sett for overshot quotation

I was recently weaving an overshot pattern that used 10/2 cotton for the warp/ground weft and 5/2 cotton for the pattern weft. I also have a few cones of 3/2 cotton, but I didn’t know if they’d be too big compared with the 10/2. I have a large collection of 8/2 yarn as well, would the 5/2 yarn be better suited as a pattern weft for a project that uses 8/2 for the warp/ground instead? Are there any guidelines about what size yarns work best as the pattern weft for overshot versus the warp/ground weft?

Too many variables (the yarns, the specific overshot draft, and the desired hand of the fabric) are involved to give a single rule of thumb for pattern-weft size vs ground warp and weft size in overshot. Probably the most common yarns/setts for contemporary overshot fabrics are 10/2 cotton for warp and tabby weft at 24 epi and either 5/2 pearl cotton or 3/2 pearl cotton for the pattern weft. The fabrics woven with these yarns/setts are usually sturdy fabrics in a weight suitable for placemats and towels. 3/2 pearl cotton would also work (and not be too heavy) for the draft you’re using with 5/2 cotton, unless the pattern-weft floats are very short (this would be for a delicate design, usually looking very twill-like). In that case, the 3/2 pearl cotton weft would not pack in well enough and you’d see streaks of the tabby weft between pattern picks. By the same token, if your overshot design has long pattern-weft floats with large blocks of pattern, a 5/2 pearl cotton pattern weft is likely to be too thin to cover the blocks; in that case, you’d also see streaks of the tabby weft between pattern picks.

Wool pattern wefts have the capacity to full to cover the blocks with wet-finishing, so their size can vary depending on the nature of the wool. With 10/2 pearl cotton warp and tabby weft, I like using Harrisville Shetland (its heathered colors add to the effectiveness of an overshot design) or other 8/2 wools. These fabrics (cotton ground cloth, wool pattern weft) are also usually sturdy, with a hand similar to colonial coverlets. If a soft fabric is desired, as for a shawl or scarf, wool, wool/silk, or silk would be good choices for warp and tabby weft. For a soft overshot fabric in all wool, the sett should be as for plain weave, but open enough that the wool threads have room to swell with fulling. For a wool pattern weft to show well on a wool ground cloth, it should be two to three times as heavy as the ground warp and weft. I’d follow that principle for silk, too: Sett the warp as for plain weave and choose a weft two to three times as heavy as the the ground yarns.

8/2 cotton is usually sett at 20 ends per inch for plain weave. 3/2 pearl cotton would be a good size for the patten weft, but it is mercerized whereas the 8/2 cotton is not. The contrast between the sheen of the pearl cotton and the matte finish of the 8/2 cotton might work well, or might not. You’d have to sample to see. Another option is to use the 8/2 cotton doubled for a pattern weft.

Although I know that traditionally overshot was used for coverlets, I have an idea for a shawl. I"m willing to sample, but I"m not sure where to start. I would like to weave it using 18/2 wool/silk as warp and tabby weft. Can I use that yarn doubled for my pattern weft? Normally with this yarn, I use a sett of 24 or 26 ends per inch for plain weave. If I use 24 epi, will I be in the ballpark to weave a lovely drapey shawl? I don"t want it to be too stiff so perhaps I should start with a looser sett?

Overshot drafts presume a 50/50 plain-weave ground cloth. Since the tabby weft creates that cloth and alternates with a pattern weft, if you sett your 18/2 wool/silk at 24 ends per inch and follow an overshot treadling draft from a specific source, the picks per inch should be double the number of warp threads per inch (I.e., 48) to produce the intended results. (Treadling drafts usually give the number of pattern picks that create square motifs--as wide as they are tall--if the weft sett is twice as many picks per inch as warp threads per inch.)

Most traditional overshot fabrics, as you say, are firmly woven utility fabrics, such as bedspreads or table runners, and you want something soft and drapable. A check of the

Be sure to put on extra warp for sampling to see what number of picks works well to create symmetrical motifs (and wash the sample to check the size and look of the finished motifs). I would sample on the complete threading (warping the loom at 20 ends per inch). If the washed sample proves too loose in both warp and weft directions, I’d then re-sley to 24 ends per inch. The shawl would then be slightly narrower, but it is always better to sample on the actual width of an intended piece to accurately judge the result.

I LOVE double-bobbin boat shuttles when I’m doubling the weft. You have to get used to “throwing” the shuttle when you use it; it only works if the unwinding bobbin jerks on both weft threads enough to turn them both smoothly at the selvedges. Doubling the weft on a single bobbin always requires adjusting the two lengths at the selvedge unless you ply them on a spinning wheel first. (I like them not plied better, anyway, for covering the blocks. They will tend to lie side by side like a ribbon.)

This post may help explain how my needle pillow cloth was woven. These pieces were made on the same warp. I had made a dozen or so pillow fronts and backs (in plain weave or tabby). Then I got creative and played with ideas of what else could be woven on the same warp. This is a scroll I made. I used the fabric I wove on the needle pillow warp for the background. It measures 7 ¾” x 26” including fringe.

I wove some samples and decided to make this for my scroll. The warp was handspun singles from Bouton. I wanted to see if I could use this fragile cotton for a warp. I used a sizing for the first time in my weaving life. The pattern weft is silk and shows up nicely against the matt cotton.

Here is a piece with two samples. The I used silk chenille that I’ve been hording dyed with black walnuts. In one part I used the chenille as the pattern weft. It looks similar to the needle pillows except I used only 1 block. The tabby was black sewing thread, I believe. For the flat sample, I used the reverse: the chenille for the tabby weft and the sewing thread for the pattern weft. Again I only used one of the blocks.

For this sample I used all sewing thread (easier with only one shuttle.) Again I used only one block and the pattern and tabby wefts were sewing thread. I do love to try things.

This illustration and quote are in The Weaving Book by Helen Bress and is the only place I’ve seen this addressed. “Inadvertently, the tabby does another thing. It makes some pattern threads pair together and separates others. On the draw-down [draft], all pattern threads look equidistant from each other. Actually, within any block, the floats will often look more like this: [see illustration]. With some yarns and setts, this pairing is hardly noticeable. If you don’t like the way the floats are pairing, try changing the order of the tabby shots. …and be consistent when treadling mirror-imaged blocks.”

The origin of the technique itself may have started in Persia and spread to other parts of the world, according to the author, Hans E. Wulff, of The Traditional Crafts of Persia. However, it is all relatively obscured by history. In The Key to Weavingby Mary E. Black, she mentioned that one weaver, who was unable to find a legitimate definition of the technique thought that the name “overshot” was a derivative of the idea that “the last thread of one pattern block overshoots the first thread of the next pattern block.” I personally think it is because the pattern weft overshoots the ground warp and weft webbing.

Overshot gained popularity and a place in history during the turn of the 19th century in North America for coverlets. Coverlets are woven bedcovers, often placed as the topmost covering on the bed. A quote that I feel strengthens the craftsmanship and labor that goes into weaving an overshot coverlet is from The National Museum of the American Coverlet:

Though, popular in many states during the early to mid 19th centuries, the extensive development of overshot weaving as a form of design and expression was fostered in rural southern Appalachia. It remained a staple of hand-weavers in the region until the early 20th century. In New England, around 1875, the invention of the Jacquard loom, the success of chemical dyes and the evolution of creating milled yarns, changed the look of coverlets entirely. The designs woven in New England textile mills were predominantly pictorial and curvilinear. So, while the weavers of New England set down their shuttles in favor of complex imagery in their textiles, the weavers of Southern Appalachia continued to weave for at least another hundred years using single strand, hand spun, irregular wool yarn that was dyed with vegetable matter, by choice.

Designs were focused on repeating geometric patterns that were created by using a supplementary weft that was typically a dyed woolen yarn over a cotton plain weave background. The designs expressed were often handed down through family members and shared within communities like a good recipe. And each weaver was able to develop their own voice by adjusting the color ways and the treadling arrangements. Predominately, the homestead weavers that gave life and variations to these feats of excellent craftsmanship were women. However, not every home could afford a loom, so the yarn that was spun would have been sent out to be woven by the professional weavers, who were mostly men.

And, due to the nature of design, overshot can be woven on simpler four harness looms. This was a means for many weavers to explore this technique who may not have the financial means to a more complicated loom. With this type of patterning a blanket could be woven in narrower strips and then hand sewn together to cover larger beds. This allowed weavers to create complex patterns that spanned the entirety of the bed.

What makes overshot so incredibly interesting that it was fundamentally a development of American weavers looking to express themselves. Many of the traditional patterns have mysterious names such as “Maltese Cross”, “Liley of the West”, “Blooming Leaf of Mexico” and “Lee’s Surrender”. Although the names are curious, the patterns that were developed from the variations of four simple blocks are incredibly intricate and luxurious.

This is only the tip of the iceberg with regard to the history of this woven structure. If you are interested in learning more about the culture and meaning of overshot, check out these resources!

The National Museum of the American Coverlet- a museum located in Bedford, Pennsylvania that has an extensive collection of traditional and jacquard overshot coverlets. Great information online and they have a “Coverlet College” which is a weekend series of lectures to learn everything about the American coverlet. Check out their website - coverletmuseum.org

Textile Art of Southern Appalachia: The Quiet Work of Women – This was an exhibit that traveled from Lowell, Massachusetts, Morehead, Kentucky, Knoxville, Tennessee, Raleigh, North Carolina, and ended at the Royal Museum in Edinburgh, Scotland. The exhibit contained a large number of overshot coverlets and the personal histories of those who wove them. I learned of this exhibit through an article written by Kathryn Liebowitz for the 2001, June/July edition of the magazine “Art New England”. The book that accompanied the exhibit, written by Kathleen Curtis Wilson, contains some of the rich history of these weavers and the cloth they created. I have not personally read the book, but it is now on the top of my wish list, so when I do, you will be the first to know about it! The book is called Textile Art of Southern Appalachia: The Quiet Work of Women and I look forward to reading it.

I recently wove a towel using a strip of birds eye and then mostly plain weave (in the threading). I used 2/8 cotton and I chose to use a sett in between plain weave of 18 and twill 22. I used 20 epi. and I think it worked well. I was worried if I chose 2 different setts, it would show as more crammed (in the twill section) when I just wove plain weave across the whole width.

If the birds eye is across the weft, as you’ve threaded birds eye and you want to weave a few rows of birds eye twill in the weft, but the towel is more plain weave then use epi for plain weave. Just remember that those rows of twill will shrink more after washing, giving you a scalloped selvedge. I hope this answers your ?

Then there is overshot. If you’re  using a thin fibre such as 2/16 cotton for your towel, and you just want to add a few rows of birds eye across the width of the towel,  then I would use 2/8 for the overshot pattern (birds eye) only  and use a sett for overshot based on your ground fibre. In this case it is 2/16 so I would use 22 epi.

A water wheel is a machine for converting the energy of flowing or falling water into useful forms of power, often in a watermill. A water wheel consists of a wheel (usually constructed from wood or metal), with a number of blades or buckets arranged on the outside rim forming the driving car. Water wheels were still in commercial use well into the 20th century but they are no longer in common use. Uses included milling flour in gristmills, grinding wood into pulp for papermaking, hammering wrought iron, machining, ore crushing and pounding fibre for use in the manufacture of cloth.

Some water wheels are fed by water from a mill pond, which is formed when a flowing stream is dammed. A channel for the water flowing to or from a water wheel is called a mill race. The race bringing water from the mill pond to the water wheel is a headrace; the one carrying water after it has left the wheel is commonly referred to as a tailrace.

Waterwheels were used for various purposes from agriculture to metallurgy in ancient civilizations spanning the Hellenistic Greek world, Rome, China and India. Waterwheels saw continued use in the Post-classical age, like the Middle Ages of Europe and the Islamic Golden Age, but also elsewhere. In the mid to late 18th century John Smeaton"s scientific investigation of the water wheel led to significant increases in efficiency supplying much needed power for the Industrial Revolution.turbine, developed by Benoît Fourneyron, beginning with his first model in 1827.elevations, that exceed the capability of practical-sized waterwheels.

Overshot and backshot water wheels are typically used where the available height difference is more than a couple of meters. Breastshot wheels are more suited to large flows with a moderate head. Undershot and stream wheel use large flows at little or no head.

There is often an associated millpond, a reservoir for storing water and hence energy until it is needed. Larger heads store more gravitational potential energy for the same amount of water so the reservoirs for overshot and backshot wheels tend to be smaller than for breast shot wheels.

Overshot and pitchback water wheels are suitable where there is a small stream with a height difference of more than 2 metres (6.5 ft), often in association with a small reservoir. Breastshot and undershot wheels can be used on rivers or high volume flows with large reservoirs.

Stream wheels mounted on floating platforms are often referred to as hip wheels and the mill as a ship mill. They were sometimes mounted immediately downstream from bridges where the flow restriction of the bridge piers increased the speed of the current.

The word breastshot is used in a variety of ways. Some authors restrict the term to wheels where the water enters at about the 10 o’clock position, others 9 o’clock, and others for a range of heights.

Breastshot wheels are less efficient than overshot and backshot wheels but they can handle high flow rates and consequently high power. They are preferred for steady, high-volume flows such as are found on the Fall Line of the North American East Coast. Breastshot wheels are the most common type in the United States of America

A vertically mounted water wheel that is rotated by water entering buckets just past the top of the wheel is said to be overshot. The term is sometimes, erroneously, applied to backshot wheels, where the water goes down behind the wheel.

A typical overshot wheel has the water channeled to the wheel at the top and slightly beyond the axle. The water collects in the buckets on that side of the wheel, making it heavier than the other "empty" side. The weight turns the wheel, and the water flows out into the tail-water when the wheel rotates enough to invert the buckets. The overshot design is very efficient, it can achieve 90%,

Overshot wheels require a large head compared to other types of wheel which usually means significant investment in constructing the headrace. Sometimes the final approach of the water to the wheel is along a flume or penstock, which can be lengthy.

A backshot wheel (also called pitchback) is a variety of overshot wheel where the water is introduced just before the summit of the wheel. In many situations, it has the advantage that the bottom of the wheel is moving in the same direction as the water in the tailrace which makes it more efficient. It also performs better than an overshot wheel in flood conditions when the water level may submerge the bottom of the wheel. It will continue to rotate until the water in the wheel pit rises quite high on the wheel. This makes the technique particularly suitable for streams that experience significant variations in flow and reduces the size, complexity, and hence cost of the tailrace.

The direction of rotation of a backshot wheel is the same as that of a breastshot wheel but in other respects, it is very similar to the overshot wheel. See below.

Some wheels are overshot at the top and backshot at the bottom thereby potentially combining the best features of both types. The photograph shows an example at Finch Foundry in Devon, UK. The head race is the overhead timber structure and a branch to the left supplies water to the wheel. The water exits from under the wheel back into the stream.

A special type of overshot/backshot wheel is the reversible water wheel. This has two sets of blades or buckets running in opposite directions so that it can turn in either direction depending on which side the water is directed. Reversible wheels were used in the mining industry in order to power various means of ore conveyance. By changing the direction of the wheel, barrels or baskets of ore could be lifted up or lowered down a shaft or inclined plane. There was usually a cable drum or a chain basket on the axle of the wheel. It is essential that the wheel have braking equipment to be able to stop the wheel (known as a braking wheel). The oldest known drawing of a reversible water wheel was by Georgius Agricola and dates to 1556.

The earliest waterwheel working like a lever was described by Zhuangzi in the late Warring States period (476-221 BC). It says that the waterwheel was invented by Zigong, a disciple of Confucius in the 5th century BC.Chinese of the Eastern Han Dynasty were using water wheels to crush grain in mills and to power the piston-bellows in forging iron ore into cast iron.

In the text known as the Xin Lun written by Huan Tan about 20 AD (during the usurpation of Wang Mang), it states that the legendary mythological king known as Fu Xi was the one responsible for the pestle and mortar, which evolved into the tilt-hammer and then trip hammer device (see trip hammer). Although the author speaks of the mythological Fu Xi, a passage of his writing gives hint that the water wheel was in widespread use by the 1st century AD in China (Wade-Giles spelling):

Fu Hsi invented the pestle and mortar, which is so useful, and later on it was cleverly improved in such a way that the whole weight of the body could be used for treading on the tilt-hammer (tui), thus increasing the efficiency ten times. Afterwards the power of animals—donkeys, mules, oxen, and horses—was applied by means of machinery, and water-power too used for pounding, so that the benefit was increased a hundredfold.

In the seventh year of the Chien-Wu reign period (31 AD) Tu Shih was posted to be Prefect of Nanyang. He was a generous man and his policies were peaceful; he destroyed evil-doers and established the dignity (of his office). Good at planning, he loved the common people and wished to save their labor. He invented a water-power reciprocator (shui phai) for the casting of (iron) agricultural implements. Those who smelted and cast already had the push-bellows to blow up their charcoal fires, and now they were instructed to use the rushing of the water (chi shui) to operate it ... Thus the people got great benefit for little labor. They found the "water(-powered) bellows" convenient and adopted it widely.

Water wheels in China found practical uses such as this, as well as extraordinary use. The Chinese inventor Zhang Heng (78–139) was the first in history to apply motive power in rotating the astronomical instrument of an armillary sphere, by use of a water wheel.mechanical engineer Ma Jun (c. 200–265) from Cao Wei once used a water wheel to power and operate a large mechanical puppet theater for the Emperor Ming of Wei (r. 226–239).

The ancient Greeks invented the waterwheel independently and used it in nearly all of the forms and functions described above, including its application for watermilling.Hellenistic period between the 3rd and 1st century BC.

The compartmented water wheel comes in two basic forms, the wheel with compartmented body (Latin tympanum) and the wheel with compartmented rim or a rim with separate, attached containers.sakia gear.

The earliest literary reference to a water-driven, compartmented wheel appears in the technical treatise Pneumatica (chap. 61) of the Greek engineer Philo of Byzantium (ca. 280−220 BC).Parasceuastica (91.43−44), Philo advises the use of such wheels for submerging siege mines as a defensive measure against enemy sapping.dry docks in Alexandria under the reign of Ptolemy IV (221−205 BC).papyri of the 3rd to 2nd century BC mention the use of these wheels, but don"t give further details.Ancient Near East before Alexander"s conquest can be deduced from its pronounced absence from the otherwise rich oriental iconography on irrigation practices.

The earliest depiction of a compartmented wheel is from a tomb painting in Ptolemaic Egypt which dates to the 2nd century BC. It shows a pair of yoked oxen driving the wheel via a sakia gear, which is here for the first time attested, too.Museum of Alexandria, at the time the most active Greek research center, may have been involved in its invention.Alexandrian War in 48 BC tells of how Caesar"s enemies employed geared waterwheels to pour sea water from elevated places on the position of the trapped Romans.

The Romans used waterwheels extensively in mining projects, with enormous Roman-era waterwheels found in places like modern-day Spain. They were reverse overshot water-wheels designed for dewatering deep underground mines.Vitruvius, including the reverse overshot water-wheel and the Archimedean screw. Many were found during modern mining at the copper mines at Rio Tinto in Spain, one system involving 16 such wheels stacked above one another so as to lift water about 80 feet from the mine sump. Part of such a wheel was found at Dolaucothi, a Roman gold mine in south Wales in the 1930s when the mine was briefly re-opened. It was found about 160 feet below the surface, so must have been part of a similar sequence as that discovered at Rio Tinto. It has recently been carbon dated to about 90 AD, and since the wood from which it was made is much older than the deep mine, it is likely that the deep workings were in operation perhaps 30–50 years after. It is clear from these examples of drainage wheels found in sealed underground galleries in widely separated locations that building water wheels was well within their capabilities, and such verticals water wheels commonly used for industrial purposes.

Taking indirect evidence into account from the work of the Greek technician Apollonius of Perge, the British historian of technology M.J.T. Lewis dates the appearance of the vertical-axle watermill to the early 3rd century BC, and the horizontal-axle watermill to around 240 BC, with Byzantium and Alexandria as the assigned places of invention.Strabon (ca. 64 BC–AD 24) to have existed sometime before 71 BC in the palace of the Pontian king Mithradates VI Eupator, but its exact construction cannot be gleaned from the text (XII, 3, 30 C 556).

About the same time, the overshot wheel appears for the first time in a poem by Antipater of Thessalonica, which praises it as a labour-saving device (IX, 418.4–6).Lucretius (ca. 99–55 BC) who likens the rotation of the waterwheel to the motion of the stars on the firmament (V 516).central Gaul.Barbegal watermill complex a series of sixteen overshot wheels was fed by an artificial aqueduct, a proto-industrial grain factory which has been referred to as "the greatest known concentration of mechanical power in the ancient world".

Apart from its use in milling and water-raising, ancient engineers applied the paddled waterwheel for automatons and in navigation. Vitruvius (X 9.5–7) describes multi-geared paddle wheels working as a ship odometer, the earliest of its kind. The first mention of paddle wheels as a means of propulsion comes from the 4th–5th century military treatise

Cistercian monasteries, in particular, made extensive use of water wheels to power watermills of many kinds. An early example of a very large water wheel is the still extant wheel at the early 13th century Real Monasterio de Nuestra Senora de Rueda, a Cistercian monastery in the Aragon region of Spain. Grist mills (for corn) were undoubtedly the most common, but there were also sawmills, fulling mills and mills to fulfil many other labour-intensive tasks. The water wheel remained competitive with the steam engine well into the Industrial Revolution. At around the 8th to 10th century, a number of irrigation technologies were brought into Spain and thus introduced to Europe. One of those technologies is the Noria, which is basically a wheel fitted with buckets on the peripherals for lifting water. It is similar to the undershot water wheel mentioned later in this article. It allowed peasants to power watermills more efficiently. According to Thomas Glick"s book, Irrigation and Society in Medieval Valencia, the Noria probably originated from somewhere in Persia. It has been used for centuries before the technology was brought into Spain by Arabs who had adopted it from the Romans. Thus the distribution of the Noria in the Iberian peninsula "conforms to the area of stabilized Islamic settlement".Spaniards, the technology spread to the New World in Mexico and South America following Spanish expansion

The type of water wheel selected was dependent upon the location. Generally if only small volumes of water and high waterfalls were available a millwright would choose to use an overshot wheel. The decision was influenced by the fact that the buckets could catch and use even a small volume of water.

Harnessing water-power enabled gains in agricultural productivity, food surpluses and the large scale urbanization starting in the 11th century. The usefulness of water power motivated European experiments with other power sources, such as wind and tidal mills.canals, put Europe on a hydraulically focused path, for instance water supply and irrigation technology was combined to modify supply power of the wheel.feudal state.

The water mill was used for grinding grain, producing flour for bread, malt for beer, or coarse meal for porridge.fulling mill, which was used for cloth making. The trip hammer was also used for making wrought iron and for working iron into useful shapes, an activity that was otherwise labour-intensive. The water wheel was also used in papermaking, beating material to a pulp. In the 13th century water mills used for hammering throughout Europe improved the productivity of early steel manufacturing. Along with the mastery of gunpowder, waterpower provided European countries worldwide military leadership from the 15th century.

Millwrights distinguished between the two forces, impulse and weight, at work in water wheels long before 18th-century Europe. Fitzherbert, a 16th-century agricultural writer, wrote "druieth the wheel as well as with the weight of the water as with strengthe [impulse]".Leonardo da Vinci also discussed water power, noting "the blow [of the water] is not weight, but excites a power of weight, almost equal to its own power".laws of force. Evangelista Torricelli"s work on water wheels used an analysis of Galileo"s work on falling bodies, that the velocity of a water sprouting from an orifice under its head was exactly equivalent to the velocity a drop of water acquired in falling freely from the same height.

The water wheel was a driving force behind the earliest stages of industrialization in Britain. Water-powered reciprocating devices were used in trip hammers and blast furnace bellows. Richard Arkwright"s water frame was powered by a water wheel.

Water wheels were used to power sawmills, grist mills and for other purposes during development of the United States. The 40 feet (12 m) diameter water wheel at McCoy, Colorado, built in 1922, is a surviving one out of many which lifted water for irrigation out of the Colorado River.

Two early improvements were suspension wheels and rim gearing. Suspension wheels are constructed in the same manner as a bicycle wheel, the rim being supported under tension from the hub- this led to larger lighter wheels than the former design where the heavy spokes were under compression. Rim-gearing entailed adding a notched wheel to the rim or shroud of the wheel. A stub gear engaged the rim-gear and took the power into the mill using an independent line shaft. This removed the rotative stress from the axle which could thus be lighter, and also allowed more flexibility in the location of the power train. The shaft rotation was geared up from that of the wheel which led to less power loss. An example of this design pioneered by Thomas Hewes and refined by William Armstrong Fairburn can be seen at the 1849 restored wheel at the Portland Basin Canal Warehouse.

Australia has a relatively dry climate, nonetheless, where suitable water resources were available, water wheels were constructed in 19th-century Australia. These were used to power sawmills, flour mills, and stamper batteries used to crush gold-bearing ore. Notable examples of water wheels used in gold recovery operations were the large Garfield water wheel near Chewton—one of at least seven water wheels in the surrounding area—and the two water wheels at Adelong Falls; some remnants exist at both sites.Walhalla once had at least two water wheels, one of which was rolled to its site from Port Albert, on its rim using a novel trolley arrangement, taking nearly 90 days.water wheel at Jindabyne, constructed in 1847, was the first machine used to extract energy—for flour milling—from the Snowy River.

The engineers of the Islamic world developed several solutions to achieve the maximum output from a water wheel. One solution was to mount them to piers of bridges to take advantage of the increased flow. Another solution was the shipmill, a type of water mill powered by water wheels mounted on the sides of ships moored in midstream. This technique was employed along the Tigris and Euphrates rivers in 10th-century Iraq, where large shipmills made of teak and iron could produce 10 tons of flour from corn every day for the granary in Baghdad.flywheel mechanism, which is used to smooth out the delivery of power from a driving device to a driven machine, was invented by Ibn Bassal (fl. 1038–1075) of Al-Andalus; he pioneered the use of the flywheel in the saqiya (chain pump) and noria.Al-Jazari in the 13th century and Taqi al-Din in the 16th century described many inventive water-raising machines in their technological treatises. They also employed water wheels to power a variety of devices, including various water clocks and automata.

Overshot (and particularly backshot) wheels are the most efficient type; a backshot steel wheel can be more efficient (about 60%) than all but the most advanced and well-constructed turbines. In some situations an overshot wheel is preferable to a turbine.

The development of the hydraulic turbine wheels with their improved efficiency (>67%) opened up an alternative path for the installation of water wheels in existing mills, or redevelopment of abandoned mills.

The kinetic energy can be accounted for by converting it into an equivalent head, the velocity head, and adding it to the actual head. For still water the velocity head is zero, and to a good approximation it is negligible for slowly moving water, and can be ignored. The velocity in the tail race is not taken into account because for a perfect wheel the water would leave with zero energy which requires zero velocity. That is impossible, the water has to move away from the wheel, and represents an unavoidable cause of inefficiency.

The power is how fast that energy is delivered which is determined by the flow rate. It has been estimated that the ancient donkey or slave-powered quern of Rome made about one-half of a horsepower, the horizontal waterwheel creating slightly more than one-half of a horsepower, the undershot vertical waterwheel produced about three horsepower, and the medieval overshot waterwheel produced up to forty to sixty horsepower.

These type of water wheels have high efficiency at part loads / variable flows and can operate at very low heads, < 1 m (3 ft 3 in). Combined with direct drive Axial Flux Permanent Magnet Alternators and power electronics they offer a viable alternative for low head hydroelectric power generation.

Oleson 2000, pp. 235: The sudden appearance of literary and archaological evidence for the compartmented wheel in the third century B.C. stand in marked contrast to the complete absence of earlier testimony, suggesting that the device was invented not long before.

As for a Mesopotamian connection: Schioler 1973, p. 165−167: References to water-wheels in ancient Mesopotamia, found in handbooks and popular accounts, are for the most part based on the false assumption that the Akkadian equivalent of the logogram GIS.APIN was nartabu and denotes an instrument for watering ("instrument for making moist").As a result of his investigations, Laessoe writes as follows on the question of the saqiya: "I consider it unlikely that any reference to the saqiya will appear in ancient Mesopotamian sources." In his opinion, we should turn our attention to Alexandria, "where it seems plausible to assume that the saqiya was invented."

Terry S, Reynolds, Stronger than a Hundred Men; A History of the Vertical Water Wheel. Baltimore; Johns Hopkins University Press, 1983. Robert, Friedel, A Culture of Improvement. MIT Press. Cambridge, Massachusetts. London, England. (2007). p. 33.

Wikander 2000, p. 400: This is also the period when water-mills started to spread outside the former Empire. According to Cedrenus (Historiarum compendium), a certain Metrodoros who went to India in c. A.D. 325 "constructed water-mills and baths, unknown among them [the Brahmans] till then".

Gies, Frances; Gies, Joseph (1994). Cathedral, Forge, and Waterwheel: Technology and Invention in the Middle Ages. HarperCollins Publishers. p. 115. ISBN 0060165901.

al-Hassani, S.T.S., Woodcock, E. and Saoud, R. (2006) 1001 inventions : Muslim heritage in our world, Manchester : Foundation for Science Technology and Civilisation, ISBN 0-9552426-0-6

Lucas, A.R. (2005). "Industrial Milling in the Ancient and Medieval Worlds: A Survey of the Evidence for an Industrial Revolution in Medieval Europe". Technology and Culture. 46 (1): 1–30. doi:10.1353/tech.2005.0026. S2CID 109564224.

Murphy, Donald (2005), Excavations of a Mill at Killoteran, Co. Waterford as Part of the N-25 Waterford By-Pass Project (PDF), Estuarine/ Alluvial Archaeology in Ireland. Towards Best Practice, University College Dublin and National Roads Authority

Quaranta Emanuele, Revelli Roberto (2015), "Performance characteristics, power losses and mechanical power estimation for a breastshot water wheel", Energy, Energy, Elsevier, 87: 315–325, doi:10.1016/j.energy.2015.04.079

This website is using a security service to protect itself from online attacks. The action you just performed triggered the security solution. There are several actions that could trigger this block including submitting a certain word or phrase, a SQL command or malformed data.

The requirement was to take a "traditional" overshot threading, weave a repeat of that, then weave it in "rose" fashion, then in "monk"s belt" fashion. (There were other options as well, but this is what fit on the scanner flat bed. Besides, it"s the "star" and "rose" fashions I want to talk about here.)

Not every overshot draft can be effectively converted to "rose". If you look at the above photo, the top design has very strong diagonal lines running through the entire motif. The middle sample, has very strong circles in the design - the "rose".

An overshot threading can be woven in other weave structures. If the design has small units/blocks, it can be woven in a 2:2 twill, lacey, honeycomb along with others.

Overshot is characterized by areas of floats (generally considered the design/motif), half-tones and plain weave. Larger sized designs may have very long pattern floats, so sometimes the pattern float is tied down so that there is no plain weave area as such, but only the floats and half-tones.

When going to overshot on eight shafts, it is possible to have no half-tones at all, or weave the overshot motif in double weave so that you don"t have long floats, but still retain the motif. Much like I have been taking overshot motifs and converting them to twill blocks (because I have the 16 shafts needed to do that.)

I frequently use the traditional Snail"s Trails and Cat"s Paws motif for tea towels. It"s a fairly large motif which has a strong graphic look to it.

2004, Donella Meadows; Jorgen Randers; Dennis Meadows, “Author"s preface”, in Limits to Growth: The 30-Year Update,With appropriate choice and action such uncontrolled decline could be avoided; overshoot could instead be resolved by a conscious effort to reduce humanity"s demand on the planet.

2020, Karen Cheng, Designing Type, second edition, page 88:The bowl of the D and the O are usually not identical, as most D forms do not have overshoot or undershoot.

1961 November, “Talking of Trains: Aircraft on rail tracks”, in Trains Illustrated, page 650:As a result of the accident at Southend Airport when a Hermes aircraft overshot the runway and fouled the down Shenfield to Southend Victoria line between Rochford and Prittlewell, the Eastern Region is considering warning arrangements, which have already been provided on some lines running past aerodromes.

2021 December 15, Paul Clifton, “There is nothing you can do”, in RAIL, number 946, page 37:A ScotRail Driver: [...] A good friend of mine overshot two stations back-to-back a couple of years ago. He tried to stop at one station and slid by it. Tried to stop at the next station. He slid by that, too.

1692–1717, Robert South, Twelve Sermons Preached upon Several Occasions, volume (please specify |volume=I to VI), 6th edition, London: […] J[ames] Bettenham, for Jonah Bowyer,[…], published 1727,not to overshoot his game

2004, Donella Meadows; Jorgen Randers; Dennis Meadows, “Author"s preface”, in Limits to Growth: The 30-Year Update,Measured this way humanity was last at sustainable levels in the 1980s. Now it has overshot by some 20 percent.

Jane has spent her life sampling and testing yarns on their own and in different combinations, for her workshops and production lines. She knows everyone doesn’t have time to sample to this extent so she is sharing the knowledge gained from that testing with everyone.

Jane’s Master Sett Chart encompasses more than 40 years of weaving experience, trial & error and extensive sampling with many of our yarns. This chart is an invaluable treasure trove of weaving advice.

The PID circuit is often utilized as a control loop feedback controller and is very commonly used for many forms of servo circuits. The letters making up the acronym PID correspond to Proportional (P), Integral (I), and Derivative (D), which represents the three control settings of a PID circuit. The purpose of any servo circuit is to hold the system at a predetermined value (set point) for long periods of time. The PID circuit actively controls the system so as to hold it at the set point by generating an error signal that is essentially the difference between the set point and the current value. The three controls relate to the time-dependent error signal; at its simplest, this can be thought of as follows: Proportional is dependent upon the present error, Integral is dependent upon the accumulation of past error, and Derivative is the prediction of future error. The results of each of the controls are then fed into a weighted sum, which then adjusts the output of the circuit, u(t). This output is fed into a control device, its value is fed back into the circuit, and the process is allowed to actively stabilize the circuit’s output to reach and hold at the set point value. The block diagram below illustrates very simply the action of a PID circuit. One or more of the controls can be utilized in any servo circuit depending on system demand and requirement (i.e., P, I, PI, PD, or PID).

Through proper setting of the controls in a PID circuit, relatively quick response with minimal overshoot (passing the set point value) and ringing (oscillation about the set point value) can be achieved. Let’s take as an example a temperature servo, such as that for temperature stabilization of a laser diode. The PID circuit will ultimately servo the current to a Thermo Electric Cooler (TEC) (often times through control of the gate voltage on an FET). Under this example, the current is referred to as the Manipulated Variable (MV). A thermistor is used to monitor the temperature of the laser diode, and the voltage over the thermistor is used as the Process Variable (PV). The Set Point (SP) voltage is set to correspond to the desired temperature. The error signal, e(t), is then just the difference between the SP and PV. A PID controller will generate the error signal and then change the MV to reach the desired result. If, for instance, e(t) states that the laser diode is too hot, the circuit will allow more current to flow through the TEC (proportional control). Since proportional control is proportional to e(t), it may not cool the laser diode quickly enough. In that event, the circuit will further increase the amount of current through the TEC (integral control) by looking at the previous errors and adjusting the output in order to reach the desired value. As the SP is reached [e(t) approaches zero], the circuit will decrease the current through the TEC in anticipation of reaching the SP (derivative control).

Please note that a PID circuit will not guarantee optimal control. Improper setting of the PID controls can cause the circuit to oscillate significantly and lead to instability in control. It is up to the user to properly adjust the PID gains to ensure proper performance.

Integral control is highly effective at increasing the response time of a circuit along with eliminating the steady-state error associated with purely proportional control. In essence integral control sums over the previous error, which was not corrected, and then multiplies that error by Ki to produce the integral response. Thus, for even small sustained error, a large aggregated integral response can be realized. However, due to the fast response of integral control, high gain values can cause significant overshoot of the SP value and lead to oscillation and instability. Too low and the circuit will be significantly slower in responding to changes in the system.

Unlike proportional and integral control, derivative control will slow the response of the circuit. In doing so, it is able to partially compensate for the overshoot as well as damp out any oscillations caused by integral and proportional control. High gain values cause the circuit to respond very slowly and can leave one susceptible to noise and high frequency oscillation (as the circuit becomes too slow to respond quickly). Too low and the circuit is prone to overshooting the SP value. However, in some cases overshooting the SP value by any significant amount must be avoided and thus a higher derivative gain (along with lower proportional gain) can be used. The chart below explains the effects of increasing the gain of any one of the parameters independently.

In general the gains of P, I, and D will need to be adjusted by the user in order to best servo the system. While there is not a static set of rules for what the values should be for any specific system, following the general procedures should help in tuning a circuit to match one’s system and environment. In general a PID circuit will typically overshoot the SP value slightly and then quickly damp out to reach the SP value.

Manual tuning of the gain settings is the simplest method for setting the PID controls. However, this procedure is done actively (the PID controller turned on and properly attached to the system) and requires some amount of experience to fully integrate. To tune your PID controller manually, first the integral and derivative gains are set to zero. Increase the proportional gain until you observe oscillation in the output. Your proportional gain should then be set to roughly half this value. After the proportional gain is set, increase the integral gain until any offset is corrected for on a time scale appropriate for your system. If you increase this gain too much, you will observe significant overshoot of the SP value and instability in the circuit. Once the integral gain is set, the derivative gain can then be increased. Derivative gain will reduce overshoot and damp the system quickly to the SP value. If you increase the derivative gain too much, you will see large overshoot (due to the circuit being too slow to respond). By playing with the gain settings, you can maximize the performance of your PID circuit, resulting in a circuit that quickly responds to changes in the system and effectively damps out oscillation about the SP value.

While manual tuning can be very effective at setting a PID circuit for your specific system, it does require some amount of experience and understanding of PID circuits and response. The Ziegler-Nichols method for PID tuning offers a bit more structured guide to setting PID values. Again, you’ll want to set the integral and derivative gain to zero. Increase the proportional gain until the circuit starts to oscillate. We will call this gain level Ku. The oscillation will have a period of Pu. Gains are for various control circuits are then given below in the chart.

Like all new weavers I tried many techniques. One technique, overshot, I have tried only twice. There is a pattern called Norse Kitchen on page 186 in the book. I wove this table runner on a four shaft table loom and only made one mistake! I was so proud of it. It is woven in cottolin.

I signed up for the Discover Color Weave-Along! last week. I am weaving mug mats in overshot on 8 shafts. Five thousand weavers have also joined the workshop which is free. This is a 3-week weave-along delivered via an online course with plenty of information. https://www.warpandweave.com/classes/discover-color/

I am using cottolin instead of 8/2 cotton sett at 18 epi. Here is my first attempt on the loom. I am using a double cottolin thread for the pattern weft. I have a useful shuttle which takes two bobbins.

The first mat was woven using a doubled red cottolin yarn for the pattern thread. I do not think that I beat hard enough. For the second mat I used a 3/2 cotton for the pattern weft. I beat as hard as I could.

The workshop indicates that the mug mats should be about 8" by 8" but perhaps the cottolin is making the dimensions different. The first red mat is 6.5 inches in width and 8.25 inches in length. Examining it closely I can see that the plain weave tabby has not been beaten in hard enough. The sett is 18 epi.

I need to wash them to check on the final size before I weave any more. Perhaps a sett of 20 epi might be more useful. They do seem rather large for a normal sized mug.

Electrification alone is not enough: report recommends a 3-lever approach to set industry on the right path and calls for new forms of collaboration to build rapid momentum

Polestar (Nasdaq: PSNY) and Rivian (Nasdaq: RIVN) have collaborated on a ‘Pathway Report" which concludes that the automotive industry is set to overshoot the IPCC’s 1.5-degree pathway by at least 75% by 2050. The two pioneering EV makers initiated the report in response to the climate crisis. The report, which uses existing, open-source data to model the current trajectory for emissions stemming from the car industry, was carried out by global management consulting firm Kearney.

Passenger vehicles currently account for 15% of all greenhouse gas (GHG) emissions globally.1 The IPCC has stated that all GHG emissions need to be reduced by 43% by 2030, and the report makes clear that the automotive industry is far off track, and, alarmingly, will have spent its full CO2e budget already by 2035 without urgent action.

The data presents a pathway based around three key levers. Lever 1 looks at the speed at which fossil fuel-powered cars need to be replaced by electric cars but points out that this alone will not be enough. A lot more work will be required for levers 2 and 3:

Pulling just one or two levers in isolation will be insufficient and only reduce the overshoot. Collective action from automakers is needed on all three levers, in parallel, at a global level. Firstly, the industry must accelerate the transition to electric vehicles by investing in manufacturing capabilities, as well as implementing a firm end date for fossil fuel car sales globally. Secondly, build out renewable energy supply to global grids that enable EV"s to reach their full potential through green charging. Thirdly, decarbonize the manufacturing supply chains for these vehicles through switching to low carbon materials, and investing in renewable energy solutions for supply chains.

Fredrika Klarén, Polestar Head of Sustainability, says: “Car companies may be on different paths when it comes to brand, design, and business strategies, and some won’t even admit that the road to the future is electric. I believe it is, and that the climate crisis is a shared responsibility, and we must look beyond tailpipe emissions. This report makes clear the importance of acting now and together. There’s a clear cost to inaction, but there’s also a financial opportunity for innovators who find new answers to the challenges we face.”

Kearney’s report has also been shared with several of the world’s leading car makers, together with an invitation to a roundtable held at the end of January to discuss areas of collective action. The aim is to find a path towards unprecedented, relevant and collective climate action for the car industry.

Anisa Costa, Rivian’s Chief Sustainability Officer, adds: “The report’s findings are sobering. Our hope is that this report lays the groundwork for the automotive industry to collaborate in driving progress at the pace and scale we need – and ideally inspiring other industries to do the same. Together, I’m confident we can win the race against time.”

The Pathway Report clearly shows the cost of inaction and the strong case for sustainable development.The investment community is moving, and capital flows are shifting from traditional investment to sustainable investment, recognizing an increasing link between sustainable transformation and financial benefits. In 2021, global sustainability investments totaled USD 35.3 trillion, representing over a third of all assets in five of the world’s biggest markets.

Angela Hultberg, global sustainability director at Kearney, says: “We are proud to have been chosen as a trusted expert to develop this report. The result of our modeling clearly shows that the industry needs to accelerate the pace of becoming a low carbon industry. We looked at different scenarios, different data points, and the conclusion is that no matter how you model it, we are far too close for comfort. We sincerely hope this report will be a starting point for the industry to focus on areas where there is agreement and find specific initiatives. It will take collective action to solve some of the issues at hand, and we look forward to seeing what the manufacturers will do in the near future.”

The report suggests three "levers" to have a chance at achieving the target by 2050: including a firm end date for selling fossil-fuel cars and investing more in manufacturing capabilities of electric cars; creating more green charging options by investing in renewable energy supplies to global grids; and focusing on more sustainable supply chains.

Climate goals have been at the forefront of carmakers" priority for the past decade as customers become increasingly sustainability-conscious, with the recent energy crisis and war in Ukraine underscoring the importance of accelerating the green shift.

Despite the will of auto makers to make the shift, geopolitical and macroeconomic conditions have continued to make life difficult for the industry, with higher costs, component shortages and supply chain issues continuing.

Rivian is one of the companies that has struggled with production ramp-up for its vehicles, and has been squeezed further as EV giant Tesla (TSLA.O) cut its prices. In early February, Rivian said it would lay off 6% of its workforce in an effort to cut cost.

Auto suppliers are also struggling with coping with the additional costs for making their components sustainable in order to meet carmakers" sustainability goals.

Assuming that passenger vehicles continue to account for around 15% of global emissions, the motor industry has a budget of 75-80 gigatons remaining, which, based on its current trajectory, will be entirely spent by 2032.

Three major offensives (or “levers”) are required, according to the report, in order for the car industry to stay within its emissions budget and, wildly optimistic though they are, even if all three are followed through successfully, the global motor manufacturing industry will still only barely avoid overshooting its budget.

The third lever that needs to be “pulled” in order for the global car industry not to exceed its budget would see automotive supply chains reducing their greenhouse gas emissions by 81% by 2032, with particular emphasis required on reducing the emissions impact of manufacturing electric vehicles compared with their combustion-powered equivalents.

“Today, supply chain emissions for an EV are approximately 35-50% higher than for ICE [internal combustion] vehicles, primarily due to [the] batteries,” the report claims.

At present, battery manufacturing accounts for some 27% of an electric vehicle’s manufacturing emissions and, according to the report, these production process need to be 100% electrified by 2032, with all material extraction and processing powered by a fossil-free mix.

With steel, iron and aluminium making up 40-60% of the average car’s supply chain emissions, a major effort on the part of manufacturers is needed to reduce the quantity of CO2-intensive materials used through an emphasis on recycling or on replacing those materials with lower-impact alternatives.

Both Polestar and Rivian have invited other manufacturers to participate in a round-table discussion aimed at exploring ways in which a concerted effort can be made to address the challenges laid out in the report.

“Our hope is that this report lays the groundwork for the automotive industry to collaborate in driving progress at the pace and scale we need — and ideally inspiring other industries to do the same.”

But refers to something pretty simple: how many strands of warp yarn there are in a single inch of weaving width. Because sett describes how many warp ends there are in an inch, it is commonly expressed using the term “ends per inch” or “epi” for short. A project with a sett of 20 epi, for example, has 20 warp ends in each inch of weaving while the project is on the loom.

Determining what sett a piece has is pretty easy: count the number of warp ends and divide by the number of inches in the width. Determining what sett a piece shouldhave is a little more complex, and a key element in planning a successful project.

The simplest way to determine sett is to check wraps per inch. This is how many times you can comfortably wrap a yarn around a ruler (or our handy-dandy Sett Checker!) in one inch. When you are wrapping yarn, do not leave gaps between wraps, and do not wrap so closely that the yarn overlaps. Hold yarn with a firm and steady tension. Don’t hold it so tightly that you stretch it out and make it look skinnier than it is.

All done? Just count the wraps within one inch. Take that number and divide it in half for plain weave. If you are weaving twill, take two thirds of your wraps per inch instead. This is your standard sett. Here’s an example. Say you had a yarn that came out to 30 wraps per inch. You would use a sett of 15 epi for plain weave (30 x 0.5 = 15). For twill, you would use a closer sett of 20 epi (30 x 0.66 = 20).

Wraps per inch give you a solid starting point. But for every material, there are multiple usable setts. Good sett comes in a range of possibilities, not in a single answer. Mercifully, other weavers are here to help you with this part. Gather’s Sett Chart shows ranges for many popular warp materials so that you don’t have to waste time (and yarn!) in trial-and-error experimentation.

Choosing a sett from the range of options is where you can get clever. Adjusting the sett changes the characteristics of your finished product. A close or dense sett makes stronger and stiffer cloth. A loose or open sett makes drapier, gauzier cloth.

Let’s look at 8/2 cotton for example. Gather’s Sett Chart lists a range of setts from 16-20 epi. If you’re planning tea towels, you will want to aim at the higher end of those scales for a close sett and hardy cloth--18 epi for plain weave or 20 epi for twill. On the other hand, if you’re aiming at a nice drapey scarf or gauzy window-covering, use the lower end of the range--16 for plain weave or 18 for twill.

In addition to thinking about the best sett for a particular piece, it can be helpful to think about the best sett for an overall warp. If you want the freedom to go back and forth between plain weave and twill on a long warp, choose a sett that is within the range for both structures.

If you’re using an unusual weave structure or combination of different yarns, if you’re aiming at a very specific “hand” or feel in your finished product, or if you just love experimenting and discovering things for yourself, sampling for sett is a great idea.

Sett is determined by one of the last steps in dressing your loom: sleying the reed. The reed spaces out your warp threads, which translates directly into how many ends per inch your project has. To sample for sett, sley your reed at one sett, lash on, and weave your sample. Then cut your sample off, re-sley at a different sett, and weave the next piece. Repeat as many times as needed.

If you’re weaving on a rigid heddle loom, your options for sett are limited to which rigid heddle reeds you have on hand. But you can definitely thread a warp in a 10-dent reed, then cut it off and re-thread in a 12-dent reed. To keep threads from tangling during the switch, pull your threads out of the reed about 10 threads at a time and tie them in a slip knot.

Finally, remember that wet finishing will make many fibres bloom and pull together. To get a true sense of the impact of sett, be sure to wet finish all your samples in the same way you intend to finish your final piece.

The advice above, as well as most advice out there about sett, applies to more-or-less balanced weave structures. In a balanced piece, the number of warp ends per inch (epi) and the number of weft picks per inch (ppi) are the same.

There are, however, several styles of weaving that deliberately aim at an unbalanced result. Rug weaving has a much higher ppi than epi. It is weft-faced: the weft dominates the piece, and you can barely see the warp. On the opposite end of the spectrum, techniques like rep weave have much higher epi than ppi. Rep weaving produces warp-faced pieces commonly used for placemats. There are so many warp ends per inch that sometimes the weft is only visible where it peeks out at the selvedges.