Before the industrial revolution, manufacturing meant something very different than what we might imagine today. Every machine was its own unique design. Mass production was an impossibility, both for good and the machines that made them. Then came the idea of interchangeable parts. Here’s more from Interesting Engineering:
First conceptualized by French General Jean-Baptiste Vaquette de Gribeauval in the mid-18th century, the idea had been around for some time. Gribeauval even started producing firearms with interchangeable flintlocks in 1778. However, the idea never really made it much further than that.
The idea was simple, if individual pieces of a machine were produced identically, then the final product would be identical to others. This would also allow for easy fixing of broken parts, allowing machine owners to simply order a replacement.
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The process of interchangeable parts transformed manufacturing from a high-skilled artisan-based profession into one that was low/ lower-skilled and in more of an assembly line production style. This ultimately increased productivity in the industry, lowered costs, and increased the number of jobs that were available to the public.
The unfortunate side-effect of interchangeability was that it practically wiped out the world’s class of skilled craftsmen. These skilled workers could no longer compete with high-volume manufacturing methods. Thus the professions were either completely eliminated or craftsmen were relegated to high cost artistic based labor.