Parachute patterns

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Handeman

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I think that's a large part of my problem. The bottom edge of corrugated cardboard actually sticks out slightly, and the hot knife is welding the nylon to that edge.
I think the other issue is that unlike the hard board, the cardboard has fibers that stick out and end up inside the melted nylon and you actually have to break the fibers to get the nylon off. With the hardboard, it might stick, but it is just surface contact.
 

Dane Ronnow

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I would sand the edges to have a small radius
Using your idea, I beveled the edge of the cardboard with an X-Acto knife, then wrapped it in a 1-inch strip of aluminum foil, and it works great. The bevel moves the bottom edge of the cardboard almost an eighth of an inch away from the hot knife cut, and the foil keeps the edge from burning, so I can cut a little slower.

Anyway, your idea saved hot-knife cutting of gores for me. Thanks!

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Greg Furtman

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Using your idea, I beveled the edge of the cardboard with an X-Acto knife, then wrapped it in a 1-inch strip of aluminum foil, and it works great. The bevel moves the bottom edge of the cardboard almost an eighth of an inch away from the hot knife cut, and the foil keeps the edge from burning, so I can cut a little slower.

Anyway, your idea saved hot-knife cutting of gores for me. Thanks!

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You could probably also the aluminum tape they use to seal ductwork joints.
 
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