The drill spindle is a vertical shaft, which holds the drill. A long keyway is cut on the spindle and a sliding key connects it with a bevel gear or a stepped cone pulley. It receives motion from the driving motor. The spindle rotates within a non-rotating sleeve known as quill. The spindle and the sleeve are connected by a thrust bearing.
Rack teeth are cut on the outer surface of the quill. The sleeve (quill) may be moved up and down by rotating a pinion which meshes with the rack. This movement is given to the spindle for providing the required feed. As there is a long keyway on top of the spindle, it is connected to the driving mechanism even during the feed movement.
A morse taper hole is provided at the lower end of the spindle. It is useful in accommodating a taper shank drill. The tang of the drill fits into a slot provided at the end of the taper hole. To remove the drill from the spindle a drift may be pushed through the slot.
The spindle drive is obtained in three methods. They are:
- Step cone pulley drive
- Step cone pulley with back gear arrangement
- Gear box drive