Grindstone

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.

[3] Grindstone machines work by spinning a circular piece of stone around its center point.

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.

[7] The Luttrell Psalter, dating to around 1340, describes a grindstone rotated by two cranks, one at each end of its axle.

The Knife-grinder by Goya shows a man using a portable grindstone.
Aboriginal grinding grooves in the Blue Mountains , New South Wales, Australia
Large waterwheel powered grindstone. The user would lie on the plank above the grindstone while grinding metal items, giving rise to the phrase nose to the grindstone . [ 5 ]