Grindstone

A grindstone, also known as grinding stone, is a sharpening stone used for grinding or sharpening ferrous tools, used since ancient times. In Australia, Aboriginal peoples created grinding grooves by repeatedly shaping stone axes by grinding them against outcrops of sandstone.

Grindstones have been used since ancient times, to sharpen tools made of metal. They are usually made from sandstone.[2][3]

Aboriginal grinding grooves, or axe-grinding grooves, have been found across the continent.[4] 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,[5] 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.[4]

Grindstone 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]

In Estonian, one of the most common insults is "käi perse"; which literally translates to "(may somebody put) a grindstone to your arse."[10]

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