Interchangeable Parts

Paris, France, July 1785. It was 18 months after the end of the Revolutionary War in America, and four years before the start of the French Revolution. The need for weapons was on everyone's mind when Honoré Blanc invited high-ranking military men and diplomats to his gunsmith shop in Paris. He had taken apart 50 firing mechanisms (called "locks") and placed the pieces in boxes. The astonished visitors took random parts from the bins, assembled them into locks, and added them to muskets. They found that the parts fit together perfectly. For the first time it seemed possible to make guns out of interchangeable parts.

Thomas Jefferson, a diplomat in Paris at the time, was at the demonstration. The future United States president saw a way to address a big problem in his fledgling country. The United States was facing a shortage of weapons to defend itself and expand its boundaries. If interchangeable parts could be easily produced, then relatively unskilled workers could assemble a lot of guns at low cost, a real boon to the start-up country that had neither the money to buy guns nor the craftsmen to make them.

The challenge of creating a manufacturing process precise enough to make interchangeable parts for guns was taken up by Eli Whitney, who had recently patented the cotton gin. In 1798 Whitney was awarded a government contract to make 10,000 guns in two years. Ten years and several cost overruns later he finally delivered the guns, and even then the parts were not fully interchangeable. Nevertheless, Whitney is considered a central figure in developing the "American system of manufacture," a manufacturing system in which semi-skilled workers use machine tools and precise jigs to make standardized parts that are then assembled into products.

During the 1800s the United States grew dramatically as an industrial power, with much of the credit given to the new manufacturing system. Meanwhile in Europe there was strong resistance to replacing craft production. In France, Honoré Blanc's work was terminated by a government that feared losing its control over manufacturing if unregulated workers could assemble a musket. In England, the inventors of machines that automated both spinning and weaving were attacked by angry crowds who feared losing their jobs. But in America, labor was scarce and there were few craft traditions, so the new industrial model of interchangeable parts took root and flourished.