I need to make landing light lenses. They are installed in the leading edge, not the tip so not a complex curve. Wondering if I could just use a heat gun and the leading edge skin as a form instead of making a separate form.
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Forming Lexan
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The only thing I'd be worried about with a heat gun is localized heating causing uneven shrinking and goofing with your optics. Just speculating on my part, I think perhaps an oven would provide more even heat, and "melt" the glass over a form more evenly? I'm not so sure my wife would be too keen on my trying this in hers, though
Certainly can't hurt to try with a heat gun, though.Christopher Owens
Bearhawk 4-Place Scratch Built, Plans 991
Bearhawk Patrol Scratch Built, Plans P313
Germantown, Wisconsin, USA
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I think the wood stove idea is a good one. We experimented a bit with heat gun forming some scratch resistant coated lexan and it didn't work very good but I think you could do it with the stuff you'd use for a landing light lens.Scratch Built 4-place Bearhawk. Continental IO-360, 88" C203 McCauley prop.
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I have made very nice landing light covers using hardware store plexiglass type plastic. Make a leading edge shaped form using MDF and very thin plywood. Cut the clear plastic oversized since it will shrink when heated. Attaché it to the form with two sheet metal screws on either side of the leading edge to keep it in place as you go through the following. Place form/plastic in an oven and slowly heat until the plastic begins to sag over the form. Briefly remove and use a terry cloth towel to gently encourage the plastic to take the shape of the form. Continue heating/smoothing cycle until plastic has the desired shape. Let the plastic cool before removing from form. Cut to final size using a Drexel cutting disc.
Ray Strickland
Plans-built 4-place
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Rod,
I did the same thing with 1/8 plexiglas, I made a couple of nose ribs out of 3/4 plywood and fastened them to a 8 x 12 piece of plywood with some alum to form the shape of the leading edge. Put the whole thing in the oven with the plexi balanced on the leading edge and heated it up. Works like magic. I cut the ply nose ribs in about an eighth so the finished lens matched the wing.
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I made my lense much the way the others above did except I put two layers of T shirt between my form and the lexan to protect it from form damage. I soaked the lexan with the T shirt and form in the oven for an hour below the forming temperature to drive out moisture before bringing everything up to forming temperature and finishing the lenses.
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325 F for plexiglas, not sure about lexan. Good reference http://www.plexiglas.com/export/site...ing-manual.pdf
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350F-360F for Lexan (Polycarbonate), and sometime higher? https://www.tapplastics.com/uploads/...tion_Guide.pdf Page 8
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Thanks for the advice guys. I made the form like suggested and covered it with flannel. I made it a little small as the lexan was going on the inside of the nose skin. The lexan started drooping around 320 deg and formed easily at 350. Made 4 lenses so I would have a couple spares.
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