A grindstone, also known as grinding stone, is a sharpening stone used for grinding or sharpening ferrous tools, used since ancient times. Tools are sharpened by the stone's abrasive qualities that remove material from the tool through friction in order to create a fine edge. Similar to sandpaper, each stone has a different grit that will result in sharper or duller tools. In Australia, Aboriginal peoples created grinding grooves by repeated shaping of stone axes against outcrops of sandstone.
Grindstones have been used since ancient times, to sharpen tools made of metal. They are usually made from sandstone. [1] [2]
Aboriginal grinding grooves, or axe-grinding grooves, have been found across the Australian continent. [3] The working edge of the hatchet or axe was sharpened by rubbing it against an abrasive stone, eventually leading to the creation of a shallow oval-shaped groove over time, [4] The grooves vary in length from 80 mm (3.1 in) up to 500 mm (20 in), and can be up to 200 mm (7.9 in) wide and 100 mm (3.9 in) deep. They are often found near water, which was sprinkled on the stone during grinding to reduce dust. [3]
Grindstone machines work by spinning a circular piece of stone around its center point. These machines usually have pedals for speeding up and slowing down the stone to control the sharpening process. The earliest known representation of a rotary grindstone, [6] operated by a crank handle, is found in the Carolingian manuscript known as the Utrecht Psalter. This pen drawing from about 830 goes back to a late antique original. [7] The Luttrell Psalter, dating to around 1340, describes a grindstone rotated by two cranks, one at each end of its axle. [8] Around 1480, the early medieval rotary grindstone was improved with a treadle and crank mechanism. [9]
A crankshaft is a mechanical component used in a piston engine to convert the reciprocating motion into rotational motion. The crankshaft is a rotating shaft containing one or more crankpins, that are driven by the pistons via the connecting rods.
Stone tools have been used throughout human history but are most closely associated with prehistoric cultures and in particular those of the Stone Age. Stone tools may be made of either ground stone or knapped stone, the latter fashioned by a craftsman called a flintknapper. Stone has been used to make a wide variety of tools throughout history, including arrowheads, spearheads, hand axes, and querns. Knapped stone tools are nearly ubiquitous in pre-metal-using societies because they are easily manufactured, the tool stone raw material is usually plentiful, and they are easy to transport and sharpen.
In archaeology, ground stone is a category of stone tool formed by the grinding of a coarse-grained tool stone, either purposely or incidentally. Ground stone tools are usually made of basalt, rhyolite, granite, or other cryptocrystalline and igneous stones whose coarse structure makes them ideal for grinding other materials, including plants and other stones.
Millstones or mill stones are stones used in gristmills, used for triturating, crushing or, more specifically, grinding wheat or other grains. They are sometimes referred to as grindstones or grinding stones.
A saw is a tool consisting of a tough blade, wire, or chain with a hard toothed edge used to cut through material. Various terms are used to describe toothed and abrasive saws.
An abrasive is a material, often a mineral, that is used to shape or finish a workpiece through rubbing which leads to part of the workpiece being worn away by friction. While finishing a material often means polishing it to gain a smooth, reflective surface, the process can also involve roughening as in satin, matte or beaded finishes. In short, the ceramics which are used to cut, grind and polish other softer materials are known as abrasives.
Beveled glass is usually made by taking thick glass and creating an angled surface cut (bevel) around the entire periphery. Bevels act as prisms in sunlight creating an interesting color refraction which both highlights the glass work and provides a spectrum of colors which would ordinarily be absent in clear float glass.
A crank is an arm attached at a right angle to a rotating shaft by which circular motion is imparted to or received from the shaft. When combined with a connecting rod, it can be used to convert circular motion into reciprocating motion, or vice versa. The arm may be a bent portion of the shaft, or a separate arm or disk attached to it. Attached to the end of the crank by a pivot is a rod, usually called a connecting rod (conrod).
A file is a tool used to remove fine amounts of material from a workpiece. It is common in woodworking, metalworking, and other similar trade and hobby tasks. Most are hand tools, made of a case hardened steel bar of rectangular, square, triangular, or round cross-section, with one or more surfaces cut with sharp, generally parallel teeth. A narrow, pointed tang is common at one end, to which a handle may be fitted.
Quern-stones are stone tools for hand-grinding a wide variety of materials, especially for various types of grains. They are used in pairs. The lower stationary stone of early examples is called a saddle quern, while the upper mobile stone is called a muller, rubber, or handstone. The upper stone was moved in a back-and-forth motion across the saddle quern. Later querns are known as rotary querns. The central hole of a rotary quern is called the eye, and a dish in the upper surface is known as the hopper. A handle slot contained a handle which enabled the rotary quern to be rotated. They were first used in the Neolithic era to grind cereals into flour.
A grinding machine, often shortened to grinder, is any of various power tools or machine tools used for grinding. It is a type of material removal using an abrasive wheel as the cutting tool. Each grain of abrasive on the wheel's surface cuts a small chip from the workpiece via shear deformation.
Medieval technology is the technology used in medieval Europe under Christian rule. After the Renaissance of the 12th century, medieval Europe saw a radical change in the rate of new inventions, innovations in the ways of managing traditional means of production, and economic growth. The period saw major technological advances, including the adoption of gunpowder, the invention of vertical windmills, spectacles, mechanical clocks, and greatly improved water mills, building techniques, and agriculture in general.
Grinding wheels are wheels that contain abrasive compounds for grinding and abrasive machining operations. Such wheels are also used in grinding machines.
A grinding dresser or wheel dresser is a tool to dress the surface of a grinding wheel. Grinding dressers are used to return a wheel to its original round shape, to expose fresh grains for renewed cutting action, or to make a different profile on the wheel's edge. Utilizing predetermined dressing parameters will allow the wheel to be conditioned for optimum grinding performance while truing and restoring the form simultaneously.
A sharpening jig is often used when sharpening woodworking tools. Many of the tools used in woodworking have steel blades which are sharpened to a fine edge. A cutting edge is created on the blade at the point at which two surfaces of the blade meet. To create this cutting edge a bevel is formed on the blade, usually by grinding. This bevel is subsequently refined by honing until a satisfactorily sharp edge is created.
Sharpening stones, or whetstones, are used to sharpen the edges of steel tools such as knives through grinding and honing.
Sharpening is the process of creating or refining the edge joining two non-coplanar faces into a converging apex, thereby creating an edge of appropriate shape on a tool or implement designed for cutting. Sharpening is done by removing material on an implement with an abrasive substance harder than the material of the implement, followed sometimes by processes to polish/hone the sharp surface to increase smoothness.
Knife sharpening is the process of making a knife or similar tool sharp by grinding against a hard, rough surface, typically a stone, or a flexible surface with hard particles, such as sandpaper. Additionally, a leather razor strop, or strop, is often used to straighten and polish an edge.
Sydney rock engravings, or Sydney rock art, are a form of Australian Aboriginal rock art in the sandstone around Sydney, New South Wales, Australia, that consist of carefully drawn images of people, animals, or symbols. Many thousands of such engravings are known to exist in the Sydney region, although the locations of most are not publicised to prevent damage by vandalism, and to retain their sanctity, as they are still regarded as sacred sites by Indigenous Australians. There are two art environments in Sydney Basin, rock shelters and engraving sites.
There are grooves carved into rock in many places in Europe, and some of them appear on the Baltic Sea island of Gotland. They are common in France, where they were used to polish stone axes.
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