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Originally Posted by Tiabin
Were you the only guy that was experimenting with the fresnel lens originally? The thread was beefy, and it was hard to sort out useful content...
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GREENPOWERSCIENCE and myself were also experimenting with this. If you haven't been to
the GREEN POWER SCIENCE website yet, I recommend it! For my own experience, I bought some plumbing pipe, painted it black, and stuffed it with leaves and small twigs from my yard. I had a cap on one end and the other end open. The large lens I have (44" iirc) burnt the paint away and I was never able to achieve char, even though the metal was glowing orange (but only in about a 0.5" diameter area). I highly recommend reading the last 15 pages or so as that is where we start discussing different designs.
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I'm reading that the melting point of aluminum is 1200 degrees fahrenheit..... do you consider that a possible problem? I read that some of the big lens spots can get up to 2000 degrees.
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Ideally, you want to char below this temperature anyways. By unfocusing the beam slightly, you can lessen the heat dramatically.
