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Reply by runswithscissors

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Posted on bent wood rings - how do you get bent?

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runswithscissors

2843 posts in 2168 days


#1 posted 11-26-2012 06:42 AM

I first stumbled onto bending wood with heat (but no water or steam) about 20 years ago. Eventually, I wrote an article on it for WoodenBoat magazine. Don’t have the date at my fingertips, but can look it up for anyone interested. The point is, it’s the heat that does the bending, not the moisture. Steam, or boiling, is just a way to get the heat into the wood. When I’m bending thicker wood, I always use a bending strap (steel binding strap from the lumber yard dumpster works great), as this forces the bend into the inside fibers of the curve. The outer fibers don’t want to stretch, so they’ll tear and the wood will break. Looks like the wood you’re bending (oak?) is quite thin, and a heat gun should heat that through very quickly. It’s easy to burn the wood, though. I have an old infra-red propane paint stripper that I bought years ago (and I’ve never seen another like it), that works beautifully, with little risk of burning the wood. It’s my favorite bending tool, but I do use the heat gun sometimes. The curious thing about it is that once the wood has cooled (and this would take only a minute with your thin strips), the bend is set; to unbend it (and I have occasionally over bent a piece), you have to heat it again to make the wood relax. The advantage of doing it sans moisture is you don’t have to wait for drying to proceed with your project, and there are no raised fibers to sand off.
By the way, there was an article in FWW 2 or 3 years ago by a guy using a technique similar to yours, but he was heating the pipe bending form by shooting a propane flame into it from the open end. Looked scary. I’d sure wear heavy leather gloves working that way. I tried many species (researching for the WB article) and found that the usual suspects are best—white oak and ash. Red oak works fine too, as well as black locust. Doug fir and luan don’t work at all. Here in the rainy PNW, we don’t have access to some of your good bending woods in the east, which to me are legendary. I read somewhere recently that Alaskan yellow cedar doesn’t heat bend, but I’ve seen enough bentwood boxes made by NW coastal tribes to know that isn’t true.
It’s even possible to bend plywood this way. If you laminate 2 pieces of ply that have been pre bent to the same shape and allowed to cool, the resulting piece will be astonishingly rigid.

-- I admit to being an adrenaline junky; fortunately, I'm very easily frightened


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