The type of fixture for holding and controlling the movement of the cutting tool include the tail stock,
carriage, cross slide, and compound rest. The carriage, like the tail stock, is movable on the ways of the
bed. The motion is parallel to the rotational axis of the spindle, and this motion is commonly used for
producing cylindrical surfaces.
A compound rest is used for producing some tapered surfaces, for helping in the cutting of threads by
thread chasing, and for several other types of applications. Mounted above the compound rest, the tool
post serves to clamp the cutting tool, or tool holder, in a desired position.
At the base of the tool, post the rocker plate has a concave spherical surface facing upward.
Usually the cutting tool consists of a tool holder, which carries a tool bit. Different tool holders are
available to hold tool bits at various desired horizontal angles. A rocker for mounting the tool holder that
has a mating convex spherical surface fits above the rocker plate, and the cutting tool is clamped above
this rocker. The rocker plate and rocker thus permit the cutting edge of the cutting tool to be raised or
lowered. When the cutting tool has been properly positioned, a setscrew is tightened to clamp the
cutting tool rigidly.