LEATHER – 1

Post 235 — by Gautam Shah

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Leather Leather Harness for Horses

Leather has been used by primitive man to cover own-self, protect food items, carry water, form a place of dwelling, to tie materials and make footwear. Raw-hides or untreated skins have a tendency to putrefy very quickly in wet weather, causing foul smell and degeneration of the material itself. In dry conditions, or on loss of moisture untreated skins become very hard, rigid and brittle.

Leather_bucket_of_a_well

Leather processing is an ancient craft that has been practised for more than 7,000 years. The first lessons were how to turn raw-hides in to a stable product, Leather. For leather making raw-hides must be removed early, cleaned, washed and dried in the sun. There were two easy treatments for making leather into better lasting, soft and a wearable product. The first was to curtail leather’s reactivity with moisture by coating it with oils or wax. Other methods included, salting (to dehydrate) and smoking to retard bacterial activity, and treatment with bark extracts (for tannic acid), and alum.

Leather Boxer_of_quirinal_hands

The hides of mammals, the chief sources of leathers, are composed of three layers: epidermis, a thin outer layer, corium, or dermis, the thick central layer, and a subcutaneous fatty layer.

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The corium constitutes the main commercial leather, after the two sandwiching layers have been removed. Fresh hides contain between 60 and 70 percent waters by weight and 30 to 35 percent protein. About 85 percent of the protein is collagen, a fibrous protein held together by chemical bonds. Basically, leather making is the science of using acids, bases, salts, enzymes, and tannin to dissolve fats and non-fibrous proteins and strengthen the bonds between the collagen fibres.

Leather Homo SapiensThe term hide is used to designate skins of larger animals, e.g. cowhide or horse-hide, whereas skin refers to smaller animals (calfskin or kidskin). Fur is a hide or skin of furry or hairy animals. Use of furs precedes use of hides as several species of hominoids including Homo sapiens and Homo neanderthalensis used fur for clothing. Common animal sources for fur include fox, rabbit, mink, beaver, stoat (ermine), otter, sable, seals, cats, dogs, coyotes, chinchilla, and possum. Major sources of leather were hunted animals, but later domesticated cattle and skins of calves, goats, kids, sheep, and lambs, were used. Other sources were horse, mule, pig, kangaroo, zebra, deer, seal, walrus, and reptiles. Skins of ostrich, lizard, eel, and of aquatic creatures such as seal, walrus, whale, and alligator were used.

Leather shoes of Chalcolithic Areni 1 caveLeather cleaning included scrapping the back or underside of all residual tissues, blood, etc. and top side of hair or wool by stone or wooden scrapers. The processes for tanning of leathers were developed at many places, in stone age period. Tanning could take up two years for very thick hides. The dressing of leather involved paring or shaving it to achieve a level thickness. Leathers were surface treated with wax, oils and dissolved gums, often with colourants.

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Sumerians in Mesopotamia, during the 5th and 3rd C. BC. used skins for long dresses and diadems for ladies. Egyptians also used leather for clothing including gloves arms, belts and as ornaments. Phoenicians are credited with forming water tubes of leather. Romans and many other in central Asia were using leather footwear, clothing, shields and riding gears such as harnesses. Assyrians used leather for containing oils, and as inflated floats for rafts. In India thinned raw-hides were used as cover for percussion instruments.

Embossed leather royal chairs

Leather bag Water carrier Bhist IndiaBy 1st C Ad a vast variety of hides and skins were produced, many with unique characteristics due to local materials and protected knowledge base. Leathers for parchment or writing media were extremely thinned down and stabilized from raw hides. Skins used for gloves and footwear toppers were soft and supple. Patterned skins of reptiles formed pieces of ornaments. Leather stripes, entwined leather belts, were used for their flexibility and tensile strength. Furs, were prized items for wearing, furnishings and arms covers.

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SINGLE MATERIAL OBJECTS

Post 184 – by Gautam Shah

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We endeavour to create Single Material Objects. Objects made of single material, whether natural or man-made, have inherent efficiencies. We try to achieve the state of a single material efficiency by integrating or by synthesizing different components.

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  • A window consists of a structural frame, shutters, glazing system, mosquito-nets, curtains, weather-sheds, etc. It would be ideal if one integrated system, made up of a single material were to serve all the purposes.

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  • Similarly a roof is made of the structural slab, outer side water proofing coat, insulation, and floor finishes, and under side plaster, an acoustic ceiling, etc. It would be very efficient to have one material serving all these functions.Roof – multi layer.

elements of roof

  • A partition is designed to divide a space in terms of visual privacy, safety, stability, sound proofing, fire proofing, heat insulation, provisions for apertures and services, etc. The partitions as a result consist of a structural system and various layers, each designed for specific need. The partition is further coloured and textured for use requirements. The structural elements, layers and the surface treatments can be replaced by a single material-object system. Composite panels for partitioning, is a first attempt in integrating various sub systems.

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640px-Back_side_of_National_Parliament_of_Bangladesh_20A single material system capable of serving many different purposes is not easy to devise. Such an event takes years of effort. However, human ingenuity out-paces such attempts, by inventing superior but totally a different entity, for the given situation. The superiority of a newly invented entity may not be due to the unitary structure or the multi purposiveness of the material, but for its multiplex system of simpler and lesser number of elements.

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An automobile, a computer or a building, is formed of as many parts, as they consist of different materials. If one can reduce the number of parts, automatically the number of materials used, will come down. If a conscious attempt is made to reduce, the number materials used, then there will be reduction in number of components.

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At any cross section of time, we find a large number of materials systems either are overtly attached to other objects, or are in the process of being integrated with them. It is very desirable that an object system in such a situation, be singular in constitution or at least be effective in that manner. Designers aspire to provide a singular object system in place of a multi-component system. In designers’ world, however, there are very few situations where singular object system can satisfy all the demands in a particular time-space profile. Multi-component surface systems are reality.

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LOCKS

Post 154 by Gautam Shah

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Turkish Handmade Padlocks

Lock is a device that prevents access by those without a key or method to open it. It is nominally a self-sufficient entity, housed in a small chamber that houses its mechanism. Locking devices are of two types: One which can be used to lock and open an opening from same side, and Two which can be opened from either side.

Complex mechanisms under the lid of a safe

Locking devices have been in use for securing the end of the ropes in loops, but lock for security purposes (such as for doors)were perhaps wedges or knots (such as: a thief knot, Gordian knot) on fibre ropes. Egyptians were perhaps the first users of wooden Locks and keys, some 4000 years ago. The first locks were like puzzles that wasted thieves’ time.

Various types of notches or serrations on keys

Early Pin locks had toothed or serrated keys that activated matching levers. Later improvements included increasing the number of pins to increase security, and changing the orientation and profile of the pins. This established the principle of the modern pin tumbler lock.

Viking Age Lock

Key Hole or notch for the key, Guanajuato, Mexico

Locks are mostly mechanical, but now electro-mechanical and electronic locks are available. New locks get a combination of commands through nodes in a printed circuit board, varied electric current, or a digital messaging system which activates the lever system.

An Old Chinese lock

All locks are not intended to prevent unauthorised access through an opening system, but some are used to control the accidental opening or closing of a door system.

PADLOCKS  ⊗ Padlocks are portable locks, with their own body and foldable or a separable locking ring. Padlocks can be used over another ring or shackle, or with a chain to tie up separate objects. Ordinary padlocks are susceptible to direct attack to break the shackle or tie chain, without the use of a key or a combination. Padlocks are used to tie up the wrapped around ropes on goods bundles or packages.

LEVER LOCKS  ⊗  Levers Locks are flat set of grooved or edge shaped devices which can be rotated or pushed by a matching key to operate or activate a mechanism. Insurance companies, police department and other security agencies desire at least a 5-lever lock for external doors of home security system.

Anglo Viking key 900 AD

MORTICE LOCK  ⊗  Mortice (Mortise in American English) is concealed into a cavity (mortice section) in the stile or thickness of the door shutter. A square section pin projects out on one or both the faces to receive the operative handles. Older mortice lock had a large box, but new generation mortise locks are cylinder locks fitted from the front and back. The locking pin could be one or multiple that come out on the side of the door. The locking device is operated through a key, and an additional bolt -a closing device through a set of handles. The locking pin is square ended but the closing pin is tapered on one face for self closing. Night or safety locks have an extra slider which stops the lock being operative with key from outside. Installation of a mortise lock weakens the structure of the typical timber door, but it is stronger and more versatile than a bored cylindrical lock.

CYLINDER LOCK  ⊗  Cylinder locks have the locking mechanism and bolting as two separate systems. Such locks are also available as sets which can be opened by their individual keys and also by a master or common key. Standard cylinder systems include key-in-knob-set cylinders, a rim (also known as night-latch) cylinders. Cylinder locks are small in size and diameter, and are fitted from front and back side of a door shutter, rather than from the edge of a door stile (as in case of mortice lock), so are easier to fit and replace.

ALMIRAH LOCKS  ⊗  Almirah locks are found on commercial Mild Steel sheets (CRCA) cupboards. The Locks are housed in a box fixed on the inside face of a shutter. The closing device has three components, a locking lever that is moved through a handle, and accompanying it is two vertical locking bars that move upward and downward. Such devices are also concealed on a street side of main doors of buildings for additional security purposes.

A wood model showing mechanisms of a Combination lock

COMBINATION LOCK  ⊗  Combination locks are operated by setting a sequence of numbers or symbols, instead of a serrated key in a nominal lock. The sequence is entered by a single rotating dial which interacts with several discs or cams, by using a set of several rotating discs with inscribed numerals which directly interact with the locking mechanism, or through an electronic or mechanical keypad. A combination lock requires a correct permutation and not merely the correct combination of digits. Electronic combination locks are better then their mechanical counterparts. Such locks are used on safes and drawers. Electronic locks work with power-assisted mechanisms. The key combination can be reset, such as for modern Hotel rooms. Floor managers get a combination that can work for all locks of a floor or zone. Such locks are often connected to a central access control system of the plant or building complex, reporting its use.

Electronic Combination lock key-card

  • ‘The first known combination lock was invented in 1206 by the Arab scholar, inventor and mechanical engineer al-Jazari. He documented the device in his book al-Ilm Wal-Amal al-Nafi Fi Sina’at al-Hiyal (The Book of Knowledge of Ingenious Mechanical Devices). Muhammad al-Astrulabi (ca 1200) also made combination locks, two of which are kept in Copenhagen and Boston Museums. Gerolamo Cardano later described a combination lock in the 16th century. In 1852 a German man by the name of Joseph Loch was said to have invented the modern combination Lock for Tiffany’s Jewelers in New York City. However the rights to his invention were stolen from his business associate who thereby attained all credit of the discovery’.

Bank Safe

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HAMMERS

Post by –Gautam Shah

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A hand tool is an instrument of various forms and purposes, traditionally operated by the muscular power of the user. Major section of hand Tools are of Percussive variety. These tools are used to deliver blows such as axes, adz, and hammers, etc. Other varieties include cutting, drilling, and abrading tools such as the knife, awl, drill, saw, file, chisel, and plane.

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Carvers hammers of wood > Flickr image by Danny Ayers

Wood Pounders

Percussive tools deliver concentrated blows or impact in swift motion and so are also called dynamic tools. The prime tools in this category are the Axe and Hammer. An axe is a cutting tool, but it has been used for striking, so a percussive tool.

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Ancient tied Stone head hammers

HAMMERING TOOLS

A hammer is a striking tool also known as a pounder, beetle, mallet, maul, pestle, sledge, etc. There are many trade specific hammers, like, the carpenter’s claw type, smith’s riveting, boiler-maker’s, bricklayer’s, blacksmith’s, machinist’s ball peen and cross peen, goldsmiths’, smith’s stone (or spalling), prospecting, and tack hammers.

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Wood Hammer > Wikipedia image by Johan (GFDL)

Each hammer has a distinctive form, with minor variations in terms of weight, length and angle of the handle, and the profile of the face. A pounder, or hammer stone, was the second tool, after the axe to have a handle, marking a great technological advance. A long handle, is needed for striking effect such as in a tool used for light blows. It makes the tool easier to control, and generally reduces operators’ fatigue.

Splitting maul

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Stockhammer > Wikipedia Image by Reiner Flassig

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Forge trip hammer > Wikipedia image by William F. Durfee

Forging Hammer

Club like pounders or mallet, with a handle of the same as well as different materials are widely used. The hammer as a tool, for nailing, riveting, and smiting, originated in the Metal Age. For beating lumps of metal into strips and sheet, heavy and compact hammers with flat faces are needed, whereas lighter ones are more suited to riveting and driving nails and wooden pegs.

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Old Pick Hammer > Wikipedia image by Vassil

Hammers with dual heads are in use since Roman age. Hammers with dual heads include, clawed hammers for pulling out nails, hammers with a chisel or pointed ends to dig out shafts, toothed edges to smoothen the stone surfaces. Other special forms of the peen (-the end opposite the flat face) like hemispherical, round edged, and wedge like shapes helped the metalworker stretch and bend metal or the mason to chip or break stone or bricks.

Hammer for upholstery work

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from a catalogue of suppliers to watchmakers and jewelers

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Ritual hammers from Early Bronze age to II Mil BC

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Dressing Hammer > Wikipedia image by Rasbak

A file maker’s hammer has two chisel-like heads, to score flat pieces of lead (file blanks) that are subsequently hardened by heating and quenching. Heavy hammers are used as part of power tools, and largest are the pile drives for foundation work. Trip-hammers are gravity impulse based but steam hammers use, besides gravity a downward thrust from a steam-pushed piston.

Pneumatic hammers are driven by air and include the hammer drill used for work on rock and concrete. The rivetting hammer is used in steel construction for flattening rivet heads over girders and plates.

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Pounding Rice Cake in Korea > Image by Cornell University @ Flickr Commons

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Making Rice Cakes > Flickr Image by A. Davey

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