[groby_b]

Yeah... coal and oil won't be lying around. Which robs you of your major energy source, breaking the "fix and use" plan.

Metals are often in refined form, which means in many cases higher melting points. (E.g. pig iron is 1500K, steel is 2800K)

We're not even mentioning electronics, because the vast majority of it isn't weather resistant, which means your "left lying around" is gone pretty quickly.

Plastic is in many instances only reusable in its exact shape. Alkaline batteries last 5-10 years, so good luck with those. Solar cells, in the best case, 25-30 years.

But all of that doesn't really matter. You'll spend the bunch of your time trying to just secure water, food, and shelter. Every day you don't get started on fixing things is decay. Every day you don't spend on food is hunger. (Subsistence farming is back-breaking, never-ending labor)

And so it goes.

[hutzlibu]

"Subsistence farming is back-breaking, never-ending labor"

Subsistence farming without machines is back-breaking, never-ending labor.

The whole idea is therefore to get machines up and running again as fast as possible.

And it all depends on the doomsday scenario. In most cases, there should be enough machines left to scavange. Or after a while, enough animals to be hunted.

Potential biggest hurdle are social dynamics. Confrontation instead of cooperation. And then the last capable electrician in the are gets shot, because some other scavenger wanted to get his corned beef.

[groby_b]

Beginning sentence: "Coal and oil won't be lying around". The amount of machines you can run is limited, and so is the duration.

Animal hunting is mostly a settler fantasy. There's not a single place in the US that has sufficient animal population to sustain human nutrition for more than a couple hundred people. You will require careful husbanding. And, for anything larger than feeding ~100 people, you'll require feedstuff. Which you transport... Ah. There's the lack of energy sources again.

Social dynamics are the least of your problem: The confrontation fans tend to die out quickly, or secure a fiefdom within which they ensure collaboration. Human beings pretty much default to tribal behavior. And they favor collaboration even across tribes. (I recommend reading Rebecca Solnit's "Paradise built in hell")

Really, it's a tougher row to hoe than you think.

[User23]

A wood fired still might be a reasonable way to turn biomass into fuel.

And while farming may seem like back-breaking labor to the Aeron chair set, it’s really not that bad. You are tied to the land, but in the scenario that’s under discussion a Disney cruise vacation isn’t in the cards anyhow. You’ll want to have draft animals though of course as tractor replacements.

[groby_b]

You need the still to start with :) But even then, you need the wood to fire them.

But yes, with draft animals you can make a go of it. It just won't leave you a lot of time to tinkertoy with the "leftover machines".

I don't think it's an unsurvivable scenario per se. I just think that the idea that you already have a starting point for an industrialized civilization is either quite naive, or takes a quite liberal view of "starting point".