Potter’s wheel

Topfer-ofen, m. potter s kiln, -scheibe, /. potter s wheel, -ton, m. potter s clay, -ware, /. pottery. 

Conventional ceramics initially take shape on a potter s wheel or by slip casting and are fired (sintered) in kilns advanced ceramics are formed and sintered in more complex processes such as hot isostatic pressing. 

BC Mesopotamia The potter wheel for modelling The use of the potter s wheel can be derived from the structure of the manufactured pottery. ... 

Turning takes place on a potter s wheel and is only suitable for so-called rotation symmetric shapes. This means that the objects which are made, such as plates, dishes and vases, are symmetric along an axis or point of symmetry. 

Using a potter s wheel requires strength and control. As the potter s wheel spins, clay is pulled up by a potter into a predetermined shape. The type of clay, along with the potter s skills, determines the range of possible shapes for resulting pieces. 

Hopper, Robin. Beginning to Throw on the Potter s Wheel. 60 min. Para Productions, 2003. potteryvideos.com. DVD. 

Introduction to Throwing on the Potter s Wheel. 53 min. Geneva, FL Thoughtful Productions, 1993. 

In fact it seems very unlikely that some of man s early machines would have worked at all without lubricants. One of the fastest ways to produce wood dust ("saw-dust") is to operate a wooden bearing without a lubricant. A very effective way to soften and weld metals is to operate a metallic bearing without a lubricant. Without lubricants the early geniuses who invented potter s wheels or chariot axles would have generated such rapid wear or seizure that they would probably have given up and gone back to some useful activity like hunting. 

Plastic forming is based on the plasticity of water-containing clay ceramic pastes and, in the form of the potter s wheel, is the oldest known sort of forming. This turning of ceramic products can be automated on a large scale using the roller process. 

The raw materials for traditional ceramics are natural clays that come from the earth as powders or thick pastes and become plastic enough after adjustment of their water content to be formed freehand or on a potter s wheel. Special ceramics (both oxide and nonoxide) require chemically pure raw materials that are produced synthetically. Close control of the purity of the starting materials for these ceramics is essential to produce finished pieces with the desired properties. In addition to being formed by hand or in open molds, ceramic pieces are shaped by the squeezing (compacting) of the dry or semidry powders in a strong, closed mold of the desired shape, at either ordinary or elevated temperatures (hot pressing). 

Traditional ceramics are characterized by mostly silicate-based porous microstructures that are quite coarse, nonuniform, and multiphase. They are typically formed by mixing clays and feldspars, followed by forming either by slip casting or on a potter s wheel, firing in a flame kiln to sinter them, and finally glazing. 

By equating uniform and circular motion it is natural for the earth to move in a circle, not an ellipse, but without a law of gravitation Galileo could never present a coherent discussion of centrifugal effects. Objects kept on flying away from the rotating earth as from a potter s wheel. 

It was widely appreciated by Newton and his contemporaries that the compressive effect of the Cartesian aether was equivalent to some hypothetical force, often likened to gravity, that puUs a planet towards the central star and bends its rectilinear motion around into a closed curve. The magnitude of such a force had to be sufficient to balance the centrifugal, potter s wheel, effect and so prevent the rotating planet firom escaping. It became vitally important to calculate the centripetal acceleration that was needed to stabilize such a closed orbit. 

Machines in the most simple of forms utilizing the basic fundamentals of modem machine tools have been existing for many thousands of years. Examples are bow drills and potter s wheels found in ancient Eg3 pt and pole lathes from before the industrial revolution. Modem concepts of a machine tool began to emerge around the sixteenth century when screw-cutting lathes were developed. Various advancements such as metal frames, more accurate pitch control, and more sophisticated power sources all contributed to the steady advancement of machining ease and improved quality (Rolt 1965) (Fig. 1). 

For thousands of years, all manufacturing was limited by the power that was available to perform the task, and metal spinning was no different. Initially, power was supplied by a foot pedal that rotated the tool—analogous to the potter s wheel. Forming power for making the metal take shape was supplied by the hands and arms of the worker as he held the blunt-end tool or, in later years, the roller, against the metal. 

B.C.E. Potter s wheel The potter s wheel is developed, allowing for the relatively rapid formation of radially symmetric items, such as pots and plates, from clay. 

B.C.E. Wheel The chariot wheel and the wagon wheel evolve—possibly from the potter s wheel. One of humankind s oldest and most important inventions, the wheel leads to the invention of the axle and a bearing surface. 

Throwing. The method of shaping pottery hollow-ware in which a ball of the prepared body is thrown on a revolving potter s wheel, where it is centred and then worked into shape with the hands. The process is now chiefly used by studio potters, although a small amount of high-class commercial pottery is still made in this way. 

Deformation of material by shearing requires, as a mle, the application of a lower stress than for other modes of applying load. Such a deformation can be achieved at many points of the clay-water mix, if tangent stress is applied to its surface. The discovery of this behaviour of the clay-water mix is believed to have been the reason behind an innovation introduced around 5,000 years ago in Sumer, namely, the formation of clay products with a potter s wheel. 

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