Claims
- 1. A method of cutting vegetation using a powered head rotatable about an axis of rotation, and at least one string of primarily non-metallic material having a first long axis and a second short axis, with the second axis less than 85% of the first axis, the string having at least one free end and at least one substantially permanent twist remote from the free end and adjacent a living hinge; said method comprising the steps of:
(a) mounting the string in the head at a first portion of the string so that the string extends radially outwardly from the head with the at least one free end remote from the head and a portion of the string on the opposite side from the free end as the twist operatively engaging the head, while orienting the string so that the first axis is substantially perpendicular to the axis of rotation; and (b) powering the head about the axis of rotation so that the first axis is substantially maintained in a cutting plane substantially perpendicular to the axis of rotation, the twist providing pitch control and the living hinge allowing deflection of the string when impacting an object substantially incapable of being cut.
- 2. A method as recited in claim 1 wherein the head includes a groove or slot having a receiving dimension about at least as large as said second axis but not as large as said first axis; and wherein step (a) is practiced so that the second axis of the string portion opposite the twist from the free end is received by the groove or slot.
- 3. A method as recited in claim 1 wherein the string had two twists therein, with a portion of the string between the twists; and wherein step (a) is practiced to mount the portion of the string between the twists to the head.
- 4. A method as recited in claim 3 wherein the head is configured and step (a) is practiced so that the free ends of the string are about 90 degrees apart during the practice of step (b).
- 5. A method as recited in claim 3 wherein the head is configured and step (a) is practiced so that the free ends of the string are about 180 degrees apart during the practice of step (b).
- 6. A method as recited in claim 3 wherein step (a) is practiced by clamping the string to the head.
- 7. A method as recited in claim 2 wherein the groove or slot is non-linear, and step (a) is practiced by mounting the string so that it extends in the non-linear groove or slot.
- 8. A method as recited in claim 1 wherein step (b) is practiced so that the free end of the string moves at a tangential velocity at least 5% lower than the tangential velocity of the free end of a conventional round cross-section nylon string powered by the head, with the same or enhanced cutting action.
- 9. A method as recited in claim 1 wherein step (b) is practiced by powering the head at a speed of about 2500-7500 rpm.
- 10. A method as recited in claim 9 wherein steps (a) and (b) are further practiced so that the swath width during cutting is between about 15-17 inches.
- 11. A string, primarily of non-metallic material, for a vegetation cutter, said string having:
a first long axis and a second short axis, with said second axis less than 85% of said first axis; a length of between about 5-25 inches; a first free end; a second end, and a permanent living hinge and twist between said first and second ends.
- 12. A string as recited in claim 11 wherein said twist is between about 30-150 degrees so that said first axis on one side of said twist makes an angle with respect to said first axis on the other side of said twist of between about 30-150 degrees.
- 13. A string as recited in claim 12 made substantially of non-metallic material.
- 14. A string as recited in claim 12 wherein said twist is about 90 degrees.
- 15. A string as recited in claim 12 wherein said second end is a free end, and further comprising a second twist between said first and second ends, and a central portion between said first and second twists.
- 16. A string as recited in claim 15 wherein said central portion is non-linear.
- 17. A string as recited in claim 11 wherein said string has a substantially elliptical cross section, and said first axis is between 1.25-8 times as long as said second axis.
- 18. A string as recited in claim 11 wherein said string has a non-symmetrical cross section.
- 19. A string as recited in claim 18 wherein said string has a substantially tear drop cross section.
- 20. A string as recited in claim 11 in combination with a head of a vegetation cutter, said head rotatable about an axis, and having a mechanism which holds said string to said head on the opposite side of said twist from said free end of said string so that said free end is remote from said head, and so that said first axis of said string between said free end and said twist is substantially perpendicular to said axis of rotation.
- 21. A string as recited in claim 15 in combination with a head of a vegetation cutter, said head rotatable about an axis, and having a mechanism which holds said string to said head at said central portion of said string so that said free ends are remote from said head, and so that said first axis of said string between each free end and a twist is substantially perpendicular to said axis of rotation.
- 22. A string as recited in claim 21 wherein said first and second free ends are approximately 90 degrees spaced apart during rotation of said head.
- 23. A string as recited in claim 21 wherein said string is held to said head by a slot or groove in said head having a string-receiving opening with a width substantially the same as or greater than said second axis but less than said first axis.
- 24. A string as recited in claim 21 wherein said first and second free ends are approximately 180 degrees spaced apart during rotation of said head.
- 25. A vegetation cutter comprising:
a head, handle, and motor; a substantially non-metallic cutting string having at least a first free end, the capability of a drag coefficient of less than 0.8, a living hinge, a twist, and a mounting portion opposite said free end from said twist; and said cutting string mounting portion mounting said cutting string to said head so that said first free end is remote from said head and said cutting string has a drag coefficient of less than 0.8 when rotated by said head.
- 26. A vegetation cutter as recited in claim 25 wherein said cutting string is in a cartridge; and wherein said head mounts said cartridge so that it is reversible.
- 27. A method of making string for a vegetation cutter comprising:
(a) heating a section of a primarily non-metallic material string to at least its softening point; (b) twisting portions of the string on opposite sides of the heated section of (a) with respect to each other to introduce a twist into the string; and (c) cooling the string heated section to well below the softening point thereof while the twist is held therein so that the twist becomes permanently fixed in the string.
- 28. A method as recited in claim 27 wherein (a)-(c) are practiced with string non-round in cross section and (b) and (c) are practiced to produce a twist of between 30-150°; and further comprising (d) using the string in a vegetation cutter.
- 29. A method as recited in claim 28 wherein (d) is practiced by rotating the string at a slower speed than when using round, untwisted, string with a vegetation cutter of the same size and type.
- 30. A string, vegetation cutter, and methods of manufacture and use thereof, substantially as shown and described.
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This is a utility application based upon U.S. provisional applications serial no. 60/074,899 filed Feb. 17, 1998, and serial no. 60/103,549 filed Oct. 8, 1998.
Provisional Applications (1)
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Number |
Date |
Country |
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60074899 |
Feb 1998 |
US |