I think that John Plant[1] and some friends could get us from the stone age to ironworking. He's shown how to start with stones and get that far, albeit on a ve

I think that John Plant[1] and some friends could get us from the stone age to ironworking. He's shown how to start with stones and get that far, albeit on a very small scale. Going from iron to precision screws is a matter of first making precision flat surfaces, then lathes, and onward from there.[2] You can do that with just iron and heat treating, but it won't be easy. If you want an alternate history where something slightly less drastic is dealt with, the book "Ring of Fire - 1632" by the late Eric Flint[3] is an interesting place to start. In the book, a town from West Virginia circa 2000 is thrown back into the middle of the 30 years war in Germany. Lots of exposition of the book is about the supply chains we all depend on, and how they work. It's the start of an awesome series. Books and working knowledge, are a precious resource. As long as we have a critical mass of them, and conditions remain reasonably tolerable for human life, we can recover. [1] https://www.youtube.com/channel/UCAL3JXZSzSm8AlZyD3nQdBA https://www.youtube.com/channel/UCAL3JXZSzSm8AlZyD3nQdBA [2] https://ia800104.us.archive.org/20/items/FoundationsOfMechanicalAccuracy/Foundations_of_Mechanical_Accuracy.pdf https://ia800104.us.archive.org/20/items/FoundationsOfMechan... [3] http://www.baen.com/chapters/0671578499/0671578499.htm http://www.baen.com/chapters/0671578499/0671578499.htm