Many of the common uses of a rotary table have become redundant with the introduction of numerical control. Radial profiles are now achieved by circular interpolation, and the positioning of holes or slots in angular relationship to each other, possibly using polar coordinates, has been reduced to nothing more complicated than a simple one-block data entry in the machine program.
Rotary tables of this type may be attached to the machine bed in the normal way or be a built-in feature of the machine table, as illustrated.
Conventional dividing heads are also redundant as far as computer numerical control is concerned. They have been replaced by indexers, fully programmable and controlled via the machining program. Simple versions allow up to 24 positions, or increments of 15°, rather like the direct indexing plate fitted to conventional dividing heads.
For more complex indexing or where regular rotation is required, for example when cutting a helix, a slightly more sophisticated version is needed, with up to 360,000 positions and feed-rate controls. Some of these devices are capable of rotating in two.