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0 pointsderefr6y ago0 comments

That's, to me, the amazing thing about machining: pretty much any invention from the dawn of civilization up until the vacuum tube can be made in "a moderately equipped machine shop." Because, if a part requires a custom tool to build, it's very likely there's a version of that tool you can build with just the same 1930s tech you use to build anything else, in about four hours.

A good chunk of hobbyist-machinist YouTube is essentially just people bootstrapping themselves into a complete shop's worth of tools starting from three or four primitives, and it's kind of wonderful to watch.

(I'm always kind of disappointed whenever one of these hobbyist folks get a CNC mill or something, because it throws off that bootstrapping feeling. I know it was never their goal, but they were coincidentally pulling it off until that point.)

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Aloha6y ago· 2 in thread

Including the vacuum tube, you just need glassblowing equipment and a good vacuum pump, and some other specialized tools. That said, the first voice transmissions used either alternators or high speed rotary spark gap transmitters.

Another thing is audio amplification can be done without tubes or transistors, you can use a mechanical amplifier which is literally a transducer that is mechanically coupled to a carbon microphone, and a local power source (battery) making it possible to build analog phone lines that run several hundred miles without tube type amps.

See https://www.youtube.com/user/glasslinger

derefrOP6y ago

Sure, I mostly brought up vacuum tubes as an endpoint because constructing the specialized tools to make one is no longer a four-hour job. You run into a wall where, to get to the point where you can do the glassblowing, you have to first bootstrap an entirely-separate set of primitives (kiln, quench, anvil, grinding/polishing stones, etc.) that you may not have needed up until that point if you’d just been working with scrap stock.

(And then the same is true of everything after that, because transistors require photolithography, and photolithography requires good lenses.)

Of course, if you’re unlocking your tech-tree in a breadth-first direction, you’ll already have the glassworking primitives around due to them being common prerequisites for refining metal ore :)

jdkee6y ago

Speaking of vacuum tubes, this gentleman makes them by hand.

https://www.youtube.com/watch?v=EzyXMEpq4qw

zipwitch6y ago· 1 in thread

Anyone who is interested in this sort of thing may wish to take a look at the seven-book Build Your Own Metal Working Shop From Scrap series by the late David Gingery. While intended as a guide for the hobbyist, the series could easily serve as a blueprint for how to go from scraps of metal, wood and earth to a fully functioning machine shop in a post-apocalyptic scenario. And if you add in Herbert and Lou Hoover's excellent translation of De Re Metallica you're well on your way to having a blueprint for rebuilding humanity's pre-WWII tech base from scratch.

kbr20006y ago

Thanks, first time I've heard of them, will be going through those (they seem to be available at archive.org [0]) soon!

I'd like to point out another interesting 18-part series of videos about prototyping (in his words "a short course on how to build stuff" :)), by engineer/inventor/professor Dan Gelbart: [1]

[0] https://archive.org/details/GingeryMetalWorkingShop/mode/2up

[1] https://www.youtube.com/watch?v=xMP_AfiNlX4

treve6y ago

Do you have a link to one of those videos? Would love to see one. Also reminds me of Factorio

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