A spindle is a rotating shaft with a fixture for holding a tool (in the case of a milling, grinding, or drilling spindle) or a workpiece (in the case of a turning spindle). The spindle shaft serves as a support, a positioner, and a rotary drive for the tool or workpiece.
In machine tools, a spindle is a rotating axis of the machine, which often has a shaft at its heart.On a lathe (whether wood lathe or metal lathe), the spindle is the heart of the headstock.
How Do Spindles Work? Machining spindles are often powered by electricity, but they can also be powered by compressed air. They're available in a wide range of sizes to meet many different needs. A spindle is devised of a motor, a taper for holding tools, and a shaft that holds together all the separate components.