Millwright Level 1 Practice Exam

What is the included point angle of a countersunk hole for most flathead screws?

1. 45 degrees

2. 60 degrees

3. 82 degrees

4. 90 degrees

The correct answer is: 82 degrees

The included point angle of a countersunk hole for most flathead screws is 82 degrees. This angle is designed to allow the head of the screw to sit flush with or slightly below the surface of the material when fully driven in. The 82-degree angle helps ensure a secure fit and optimal engagement with the screw's thread, which is crucial for the screw's performance and the integrity of the assembly. When countersunk holes are made with a 82-degree angle, they facilitate a proper alignment for the screw, leading to enhanced load distribution and reduced risk of material splitting. This is especially important in applications where aesthetics matter, such as in woodworking or metal fabrication, as it allows for a neat finish. While other angles like 45 degrees and 60 degrees may be used in specific applications, they do not provide the same balance of strength and aesthetic appearance as the 82-degree angle does for flathead screws. A 90-degree angle, on the other hand, would not allow for the screw head to be properly seated and is unsuitable for most screw designs. Thus, the 82-degree included angle is the standard in various industrial applications, ensuring both effective functionality and a neat finish.