The Evolution of Torx: From Torx to Torx Plus and Beyond

Despite seeming like a relative newcomer to the scene, the internal Torx (also known as “star”) design has been around for a relatively long time. These six-pointed, star-shaped bits were invented by Bernard F Reiland in 1967 and patented in 1971, while he was working for the Camcar Textron company. Reiland’s goal was to make a fastener head that could reliably drive at higher torque values without the dreaded “cam-out” or slipping that plagued Phillips and hex screws in a production environment. Reiland felt that with new tools that were much more controllable in their torque output, a design that gripped more tenaciously would allow for a longer tool life and less chance of damaging the fastener. So, the Torx (or officially the “hexalobular internal”) standard was born. It’s six-point, nearly straight head offered a much greater surface area, and thus grip, for users. Just witness how the construction industry has embraced the Torx standard for construction screws.

Not content with the design of the Torx system (or anticipating the eventual expiration of the Torx patent), the Torx Plus design was introduced in 1990, and while the two can look very similar, there are some subtle differences. Instead of a more pointed shape to ends of the “star”, the Torx Plus has more gently rounded lobes and vertical sides. The result is a greater engagement area between the bit and the fastener head. This means in practice that higher torque loads can be applied without cam-out, and results in an increase in the life of the drivers and fasteners. As many of us don’t often encounter Torx Plus very often, you might take comfort in knowing that standard Torx drivers and bits can be used on Torx Plus fasteners (though they might slip at very high torque ratings). Torx Plus tools on the other hand, cannot be used on standard Torx fasteners. One handy variation as well (looking at you, bicycle mechanics) is the ball-end torx driver, which is perfect for those who need to access torx fasteners from an angle.

A quick note on nomenclature and sizing. Both Torx and Torx Plus come in sizes from 1 to 100, and are typically labelled as T1, T2, etc. for Torx and IP1, IP2, etc. (“Internal Plus”) for Torx Plus.

Variations

Increasingly common, especially in the automotive sector, is External Torx and External Torx Plus. Think of it like you would hex: there are internal hex L-keys, drivers and bits, and there are external hex sockets and wrenches. The same holds true with Torx, but not being metric or standard, there is only one set. Instead of the “T” or “IP” prefix, external Torx uses the prefix “E” and Torx Plus “EP”. Sizes range from 2 – 24, but are not comparable to internal sizes, e.g. an E4 Torx socket fits a T20 head.

After the introduction of Torx, manufacturers realized that using Torx fasteners could offer a bit of security from folks trying to disassemble their products, because Torx drivers were still relatively rare. As Torx drivers started to be generally available, however, manufacturers who wanted to continue having that security feature adopted a new variation of Torx: Security Torx. Sizing is exactly the same as a regular Torx fastener; however, a small cylindrical pin sits in the center of the star on the fastener, making it impossible for a regular Torx driver to function. To get around this, a security Torx driver has a small hole bored out of the center, allowing that pin on the fastener to slip right in. Of course, there is also a security Torx Plus standard, with the same post and hole feature.

One more variation that is worth noting, is a five-lobed, or Pentalobe standard. First appearing widely on Apple products, these were the bane of hackers’ existence, until third-party manufacturers began offering drivers for these products. Usually produced in a Torx Plus profile, they are also available in a security or tamper-resistant version with a hole in the tip.

New standards continue to be introduced as well: the latest one to crop up is external Torx Plus Pentalobe. Adopted by many in the world of automated/robotic production, these types of fasteners have begun to crop up on cars and machines. And while none of KC Tool’s current vendors offer these yet, stay tuned, as they are certain to be available soon.

A last word on nomenclature, as many sizes, especially in the smaller range, are nearly indistinguishable, one often has to rely on the markings of the driver or bit to get a good idea of what size is in use. There are official naming conventions, but for some types, individual companies may use their own abbreviations.

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[cthompson]

I've gotten to the point where I need a magnifying glass to discern a tiny torx from a tiny hex.

[VABrowneMDPhD]

This was a wonderfully informative video!

[xTHORx]

Great video. That really cleared everything up for me. At 53 and being somewhat of a shade tree mechanic and former industrial maintenance worker (out of that profession for 20 years) I’d never heard of or seen a torx plus until 2 years ago.

[abdulrahmansalem]

If only there was a fastener that fit securely in the driver, was mass produced, and available before torx or even Philips were invented, wait there was such fastener!! It was the square.

[MarzNet]

T-25 headed screws beat slotted and cross by a least one order of magnitude, particularly with drill/impact drivers. I built a 300 foot fence and not one fastener failed. Deckmate #10 x 3-1/2 in coated screws for lower friction driving (more fasteners per charge) and corrosion resistance.

[thaddeusshell]

Great video. Could you do an explanation on the tripple square fasteners and tools available. Thanks 👍

[albertaoridge]

So yeah a torx might fit in a torx plus screw head but will it actually work fine or will it eventually damage the screw and torx bit? Just cuz it technically fits doesn’t mean it should be done with no adverse problems.

[ryanfry]

External torx might be the greatest fastener head design ever.

[andyvernon]

So the Torx Plus look very similar to Ribe keys ? Are they actually different ? Also agree with adding info abiut Triple Square as well

[siriosstar]

The Spax version of Star Plus is a rather odd configuration .
It's a regular star bit with an added small protruding circle at the tip which is suppose to force the bit and the screw into a straight line elimi acting play between the bit and the screw . it DOES do that but personally i
don't t like it because one of the advantages of the star bit is i can drive a screw even if i can't get the driver directly above the screw .

[Gallardo]

Tomorrow they come up with torx minus...

[TheMadComputerScientist]

I'm opening a small woodworking shop to supplement my impending retirement. I've put a significant investment into Wera bits and drivers. I'd like to move away from Philips head screws toward torx, but that's going to depend on how easily I can get wood screws with torx heads (not construction screws). That leads me to a question. Could you go into detail about the differences between Wera wood torx bits vs standard torx bits, and whether they are interchangeable?

[stopthephilosophicalzombie]

The only external Torx bolts I've seen were head bolts for a Subaru.

[terrellscaife]

The issue with torx sockets is a socket is weaker than the fastener

[turboslag]

Off topic but anyway, thanks for referring to slot head screws correctly instead of the typical but incorrect

[Drunken_Hamster]

Torx Plus and really all the other variants are entirely unnecessary when Polydrive exists. A 2 fastener standard should be implemented, and the two that should be used are Robertson for most everyday stuff like electronics, household, construction fasteners, etc. and Polydrive for extra high torque industrial/commercial applications like Automotive, Aerospace, and heavy machinery. For external drive types like nuts and bolts, hex is perfectly fine. If we added another or changed over to anything else, I'd say only Polydrive, and mostly because it's just an improved Torx.

[dalriada]

Torx is okay, but I generally prefer Pozidrive. A PZ2 bit will fit most sizes of screws. I'm in the UK though. I think Pozidrive is more popular in Europe. Slotted and Phillips screws are dreadful!