Which type of screw is most suitable for securing a pulley onto a shaft?

The most suitable type of screw for securing a pulley onto a shaft is the set screw. Set screws are designed specifically for this purpose, as they are typically used to secure an object within or against another object without the need for a nut. They are often threaded to screw directly into the shaft and, when properly tightened, can hold the pulley firmly in place.

Set screws may have a flat or pointed end which allows them to dig into the shaft material, creating a friction fit that helps prevent the pulley from slipping or rotating unintentionally during operation. This tight fit is critical in mechanical applications where precision and stability are required.

In contrast, other types of screws mentioned are not ideally suited for this specific application. Hex screws and machine screws are generally used with nuts or in threaded holes and do not provide the same direct locking capability on a shaft as set screws do. Wood screws are designed for fastening into wood and would not provide the necessary grip or stability for securing a metal pulley to a metal shaft.