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engineering

Loom

Loom is a engineering topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Loom rather than just read about it. In short: A loom is a device used to weave cloth and tapestry. The basic purpose of any loom is to hold the warp threads under tension to facilitate the interweaving of the weft threads.

Loom — main illustration
Loom — illustration

Key takeaways

  • Loom belongs to engineering; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Loom to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Loom from memory before moving on to harder problems.

Reference excerpt

A loom is a device used to weave cloth and tapestry. The basic purpose of any loom is to hold the warp threads under tension to facilitate the interweaving of the weft threads. The precise shape of the loom and its mechanics may vary, but the basic function is the same.

Etymology and usage The word "loom" derives from the Old English geloma, formed from ge- (perfective prefix) and loma, a root of unknown origin; the whole word geloma meant a utensil, tool, or machine of any kind. In 1404 "lome" was used to mean a machine to enable weaving thread into cloth. By 1838 "loom" had gained the additional meaning of a machine for interlacing thread.

Components and actions

Basic structure

Weaving is done on two sets of threads or yarns, which cross one another. The warp threads are the ones stretched on the loom (from the Proto-Indo-European *werp, "to bend"). Each thread of the weft (i.e. "that which is woven") is inserted so that it passes over and under the warp threads. The ends of the warp threads are usually fastened to beams. One end is fastened to one beam, the other end to a second beam, so that the warp threads all lie parallel and are all the same length. The beams are held apart to keep the warp threads taut. The textile is woven starting at one end of the warp threads, and progressing towards the other end. The beam on the finished-fabric end is called the cloth beam. The other beam is called the warp beam. Beams may be used as rollers to allow the weaver to weave a piece of cloth longer than the loom. As the cloth is woven, the warp threads are gradually unrolled from the warp beam, and the woven portion of the cloth is rolled up onto the cloth beam (which is also called the takeup roll). The portion of the fabric that has already been formed but not yet rolled up on the takeup roll is called the fell. Not all looms have two beams. For instance, warp-weighted looms have only one beam; the warp yarns hang from this beam. The bottom ends of the warp yarns are tied to dangling loom weights.

Motions

A loom has to perform three principal motions: shedding, picking, and battening.

Shedding. Shedding is pulling part of the warp threads aside to form a shed (the space between the raised and unraised warp yarns). The shed is the space through which the filling yarn, carried by the shuttle, can be inserted, forming the weft. Sheds may be simple: for instance, lifting all the odd threads and all the even threads alternately produces a tabby weave (the two sheds are called the shed and countershed). More intricate shedding sequences can produce more complex weaves, such as twill. Picking. A single crossing of the weft thread from one side of the loom to the other, through the shed, is known as a pick. Picking is passing the weft through the shed. A new shed is then formed before a new pick is inserted. Conventional shuttle looms can operate at speeds of about 150 to 160 picks per minute. Battening. After the pick, the new pass of weft thread has to be tamped up against the fell, to avoid making a fabric with large, irregular gaps between the weft threads. This compression of the weft threads is called battening. There are also usually two secondary motions, because the newly constructed fabric must be wound onto cloth beam. This process is called taking up. At the same time, the warp yarns must be let off or released from the warp beam, unwinding from it. To become fully automatic, a loom needs a tertiary motion, the filling stop motion. This will brake the loom if the weft thread breaks. An automatic loom requires 0.125 hp to 0.5 hp to operate (100W to 400W).

Components A loom, then, usually needs two beams, and some way to hold them apart. It generally has additional components to make shedding, picking, and battening faster and easier. There are also often components to help take up the fell. The nature of the loom frame and the shedding, picking, and battening devices vary. Looms come in a wide variety of types, many of them specialized for specific types of weaving. They are also specialized for the lifestyle of the weaver. For instance, nomadic weavers tend to use lighter, more portable looms, while weavers living in cramped city dwellings are more likely to use a tall upright loom, or a loom that folds into a narrow space when not in use.

Shedding methods

It is possible to weave by manually threading the weft over and under the warp threads, but this is slow. Some tapestry techniques use manual shedding. Pin looms and peg looms also generally have no shedding devices. Pile carpets generally do not use shedding for the pile, because each pile thread is individually knotted onto the warps, but there may be shedding for the weft holding the carpet together. Usually weaving uses shedding devices. These devices pull some of the warp threads to each side, so that a shed is formed between them, and the weft is passed through the shed. There are a variety of methods for forming the shed. At least two sheds must be formed, the shed and the countershed. Two sheds is enough for tabby weave; more complex weaves, such as twill weaves, satin weaves, diaper weaves, and figured (picture-forming) weaves, require more sheds.

Heddle-bar and shed-rod

Heddle-rods and shedding-sticks are not the fastest way to weave, but they are very simple to make, needing only sticks and yarn. They are often used on vertical and backstrap looms. They allow the creation of elaborate supplementary-weft brocades. They are also used on modern tapestry looms; the frequent changing of weft colour in tapestry makes weaving tapestry slow, so using faster, more complex shedding systems isn't worthwhile. The same is true of looms for handmade knotted-pile carpet; hand-knotting each pile thread to the warp takes far more time than weaving a couple of weft threads to hold the pile in place. At its simplest, a heddle-bar is simply a stick placed across the warp and tied to individual warp threads. It is not tied to all of the warp threads; for a plain tabby weave, it is tied to every other thread. The little loops of string used to tie the wraps to the heddle bar are called heddles or leashes. When the heddle-bar is pulled perpendicular to the warp, it pulls the warp threads it is tied to out of position, creating a shed.

… excerpt ends here. Continue reading the full article.

Illustrations

Loom: Wooden loom in Lesbos, Greece.
Wooden loom in Lesbos, Greece.
Loom: A treadle-driven Hattersley & Sons Domestic Loom, built under licence in 1893, in Keighley, Yorkshire. This loom has a flying shuttle and automatically rolls up the woven cloth; it is not just controlled but powered by the pedals.
A treadle-driven Hattersley & Sons Domestic Loom, built under licence in 1893, in Keighley, Yorkshire. This loom has a flying shuttle and automatically rolls up the woven cloth; it is not just controlled but powered by the pedals.
Loom: A simple treadle floor loom. Mouse over components for pop-up links. The warp runs horizontally. On the left the warp beam, held from turning by with a weighted trough to keep the warp taut; on the right, the cloth beam (also called a breast beam on this type of loom), with a pawl and ratchet to allow the weaver to roll up the fell. In the center, devices for performing the motions of weaving.
A simple treadle floor loom. Mouse over components for pop-up links. The warp runs horizontally. On the left the warp beam, held from turning by with a weighted trough to keep the warp taut; on the right, the cloth beam (also called a breast beam on this type of loom), with a pawl and ratchet to allow the weaver to roll up the fell. In the center, devices for performing the motions of weaving.
Loom: A simple handheld frame loom
A simple handheld frame loom
Loom: Passing the shuttle through the shed
Passing the shuttle through the shed

Worked examples

Example 1 — a first encounter with Loom

Start with the simplest possible case. Write down what Loom claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Loom before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Loom ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Loom

In research
Loom appears in engineering research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Loom in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Loom is common in secondary-school and first-year university syllabi. It links to neighbouring topics Culture of the Han dynasty, Egyptian inventions, Machines, so understanding it makes those chapters shorter.
In everyday life
Look for Loom outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Loom in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Loom means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Loom out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Loom in simple terms?

A loom is a device used to weave cloth and tapestry. The basic purpose of any loom is to hold the warp threads under tension to facilitate the interweaving of the weft threads.

Why does Loom matter?

Because it connects several engineering ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Loom?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Loom.

Tags

  • Culture of the Han dynasty
  • Egyptian inventions
  • Machines
  • Textile engineering
  • Textile industry
  • Weaving equipment

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