Screws are one of the oldest construction materials used by man. It may be of interest to know that scientists believe that the first screw thread was actually developed and used sometime around 400 BC by Archytas of Tarentum, an ancient Greek mathematician, astronomer, and philosopher.
These first screws and the ones that would follow weren’t used to create fasteners but rather to press olives into oil and grapes into wine. Later in Egypt, screws were used to transfer water more like a modern day auger.
It wasn’t until the invention of the lathe and the perfection of the method to produce screws that they came into production in the late part of the 1770s. These were used in all types of applications including in the design and manufacturing of steam engines. These screws all had the standard flat bottom, which means that a hole had to be drilled into wood or metal before the screw could be used.
By adding a point to the end of the screw, the first self drilling metal screws were manufactured. In essence, a small cutting tool, or the point of the screw and the turn into the thread, the flute, give these screws the ability to not just tighten into metal, but to also cut through the metal, eliminating the need to pre-drill a hole.
Some types of self drilling metal screws can also be used to attach wood or another softer material to metal. These screws have thin wings or protrusions between the pilot section (the point and flute), and the threads.
These wings make the hole slightly larger after the point goes through, which prevents that threads from catching and holding into the wood. Then, when the point hits metal and goes through the wings break off, allowing the screw to tighten into the metal. By only tightening into the metal and not the wood, it prevents the materials from pulling apart and creating gaps between to prevent buckling of the surface softer material.
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