The cutting angle of twist drill is:

Explanation:

Drill Angles:

They are different angles for different purposes:

• Point Angle
• Helix angles
• Rake angle
• Clearance angle
• chisel edge angle.

Helix Angle:

• Twist drills are made with different helix angles.
• The helix angle determines the rake angle at the cutting edge of the twist drill.
• The helix angles vary according to the material being drilled.

Point Angle/Cutting Angle:

• The point angle of a general-purpose (standard) drill is 118°.
• This is the angle between the cutting edges (lips).
• This angle according to the hardness of the material to be drilled

Clearance Angle:

• The clearance angle is to prevent the friction of the tool behind the cutting edge.
• This will help in the penetration of the cutting edges into the material.
• If the clearance angle is too much, the cutting edges will be weak, and if it is too small the drill will not cut.
• The clearance angle of a drill is between 8° to 12°.

Rake angle:

• The rake angle is the angle of the flute (helix angle).

Chisel Edge Angle/ Web Angle:

• This is the angle between the chisel edge and the cutting lip.