Francisco de Goya y Lucientes - Knife Grinder - WGA10060

A grindstone, also known as grinding stone, is a

sharpening stone Sharpening stones, or whetstones, are used to sharpen the edges of steel tools such as knives through grinding and honing. Such stones come in a wide range of shapes, sizes, and material compositions. They may be flat, for working flat edg ...

used for

grinding Grind is the cross-sectional shape of a blade. Grind, grinds, or grinding may also refer to: Grinding action * Grinding (abrasive cutting), a method of crafting * Grinding (dance), suggestive club dancing * Grinding (video gaming), repetitive and ...

or sharpening

ferrous In chemistry, the adjective Ferrous indicates a compound that contains iron(II), meaning iron in its +2 oxidation state, possibly as the divalent cation Fe2+. It is opposed to "ferric" or iron(III), meaning iron in its +3 oxidation state, such a ...

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 upright=1.35, Sheets of sandpaper with different grit sizes (40 (coarse), 80, 150, 240, 600 (fine)). Sandpaper and glasspaper are names used for a type of coated abrasive that consists of sheets of paper or cloth with abrasive material glued to ...

, each stone has a different grit that will result in sharper or duller tools. In Australia,

Aboriginal peoples Indigenous peoples are culturally distinct ethnic groups whose members are directly descended from the earliest known inhabitants of a particular geographic region and, to some extent, maintain the language and culture of those original people ...

created grinding grooves by repeated shaping of

stone axe A hand axe (or handaxe or Acheulean hand axe) is a prehistoric stone tool with two faces that is the longest-used tool in human history, yet there is no academic consensus on what they were used for. It is made from stone, usually flint or che ...

s against

outcrop An outcrop or rocky outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth. Features Outcrops do not cover the majority of the Earth's land surface because in most places the bedrock or superficial ...

s of

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...

History and description

Grindstones have been used since ancient times, to sharpen tools made of metal. They are usually made from

Grinding grooves

Aboriginal grinding grooves, or axe-grinding grooves, have been found across the Australian continent. 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 An oval () is a closed curve in a plane which resembles the outline of an egg. The term is not very specific, but in some areas (projective geometry, technical drawing, etc.) it is given a more precise definition, which may include either one or ...

-shaped groove over time, The grooves vary in length from up to , and can be up to wide and deep. They are often found near water, which was sprinkled on the stone during grinding to reduce dust.

Machines

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, operated by a crank handle, is found in the

Carolingian The Carolingian dynasty (; known variously as the Carlovingians, Carolingus, Carolings, Karolinger or Karlings) was a Frankish noble family named after Charlemagne, grandson of mayor Charles Martel and a descendant of the Arnulfing and Pippin ...

manuscript known as the

Utrecht Psalter The Utrecht Psalter (Utrecht, Universiteitsbibliotheek, MS Bibl. Rhenotraiectinae I Nr 32.) is a ninth-century illuminated manuscript, illuminated psalter which is a key masterpiece of Carolingian art; it is probably the most valuable manuscript ...

. This pen drawing from about 830 goes back to a late antique original. The

Luttrell Psalter The Luttrell Psalter (British Library, Add MS 42130) is an illuminated manuscript, illuminated psalter commissioned by Sir Geoffrey Luttrell (1276–1345), lord of the manor of Irnham in Lincolnshire, written and illustrated on parchment ''circa'' ...

, dating to around 1340, describes a grindstone rotated by two cranks, one at each end of its axle. Around 1480, the early medieval rotary grindstone was improved with a

treadle A treadle (from oe, tredan, "to tread") is a mechanism operated with a pedal for converting reciprocating motion into rotating motion. Along with cranks, treadmills, and treadwheels, treadles allow human and animal machine power in the absenc ...

and

crank mechanism 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 vic ...

References

Sources

* * Woodworking Grinding and lapping Knives {{metalworking-stub

History and description

Grinding grooves

Machines

See also

References

Sources