Claims
- 1. An improved thread snips comprising:
- a first metal blade including: a first, front relatively pointed end; a second, generally rounded rear end; an inner facing side surface; an outer facing side surface; and first and second longitudinal edges extending between the first and second ends, with the first metal blade having a sharpened cutting edge that extends along a portion of its first longitudinal edge and rearwardly from its first end a first predetermined distance and also having a reduced thickness portion that has a different thickness, as measured from the inner facing side surface, with the reduced thickness portion extending between its first and second longitudinal edges and forwardly a second predetermined distance from its second end, facing the same direction as the inner facing side surface, having a predetermined shape, and having predetermined length and width dimensions;
- a second metal blade including: a first, front relatively pointed end; a second, generally rounded rear end; an inner facing side surface; an outer facing side surface; and first and second longitudinal edges extending between the first and second ends, with the second metal blade having a sharpened cutting edge that extends along a portion of its first longitudinal edge and rearwardly from its first end a first predetermined distance;
- a first plastic insert that has longitudinal edges, and that has an inner facing side surface and an oppositely facing side surface;
- means for securing the first plastic insert within the reduced thickness portion of the first metal blade so that the inner facing side surface of the first plastic insert faces in the same direction as and is generally a continuation of the inner facing side surface of the first metal blade;
- means for connecting the first and second metal blades together, between their ends, so that the metal blades are disposed side by side, with their respective inner facing side surfaces and their respective cutting edges being adjacent, so that the first and second ends of the first metal blade coincide with the first and second ends, respectively, of the second metal blade, so that the first and second metal blades may be moved, relative to each other, in planes generally parallel to their inner facing side surfaces and about an axis substantially perpendicular to their inner facing side surfaces whereby the cutting edges of the metal blades may cooperate together and provide a cutting action therebetween, with the axis being located between the ends of the first and second metal blades and between the longitudinal edges of the first and second metal blades;
- means for biasing the first and second metal blades apart in the planes generally parallel to their inner facing side surfaces; and
- means for limiting the angle, about the axis, through which the first and second metal blades may move, relative to each other, in the planes generally parallel to their inner facing side surfaces.
- 2. The improved thread snips of claim 1 wherein the second metal blade has a reduced thickness portion that has a different thickness, as measured from the inner facing side surface, that extends between its first and second longitudinal edges, that extends a third predetermined distance forwardly from its second end, that faces in the same direction as the inner facing side surface of the second metal blade, that has a predetermined shape, and that has predetermined length and width dimensions; which includes a second plastic insert that has longitudinal edges, and that has an inner facing side surface and an oppositely facing side surface; and which includes means for securing the second plastic insert within the reduced thickness portion of the second metal blade so that the inner facing side surface of the second plastic insert faces in the same direction as the inner facing side surface of the second metal blade, and so that the inner facing side surface of the first plastic insert faces and is adjacent to the inner facing side surface of the second plastic insert.
- 3. The improved thread snips of claim 2 wherein the thickness, as measured between the inner and opposite side surfaces, of at least one of the first and second plastic inserts is greater adjacent to the second ends of the metal blades than it is adjacent to the first end of its metal blade; and wherein this greater thickness tends to force the inner facing side surfaces of the second ends of the first and second metal blades apart and thereby provide improved cutting action.
- 4. The improved thread snips of claim 2 wherein the reduced thickness portions of the first and second metal blades have a reduced thicknesses, as measured between their respective inner and outer facing side surfaces; wherein the thickness, as measure between the inner and opposite facing side surfaces, of each of the first and second plastic inserts is greater adjacent to the second ends of the first and second metal blades than it is adjacent to the first ends of the first and second metal blades; wherein the greater thicknesses tend to force the inner facing side surfaces of the second ends of the first and second metal blades apart and thereby provide improved cutting action; wherein the first plastic insert has a shape congruent to the shape of the reduced thickness portion of the first metal blade and has length and width dimensions substantially identical with the length and width dimensions of the reduced thickness portion of the first metal blade; wherein the second plastic insert has a shape congruent to the shape of the reduced thickness portion of the second metal blade and has length and width dimensions substantially identical with the length and width dimensions of the reduced thickness portion of the second metal blade; and wherein the longitudinal edges of the first and second plastic inserts are generally aligned with portions of the longitudinal edges of the first and second metal blades, respectively, rearwardly of their cutting edges.
- 5. The improved thread snips of claim 3 wherein the inner facing side surface of at least one of the first and second plastic inserts is generally concave and defines a sector of an inner surface of a cylinder; and wherein the inner facing side surface of the one plastic insert provides a generally smooth continuation of the inner facing side surface of its metal blade.
- 6. The improved thread snips of claim 4 wherein the inner side surface of the first plastic insert is generally concave and defines a sector of an inner surface of a first cylinder; wherein the inner side surface of the second plastic insert is generally concave and defines a sector of an inner surface of a second cylinder; wherein the inner facing side surface of the first plastic insert provides a generally smooth continuation of the inner facing side surface of the first metal blade; and wherein the inner facing side surface of the second plastic insert provides a generally smooth continuation of the inner facing side surface of the second metal blade.
- 7. The improved thread snips of claim 6 wherein the first and second cylinders have the same radii; and wherein the second and third distances are substantially the same.
- 8. The improved thread snips of claim 4 wherein one of the first and second plastic inserts includes an integral portion that projects from one of the longitudinal edges of the one plastic insert and beyond the adjacent longitudinal edges of the first and second metal blades; and wherein the projecting integral portion includes a finger ring.
- 9. The improved thread snips of claim 4 wherein the biasing means includes a spring having first and second ends that are disposed in two generally parallel, spaced apart planes, and that are normally disposed at an angle with respect to each other; wherein a first pocket is formed in the first plastic insert, with the first pocket opening to the inner facing side surface of the first plastic insert and receiving the first end of the spring; and wherein a second pocket is formed in the second plastic insert, with the second pocket opening to the inner facing side surface of the second plastic insert and receiving the second end of the spring.
- 10. The improved thread snips of claim 9 wherein the first pocket is disposed adjacent to but at an angle with respect to a longitudinal edge of the first plastic insert; wherein the connecting means includes a shaft that extends through the first and second plastic inserts and into the first and second metal blades; and wherein a portion of the spring, between its first and second ends, is coiled about a portion of the shaft that extends through the first and second plastic inserts.
- 11. The improved thread snips of claim 4 wherein each of the first and second metal blades include a plurality of relatively small apertures communicating with the reduced thickness portion of the metal blade; wherein the first plastic insert is molded onto the reduced thickness portion of the first metal blade so that the plastic may flow into each aperture in the first metal blade and serve as the means for securing the first plastic insert in the reduced thickness portion of the first metal blade; and wherein the second plastic insert is molded onto the reduced thickness portion of the second metal blade so that the plastic may flow into each of the apertures in the second metal blade and serve as the means for securing the second plastic insert within the reduced thickness portion of the second metal blade.
- 12. The improved thread snips of claim 2 wherein the limiting means includes an elongated pocket in one of the first and second plastic inserts, with the elongated pocket opening to the inner facing side surface of the one plastic insert, and a projection extending from the inner facing side surface of the other of the plastic inserts and into the elongated pocket.
- 13. The improved thread snips of claim 6 wherein one of the first and second plastic inserts includes an integral portion that projects from one of the longitudinal edges of the one plastic insert and beyond the adjacent of the longitudinal edges of the first and second metal blades; wherein the projecting integral portion includes a finger ring; wherein the biasing means includes a spring having first and second ends that are disposed in two generally parallel, spaced apart planes, and that are normally disposed at an angle with respect to each other; wherein a first pocket is formed in the first plastic insert, with the first pocket opening to the inner facing side surface of the first plastic insert and receiving the first end of the spring; and wherein a second pocket is formed in the second plastic insert, with the second pocket opening to the inner facing side surface of the second plastic insert and receiving the second end of the spring.
- 14. The improved thread snips of claim 13 wherein each of the first and second metal blades include a plurality of relatively small apertures communicating with the reduced thickness portion of the metal blade; wherein the first plastic insert is molded onto the reduced thickness portion of the first metal blade so that the plastic may flow into each aperture in the first metal blade and serve as the means for securing the first plastic insert into the reduced thickness portion of the first metal blade; wherein the second plastic insert is molded onto the reduced thickness portion of the second metal blade so that the plastic may flow into each of the apertures in the second metal blade and serve as the means for securing the second plastic insert within the reduced thickness portion of the second metal blade; and wherein the limiting means includes an elongated pocket in one of the first and second plastic inserts, with the elongated pocket opening to the inner facing side surface of the one plastic insert and a projection extending from the inner facing side surface of the other of the plastic insert and into the elongated pocket.
- 15. The improved thread snips of claim 14 wherein the first pocket is disposed adjacent to but at an angle with respect to a longitudinal edge of the first plastic insert; wherein the connecting means includes a shaft that extends through the first and second plastic inserts and into the first and second metal blades; and wherein a portion of the spring, between its first and second ends, is coiled about a portion of the shaft that extends through the first and second plastic inserts.
- 16. The improved thread snips of claim 15 wherein the first and second cylinders have the same radii; and wherein the second and third distances are substantially the same.
BACKGROUND OF THE INVENTION
This application is a continuation of application Ser. No. 07/293,991, filed Jan. 6, 1989, now abandoned.
The present invention relates to thread snips and, particularly, to high-quality thread snips of the type employed in the garment and dressmaking industries.
Thread snips are small, scissors-like cutting tools utilized by professional seamstresses, tailors, and other garment makers to cut threads and the like during the making of dresses and other garments. They generally comprise two substantially flat steel blades that are disposed side-by-side and that have cooperating, sharpened cutting edges adjacent to their front pointed ends. The blades are pivoted or hinged together about a transverse pivot shaft located adjacent their rear, rounded or blunted ends so that their front sharpened ends may be opened and closed. Examples of such thread snips are described in U.S. Pat. Nos. 3,453,731 and 3,608,196.
The manufacture of conventional, high-quality thread snips requires a number of expensive machining operations and extensive hand work, approximately a third of which can normally only be done by skilled, experienced artisans. The blades used in such high-quality thread snips are forged from stainless steel so as to form the conventional, integral finger ring and the pockets to receive the ends of the spring used to bias the metal blades apart, that is, to their open position. The metal blades must also be drilled to receive the pivot shaft that serves to connect the blades together. The side of one of the blades has to be tapped and threaded to receive a stop screw. That screw projects from the side of the blade and into an elongated, aligned slot that is milled into the inner facing side of the other blade. The stop screw and slot cooperate to limit the degree of opening and closing of the blades. The metal blades must be finished or polished and have cutting edges honed along the forward portions of their front pointed ends.
An important part of the "art" of making high-quality thread snips, like the making of high-quality scissors, is in the shaping and bending of the stainless steel blades so that their cutting edges will cross or contact each other at a point and so that this crossing and contacting point will move forward, along the cutting edges, as the blades are closed during a cut. How skillfully the blades are bent or arched, and how this bend or arch comes out during cutting, determines the quality of the "feel" of the cutting action of the thread snips, as well as how long the cutting edges will retain their sharpness. If the blades are not bent properly, the blades will pass, side-by-side, like a guillotine. Rather than cut materials, particularly heavy materials, the blades will then just fold the material over, that is, the material will force the blades apart so that it just passes between them. If the blades are bent too much, the "feel" will be heavy or hard and thus be unacceptable to a seamstress or similar professional tradesperson who must use the thread snips throughout his or her work day. Additionally, the cutting edges will become dull relatively rapidly. This is a serious economic drawback since thread snips are usually discarded, rather than resharpened, after they have become dull.
In an effort to maintain a consistently acceptable "feel," some high-quality thread snips, such as those sold under the CUTRITE trademark by John A. Eberly, Inc. of Syracuse, N.Y., partially affect the bending of the blades by biasing them apart at a point to the rear of the blade pivot shaft. More specifically, these thread snips employ a small, coil compression spring biased ball that urges the rear ends of the blades apart. This serves to bend or arch the blades. Adding this feature obviously increases the cost of manufacturing, but it does provide a more uniform "feel" and cutting action that could otherwise only be consistently achieved through the expenditure of a commercially unacceptable amount of time by skilled craftsmen.
In an apparent attempt to reduce manufacturing costs, others have made thread snips with molded, plastic blades. Metal knife sections are attached or secured to the fronts of the plastic blades and serve as the sharpened, pointed ends of the snips, as well as providing the cutting edges necessary for the thread snips. Examples of such plastic thread snips are described in U.S. Pat. Nos. 3,453,651, 3,524,363, and 4,089,113.
One of the serious drawbacks with such plastic thread snips is that the plastic blades have to be relatively large and bulky in order to have sufficient strength to provide even a reasonably good cutting action. This larger size and bulk is perceived as a significant disadvantage by people, principally women, whose jobs require them to use a thread snip all or most of their working day.
A primary object of the present invention is to provide an improved thread snips that have the same superior feel, cutting ability, and workmanship as the prior conventional, high-quality stainless steel thread snips but that can be manufactured for a fraction of the cost of the conventional thread snips. A related object of the present invention is to provide an improved lighter weight thread snips, as described, that will have a consistently appropriate blade bend or arch, thread snip after thread snip, without the need to employ a spring biased ball to urge the rear ends of the blades apart or to have a skilled artisan spend inordinate amounts of time carefully bending or shaping the blades. Still another object of the present invention is to provide an improved thread snips, as described, where a craftsman is not required to forge the metal blades to form the finger ring and spring pockets or to tap, thread and mill the metal blades to fashion the cooperating stop screw and slot used to limit the relative movement between the blades.
These objects and advantages of the present invention are achieved by making the stainless steel thread snip blades so that their inner facing side portions, adjacent to the rear ends of the metal blades, have a reduced thickness, as measured between their inner and outer facing side surfaces. Plastic inserts are then molded onto those reduced thickness portions of the metal blades so that when the thread snips are assembled, the inner facing sides of these plastic inserts face each other. These plastic inserts have the same general shape and dimensions as the reduced thickness portions of the metal blades. Their inner facing side surfaces define a generally smooth continuation of the inner facing side surfaces of the metal blades.
The plastic inserts are, however, made thicker adjacent to the rear ends of the metal blades than they are adjacent to the front ends of the blades. The additional "rear" thicknesses urge or force apart the rear ends of the metal blades, that is, the portions of the blades to the rear of the pivot shaft. By selection of the predetermined rear thicknesses, the metal blades will be appropriately bent or arched so as to achieve the desired "feel" and cutting action without the need for any significant additional labor by experienced, skilled artisans.
A finger ring is molded as an integral part of one of the plastic inserts. Spring pockets are also molded into the plastic inserts. The metal blades can thus be stamped instead of forged. This and the avoidance of having to machine and finish the finger ring and spring pockets significantly reduces the cost of manufacturing the blades. Similarly, the slot used to limit the relative opening movement of the metal blades can be molded in one of the plastic inserts, and if desired, a cooperating projection, can be molded on the other plastic insert, and may be used instead of the stop screw. The employment of the plastic inserts significantly reduce costs since they eliminate manufacturing operations. They also reduce the overall weight of the snips.
Preliminary comparative evaluations of the manufacturing costs of the improved thread snips of the present invention, vis-a-vis the prior high-quality, all-stainless steel thread snips, discloses a cost savings of as much as fifty percent. Notwithstanding this significant reduction in manufacturing costs, the improved thread snips of the present invention provides the same high-quality, long-lasting cutting action and feel as those prior more expensive, high-quality thread snips, while being considerable lighter in weight. This latter advantage is significant to a person, such as a woman, who must use the snips through the entire workday.
Further, the improved thread snips can be attractively personalized by adding a colored dye or pigment to the plastic used for the plastic inserts. This is an important, marketing feature since the sales of thread snips tend to be made or directed by women customers/users.
In summary, the present invention provides improved thread snips having the same superior cutting action, and consistently proper feel heretofore found only in the highest quality all-metal thread snips while having a manufacturing cost that is but a fraction of that of these all-metal snips. This reduction of manufacturing costs does not, however, impose commercially unacceptable penalties, such as the increase in size and bulkiness found in plastic thread snips. In addition, the improved thread snips of the present invention are much lighter and ergonomically easier to use over the long periods of continuous, repetitive work performed by professional seamstresses, tailors, and other garment workers.
US Referenced Citations (14)
Continuations (1)
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Number |
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293991 |
Jan 1989 |
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Patent Grant
4924572
