Explanation
Machine tool operators must be able to install or remove tool bits quickly and easily. A lathe, for example, has a rotating spindle in its headstock, to which one may want to mount a spur drive or work in a collet. Another example is a drill press, to which an operator may want to mount a bit directly, or using a drill chuck.
Virtually all milling machines, from the oldest, manual machines up to the most modern CNC machines utilize tooling that is piloted on a tapered surface.
The machine taper is a simple, low-cost, highly repeatable, and versatile tool mounting system that uses tool bits (or holders) with gradually tapered shanks, and a matching hollowed-out spindle.
For light loads (such as encountered by a lathe tailstock), tools are simply slipped onto or into the spindle; the pressure of the spindle against the workpiece drives the tapered shank tightly into the tapered hole. The friction across the entire surface area of the interface provides a large amount of torque transmission, so that splines or keys are not required.
For use with heavy loads (such as encountered by a milling machine spindle), there is usually a key to prevent rotation and/or a threaded section, which is engaged by a matching drawbar. The drawbar is then tightened, drawing the shank firmly into the spindle.
Read more about this topic: Machine Taper
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