Yes, mass production is what I've always been told was the driving force behind Torx which was apparently invented by/for GM. I understand it gained its real popularity and general acceptance once it started getting used in robotic production lines. The extra gripping area of the star design gives makes for both better holding by the drive bit and more torquing ability out of the same size fastener head. I've run into small Torx a fair bit, mostly in automotive and electronic stuff, and the odd large Torx such as my old 140 hinges. I think it's a great fastener, but it's one more collection of drivers and bits you have to keep in the workshop. When you don't use them frequently they are always at the bottom of the toolbox.

I really have to believe the conspiracy theorists. I think the general acceptance of Torx was, in part, due to the failure of the "No User Servicable Parts Inside" warnings, which serve mostly as a challenge to the likes of me. As was mentioned, in the early days, the chance of your average clod having access to a full set of Torx bits was remote. Torx is also useful in minimizing tampering of items for warranty or liability purposes.

Need more proof of a conspiracy? Then how come so soon after Torx bits became available in your local hardware store they invented the Security Torx bit? These are the Torx heads with the center pin. I've got the bits, but I've only run into the screws once. The neat thing is you only need to own Security Torx bits as they work just fine in standard Torx heads.

And now that you mention it, I always wondered why the square head (more properly called Robertson) wasn't more popular in the U.S. They are obviously superior to both Phillips and slot head in many regards and don't require the more complicated and tighter production tolerances of Allen (hex) and Torx (star). Turns out it's due to Mr. Robertson (of Ontario) refusing to sellout his patent rights to Henry Ford way back in 1908. Some years later, Ford reached agreement with Mr. Phillips (of Oregon) to use his newly patented cross-style screw head on the production line instead of the old slot head. Ford apparently regretted that decision because of the tendency for workers to over-torque Phillips screws. With a Phillips head, a worker tends to really lean on the driver to keep it from skipping in the screw head, hence the tendency to damage the screw head or the assembly when the screw hits bottom.

Robertson heads come in just 4 sizes, #0, #1, #2, #3 using colour coded driver handles, yellow, green, red and black. Unfortunately, Phillips heads, apparently to get around patent issues, come in all sorts of sizes, tapers and nose depths. If you find yourself in a bind and only get to use a Phillips screwdriver, make it a vodka with milk of magnesia. :)