Steam Bending

But everyone likes steam bending—it's captivating to watch. I've seen hickory snow skis bent after a hot water bath, seen walking cane handles bent in tight circles after boiling in a metal drum. I've seen long, thick pine planking for ships pulled from a huge steam box and twisted and bent into place by six men, still steaming as they clamped it to the massive ribs. Even if it's just tiny strings of holly inlay curled around a hot brass rod, it always seems magical—when it works.

Bending wood works sort of like bending your arm. Muscles can only pull. They bend your arm by contracting on the inside of the bend. Keep that inside muscle contracted, and your arm stays bent. It's the same with steam bending wood. Heat softens wood fibers and the stuff that holds them together. Bend the wood while it is hot and the fibers inside the curve will compress. Keep the wood compressed until it hardens up again and it will stay compressed. It will hold the curve.

Or, it may break. When you bend wood, something has to give. All the wood is bending, but the convex face is under tension and the concave face is under compression. Either the inner face gets compressed or the outer face breaks apart. A metal compression strap helps wood stay intact for intense bends. With stops at each end spaced at the unbent length of the wood, they ensure that the bend is all compression, and no tension. Things like chair backs and hayforks with gentler bends can do fine without straps, as they have for centuries.

The initial moisture content of the wood influences the success of the bending. Green wood bends easily but springs back unless you let it dry thoroughly. Kiln-dried wood is already so compressed that it just snaps. If you want to bend

Boiling or steaming softens the wood so it can compress on the inside of the curve.
Once the bent wood piece is cooled and dry it will hold its new shape.

wood, choose air-dried stock with as much straight grain as possible. I would advise you to work only with riven out wood, but two of the best bending woods are unsplitable elm and sweet gum. The other good benders — ash, beech, birch, hackberry, hickory, maple, oak, and walnut—are best when riven, but can also be sawn from straight-grained, knot-free stock.

Steam gets the heat deep into the wood. The larger the piece, the more time it takes for the heat to soak in. The time required also depends on how hot your steam box gets. I use a teakettle on the woodstove connected by a short radiator hose to a double-walled pine box about four inches square inside and six feet long. The most cooperative wood needs an hour per inch of thickness, while resistant wood gets twice that.

Of course you can also bend in hot water, or just with raw heat. But steam keeps the wood from scorching, so even when dry bending thin wood on a heated pipe, some moisture on the wood helps.

The wood starts cooling and setting up right away, so you have to work fast. The wood will spring back to a certain degree, so your mold needs to be perhaps 10 percent tighter than the bend you want. The wood needs to stay in the jig for several days before you can tie it with string and take it out.

Lay out parallel pieces at one stroke.
Fit subsequent pieces into the spaces created by previous work.
Woodworking Tools and Installation Tips

Woodworking Tools and Installation Tips

There are a lot of things that either needs to be repaired, or put together when youre a homeowner. If youre a new homeowner, and have just gotten out of apartment style living, you might want to take this list with you to the hardware store. From remolding jobs to putting together furniture you can use these 5 power tools to get your stuff together. Dont forget too that youll need a few extra tools for other jobs around the house.

Get My Free Ebook

Post a comment