US2968057A - Adjustable contour knife - Google Patents

Description

Jan. 17, 1961 w. J. PRATT 2,968,057

ADJUSTABLE CONTOUR KNIF E Filed Nov. 13, 1958 INVENTOR.

WILLIAM J. PRATT ADJUSTABLE CONTOUR KNIFE William J. Pratt, North Bellmore, N.Y., assignor of one-half to James P. Malone, Mineola, NY.

' Filed Nov. 13, 1958, Ser. No. 773,758

1 Claim. (Cl. 15-236) This invention relates to means for spreading plastic material smoothly over a curved surface, and more particularly to a flexible knife spreader having an adjustable curvature.

Spreader knives such as putty knives are used for spreading and smoothing plastic materials over a work surface. Spreaders which utilize the knife edge for smoothing are called knives and those which use the flat portion are called trowels. The common putty knife is not suitable for working on curved surfaces since it has a straight edge. Typical curved surfaces are the body surfaces of automobiles. Dents and holes in these surfaces are generally repaired by applying a quick hardening plastic and smoothing, sanding, and painting. Commercially available plastics are used which when mixed with a solvent can be applied and then harden quickly in about 4 or 5 minutes so that it may be filed or sanded at the end of that time. It is, therefore, important that the plastic material be quickly and accurately applied while the material is still workable. Straight edge knives such as putty knives are not too adaptable for curved surfaces since many strokes have to be made and the result is still a series of straight surfaces rather than a curve.

The present invention solves this difiiculty by providing a spreader knife having a screw adjustment clamp connected to its sides which is adapted to impart a curvature to the knife which will match the curved surface being worked. The present invention provides a flat flexible member, for instance, of steel having a first straight end,

a smaller end, and two tapering sides connecting the ends.

The smaller end may be provided with a plastic or rubber holding strip so that it may be conveniently held in the hand without contacting any edge of the blade. An adjustable clamp is connected to each side of the flexible member near the holding end and the clamp is provided with a wing nut so that a proper curvature may be given to the knife. The clamping screw is mounted close to the surface of the member so as to provide the minimum obstruction. The. present invention may be called a contour knife as it is adapted to match the contour of the surface being worked.

Accordingly, a principal object of the invention is to provide a new and improved spreader knife.

Another object of the invention is to provide a new and improved spreader knife having an adjustable curvature.

Another object of the invention is to provide a new and improved contour knife.

Another object of the invention is to provide a new and improved adjustable curvature contour knife.

Another object of the invention is to provide a new and improved spreader knife comprising a flat flexible member and adjustable clamping means connecting the sides thereof and operable to impart adjustable curvature to match the contour of the surface being worked.

These and other objects of the invention will become 2,968,057 Patented Jan. 17,- 1961 apparent from the following specification and drawings, of which;

Figure 1 is a perspective view of an embodiment of the invention.

Figure 2 is a sectional view along the line 2-2 of Figure 1, and

Figure 3 is a diagram illustrative of the operation of the invention.

Referring to the figures the invention comprises a flat flexible member 1 which is preferably of a good grade of steel. It has a straight edge 2 at one end, the other end 3 being smaller and preferably curved to provide a convenient hand hold. The sides 4 and 5 of the member 1 are smoothly tapering except that they may have notches 4' and 5 to accommodate the adjustable clamping member.

The adjustable clamping member comprises a threaded stud or bolt 10 having a wing nut 11 connected at one end and a notched hook portion 12 at the other end. The stud 10 is connected to the member 1 by means of a tubular ferrule 14 having notch 14' and the notch in hook 12 adapted to fit the side edges of the flexible member.

The clamping means is assembled by passing the bolt 10 through the notched ferrule, mounting the notches in book and ferrule against the side edges of the member 1 and then tightening the bolts in the nut 12 so as to impart a curvature to the member 1 as illustrated by the curved edge 2 of Figure 2. The curvature is along an axis perpendicular to the bolt 10. The member 1 is preferably made of a good grade of steel so that it has a spring action which securely holds the clamping member in place. Other means of mounting the clamping member may be provided, for instance, by welding or otherwise connecting one or more ferrules onto the member 1 or by cutting the member 1 in a pattern having mounting ears for accommodating the clamp. However, applicant has found that the present method of mounting the notched ferrule and hook is adequate and eliminates the possibility of breaking the welded connections or the mounted ears. A washer 15 is preferably placed between the ferrule 14 and the wing nut 11. Figure 3 shows the use one typical curved surface of an automobile fender 20.

The contour knife preferably has a cylindrical rubber or plastic lip 16 mounted on the holding end to facilitate holding in the hand. The knife is held by placing the curved end 3 in the palm of the hand with the thumb on one side and the other four fingers on the other side. The thumb may be braced against the clamp bolt 10 if desired. The clamping means does not provide a perfect curve along the full extent of the edge 2 as the outer sides tend to flatten off. However, the whole area is generally not used and, if necessary, a larger size knife may be used for a larger size curved surface.

The flexible member of the present invention may be adjusted to an infinite variety of curves going from a completely flat surface to a horseshoe shaped surface. For the high degrees of curvature the ferrule type mounting shown is preferable to a mounting welded or otherwise fixed to the knife since the member 1 may move within the notches of the ferrules without straining any fixed connections such as welded connections.

The ferrule type mounting has been chosen since it holds the bolt as close as possible to the surface and there are no projecting knobs to limit the angle at which the knife is held to the work surface.

The present type mounting of the adjustment means also permits reversing the mounting means to the other side of the member 1 in order to straighten it out if the member 1 should take a permanent set.

The present invention may also be used for cutting 3 i knives for making curved cuts in materials such as sheet rubber. In this embodiment the edge 2 of the spreader would be sharpened to provide a cutting edge.

The present invention has been illustrated in connection with auto body repair work but is not limited to such use and may be used Wherever it is desired tos rn ooth a plastic material along a curved surface. For instance, it could be used in plastering curved walls, repairing statues or other objects having curved surfaces.

I claim:

A contour knife comprising a flat flexible member having a first straight end, a second smaller end, and two tapering sides connecting said ends, means to curve said References Cited in the file of this patent UNITED STATES PATENTS 1,167,797 Clawson Jan. 11, 1916 1,264,350 Unsinger Apr. 30, 1918 2,756,499 Liesunaitis July 31, 1956

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