Abstract: A machining unit comprising a quill carrying a spindle, a tool clamping mechanism on a forward end of the spindle, a drive shaft for rotatably driving the spindle through the quill, a tool feed actuator for extending and retracting the quill to and from a home position in both axial directions, the clamping mechanism being arranged to grip a tool holder when the quill is at or forward of the home position and to release or accept a tool holder when it is rearward of the home position.

Abstract: A self-contained precision quill-feed unit is provided with a positive stop arrangement to control depth of tool feed. The stop position is adjustable from the exterior of the unit and the stop abutments associated with moving and stationary members are positioned in such manner that no yawing forces are imposed on the quill, drive shaft and spindle of the unit. Additionally, yawing forces generated by the mechanical resistance of a known type of hydraulic constant velocity control (CVC) cylinder are opposed by reaction forces associated with the anti-rotation linkage that prevents rotation of the quill. Together these features provide overall a machine in which quill, drive shaft and spindle deflection or yawing is minimized or prevented.