What is the included angle of a drill bit?

What is the included angle of a drill bit?

• A. 118 Degrees
• B. 90 Degrees
• C. 135 Degrees
• D. 100 Degrees

Answer: (A)

The included angle is the angle between the two cutting edges at the tip of the drill, i.e., the point angle of the bit. For most standard twist drills, that angle is about 118 degrees. This provides a solid balance: the tip is sharp enough to cut efficiently and produce a clean hole, but still durable enough to resist chipping and wear. A sharper point (like 90 degrees) would be more prone to dulling and wandering, while a blunter point (like 135 degrees) would cut more slowly and generate more heat. So 118 degrees is the typical, reliable choice for general drilling tasks.

The included angle is the angle between the two cutting edges at the tip of the drill, i.e., the point angle of the bit. For most standard twist drills, that angle is about 118 degrees. This provides a solid balance: the tip is sharp enough to cut efficiently and produce a clean hole, but still durable enough to resist chipping and wear. A sharper point (like 90 degrees) would be more prone to dulling and wandering, while a blunter point (like 135 degrees) would cut more slowly and generate more heat. So 118 degrees is the typical, reliable choice for general drilling tasks.