But the construction of it ??! It's one thing to put the numbers down, we know they round out nicely, but in my head this needs a very minute level of construct

But the construction of it ??! It's one thing to put the numbers down, we know they round out nicely, but in my head this needs a very minute level of construct engineering.. For example: If 1 gear(cog?) is 1/1000 of a cm out, would that not effect the ratio over this 'distance' ? Edit: I might just sound like an idiot right now, but when we get down (or up) to these numbers, i can't help but feel manufacturing numbers play a bigger role