<P> The headstock (H1) houses the main spindle (H4), speed change mechanism (H2, H3), and change gears (H10). The headstock is required to be made as robust as possible due to the cutting forces involved, which can distort a lightly built housing, and induce harmonic vibrations that will transfer through to the workpiece, reducing the quality of the finished workpiece . </P> <P> The main spindle is generally hollow to allow long bars to extend through to the work area . This reduces preparation and waste of material . The spindle runs in precision bearings and is fitted with some means of attaching workholding devices such as chucks or faceplates . This end of the spindle usually also has an included taper, frequently a Morse taper, to allow the insertion of hollow tubular (Morse standard) tapers to reduce the size of the tapered hole, and permit use of centers . On older machines (' 50s) the spindle was directly driven by a flat belt pulley with lower speeds available by manipulating the bull gear . Later machines use a gear box driven by a dedicated electric motor . A fully' geared head' allows the operator to select suitable speeds entirely through the gearbox . </P> <P> The bed is a robust base that connects to the headstock and permits the carriage and tailstock to be moved parallel with the axis of the spindle . This is facilitated by hardened and ground bedways which restrain the carriage and tailstock in a set track . The carriage travels by means of a rack and pinion system . The leadscrew of accurate pitch, drives the carriage holding the cutting tool via a gearbox driven from the headstock . </P> <P> Types of beds include inverted "V" beds, flat beds, and combination "V" and flat beds . "V" and combination beds are used for precision and light duty work, while flat beds are used for heavy duty work . </P>

Which tool is used where there is not enough room to move a regular wrench