ABSTRACT
Of the immense variety of tools and mechanical contrivances employed in modern times, by far the greatest number are designed to impart to certain materials some definite shape. The brickmaker’s mould, the joiner’s plane, the stonemason’s chisel, the potter’s wheel, are examples of simple tools. The method of forming screws by dies and taps is applicable only to those of small dimensions, and even for these it is not employed where great accuracy is required. A good example of a machine-tool is the Drilling Machine, which is used for drilling holes in metal. The first obvious difference between an ordinary lathe and Blanchard’s invention is that in the former the work revolves rapidly and the cutting-tool is stationary, or only slowly shifts its position in order to act on fresh portions of the work, while in the latter the work is slowly rotated and the cutting-tools are made to revolve with very great velocity.
