I use Torx head screws for almost every woodworking application. They are sold as exterior, construction and deck screws and the Home Depot Deckmate and Grip Rite brands come with the required T-25 Torx bit, one in each box screws.
Torx screws were invented in 1967 by Camcar Textron and is a type of screw drive with a 6-point star-shaped pattern. The International Organization for Standardization (ISO) has given them the designation of ISO 10664 and are called hexalobular internal (6lobe). They were initially used on automobiles, motorcycles, bicycle brake systems (disc brakes), hard disk drives, computer systems and consumer electronics.
They were designed to use instead of common Phillips heads that tend to cam-out under high torque. Cam-out is when the screwdriver, or the screwdriver bit, you’re using slips out of the screw’s head while you’re trying to tighten or loosen the screw which can lead to a stripped screw head. Torx was designed to not cam-out and can withstand higher torques than internal hex at a given head size.
Vertical sidewalls maximize tool engagement and produce no cam-out forces to push the driver out of the screw head, resulting in less fatigue as no end load is required. It’s also less likely to damage the driver or driven screw.
Torx sizing is from T1-T100 with the smaller number corresponding to a smaller point-to-point dimension of the screw head (diameter of circle circumscribed on the cross-section of the tip of the screw driver).
