and it.

As shown in Fig. 5 a single guide groove 15 can be substituted for the two guide grooves i and Hi. The bottom of guide groove l5 may be convexly curved, same as that of guide groove 4, so that the grind stones ll can be adjusted in vertical direction on this rest upon removable bars I8. If these bars I5 have been removed, the grid stones I! drop and the bars 58 can be inserted on top of the grind stones.

The knife rest shown in Fig. 6 has one grinding face 2| and two guide grooves l9, 2E! one at each side of the grinding face.

In the knife-rest shown in Fig. '7 the concave grind stones I8, having concave grinding faces 1, are mounted on a rest body pressed from a piece of artificial resin, for instance Bakelite, this body having two guide grooves 25. The grind stones Ill are securely held on the knife-rest by means of a top bar 23 removably fixed by a screw bolt 22. The knife-rest has at the righthand side an extension 25 adapted to serve as handle or to be fixed on a table top. As shown in Fig. 8 the side walls of grooves 26 may be convex in order that the knife back bears only at one point and the knife edge is slightly shifted in vertical direction during the sharpening.

V'Jhat is claimed is:

1. In a knife sharpener, an elongated block having a flat bottom adapted to be pressed and securely held on a support, a grind stone fixed on the front face of said block and having a concaved surface, an extension on the front side of said block having an elongated groove extending substantially parallel to the outer surface of said grind stone and adapted to hold the back of a knife to be sharpened, said surface of the grind stone adapted to guide at the correct grinding angle the cutting edge of the knife to be sharpened, a portion of the block carrying the grind stone being oscillatably mounted on a hori- Zontal axle to adjust the outer surface of the grind-stone at different angles to the guide groove to vary the adjustment of the grinding angle.

2. In a knife sharpener, an elongated block having a flat bottom adapted to be pressed and securely held on a support, a grind-stone fixed on the front face of said block and having a concaved surface, an extension on the front side of said block having an elongated groove extending substantially parallel to the outer surface of said grind-stone and adapted to hold the back of a knife to be sharpened, said surface of the grind-stone adapted to guide at the correct grinding angle the cutting edge of the knife to be sharpened, the outer surface of the grindstone being concaved perpendicularly to the direction of movement of the knife to be sharpened to maintain a constant grinding angle for knives of difierent widths.

3. In a knife sharpener, an elongated block having a fiat bottom adapted to be pressed and securely held on a support, a grind-stone fixed on the front face of said block and having a concave surface, an extension on the front side of said block having an elongated groove extending substantially parallel to the outer surface of said grind-stone and adapted to hold the back 7 of a knife to be sharpened, said surface of the grind-stone adapted to guide at the correct grinding angle the cutting edge of the knife to be sharpened, a shoulder on the block upon which the grind-stone is removably placed, and a removable top bar engageable with the grindstone for holding the same in position.

ELSE MOELLER, min KNUPFER, Legal Representative of Morten Vz'lhelm Moeller,

Deceased.

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