Over time things like machine tools have gotten more accurate, ie I assume early metalworking lathes had a much higher range of error than modern ones.
So how were the more accurate machines made using what must have been a less accurate machine?
In: Engineering
Good question! In a word, levers. Say I wanted to make a small, precise drawing. But, I’m not very good. I can do a large scale drawing that’s precise, but not small. One thing I could do is attach my pencil to a long lever. We tend to think of levers as a way of gaining a mechanical advantage, i.e. allowing us to push or pull with a greater force. But the way they do this is by reducing distance.
Take a rod 1m long, and attach one end to a pivot. Put a pencil at the free end, and then another pencil 1cm along from the pivot Now, when I draw an arc with the pencil at the end, the pencil near the pivot will make a similar arc. Except the arc it makes will be just a 100th of the size. Any errors I make will also be scaled down proportionately. If I can rig up a similar system with levers to allow me to draw more freely (it involved criss-crossing levers), then I can make accurate, scaled-down drawings. Say I was able to draw accurately to the nearest cm. The smaller drawing would be accurate to 0.1mm.
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