The screw is one of the six simple machines, but it is nothing more than an axis and an inclined plane winding around it. Today, screws have been developed in standard sizes. The typical way to use a screw is to tighten it with a clockwise rotation (as opposed to a counterclockwise rotation to loosen it).

The screw is not some ancient invention. It took 2,000 years to invent a tool we take for granted. It is believed that Plato's friend, Archiytas of Tarentum, invented the screw in 400 BC. Archimedes was the first to realize that you could use screws to hold things together, and you could also use them to lift water.

The Romans used bronze and silver as materials to cut the screws by hand. In the early days, various kinds of screws were used to press olive oil, to irrigate canals, to drain water from bilges, and, of course, to hold things together.

So why are bolts almost always tightened clockwise?

The study believes that because the screws at the beginning of the invention are man-made, the degree of fineness of the screws is not consistent, often determined by the personal preferences of the artisan.

By the mid-16th century, Jaques Besson, a French court engineer, had invented a lathe that could be cut into screws, a technique that took 100 years to popularize. The Englishman Henry Maudsley invented the modern lathe in 1797, with which the degree of fineness of threads was significantly improved. However, there is still no uniform standard for the size and fineness of screws.

This changed in 1841. Maudsley's protege, Joseph Whitworth, submitted an article to the Institute of Municipal Engineers calling for a unified screw model. He made two suggestions: 1. The Angle of screw thread should be 55° as the standard; 2. Regardless of the diameter of the screw, the number of wires per foot should take a certain standard.

From an ergonomic point of view, the vast majority of people in the world are right-handed, and right-handed people are more likely to exert force when tightening screws to the right. This is because the human body structure and daily activity habits make the right hand more flexible and powerful, so in the design and use of tools, in order to maximize the use of human natural capabilities, the thread is designed to be right-handed structure, that is, clockwise rotation and tightening, which is more in line with the use of most people ‌.