While no one exactly when screws were first invented, we have evidence of them dating back as far as the first century B.C. They started as devices to help in agriculture, and only began to be used as fasteners in the 15th century.
Screws are one of the six simple tools that everyone learned about in elementary school. Because they’re listed along with ramps and levers, it’s often assumed that screws are as old as these types of machines. In actuality, however, screws are one of the more recent inventions among the simple machines.
The First Screws
The very first screws that we have a record of were not used as fasteners. In fact, we have several examples of screws being used in the early Greek and Roman empires, but they were used to tighten the boards of wine and olive oil presses. These screws were carved from wood, and they were made in variety of sizes depending on the size of the press they were being used for.
No one considered that screws could be used to join things together at this point, because it would have been very difficult to make a screw out of metal. Hand carved wooden screws were rarely smaller than a few inches, making them impractical for joining small pieces of wood. For that matter, because the screws were made of wood, it would have been very difficult to use them for any type of real construction.
Over the next several centuries, screws grew in size, but they were rarely used for anything beyond bigger presses. Illustrations of these devices continued to show up for centuries after the invention of the screw, but we virtually nothing showing that they were used for any other purpose.
Screws Being Used as Fasteners
The first time that we see archeological evidence of screws being used as fasteners is during the Renaissance. However, they were not used in heavy construction. Instead, relatively small screws were used in complex machinery, at the time, that was mostly weapons. The earliest examples we have of screws being used to hold two things together was in early gun manufacturing.
Using screws to hold together large beams or for other uses in heavy construction projects wasn’t put into common use until the Industrial Revolution. The reason for this had a lot to do with how screws were made.
How Screws Were Made?
The very earliest screws were carved from wood. By attaching them to a handle, it was possible to multiple the force that a person was able to exert on a wine press by nearly 5000%. It’s estimated that a typical person would be able to exert, at most, about 40 pounds of pressure by squeezing grapes or olives between two boards. By using a screw press, they were able to exert about 2,000 pounds of force.
Hand carving each of these screws was a very time-consuming process, however. For this reason, large presses were often shared between several families, and only more well-to-do farmers would own their own press.
Having your own press meant, however, that a family could produce their own oils, allowing them to make a product that very few people could make. This made screw presses extremely valuable pieces of equipment that were often passed down from generation to generation.
Metal screws were not terribly common by this point. In order to produce the helix or threading on a screw, it was necessary to have the ability to create more detail than what most blacksmiths were able to produce. Jewelers or metalsmiths could create the level of detail necessary, but the metals they worked with were often too soft to be practical for wine presses.
Screws Used As Fasteners
That’s why small metal screws were first used as fasteners for weaponry. These screws were small, and the fact that they were made from softer metal wasn’t much of a factor because the things that were held together were relatively lightweight. These screws were made by a metal worker or jeweler who was trained in producing weaponry.
In the early days of the Renaissance, there were very few craftsmen who specialized in the making of guns. Within a few decades, however, this quickly changed, and gunsmiths became highly respected professionals.
Screws were individually made by metal workers or gunsmiths, and each one was specialized for the gun it was being used on. They were necessary to keep the gun together despite the massive recoil force that it would experience after firing a bullet. This was part of the reason why guns were so expensive throughout the 15th and 16th centuries.
Screws were only very rarely used for larger construction projects by the end of this time period. Larger screws still had to be made individually, although more blacksmiths were becoming capable of making them.
This made them very expensive, so it was rare that they were used in construction projects such as common homes and barns. There are very few examples of them in heavy construction, but they do appear in musical instruments and other types of machinery.
Nonetheless, it wasn’t until the late-1700s, at the start of the Industrial Revolution, that mass production of screws was made possible. It’s believed that instrument maker Jesse Ramsden invented the first screw-cutting lathe in 1770.
Once screws were able to be mass produced and standardized, the floodgates opened to inventors. Soon, screws were being used in all types of machinery. In fact, the ready availability of screws helped to usher in the Industrial Revolution, allowing people to make all types of manufacturing equipment.
The Invention of Standardized Screws
At this point, screws essentially had the same round head, but it was possible to make them in different sizes. In order to simplify ordering and the manufacturing process, the sizes of screws were standardized, allowing individuals to place orders for specific sizes, but also ensuring that every screw in the order would be exactly the same. This allowed manufacturers to start using screws in the products they created.
Within a few decades, the availability of standardized screws brought down the cost of machines such as musical instruments, guns, and presses, making all of these items much more accessible to most households. Screws also started appearing in toys and kitchen appliances. Around this time, they also started appearing more often in heavy construction.
New Screwhead Shapes
By the early 1900s, different types of screw heads started appearing. The Robertson screw was one of the first of these new shapes, invented in 1908. The screw featured a square head, and was renowned for its non-slip qualities during installation. The most famous use of this type of screw was in the Model T, which used over 700 Robinson screws.
By 1930, the Phillips head screw was invented. This shape quickly became popular due to its popularity on the car assembly line. It was more durable and provided a tighter fastening than the Robertson screw.
Today, screws are so easy to manufacture that they are often sold for less than a penny a piece. However, there are some specially made screws that can cost hundreds of dollars a piece.