Building techniques

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Re: Building techniques

Post by jander14indoor » April 1st, 2011, 9:14 am

Most curved balsa ribs are sliced using a pattern. Don't remember if we covered it this year for helicopter, but its been covered in the past for Wright Stuff, check the archives.

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Re: Building techniques

Post by thewinner » April 1st, 2011, 12:22 pm

Another way to curve balsa is to soak the balsa and curve it around a form block (a curved surface, you can carve your own out of wood or just use a flowerpot or something), then secure the balsa and blow dry it. Watch out for springback, though.
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Re: Building techniques

Post by lllazar » April 1st, 2011, 4:13 pm

I typically use my large can of water (it has a bit larger diameter than a 2 liter coke can) and soak the wood, bending it around it, and using tape to secure it while blow drying. Typically if you let it dry enough, there should be very little spring back.
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Re: Building techniques

Post by chalker7 » April 1st, 2011, 4:47 pm

Slicing curved wood off of sheet wood with a template is far quicker process. It's also more stable and precise since there is no dependence on moisture/drying. I would highly recommend hunting through the archives to find the process described in more detail.
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Re: Building techniques

Post by illusionist » April 1st, 2011, 6:54 pm

I use a stove top pressure cooker in which I heat up the wood. It kinda curves around the interior, and if it doesn't, i'll press it down with some clamps.
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Re: Building techniques

Post by chia » April 1st, 2011, 9:42 pm

I'm surprised so many people bend their wood. I haven't made any curved ribs for helicopter yet, but I would always cut my ribs for Wright Stuff. Like chalker said, it's faster and there's less variation between individual ribs.
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Re: Building techniques

Post by illusionist » April 2nd, 2011, 6:59 am

I actually don't use curved ribs that much, but that's the method I prefer. I haven't tried the other ones, but it seems kinda hard to cut balsa in a curve using a razor blade...
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Re: Building techniques

Post by chia » April 2nd, 2011, 7:17 am

It was a little hard to find really good wood for cutting ribs. It has to be softer than the stuff you'd use for spars and such, and have a shorter grain.
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Re: Building techniques

Post by thewinner » April 2nd, 2011, 9:30 am

Yeah, I tried cutting ribs once and they just ended up splitting along the grain. :( So now I just use a form block.
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Re: Building techniques

Post by kjhsscioly » April 2nd, 2011, 9:42 am

I used an online airfoil template to make plastic guides, and the wood doesn't split as much if you use lighter colored pieces, because they have less grain. Sharp blades help quite a bit, so you cut the wood instead of splitting it.

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