Millwright Level 1 Practice Exam

What are the drill point included angles for soft, general, and hard materials?

1. 30-60, 90, 120 degrees

2. 60-90, 118, 150 degrees

3. 80-100, 120, 160 degrees

4. 45, 90, 135 degrees

The correct answer is: 60-90, 118, 150 degrees

The drill point included angles for different types of materials are essential for achieving optimal drilling performance and material removal. For soft materials like wood and plastic, a drill point angle in the range of 60 to 90 degrees allows for easier penetration and a more efficient cutting action. The larger included angle (approaching 90 degrees) helps to create a cutting edge that can efficiently carve through softer materials without excessive friction. For general materials, which include some mild steels and non-ferrous metals, an included angle of around 118 degrees is typical. This angle strikes a balance that allows for good cutting efficiency and chip removal while minimizing drill wear. When drilling hard materials such as stainless steel or hardened alloys, a larger included angle of about 150 degrees is often employed. This wider angle reduces the amount of cutting edge that contacts the material, helping to prevent overheating and excessive wear on the drill bit. Understanding these angles is crucial for millwrights and maintenance personnel, as using the appropriate drill point angle enhances tool life and performance, reduces the likelihood of drill bit breakage, and ensures better overall results in various drilling applications.