How To

Bit History: The Torx

This is the sixth and final article in our ongoing series of posts on the history of screwdriver bits. We’ve be posting one a day leading up to tomorrow’s launch of the Manta Driver Kit and Mahi Driver Kit.

So you know when you’re sitting in a bathroom stall and you hatch a diabolical plan to disassemble the entire room?

Just me? Admittedly, I do have some strange tendencies—but I’m a teardown engineer. A passion for reverse engineering is pretty much a job requirement. As an added benefit, my fascination with disassembly has made me all too aware just how many Torx screws are floating around the bathrooms and vending machines in this world. (By the way, I’m not the only one who has noticed.)

More technically named the hexalobular bit (and commonly referred to as star-drive by people wielding power tools), the Torx screw (not its bastard brother, the Torx Security screw) holds a special place in my heart.

First developed in 1967 by Camcar Textron and patented in 1971, the Torx bit was designed to complement a new wave of more accurate torque-limiting machinery. Prior to this, automatic screwdrivers relied on the sloping walls of Phillips screws to cam out when they reached their torque limit—a compromise that meant a little extra wear on the screw and driver to save both from breaking due to over-torquing.

However, with the advent of more precise machinery, this camming wasn’t required—and a bit with more solid contact could be used. As the Torx name suggests, the absence of tapered side walls and a much larger contact surface on the Torx bit allowed machines to torque fasteners up to their mechanical limits without slipping or camming out.

Hex vs Torx
Hex bit vs Torx: Torx bits have a higher surface area for torque application, as well as a 15º drive angle compared to the hex’s 60º

The benefits of limited torque application are twofold: it protects tool and workpiece from the wear of camming out. Because stripped screws universally suck.

Mangled Torx bit
Mangled bit
Mangled torx screw
Mangled screw

The development of accurate torque-limiting machinery changed manufacturers’ needs, and the tools of their trade. Torx screws, for example, radically changed the trade of gunsmithing.

“Before Torx, which appeared in 1967, all firearms relied on slothead screws, which were designed to make ordinary shooters miserable and enable gunsmiths to drive around in Bentleys,” writes Field and Stream’s David Petzal.

With slot heads, the blade slipped from the screw—mangling the screw, the gun, or the owner. Torx screws, on the other hand, were mechanically superior and nearly impossible to strip. The Torx, in a word, is tough.

But the story of Torx screws isn’t all sunshine and repair daisies. In fact, one of its initial selling points was that it was a patented, proprietary, security screw. In other words, it kept device owners out of their stuff. Initially, Torx screws were used to lock emissions units in automobiles. Even Apple was quick to jump on the tamper-proof train with the original 128K Macintosh.

iFixit Bit Chart

But where there’s a will to tinker, there’s a way. And reverse-engineers of the world found a way to un-screw themselves by creating Torx bits, Torx Security bits, and in most recent years, Torx Plus bits. So, now any member of the general public with access to a hardware store also has access to their Torx-guarded things.

Today, Torx bits are hugely popular—trailing behind only the age-old Phillips and Flathead we know and love. Formerly king of the tamper-proof automotive domain, the now-ubiquitous standard is found everywhere from mobile phones to residential construction. (I even found it lurking behind the odd Snapchat Spectacles Bot. No, I didn’t take the Bot apart—though I was sorely tempted to.)

And while many of us have experienced the pain of looking down the head of a Torx screw while wielding only a Phillips or slotted driver, take solace in knowing the Torx can take all the abuse you throw at it. Both our Manta Driver Kit and Mahi Driver Kit include the Torx bit in a full range of sizes—something you may want to keep in mind next time you find yourself stuck in a bathroom stall somewhere.

While you’re here, check out our previous posts on the Flatheadthe Robertsonthe Phillipsthe Pentalobe, and the SpannerAnd be sure to join our mailing list—you’ll be the first to find out when the Manta Driver Kit and Mahi Driver Kit drop tomorrow.