Around 1480, the early medieval rotary grindstone was improved with a treadle and crank mechanism. A dobby loom is an alternative to a treadle loom. Some women have learned to sew and own sewing machines (often antique treadle machines). The old-fashioned pointed driven spindle is not a common feature of the treadle wheel. In 1810, the foot treadle broom machine was invented. Around 1480, the crank mechanism is further mechanized by adding a treadle. Early machines compatible with Edison cylinders were modified treadle machines. The device is operated by a foot treadle that opens and closes a potentiometer. The clamp is operated by the operator pressing their feet onto a treadle bar below. Early electric conversions consisted of mounting a motor in the treadle cabinet. A feeder operated by a treadle is called an underfeeder. Later motor kits dispensed entirely with the treadle, treadle belt, and cabinet. Jigsaws first emerged in the 19th century and employed a treadle to operate the blade. The crossbow was drawn using a treadle and shot 10 foot long arrows. It also cost significantly less than a full treadle.