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pipersmitty87 (November 30, 1999 at 12:00 am)
any idea on how to cook down a larger plexiglass mirror on a larger parabolic circle? like 36"
GREENPOWERSCIENCE (November 30, 1999 at 12:00 am)
Yes, the temperature is enough to melt very small amounts of aluminum but not a can as it acts as a giant heat sink and is shiny. You can get 1 pound of aluminum up to 475 with the 38" spot lens. This will save you some heat. Do it in a crucible and you can get 3 pounds to 300 F or 1 pound to 700f.
Use your furnace to finish the job. Make sure it is tightly compacted or the lens will just burn the can vs heating it.
fly2000jtb (November 30, 1999 at 12:00 am)
I have a home built furnace, could the fresnel lens (38") that you have on ebay, be used to premelt aluminium cans? It did a number on a steel washer. Just tring to save money and, cut down CO2 from charcoal that heats my furnace.
kurwinsky (November 30, 1999 at 12:00 am)
I'll recommend to use security glasses for cutting Plexiglas.
GREENPOWERSCIENCE (November 30, 1999 at 12:00 am)
They all produce the same results but the mirror is reflective. A Fresnel lens is basically a magnifying glass flattened. The rings are cut at different angles to redirect light to a focal point.
RetroTheory (November 30, 1999 at 12:00 am)
What are the different results you can get from a Parabolic Mirror than you can get from using a magnifying glass? Are Fresnel lenses the same as a magnifying glass in general?
GREENPOWERSCIENCE (November 30, 1999 at 12:00 am)
:-)
theunknownknows (November 30, 1999 at 12:00 am)
I have the same model oven. I only make chicken and meatloaf with mine, though.lol
luvofcountry (November 30, 1999 at 12:00 am)
I don't think my last post got printed because I included a web link...
For those without access to table saws, McMaster-Carr (mcmaster "dot-com") has acrylic and plastic mirror disks in several thicknesses in up to 12" widths for $25.
Good luck to all.
luvofcountry (November 30, 1999 at 12:00 am)
The mold could then be used to make several accurate mirrors, using your technique. While probably not of the highest optical quality for telescopes, they would be very suitable for solar energy production. When I get some extra money (LOL), I plan to build a spin-mold. Would be nice if a mold 3+ feet in diameter could be spun! |