A pile of Phillips head screws. (Photo: nukeaf/shutterstock.com)
A version of this post originally appeared on Tedium, a twice-weekly newsletter that hunts for the end of the long tail.
The screw is the ultimate example of an object that hides under our noses but we never think about.
It's the most basic of building blocks, something that connects every one of our devices, manufacturing processes, and likely even the chair you're sitting in right now. (One device that doesn't tend to have screws? The air mattress.)
And generally, we never give screws a second thought. But I was thinking about them a lot the other night when I tried to screw a nut around a screw and misaligned it so annoyingly that it took a lot of physical might to unscrew that screw.
Where do screws come from? And what did we do in a world before them? As it turns out, screws have a surprisingly diverse and unexpected history, stretching from ancient Greece to what we think of them as today, essential parts of our literal foundations. In ancient Greece, for example, it's claimed Archytas of Tarentum invented an early version. Leonardo da Vinci also had one, and, later, of course, it was a key part of the Industrial Revolution.
Today, though, we mostly use a combination of Phillips head screws and flathead screws, though for decades, these haven't been the only variety out there.
British Engineer John Frearson, for example, came up with an alternative to the flathead in the 19th century. (It's still popular today in some specific uses, such as boating.)
Here was his reasoning in his patent application:
It is well known to persons who use screws that if the nicks are narrow and shallow it is difficult to drive the screw without the screw-driver slipping out of the nicks, and if the nicks are wide and deep to afford a good gripe, the head of the screw is weakened, and the screw-driver is liable to slip out sidewise and deface the finished surface of the work, and if the screw-driver is the same width as or wider than the head of the screw, the countersink work is liable to be defaced, and the angles of the screw-driver are often broken."
The Frearson screw, as it came to be known, also used a cross design like the Phillips screw, but differ in a significant way: The Phillips screw, unlike the Frearson, has a slight curvature in the center, which makes it so that when the screw is in all the way, the screwdriver would inevitably fall out (or if you're me, you would continue twisting anyway until you've fully stripped the metal and made the screw useless).
Robertson's 1907 patent application. (Photo: Google Patents US975285A)
A few other screw types you may or may not have run into at the hardware store:
The square-headed Robertson Screw predated the Philips screwdriver by about 30 years, and for decades it was more common than the Philips in the U.S., which eventually won out not due to a more efficient design, but because of licensing drama. See, Henry Ford wanted inventor P.L. Robertson to license out his screw design. Robertson refused, and that led the design to lose out to the Phillips screwhead in the U.S. market. The Robertson screw is still popular in Canada, however.
The hex socket set screw, named for its six-sided hexagon design, isn't named after a person, but its corresponding tool is. The Allen wrench, named for William G. Allen, has existed for more than 100 years. The reason the wrench is named for Allen rather than the socket? Because the hex screw predates the Allen wrench by a few decades.
The Bristol screw, which is now called the Bristol Spline Drive, has an unusual spline-driven circular design that is claimed to be excellent at producing torque. The invention, which initially had an Allen wrench-style design, dates to 1911, with the invention credited to a guy named Dwight S. Goodwin.
The Torx screwdriver, which first appeared in 1967, introduced a star shape that has become fairly common in certain technical uses, such as cars, bikes, and consumer electronics. Unlike a Phillips screw, it's designed not to fall out, and at first, to prevent people from unscrewing it, as the screwdrivers were proprietary. They also came in handy for guns. "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," Field & Stream's David E. Petzal wrote.
Perhaps the most interesting and unusual screw design in the past few decades is the Outlaw Fastener, a multi-tier screw that is akin to combining an Allen wrench with a three-layer cake. It was the subject of a successful Kickstarter campaign in 2013. The design, if fairly advanced, isn't totally new; it appears to be the direct descendant of the Uni-Screw, a design that dates back to the 1960s.
A set of Allen wrenches. (Photo: Papa Annur/shutterstock.com)
It was in the early 20th century, an era of screw-head innovation that led to the creation of both Robertson and Phillips screws, that the U.S. government … well, they spent a lot of time researching screw threads.
(For people who don't regularly screw stuff in, the thread is the pointed metal line that twists around the metal rod. It's part of what makes a screw a screw and not a peg.)
In 1918, Congress passed a law establishing an organization called the National Screw Thread Commission, with the goal of ascertaining consistent standards for screws. The goal of this effort, which you might guess given the timing of the law's passage, is military-related: the military uses a lot of screws, and inconsistencies were apparently bad enough after World War I that Congress had to do something about it.
John Q. Tilson, a Connecticut congressman, argued that the measure was necessary due to the problems a lack of consistent screw thread were creating. He also made the case for businesses—who he argues also will benefit from screw compatibility.
"Private manufacturers, however, desire this done just as much as everybody else," he said, according to The Journal of the Society of Automotive Engineers. "They would like to have the standard of tolerance for screw threads all over the United States."
The law, of course, passed, and we had the National Screw Thread Commission, perhaps the most obscure bureaucratic organization to ever exist.
But it had a perfectly good reason to exist. A 1926 New York Times article about the commission highlighted the 1904 Baltimore fire, in which fire departments from other major cities came in to help. Unfortunately, the other cities had hoses that were incompatible with the screws used by Baltimore, making their help useless.
A Torx screwdriver bit. (Photo: Donald Kautz/CC BY-ND 2.0)
The article noted that the government was working closely with the U.K. on the issue, and differences between those two countries did a lot to underline the problem:
There is, however, a fundamental difference in the angle of the thread of the two systems. This is 60 degrees for the American and 55 degrees for the British thread. Still another difference is that the American thread has flattened crests and roots, whereas those of the British thread are rounded.
This difference surfaced essentially because the U.K. had created its own standard, the Whitworth Thread, but an American thought he could do things better. In 1864, William Sellers introduced the screw design for the American market that borrowed inspiration from Sir Joseph Whitworth's design, but pitched a new path forward.
Now, the U.S. was trying to convince the rest of the world that Sellers' design was the way to go. And it took a long time to sell them on the idea. The National Screw Thread Commission was active for three decades, partly because of all the details to go over, and partly because another war threw a wrench in the mix. (We haven't even talked about wrenches!)
What eventually ended the commission's long reign of terror was a deal with Canada and the U.K. to embrace the 60-degree screw thread, something that's called the Unified Thread Standard. (The Second World War, of course, highlighted just how big a problem the different screw standards were.) The good news, then, was that the screw design chosen was the same angle as an American screw. The bad news? They set the design on the metric system, when the U.S system was based on inches.
A set of screwdriver heads. (Photo: Dmitriy Rikov/shutterstock.com)
So much for a unified system, then, though Americans don't seem to mind it. The U.K. moved over to the metric system in 1960, losing an ally, but Canada is hanging tough, and we roll on.
In a lot of ways, the various types of screws highlight some important modern debates we're having with technology.
Specifically, regarding the 3.5mm headphone jack, that thing Apple is apparently trying to kill.
Apple, it should be said, is a company that knows its screws.
There are 69 screws in a full screw kit for the iPhone 6S sold on Amazon. (Yes, I counted. It was tedious.) While it's still early to report on how many screws the iPhone 7 has, I can reveal that iPhone 6 had just 52 screws, according to one online seller.
Screws have periodically been a source of controversy for Apple, particularly when the company introduced pentalobe screws with the iPhone 4 at a time when pentalobe screwdrivers were very rare. (They're similar to Torx screws, except rounded instead of pointed.)
(Photo: Daiji Hirata/CC BY-ND 2.0)
The screws were seen by repair experts, such as iFixIt's Kyle Wiens, as a way to prevent users from repairing their own devices.
Headphone jacks and screws are two examples of very analog things that have traditionally shown up in Apple's devices.
So, let's put the company's headphone argument in screw terms: The headphone jack, as it currently stands, is the musical equivalent of a Phillips screwdriver, better than what we originally had (flathead screws) but also greatly lacking in terms of what could be.
Which means that the company is still giving you an option for screwing stuff in for now, but maybe not so much in the long run, as Apple, as we know, has never been one to follow standard.
Just look at the pentalobe screw.
A version of this post originally appeared on Tedium, a twice-weekly newsletter that hunts for the end of the long tail.