Interchangeable parts are perhaps one of the greatest and least-discussed engineering inventions. These are parts that are designed to fit in any device of the same type, rather than being designed for one specific item, and they revolutionized the world of manufacturing. With their development, the groundwork for mass manufacturing and distribution was laid, and the Industrial Revolution was born.
Most people take interchangeable parts for granted. When a car breaks down, for example, drivers know that they can order parts and have them installed by a mechanic. These parts are made in a centralized manufacturing facility and stored until they are needed, and they fit in all cars of the same make, model, and year. Often, manufacturers even standardize parts across several models and years to make replacement parts even easier to access.
Prior to the late 1700s, such a thing would have been unthinkable. Every manufactured item, from clocks to carriages, was made by hand, with parts uniquely crafted for that particular item. If the item broke, it needed to be brought to a skilled craftsman for repair, and this craftsman would either repair the damaged part or fabricate a new one. This was an expensive and time consuming process, and many handmade goods had unreliable performance records; cannons, for example, could easily misfire or develop other problems in operation.
In the late 1700s, several manufacturers of guns came up with the idea of making guns with interchangeable parts. In one notable demonstration, Eli Whitney brought ten guns into the United States Congress, broke them into their component parts, scrambled the parts, and then put the guns back together. His demonstration proved that it was possible to make parts that were truly interchangeable, and demonstrated their clear benefits: when a gun failed in the field, instead of sending it out for repair, a soldier could quickly replace a missing or damaged part and keep on fighting.
Whitney failed to take the next logical step, which would have been devising equipment to make these parts on a factory line. His guns were fabricated by hand by skilled gunsmiths. John Hall, Simeon North, and Eli Terry did take this step, however, developing equipment that could be used for mass production of products. Today, the concept seems entirely unremarkable and quite logical, but it was nothing short of a miracle for the world of industry.