Bending wood is most easily done when the wood is first cut since it already has a lot of moisture in its fibres.
To ensure that the wood fibers already have a high moisture content, it is best to harvest the tree during the growing, or full moon.
This way, nature is working with you, instead of againt you. The wood should be bent as soon as possible after the tree is harvested, since it will naturally dry out on its own.
If you will be bending planks or timber, the tree should be milled right away. It is still best to quartersaw the wood as explained in the previous article, since it helps to maintain the stability of the wood after it is dried.
To bend wood, you must first force moisture into the wood fibers using steam. This additional moisture makes the wood very plyable and it can then be bent into any shape you like.
A steaming box is most often used to bend wood. It consists of a sealed box in which to place the wood and introduce the steam.
A small hole is drilled into the bottom of this box to allow the water to escape, as well as to release some of the pressure from the steam. If the pressure is not released, the box could explode, causing serious damage.
A source of heat is then used to boil the water. The steam from the water is then collected in a pipe and travels to the box where it comes into contact with the wood.
This steam eventually forces the moisture into the wood fibres and makes it possible to bend the wood. The amount of time this will take varies, depending on the system you have set up and the size of the wood you are bending.
Wood can also be placed into a pipe in order to steam. In the past, I have used a drive shaft off of a pick-up truck with one end sawed off.
The sealed end was placed into a fire pitt and placed on about a 45 degree angle and filled with water. The heat from the fire boiled the water and the wood, to be steamed, was placed into the pipe.
A rag was placed over the open end to help hold in the steam. Using this method, I have steamed 4 foot pieces of birch into complete circles. This was used in the building of traditional Mi'kmaq drums. I have also used this method to bend birch into ski runners for dog sleds.
Once the wood is bent, the next step is to place it into a mold. The mold is a piece of wood, or other material, cut into the shape in which you wish to bend the wood.
The wood is then held to this mold using clamps or pegs. The older generation often used peg boards in order to turn birch for making snowshoes. I use a combination of pegs and clamps when putting pieces into molds, since both methods have their good and bad points.
I find that pegs work more quickly to secure pieces, but they are not as good for drawing a piece of wood tight to the mold. Since the steam leaves the wood rapidly, once it is taken out of the steam box, or pipe, it is important to get the wood onto the mold as quickly as possible.
Once the piece is inside, or placed around, the mold, I tighten and secure it using clamps. This takes time, but holds much stronger. Sometimes it is easier to have an extra pair of hands to help out.
After steaming and bending the wood, and securing it to the mould for your desired shape, the wood must be dried thouroughly to ensure the shape is maintained.
The wood must remain in the mold and force dried to ensure it is brought to a reasonable level of moisture before being used in any construction project. I use my kelm drier to ensure that the wood has no more than 8% moisture.
This is shown with a moisture meter, which is pronged into the wood, and gives you a reading. There must be no question of the level of moisture left in your piece of wood.
If you don't have your own kelm, the mold and its piece of wood can be placed alongside a wood stove or any source of heat. The wood can be taken out of the mold after it is dried enough to retain its new shape.