A handle is a part of, or attachment to, an object that can be moved or used by hand. The design of each type of handle involves substantial ergonomic issues where these are dealt with intuitively or by following tradition. Handles for tools are an important part of their function, enabling the user to exploit the tools to maximum effect. Package handles allow for convenient carrying of packages; the three nearly universal requirements of are: Sufficient strength to support the object, or to otherwise transmit the force involved in the task the handle serves. Sufficient length to permit the hand or hands gripping it to reliably exert that force. Sufficiently small circumference to permit the hand or hands to surround it far enough to grip it as solidly as needed to exert that force. Other requirements may apply to specific handles: A sheath or coating on the handle that provides friction against the hand, reducing the gripping force needed to achieve a reliable grip. Designs such as recessed car-door handles, reducing the chance of accidental operation, or the inconvenience of "snagging" the handle.
Sufficient circumference to safely over the hand. An example where this requirement is the sole purpose for a handle's existence is the handle that consists of two pieces: a hollow wooden cylinder about the diameter of a finger and a bit longer than one hand-width, a stiff wire that passes through the center of the cylinder, has two right angles, is shaped into a hook at each end; this handle permits comfortable carrying, with otherwise bare hands, of a heavy package, suspended on a tight string that passes around the top and bottom of it: the string is strong enough to support it, but the pressure the string would exert on fingers that grasped it directly would be unacceptable. Design to thwart unwanted access, for example, by thieves. In these cases many of the other requirements may have reduced importance. For example, a child-proof doorknob can be difficult for an adult to use. One major category of handles are pull handles, where one or more hands grip the handle or handles, exert force to shorten the distance between the hands and their corresponding shoulders.
The three criteria stated above are universal for pull handles. Many pull handles are for lifting on objects to be carried. Horizontal pull handles are widespread, including drawer pulls, handles on latchless doors and the outside of car doors; the inside controls for opening car doors from inside are pull handles, although their function of permitting the door to be pushed open is accomplished by an internal unlatching linkage. Pull handles are a frequent host of common door handle bacteria such as e-coli, fungal or other viral infections. Two kinds of pull handles may involve motion in addition to the hand-focused motions described: Pulling the starting cord on a small internal-combustion engine may, besides moving the hand toward the shoulder exploit pushing a wheeled vehicle away with the other hand, stepping away from the engine, and/or standing from a squat; some throwing motions, as in a track-and-field hammer throw, involve pulling on a handle against centrifugal force, in the course of accelerating the thrown object by forcing it into circular motion.
Another category of hand-operated device requires grasping and rotating the hand and either the lower arm or the whole arm, about their axis. When the grip required is a fist grip, as with a door handle that has an arm rather than a knob to twist, the term "handle" unambiguously applies. Another clear case is a rarer device seen on mechanically complicated doors like those of airliners, where the axis of rotation is between the thumb and the outermost fingers, so the thumb moves up if the outer fingers move down; the handles of bicycle grips, club-style weapons and spades, hammers and hatchets, baseball bats, golf clubs, croquet mallets involve a greater range of ergonomic issues
In knot tying, a bight is a curved section or slack part between the two ends of a rope, string, or yarn. A knot that can be tied using only the bight of a rope, without access to the ends, is described as in the bight; the term "bight" is used in a more specific way when describing Turk's head knots, indicating how many repetitions of braiding are made in the circuit of a given knot. Sources differ on; the Ashley Book of Knots treats bights and loops as distinct, stating that a curve "no narrower than a semicircle" is a bight, while an open loop is a curve "narrower than a bight but with separated ends". However, The Illustrated Encyclopedia of Knots states: "Any section of line, bent into a U-shape is a bight." In order to make a slipped knot, a bight must be passed, rather than the end. This slipped form of the knot is more untied; the traditional bow knot used for tying shoelaces is a reef knot with the final overhand knot made with two bights instead of the ends. A slippery hitch is a slipped clove hitch.
The phrase in the bight means. This means that the knot can be formed without access to the ends of the rope; this can be an important property for knots to be used in situations where the ends of the rope are inaccessible, such as forming a fixed loop in the middle of a long climbing rope. Many knots tied with an end have a form, tied in the bight. In other cases, a knot being tied in the bight is a matter of the method of tying rather than a difference in the completed form of the knot. For example, the clove hitch can be made "in the bight" if it is being slipped over the end of a post but not if being cast onto a closed ring, which requires access to an end of the rope. Other knots, such as the overhand knot, cannot be tied in the bight without changing their final form. Ashley, Clifford W.. The Ashley Book of Knots. New York: Doubleday, 1944. ISBN 9780385040259. Budworth, Geoffrey; the Illustrated Encyclopedia of Knots. ISBN 9781585746262
Triple fisherman's knot
The triple fisherman's knot is a bend knot, used to join two ends of rope together. It is an extension of the double fisherman's knot and is recommended for tying slippery, stiff ultra-high-molecular-weight polyethylene and aramid cored ropes. Tying the triple fisherman's knot is nearly identical to the double fisherman's, except for a third wrap before passing the end through each half of the knot. Testing has shown that a failure mode exists at high loads with the double fisherman's knot in ropes using Spectra and Technora cores; the sheath of the rope separates at the knot, the high-lubricity core slips through the double fisherman's knot. Although the increase in ultimate strength is small, the triple fisherman's knot does not exhibit this behavior; this has led to the recommendation to use the triple fisherman's knot to avoid this particular failure mechanism. The triple fisherman's knot should not be confused with the "triple-T fisherman's knot", more akin to a one-sided overhand bend and has different properties than the triple fisherman's knot.
List of bend knots List of knots
A blood knot is most usefully employed for joining sections of monofilament nylon line while maintaining a high portion of the line's inherent strength. Other knots used for this purpose can cause a substantial loss of strength. In fly fishing, this serves to build a leader of decreasing diameter with the castable fly line attached at the large diameter end and the fly or hook at the small diameter end; the principal drawback to the blood knot is the dexterity required to tie it. It is likely to jam, not a concern in fishing line, no great loss to cut, but may be a concern in normal rope. "Blood knot" may refer to, "a double overhand knot tied in a cat-o'-nine-tails." The barrel knot, called blood knot by Keith Rollo, is the best bend there is for small, stiff or slippery line. The ends may be trimmed short and the knot offers the least resistance possible when drawn through water. A half blood knot is a knot, used for securing a fishing line to a fishing lure, snap or swivel; when two half blood knots are used to join two lines they are considered as one knot and called a blood knot.
A half blood knot is one of the strongest knots for tying a medium-size hook to a medium-size line such as hooksize 4 to 4/0 onto line size 6 lb to 30 lb. In tying the blood knot, the two lines to be joined are overlapped for 6–8 cm with the short ends of the two lines in opposite directions; the short end of one line is wrapped 4–6 times around the second line and the remaining portion of the first short end brought back and passed between the lines at the beginning of the wraps. The short end of the second line is wrapped 4–6 times around the first line and the end of this line brought back and passed through what is now an oval space between the first wrap of each set; the above method has been called by Stanle Barnes "outcoil", is contrasted with the method that resembles the finished knot from the start, "incoil". The images here are incorrect to present the finished knot as having its free/"tag" ends go from the center of the knot to the extreme ends. In fishing line, in other material if not deliberately set snug and maybe re-set after some initial tensioning, the outcoil form will transform into the incoil form.
The lines are moistened and the wraps tightened by pulling on the long ends of the line. This causes the wraps to tighten and compress, creating two short sections of "barrel", which look much like a hangman's knot, that slide together; the short ends of the line are trimmed close to the wraps, or one of the ends may be left intact to be used for a second fly or lure, called a "dropper". List of bend knots List of knots Video instructions on how to tie a half blood knot Video instructions for tying a Blood Knot Grog. "Blood Knot". Animated Knots. Retrieved September 5, 2016
The surgeon's knot is a surgical knot and is a simple modification to the reef knot. It adds an extra twist when forming a double overhand knot; the additional turn provides more friction and can reduce loosening while the second half of the knot is tied. This knot is used by surgeons in situations where it is important to maintain tension on a suture, giving it its name. Surgeon's knots are used in fly fishing, in tying quilts, for tying knots with twine; some sources categorize the surgeon's knot as a bend. Like the reef knot, the surgeon's knot capsizes and fails if one of the working ends is pulled away from the standing end closest to it. List of bend knots List of binding knots List of knots Video instructions for tying a Surgeon's Knot used for wound closure Video instructions for tying a Surgeon's Knot for fishing knot use
The Ashley Book of Knots
The Ashley Book of Knots is an encyclopedia of knots written and illustrated by the American artist Clifford W. Ashley. First published in 1944, it was the culmination of over 11 years of work; the book contains 3854 numbered entries and an estimated 7000 illustrations. The entries include knot instructions and some histories, categorized by type or function, it remains one of the most comprehensive books on knots. Due to its scope and wide availability, The Ashley Book of Knots has become a significant reference work in the field of knotting; the numbers Ashley assigned to each knot can be used to unambiguously identify them. This helps to identify knots despite local colloquialisms or identification changes. Citations to Ashley numbers are in the form: "The Constrictor Knot", "ABOK #1249" or simply "#1249" if the context of the reference is clear or established; some knots have more than one Ashley number due to having multiple forms. For example, the main entry for #1249 is in the chapter on binding knots but it is listed as #176 in a chapter on occupational knot usage.
The Ashley Book of Knots was compiled and first published before the introduction of synthetic fiber ropes, during a time when natural fiber cordage - twisted, laid, or braided rope - was most used. The commentary on some knots may fail to address their behavior when tied with modern synthetic fiber or kernmantle style ropes. Ashley suffered a debilitating stroke the year, he was not able to oversee a corrected edition. Corrections submitted by the International Guild of Knot Tyers were incorporated in 1991; the original list of revisions submitted to the publisher is believed to have been lost, but many had been collected from a series of articles in Knotting Matters, the Guild's quarterly publication. Additional errors have been identified since the 1991 corrections. At least one knot, the Hunter's bend, was added in 1979. Clifford W. Ashley; the Ashley Book of Knots. Doubleday, New York 1944. ISBN 0-385-04025-3 Reprint: Doubleday, New York 1963–1979, ISBN 0-571-09659-X The Ashley Book of Knots on Internet Archive.
Thou Shalt Knot: Clifford W. Ashley. A New Bedford Whaling Museum exhibition
Offset overhand bend
The offset overhand bend is a knot used to join two ropes together. The offset overhand bend is formed by holding two rope ends next to each other and tying an overhand knot in them as if they were a single line. Due to its common use in several fields, this bend has become known by many names, such as thumb knot, openhand knot, one-sided overhand knot or flat overhand bend, though the terms "one-sided" and "flat" are considered incorrect. Long used by weavers to join the ends of yarn, the offset water knot is old, it was one of the knots identified among the possessions of Ötzi the Iceman, who dates from 3300 BC. The knot is tied in a slipped form by mechanical balers to bind straw and hay, but this bend is not practical to use as a binding knot when tied by hand. In rock climbing, the offset water knot is a favored knot for joining two ropes for a rappel longer than half the length of the ropes. There is controversy over its safety, as it can fail by capsizing under high loads, some American climbers refer to it as the European Death Knot, abbreviated to EDK.
Failure of this knot has been implicated in some near-misses. Many sources argue that this is misnomer, the knot is safe for abseiling/rappelling, since this doesn't generate such high forces, the knot, being on one side of the twin lines used in abseil, sees only half of this force, they believe that with proper attention given to dressing and cinching the knot, the risk of capsizing is unlikely. Several sources recommend adding a second overhand as close as possible to the first for most situations, which maintains most of the benefits of the single overhand, while preventing it from capsizing. Formed in most line, the offset overhand bend is jam resistant at nominal loads of one person; the jamming threshold is thought to be 3kN. The instability threshold is thought to be 5kN – that is, a capsizing event becomes probable as loads approach 500kg, it is critically important to pay close attention to dressing and cinching of the knot before attempting to abseil. That is, climbers must exercise due diligence when tying this knot – by pulling on each of the 4 rope segments –, necessary to achieve a properly compacted and cinched dressing state.
There is no room for carelessness. Despite questions about this knot's security, it does present some advantages for use in rappels; because the knot is offset from the axis of tension, it can translate more over rough surfaces and 90 degree edges than other knots. Since a stuck rope on a descent represents a serious hazard to climbers, these advantages, along with ease of tying, have led to its popularity, it is recommended by some sources with the caveats that the tails be of sufficient minimum length, the knot be diligently dressed and tightened by pulling individually on all four rope segments, subjected only to moderate rappelling loads. Furthermore, # 1410 can be rotated to crush the tails. All testers appear to only examine this knot in its mid-rotation state, it is theorized that this mid-rotation state is in fact the orientation where the structure is most vulnerable to capsizing. A new round of testing is long overdue to investigate the potential benefits of rotating the structure to induce a choking effect.
In addition, when tying the offset overhand bend using different rope diameters, the thinner diameter rope must be positioned underneath the larger diameter rope. This tactic further inhibits any likelihood of capsizing; the Offset figure-eight bend, a similar knot using the figure-eight knot, has been used in the belief that its greater size and complexity brings more security. But testing and more than one fatal failure indicate the figure-eight variant to be less secure, more prone to capsize at lower loads, in capsizing uses more of the ends than does a capsizing overhand bend. Moreover, while there is one obvious proper dressing of the Overhand Bend, there are a couple of dressings for the Offset Figure Eight Bend. List of bend knots List of knots