

__1936: __Henry F. Phillips receives patents for a new kind of screw and the new screwdriver needed to make it work. It changes the worlds of mass production and machine repair, not to mention your home toolbox.

Phillips was a Portland, Oregon, businessman who invented something to solve a problem that few home-repair folk or do-it-yourselfers even knew existed. In those days, if you wanted to drive a screw into a hole, you just grabbed the right-size slotted screwdriver and did the deed.

The only thing you needed to puzzle over was the size. Too big wouldn't fit; too small wouldn't give you enough torque.

So why do you now need to grab the right kind, as well as size, of screwdriver? It's enough to make you cross.

Phillips wasn't trying to make life with hand tools easier. He was trying to solve an industrial problem. To drive a slot screw, you need hand-eye coordination to line up the screwdriver and the slot. If you're a machine – especially a 1930s machine – you ain't got no eye, and your hand coordination may depend on humans.

The Phillips-head screw and Phillips screwdriver were designed for power tools, especially power tools on assembly lines. The shallow, cruciform slot in the screw allows the tapering cruciform shape of the screwdriver to seat itself automatically when contact and rotation are achieved. That saves a second or two, and if you've got hundreds of screws in thousands of units (say, cars), you're talking big time here.

And not only does a power Phillips driver get engaged fast, it stays engaged and doesn't tend to slide out of the screw. Another advantage: It's hard to overscrew with a power tool. The screwdriver will likely just pop out when the screw is completely fastened.

It turns out that Peter L. Robertson had patented a self-seating, square-socket screw in Canada in 1907. Some Canadian factories adopted it, but Robertson was vexed by the onslaught of World War I and his own insistence on maintaining tight control of the technology.

Phillips applied for his own patents in 1934 and '36. After years of rejection, he got the American Screw Co. to spend $500,000 ($8 million in today's money) to develop a manufacturing process. American Screw convinced General Motors to try the newfangled fasteners on the 1936 Cadillac.

Presto, change-o. Nearly all American automakers had switched to Phillips screws by 1940. The American jeeps and tanks of World War II, not to mention the aircraft, were assembled with speed and efficiency, thanks in part to Henry Phillips.

Today, manufacturers can choose from a wide array of screws – including the Robertson square, the Allen hex and some exotic varieties developed by the Phillips Screw Co.

If you're a weekend handyperson who has to keep your toolbox stocked with all kinds of screwdrivers (or driver bits), the variety may be annoying. The Phillips cam-out – when you've gone far enough and the tool pops out of the screw – has led to plenty of workshop profanity. And loosening a machine-driven Phillips screw with a hand-held screwdriver has apparently reminded many, judging from their language, of the tenacity of a female dog protecting its newborn pups.

Still, remember Henry Phillips gently. His screws are holding your life together.

Source: American Heritage Invention & Technology magazine, 2001.

Patent diagram courtesy U.S Patent and Trademark Office.

This article first appeared on Wired.com July 7, 2008.

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