Which type of screw has a fully threaded shank and is typically installed with an allen wrench?

• A. Cap bolt
• B. Wood screw
• C. Set screw
• D. Machine bolt

Answer: (C)

The type of screw characterized by a fully threaded shank and typically installed with an allen wrench is the set screw. Set screws are designed to secure an object within or against another object, usually without requiring a nut. They feature a head that can be gripped by an allen wrench, which enables the user to apply significant torque, ensuring a tight fit.

Set screws are commonly used in machinery to secure rotating components, like gears or pulleys, onto shafts. Their fully threaded design allows for lots of adjustment and locking capability. In contrast, cap bolts, wood screws, and machine bolts have different applications and characteristics. Cap bolts, for instance, have a hexagonal head and are used with a wrench, while wood screws are designed specifically for use with wood, featuring a tapered point and coarse threads. Machine bolts are typically partially threaded and used with nuts. These distinctions underscore the unique role set screws play in fastening applications.