NIMS Milling Practice Test

The included angle at the point of a general-purpose drill is typically 118°. This angle is designed to provide a balance between cutting efficiency and drilling speed. A 118° angle allows the drill bit to create a sharp point, which facilitates easier penetration into the material being drilled. This angle is suitable for most materials, including metals and plastics, making it a standard choice for general-purpose drilling applications.

In contrast, angles such as 90° or 135° are designed for specific applications. A 90° point may create a more aggressive cut for certain tasks but can be less effective in softer materials. The 135° angle is often used for specific purposes like drilling into harder materials or for reaming applications, where precision is crucial. A 150° angle is quite blunt and generally not suitable for effective drilling in most situations. Thus, 118° remains the universally accepted angle for general-purpose drills.