Random Destructive Acts via Focused Solar Radiation
bclee.net
bclee.net
It's almost like keeping some turpentine soaked rags in a cardboard box. Sort of kidding. The point is, you can have the lense somewhere you think is safe, but the angle of the sun changes throughout the year and one day six months later rays of light hit it. Or you have kids that don't think that way, and they leave it somewhere.
Even as a fully aware adult, it's counterintuitive, because you'll be trying to take it outside and accidentally burn yourself, or set it agains something while you're getting ready, not realizing the lens was born ready and doesn't care about your plans. You always have to carry them in a sheathing material. Your brain expects something like that to have an off switch.
They're cool, but you should probably keep them in an opaque sheath in a gun safe, and leave it alone when you're drinking.
> but the angle of the sun changes throughout the year and one day six months later rays of light hit it.
almost exactly word for word :)
http://www.theguardian.com/artanddesign/2013/sep/06/walkie-t...
"The developers have blamed the problem on "the current elevation of the sun in the sky," a position Viñoly seems inclined to share.
"When I first came to London years ago, it wasn't like this," he said. "Now you have all these sunny days. So you should blame this thing on global warming too, right?""
Yes, a children's book came with a Fresnel lens inside!
A kid detached his and brought it to summer camp, and after a few days, he was asked to leave it at home.
That's how we kill creativity and curiosity in people.
My goal was to build an aluminum can smelter. At the time I had this idea that I could crush a diet Dr. Pepper can with my hands (this I often do) and then slide it down into a crucible at the focal point of the lens, and have it melt and drip into a bucket of water below, creating aluminum bb's which would be much denser than even crushed cans. The problem however was that aluminum oxidizes before it melts, so in the ideal set up you really want it running in an oxygen free environment. Way more work than I wanted to invest.
Later I discovered induction heating (which you can do with a windmill, some magnets and a coil of wire around a piece of steel (or aluminum).
Did you watch those videos of guys melting aluminum in their backyards? :)
But watching folks melting alumninum is instructive.
(Haltec is gone now, but I seem to recall some serious lasers still available at Halted.)