Screws are everywhere, and chances are you’ve lacked the right tool to remove one at some point. Using screws is a pleasure under the right conditions, yet their current state borders on chaotic.
Too Many Screws!
Philips, Torx, Pozidriv, Frearson, Robertson, Pentalobe… a resource so valuable should supposedly be standardized. So why are there so many types of screws? Perhaps it’s best to understand their origins…
The story (or the legend, depending on who tells it) says the original concept of the screw belongs to Archimedes, who allegedly developed a large-scale model to transfer water from lower areas (say, a river) to higher irrigation zones.
But many believe that the mathematician and engineer saw the screw in action during his visit to Egypt, and that its true invention dates back to the time of the Assyrian king Sennacherib, hypothetical creator of the Hanging Gardens of Babylon.
The rest was a matter of creating smaller versions, taking advantage of its strength to hold two (or more) things together. The popularity of the screw took a long time to manifest.
If access to nails was already difficult and expensive in some regions (leading to the evolution of carpentry along very interesting paths), the situation with screws was even worse.
However, everything changed when Henry Maudslay and other masters of the “machine tools” designed the first precision lathes at the end of the 18th century, aimed at mass production of screws. That’s where the storm began.
The Screw Explosion
Why? Because an explosion of creativity and engineering combined with weak (if not nonexistent) standards allowed each inventor to do almost anything with their threads and screws. Even so, within all that chaos a certain list of needs began to emerge.
For example, the flat or slotted screw is easy and cheap to manufacture, but offers neither speed nor safety—two essential aspects for industrial environments.
Here appears Canadian inventor Peter Lymburner Robertson, who successfully produced the square-slot screw, now simply known as the Robertson.
One of the most important products to adopt the Robertson was the Ford Model T. Henry Ford was delighted with the screw (it saved him up to two hours of work per car, which used about 700 of them) and tried to obtain an exclusive license to manufacture it, but Robertson refused.
Ford soon found an alternative: Henry F. Phillips’ cross-shaped screw. The Phillips screw is supposed to have three virtues: adaptability (a single screwdriver can place screws of two or three different sizes), self-centering, and the ability to “slip on purpose” to avoid excessive force.
I say “supposed” because few things are as common as a Phillips screw destroyed by rust, or by a screwdriver of the wrong size.
The evolution of the screw continued, and that extended to screwdrivers, more “intelligent” and with functions that limit torque.
The virtue of the Phillips turned into an annoyance, giving rise to the hex or Allen screw, and the famous Torx, designed by Camcar Textron in 1967. The Torx prioritizes minimizing the cases of slips and skids.
Sounds great, except for one detail: the initial rarity of the Torx was exploited by manufacturers to use it as a “security screw,” and later it received a pin in the middle, complicating things.
Today, any electronics, construction, and DIY enthusiast must be armed to the teeth with screwdrivers. Do you like repairing and/or restoring Nintendo hardware? A basic kit has at least half a dozen screwdrivers based on Torx, security Torx, Tri-Point, and Phillips. Want to replace your iPhone’s battery? You won’t get anywhere without a Pentalobe set, and be very careful about the location of the screws (they are not interchangeable).
In short, the reasons why there are so many types of screws can be divided into three instances: At first, manufacturers had to work with what they had on hand.
Then they responded to the needs of their customers, and finally, those customers decided to sideline the user, adopting “security solutions.”
Yes, many screws are already obsolete, but pleasant as the idea of a universal standard may be… remember.
