Tips for building with wood.

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Tiger Tim

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My bottom longeron has a compound curve. How would you laminate that? Out of a bunch of 1/4x1/4 strips?

When you consider that, steam bending looks better, doesn't it?
I dunno, does it? I was involved with trying to steam bend some ash in about the dimensions you're working with (E-2 Cub wing tips) and the steam box came up short. In the end we wrapped it with wet rags and poured boiling water over it as we slowly drew in the clamps against the form. On the other hand, I do know of some wing tips that have been made with about 1" x 1/8" strips that have curved two ways at once.

I guess the real question is what did the other J-1 builders do?
 

pictsidhe

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Steam bending wood at 400 degrees would require a high-pressure enclosed steam system. The only way you can get steam that hot is to increase the pressure significantly over ambient. Not something I would want in my garage.

"Normal" low pressure steam can not be over 212 degrees---that's basic physics.
Wet steam only to 212 at 1atm, dry steam, whatever you want. Well, until it dissociates at some thousands of degrees. Boil the water then superheat the steam.
 

Aerowerx

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I dunno, does it? I was involved with trying to steam bend some ash in about the dimensions you're working with (E-2 Cub wing tips) and the steam box came up short. In the end we wrapped it with wet rags and poured boiling water over it as we slowly drew in the clamps against the form. On the other hand, I do know of some wing tips that have been made with about 1" x 1/8" strips that have curved two ways at once.
Ok, if you have nice straight vertical grain it is easier to bend in one direction than the other, since wood is not anisotropic. The wood will want to twist to relieve the stress, which was the problem I was having on my previous attempt. Steam bending will soften the wood in both directions. There may still be some twist, but it should be insignificant (I am getting less than 6 degrees of twist dry bending my test piece), and what twist remains can be removed by torquing the wood in the proper direction while it dries.

I don't know for sure what a E-2 cub wing tip looks like, but the bends I need are a lot larger radius than a typical wing tip.

From what I have been reading, there are 3 main reasons why steam bending fails: 1. grain run-out---the wood breaks, 2. inadequate steaming---you need 1 hour of steaming for each inch of thickness, 3. being impatient.

1 inch by 1/8 inch?? How was it bent across the 1 inch direction? And what do you mean by "curved two ways at once"?
 

Aerowerx

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Wet steam only to 212 at 1atm, dry steam, whatever you want. Well, until it dissociates at some thousands of degrees. Boil the water then superheat the steam.
Not sure I understand your point. And, sorry, but I don't care to mess with high pressure super heated steam.
 
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