Original screw-cutting lathe, made by Henry Maudslay, end of 18th century

Henry Maudslay's original screw-cutting lathe, c.1800. This is the machine that Maudslay used to pioneer the manufacture of highly accurate screw threads. Before Maudslay's invention, screw threads were crudely manufactured by hand. The lathe is built on two parallel triangular bars. One bar carries conventional headstocks to hold the workpiece. A slide rest riding on both bars carries a tool holder equipped with a screw feed and a micrometer dial to regulate the depth of cut. The leadscrew carried between the bars moves the slide rest along, and was geared to the lathe mandrel by change wheels (now missing). The lathe was hand-driven.