[XorNot]

Knowledge goes a long way though: i.e. knowing the 3-plate method for producing perfectly flat surfaces (most easily done with cast iron) gets you bootstrapped on making accurate tools, as does knowledge of how to build a lathe and what processes it is capable of.

All of which benefits from any type of work producing engine, since the core leap you need to make is to get away from being solely dependent on human labour as a power source.