So I'm building a solar oven of a sort.

[Echo2]

....and I'm using the biggest free Fresnel lens I could find.....



I know it will ignite a picnic table almost instantly...

I'm building a aluminum frame and stand. It will be able to turn 360 degrees and tilt 180.....the tilt axis will be just under the focal point.

The focal point will fire upon table in the center of both axis....

The question...What do I put in the middle of the focal point?...a dutch oven on a turn table?....a block of iron about 1" thick and the size of a burner?

Should I completely enclose the sub framing in plexiglass?

suggestions are appreciated....

BTW.....if you have an old rear projection TV that stops working....rip the front off.....there should be 2 screens...the front is a linear diffuser....and right behind that is a Fresnel Lens.....as big as the TV picture....

[Sniper-T]

Are you talking about a standard CRT screen tv?

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With a mirror, or series of mirrors could you direct the magnified beam where you wanted it? ie, instead of burning your own picnic table, torch the neighbours? or one down the street? If so, this could have some defensive and offensive possibilities in addition to the nanosecond toasted marshmellows

[Marthony]

I learned that plexiglass won't hold up to upper temperatures. =) I'd recommend looking into either Lexan or tempered glass if it will be exposed to heat and transparency is desired.

I'd love to see a build for a focussed solar heat beam. =) You'd need to be able to adjust the shape of the lens to change the range. Picture: adjustable metal colander like this: http://www.google.com/patents/USD316505.

[Echo2]

not for center under the focal point.....it would incinerate.

[Evolver]

We have a Sunoven...


And I'm thinking you could replicate the insulated box and point the lens in it to make a true oven.

The inner box is aluminum painted black the outer box is plastic and you could line the interstitial space with some type fiberglass insulation. The lid is 1/8 glass and I'm pretty sure it's not even tempered.