Quill - Any of a number of mechanisms in which a hollow shaft surrounds another shaft.

• The carriage of a milling machine to which a spindle is attached. The carriage is hollow and surrounds the spindle shaft. Additionally, the carriage itself may also be surrounded by a hollow way structure.
• Hollow fixture in a lathe tailstock that, 1. stabilizes the workpiece from the side opposite the spindle or, 2. houses and positions a collet or chuck holding a reamer or bit for center drilling.