Set screw

To reduce the chance of slipping and to increase load capacity, a detent (often called a "flat") may be milled or ground at the part of the shaft where the set screw's point contacts.

The use of keys and keyways instead of, or in combination with, set screws is common for applications requiring high torque resistance or transmission.

For longer life, set screws are usually made of alloy steel and case hardened.

On the pro side, such deformation increases the holding power (torque resistance) of the joint, as the screw is essentially "making its own detent" on a small but effective scale.

On the con side, if one is aiming to have a blemish-free cosmetic finish on the part being set against, one must take actions to prevent the circular marks.

This can result in difficulties during dis-assembly if a bearing or other tightly toleranced part needs to slide past this area.

Durability studies show that the cup point offers superior resistance to wear while maintaining a strong grip.

The serrated ridge on the knurl cup set screw helps reduce loosening due to vibration.

Headless set screws have been around for a long time, with the straight slot being the oldest drive type (due to its ease of machining), but the demand for headless set screws experienced a marked increase in the first and second decades of the 20th century, when a penchant for better industrial safety, a campaign with the slogan "safety first",[7] swept the industrialized nations of North America and Europe as a part of the larger Progressive Movement.

It was this heightened demand that prompted Hallowell's firm to get into the screw-making business and to explore socket-head drive designs.