Sample screw from the model of the screw-cutting lathe, by Henry Maudslay, England, 1800-1820

Henry Maudslay pioneered the development of the screw-cutting lathe and improved machine tools built wholly of metal. He was accustomed to make models to illustrate and develop his ideas, and this one was preserved within the company he founded. It represents quite an advanced machine, specifically designed for making large screws. The screw being cut was turned directly by a labourer at the capstan wheel. The gears transmitted motion to a lead-screw that drew along the sliding saddle carrying the cutting tool. The machinist used the micrometer handwheel on the saddle to regulate the depth of the cut and to withdraw the tool as the machine was reversed, ready for another pass. The full-size lathe, perhaps intended to be about 2 or 3 metres long, would have been built of iron.