This Old Tony...again!

[Vort]

Saw this new This Old Tony, and for some reason I thought others might enjoy it. You laugh as you watch it, and come away feeling maybe a little bit smarter than when you went in. It's one thing to understand how something works; it's another to actually realize it in metal. This way, you get to take the middle path and watch TOT realize it in metal.

https://www.youtube.com/watch?v=3_wPH904a_8

[NeuroTypical]

Now I want to watch the Engineer's Guide to Cats again.

[Jamie123]

Now this brings back some memories. I was an engineering apprentice back in the 1980s. Milling machines, arc welders, lathes, grinding machines - I made a pig's ear out of trying to use them all! Fun stuff!

P.S. The device used to switch off-and-on machine tools was a source of fascination to me. You press a green button to start, and then press a much larger red button to stop. The start button has to be pressed quite firmly and slowly and deliberately, otherwise the machine may not stay on when the button is released. However, the red off button only needs to be nudged to make the machine stop and not turn back on again!

I eventually learned the secret behind the mechanism: the on button causes current to flow in a solenoid, which moves an actuator which pushes another separate "on" button. Once pressed, that second button carries the current to the machine, and also to the solenoid causing the button to stay pressed - even when the original on button is unpressed. And that's why its important to hold the button in a bit - you need to give the actuator time to settle itself properly into place. But once it is....

WOOOO HOOO!!!

....It's like it's holding itself up by pulling on its own bootstraps! I say the genius who invented that deserves a medal!

It's no cleverer, perhaps, than the silicon controlled rectifier, or the bistable flip-flop (which are basically the same only made out of solid state components) but those are works of genius too! Perhaps you disagree with me (I know one guy who did). But if so, would you have thought of the idea yourself unaided? Would you have thought of upstairs-and-downstairs light switches, or the cat flap, or the latch (like in this video), or the full-wave rectifier, or the fold-up umbrella, or the...the list goes on? (They say that Isaac Newton invented the cat flap, but its not what he was knighted for!)

So what about the off button? Well, that immediately cuts off the current, causing the solenoid to release the actuator, so that even when the off button is released the machine stays off. The only way of starting it is to press the on button again.

So I say three cheers for the clever chap (or chapess) who invented the electric-lathe-or-milling-machine-solenoid-switchy-onny-offy-thing! Hip hip...

Edited July 19, 2020 by Jamie123

[Plein Air]

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Edited August 2, 2020 by Plein Air

[Jamie123]

And speaking of solenoids, here's something I never imagined I'd ever see: a "V12 solonoid engine"!