Bolt Drive Style

  • Phillips

    Combination Phillips-slotted drives are used with either a Phillips or standard slotted driver. The drive style is designed so that the driver will cam out, or slip out, under pressure to prevent over-tightening. These are often used to attach knobs to furniture.

  • External

    External hex drives are six-sided, or hexagonal, and are driven by a crescent wrench, combination wrench, or sockets. They require minimal clearance above the fastener because they can be tightened or loosened from the side. External hex drives outperform external square drives in scenarios with limited fastener access, because smaller swing arcs may be used to rotate the fastener.

  • Internal

    Internal hex drives, also known as hex-socket drives, are similar to hex drives, but have a hexagonal hole in the center that requires an Allen key, also known as a hex key or Allen wrench.

  • Not

    Not applicable defines a fastener that is either hand-driven, or held in place during use. Hand driven examples include knurled screws and spade screws. Since these are head styles, the drive style is not applicable. Carriage bolts, eye bolts, J bolts, and U bolts are all held in place during use while the nut is fed onto the threaded end of the fastener, tightening the bolt in place from the end rather than the head. The carriage bolt is held by its square neck, while eye, J, and U bolts are held in place by hand or with a tool.

  • Phillips

    Phillips drives have x-shaped slots with rounded corners and are driven with a Phillips screwdriver. The slot is designed so that the driver will cam-out, or slip out, under pressure to prevent over-tightening.

  • Slotted

    Slotted drives have a linear slot and are used with a flat-bladed screwdriver. These drives are commonly used in woodworking and are prone to slippage.

  • Spline

    Spline drives have twelve splines, or rounded plateau-like ridges, on the fastener and tool. Spline drives resist cam out, so they are frequently used in high-torque applications, such as tamper-proof lug nuts.

  • Star

    Star drives, also called Torx drives, have 6-pointed indentations that provide more driving surface area. These drives resist cam-out better than Phillips drives or slotted drives. They are used with a Torx screwdriver.

  • Triple

    Triple square drives, also known as XZN, drives have 12 equally spaced tips, each with an internal 90 degree angle. Three identical overlaid squares are rotated to form a pattern. Triple square drives are useful in higher torque applications, such as drive train components. Many German vehicle manufacturers use triple square fasteners on their automobiles.